INCORPORATING ELECTRONICS MONTHLY FULLY S.O.R. £2.15 ...
EPE-1995-01 INCORPORATING ELECTRONICS MONTHLY
FULLY S.O.R. £2.15
MAGNETIC FIELD DETECTOR Check your exposure, to mair^
MODEL RAILWAY
from model tracks Vja®
METRONOME Electronic simulation of the original
f j T ) " H
BEATING THE
^
CHRISTMAS
3
^
LIGHTS Keeping the tree lights working
48 Page DISPLAY NEWS
PLt/S INGENUITY UNLIMITED Readers'Circuit Ideas
THE No. 1 INDEPENDENT MAGAZINE for ELECTRONICS, TECHNOLOGY and COMPUTER PROJECTS
PC PAL VGA TO TV CONVERTER Converts a colour TV into
a basic VGA screen Complete with built in psu. lead and s/ware
£49 95 Ideal for laptops or a cheap upgrade
EMERGENCY LIGHTING UNIT Complete unit with 2 double
bulb floodlights, built in charger and auto switch Fully cased 6v 8AH
lead acid req'd (secondhand) £4 ref MAG4P11
GUIDED MISSILE WIRE. 4,200 metre reel of ultra thin 4 core
insulated cable. 28lbs breaking strain, less than 1mm thick* Ideal
alarms, intercoms. Ashing, dolls house's etc. £14 99 ref MAG15P5
SINCLAIR C6 13" WHEELS Complete with centre bearing
(cydetype), tyre and inner tube £6 ea ref MAG 6P10 Ideal go kart
300v PANELMETER 70X60X50MM. AC. 90 degree scale Good
quality meter £5 99 ref MAG 6P14 Ideal for monitoring mains etc
ASTEC SWITCHED MODE PSU BM41012 Gives +5 © 3 75A.
+12©1 5A.-12(5 4A 230/110. cased, BM41012. £5.99refAUG6P3
TORRODIAL TX 30-0-30 480VA, Perfect for Mosfet amplifiers
etc 120mm dia 55mm thick £18.99 ref APR19.
AUTO SUNCHARGER 155x300mm solar panel with diode and
3metreleadfittedwithadgarplug 12v2watt £9 99ea refAUG10P3
FLOPPY DISCS DSDD Top quality 5.25' discs, these have been
written to once and are unused Pack of 20 Is £4 ref AUG4P1
MOD WIRE Perfect for repairing PCB's, wire wrap etc Thin
insulated wire on 500m reels Our price just £9.99 ref APR 10PS.
12v MOVING LIGHT Controller MadebyHella, 6 channels rated
at 9C^atts each Speed control, cased £34 99 ref APR35
ECLATRON FLASH TUBE As used in police car flashing lights
etc. full spec supplied, 60-100 flashes a min £9.99 ref APR10P5.
24v AC 96WATT Cased power supply New £13.99 ref APR14
MILFTARY SPEC GEIGER COUNTERS Unused and straight
from Her majesty's forces £50 ref MAG 50P3
STETHOSCOPE Fully functioning stethoscope. Ideal for listening
to hearts, pipes, motors etc £6 ref MAR6P6
OUTDOOR SOLAR PATH LIGHT Captures sunlight during
the day and automatically switches on a built in lamp at dusk.
Complete with scales lead add battery etc £19 99 ref MAR20P1
ALARM VERSION Ofabove unit comeswithbuiltin alarm and pir
to deter intruders Good value at just £24 99 ref MAR25P4
CLOCKMAKER KIT Hours of fun making your own clock, com-
plete instructions and everything you need £7 99 ref MAR8P2
CARETAKER VOLUMETRIC Alarm, will coverthewhole of the
ground floor against forcred entry Includes mains power supply and
integral battery backup Powerful internal sounder, will take external
bell if req'd. Retail £15(H. ours? £49 99 ref MAR50P1
TELEPHONE CABLE White 6 core 1C0m reel complete with a
pack of 100 dips. Ideal 'phone extns etc. £7 99 ref MAR8P3
IBM PC CASE AND PSU deal base for building your cwn PC
Ex equipment but OK. £9 99 each REF: JUN10P2.
MICRODRIVE STRIPPER Small cased tape drives ideal for
stripping, lots useful goodies induding a smart case, and lots of
components £2 each ref JUN2P3.
SOLAR POWER LABSPECIALYou getTWO6'x6'Bv 130mA
solarcells.4 LED's. wire, buzzer, switchplus 1 relayormotor.Superb
value kit just £5 99 REF MAG6P8
SOLID STATE RELAYS Will switch 25A mains. Input 3.5-26v
DC 57x43x21mm with terminal screws £3.99 REF MAG4P10
300 DP IA4 DTP MONITORBrand new but shop sd led so hence
bargain price'TTUECL inputs. 15* landscape, 1200x1664 pixel
JcUomSTpl£et1e4w.9i9th cRiErcFuiJtUdNia1g5tPo2help you interface with your projects
MU LTICORE CABLE 300 metre red of grey 8 core cable ideal
fsopred'pahldoinspeesn, siinntgerccoonmtaminse,r tcooamvpoiudtetarsn,glaelsar£m1s5 reetfcAUCGo1m5.es in
BUGGING TAPE RECORDER Small voice activated recorder,
usesmicro cassette complete with headphones £28 99 ref MAR29P1
ULTRAMINI BUGMC6mmx3 5mmmadebyAKG, 5-12velectret
condenser Cost £12 ea. Our? four for £9.99 REF MAG10P2.
RGB/CGA/EGA/TTL COLOUR MONrTORS 12* in good
condition Back anodised metal case. £79 each REF JUN79
GX4000 GAMES MACHINES eturns so ok for spares or repair
£9 each (no games) REF MAG9P1
C64 COMPUTERS Returns, so ok for spares etc £9 ref MAG9P2
FUSELAGE LIGHTS 3 foot by 4* panel 1/8" thick with 3 panels
that glow green when a voltage is applied Good for night lights.front
panels, signs.disco etc. 50-100v per strip. £25 ref MAG25P2
ANSWER PHONES 1 fault, you have to find
tRheetuortnhsewr yitohu2rsfealufltsB,TwReegsivpeoynoseut2h0e0b,sits£f1o8r
ea REF MAG18P1. PSU £5 ref MAG5P12
SWITCHED MODE PSU ex equp. 60w +&/ e5A, -5vQ 5A.
+12v@2A.-12v@ 5A 120/220v cased 245x88x55mm lECinput
socket £6.99 REF MAG7P1
PLUG IN PSU 9V 200mA DC £2.99 each REF MAG3P9
PLUG IN ACORN PSU 19vAC 14w .£2 99REF MAG3P10
POWER SUPPLY fully cased with mains and o/p leads 17v DC
900mA output Bargain price £5 99 ref MAG6P9
ACORN ARCHMEDES PSU +5v@ 4.4A on/off sw uncased,
selectable mains input. 145x100x46mm £7 REF MAG7P2
GEIGER COUNTER KIT Low cost professional twin tube, com-
plete with PCB and components Now only £19 REF AUG19.
9v DC POWER SUPPLY Standard plug in type 150ma 9v DC
with lead and DC power plug, price for two is £2.99 ref AUG3P4.
AA NICAD PACK encapsulated pack of 8 AA nicad batteries
(tagged) ex equip. 55x32x32mm. £3 a pack REF MAG3P11
13.8V 1.9A psu cased with leads Just £9 99 REF MAG10P3
360K 6.26 brand new half height floppy drives IBMcompatible
industry standard. Just £6 99 REF MAG7P3
PPC MODEM CARDS These are high"spec plug in cards made
for the Amstrad laptop computers 2400 baud dial up unit complete
with leads Clearance price is £5 REF: MAG5P1
INFRA RED REMOTE CONTROLLERS Originally made for
hi spec satellite equipment but perfect for all sorts of remote control
projects. Our clearance price is just £2 REF: MAG2
TOWERS INTERNATIONALTRANSISTORGU IDE. A very
useful book for finding equivalent transistors, leadouts, specs etc
£20 REF; MAG20P1
SINCLAIR C6 MOTORS We have a few left without gearboxes
NEW BULL ELECTRONICS STORE IN
WOLVERHAMPTON
SSA WORCESTER ST TEL 0902 22039
Spec is12v DC 3,300rpm £25 ret MAG25. NEW PRODUCT
200 WATT IN VERTER Converts 10-15v DC into either 110v or 240v AC. Fully cased 115x36x 156mm, complete with heavy duty power lead, cigar plug, AC outlet socket.Auto overload shutdown, auto short circuit shut down, a uto input over voltage shutdown, auto input under voltage shutdown (with audible alarm), auto tempcontrol, unitshuts down ifoverheated and sounds audible alarm. Fused reversed polarity protected, output frequency within 2%, voltage within 10%. A extremely well built unit at a very advantageous price!!!Price is £64.99 ref AUG65.
UNIVERSAL SPEED CONTROLLER KIT Designed by us for tehtce CA5hmeoattosrinbkutmokayfobreanreyqu1i2revdmo£t1o7ru0p0toR3E0FA: .MCAomG1p7letewith PCB MAINSCABLE Precut black 2 core 2 metre lengths ideal for repairs, projects etc. 50 metres for £1 99 ref AUG2P7. oCabfneO6dtwMcaeolelPrneUcPcoTCanbEn'sleRoec,vtCeo1r0rOas0lMoecntaMcgbdlUeIisdNdteaiIapnClscA.leo2TwClIioOncmeoNsdpStrleimvPteeeAkrtsihCtw£oK1dit5hoK9Rfi9tSccRo2om3enf2tmMaiiunAnntsReicr11fa60atic0Pnem2gs
M IN I CYCLOPS PIR 52x62x40mm runs on PP3 battery complete
with shrill sounder Cheap protection at only £5.99 ref MAR6P4.
ELECTRIC MOTOR KIT Comprehensive educational kit in-
cludes all you need to build an electnc motor £9 99 ref MAR10P4
VIDEO SENDER UNFT. Transmits both audio and video signals
faDrnoCymospetaitnPhdreiarcredaiTsvV£id1se5eotRicnEaaFm:1eM0ra0A,'rGvai1nd5geeo1l2r(vetucponsreudTeisVr,£tT5oVeaxostprraaCrRoeEmcFhp:aunMtenAreleG)t5c1P2to2v
*FM CORDLESS MICROPHONE Small hand held unit with a
500' rangel 2 transmit power levels Reqs PP3 9v battery Tuneable
to any FM receiver Price is £15 REF: MAG15P1
wLiOthWa rCanOgSeTofWabAouLtK20IE0' TIAdeLalKfoIEr gSarPdaeinr oufsbeaottrearys aonpeerdautceadtiuonniatsl
toy Price is £8 a pair REF: MAG 8P1 2 x PP3 req'd
'MINATURE RADIO TRANSCEIVERS Apairofwalkietalkies
w22itxh5a2xr1a5n5gmemof uCpomtop2lekteilwomithetrceassiensoapnednecaorupnietrcye.s.U2nxitPs Pm3earesqurde
£30 00 par REF: MAG30 .
CraOteMHPsyOnSc.ITVEsyVncID, aEnOd vKidfTeo..C1o2nvvDerCts. c£o8m0p0oRsiEteFv: iMdeAoGin8tPo2sepa-
LQ3600 PRINTER ASSEMBLIES Made by Amstrad they are
emnotitroersmetecchetacnIincaflacptreinvteerrytahsisnegmbbalritehseicnacsluedainngd eplreincttrhoenaidc,s,sategpopoedr
stripperl £5 REF; MAG5P3 or 2 for £8 REF: MAG8P3
SPEAKER WIRE Brown 2 core 100 foot hank £2 REF MAG2P1
LED PACK of 100 standard red 5m leds £5 REF MAG5P4
UNIVERSAL PC POWER SUPPLY complete with flyleads,
s(F2w3Mixtc2hT3,xRf2aA3nmNemStc)MaTnnwTdoE2tR0y0pwheosauatsve£ad2i0lianbRalEesFta1:n5Md0waArGda2tw0£oP1r3k5i(n2Rg3E1xF32A3Mxa2Ad3aGmp1tme5rP)*2i
tphFreiMcbeuigBs £Uru2Gn6sRdKEirfFeTc:tMlNyAeowGff2tdh6eesTmirgaanninswmsistihtos
ltaosatsnfyorFeMverr*adwiohy pay PCB embedded coil
£700? or for extra
stoFtadMbieltiBetycU.tiWGveoBrakgUseItnLocTaienAsyNF9MvDbTraaEtdtiSeorTy9ErveDqbsa'duttpe£re1yn4oreRrqdE'deF.s:i£gM5nAtRoGEk1Fi4t;
MAG5P5 Supplied
TALKING COIN BOX STRIPPER originally made to retail at£79
each, these units are designed to convert and ordinary phone into a
payphone The units have the locks missing and sometimes broken
hinges However they can be adapted for their onginal use or used for
something else?' Price is just £3 REF: MAG3P1
100 WATT MOSFET PAIR Same spec as 2SK343 and 2SJ413
(8A. 140v,10C*¥) 1 N channel, 1 P channel. £3 a pair REF; MA63P2
TOP QUALITY SPEAKERS MadeforHIFItelevisionstheseare
10 watt 4R Jap made 4" round with large shielded magnets Good
quality £2 each REF; MAG2P4 or 4 for £6 REF; MAG6P2
TWEETERS 2* diameter good quality tweeter 140R (ok with the
above speaker) 2 for £2 REF: MAG2P5 or 4 for £3 REF; MAG3P4
AT KEYBOARDS Made by Apncot these quality keyboards need
jtuosptuatsumpalwlimthod1 toorr2unfoorneiagnnykAeTy,ctahpesy! wPorirckep£e6rfeRcEtlFy:buMtAyoGu6wPi3ll have
PC CASES Again mixed types so you take a chance next one off the
pile £12 REF:MAG12 or two the same for £20 REF: MAG20P4
HEADPHONESExVirginAtlantic 8pairsfor£2 REF:MAG2P8
PROXMrTY SENSORS These are small PCB's with what look
like a source and sensor LED on one end and lots of components on
t3hPe5reosrto2f0thfoerP£C8B RCEoFm; pMleAteGw8iPth4flyleads Pack of5£3 REF: MAG:
·SOME OF OUR PRODUCTS MAY BE UNLICENSABLE IN THE UK
SNOOPERS EAR? Original made to clip over the earpiece of treulnenpihngonaelotnogamthpeliwfyaltlh! ePsriocuenids-£it5alRsEoFw;oMrkAsGq5uPit7e well on the cable DOS PACKS Microsoft version 3.3 or higher complete with all mcoamnpuraelsheonrsipvreicemajunsuta£l!55R.2E5F':onMlyAG5P8 Worth it just for the very DOS PACK MicrosoftversionSOnginal software but no manuals hence only £3 REF. MAG3P6 5.25" only PIR DETECTOR Made by famous UK alarm manufacturer these are hi spec, long range internal units 12v operation Slight marks on case and unboxed (although brand new) £8 REF: MAG8P5 WINDUP SOLAR POWERED RADIO AM/FM radio complete with hand charger and solar panel! £14 REF: MAG14P1 MOBILE CAR PHON E£6.99 Well almost' completein earphone emxacdluedtiongiltlhume binoaxteowf eitlhec1tr2ovnaiclssonohramsablluyilthiinddleignhtunsednesrosreasto Cdiasnplbaye only illuminates when dark Tc<ally convincing! REF MAG6P6 AbeLllAbRoxMbButEcAouCldONbeS uZseendonfosrtrcoabraevmanadseettoc.m1o2uvntoopneraantioenx.teJrnuaslt connect up and It flashes regularly) £5 REF MAG5P11 FIRE ALARM CONTROL PANEL High quality metal cased alarm panel 350x165x80mm With key Comes with electronics but no information sale price 7.99 REF MAG8P6 REMOTE CONTROL PCB Thesearereceiverboardsfor garage door opening systems Another use? £4 ea REF: MAG4P5 r13x0miArBAargMaiOn RprPicHeOjuUstS£5S9O9 LeaARREFPMANAGE6LP1122v 155x310mm FIBRE OPTIC CABLE BUMPER PACK 10 metres for £4 99 ref MAG5P13 ideal for expenmenters' 30 m for £12.99 ref MAG13P1 LOPTX Line outputtransformers believed to beforlBM hi res colour mREoFn:itoMrsAbGu2tPu1s2efbuulmfopregrepttaincgk hoifg1h0vfoolrta£g1e2sRfrEomF: lMowAoGn1e2sP!3£.2 each H EATSIN KS (finned) T0220. designed to mount vertically on a peb 50x40x25mm you can have a pack of 4 for £1 ref JUN1P11 WATERPROOF JUNCTION BOX 65mmdia 33mm deep Four cable entry exit points (adjustable for any size cable) snap fit lid. Ideal for TV. satellite use. £2 ea ref APR2 or6 for£10 ref APR10P7
BOTH SHOPS OPEN 9-5.30
SIX DAYS A WEEK
INFRARED LASER NIGHT SCOPES Second generation image intensifier complete with hand grip attachment with built in adjustable laser lamp for zero light conditions. Supplied with Pentax 42mm camera mount and normal eye piece. 1.6kg, uses lxPP3,3xAA's (all supplied )£245+Vat NEW HIGH PO^ER LASERS 15mW, Helium neon, 3 switchable wavelengths .63um,1.15um,3.39um (2 ofthem are infrared) 500:1 polarizer built in so good for holography. Supplied complete with mains power supply.790x65mm. Use with EXTREME CAUTION AND UNDER QUALIFIED GUIDANCE. £349+Vat. £££££££WE BUY SURPLUS STOCK££f££f£
TURN YOUR SURPLUS STOCK INTO CASH. IMMEDIATE SETTLEMENT WE WILL ALSO QUOTE FOR
COMPLETE FACTORY CLEARANCE
1994 CATALOGUE ODNTMUIAOUNITNYTRIIVIEIMSCCSEUOERRHMNSIIOGIDGTGHRfHITOETDEISOSREO.D&RRNTSESSLHSOSAOOECUNFRRABDTSVLJAHEEEALROCDUEST£TTAE5HOTN0OOSCD0TRSHAUITTTATNORINEELACDGSEDKEVSES\PQOORLUTCIROCHODTEEMEASRRET&WSIOASIFLSNPRELESOGCSWMIOTFLOAIGCLTDOANESVDTGSIELGUORYUPNNPAGSMLRIWIVEAENIENOTNTTHS.EFOUSEOUBCDRTJHEFQPOCOUROTRAOLTN3SOP0-.
3FT XI FT 10WATT SOLAR PANELS 14.5v/700mA £33.95
(PLUS 52.00 SPECIAL PACKAGING CHARGE) TTIOMPELQEUSSALLIITFYESPAAMNOWRIPTHHOAUNS ISNIFLINICITOENNUCEMLBLESRHOAFVEPOASSLIMBLOESTAPA PINLGIC,AFTOIORNUS,SESOOMNE BOOFAWTSHIOCRH CMAARYABVEACNASR, OBRATTAENRYYWCHHEARREGAPORTABLE 12V SUPPLY IS REQUIRED. REF: MAG34
PORTABLE RADIATION DETECTOR
BULL ELECTRICAL 250 PORTLAND ROAD HOVE SUSSEX BN3 5QT
MAIL ORDER TERMS: CASH PO OR CHEQUE WITH ORDER PLUS £3.00 POST PLUS VAT.
PLEASE ALLOW 7 -10 DAYS FOR DELIVERY B TELEPHONE ORDERS WELCOME MHI
TEL: 0273 203500 IvST FAX: 0273 323077 I J
£49.99
A Hand held personal Gamma and X Ray defector. This unit contains two Geiger Tubes, has a 4 digit LCD display with a Piezo speaker, giving an audio visual indication. The unit defects high energy electromagnetic quanta with an energy from 30K eV to over 1,2M eV and a measuring range of 5-9999 UR/h or 10-99990 Nr/h. Supplied complete with nandbook.Ref MAG50.
ISSN 0262 3617 PROJECTS . . . THEORY . . . NEWS . . . COMMENT . . . POPULAR FEATURES . . . VOL. 24 No. 1 JANUARY 1995
EVERYDAY I WITH PRACTICAL
--
ELECTRONICS INCORPORATING ELECTRONICS MONTHLY
The No. 1 Independent Magazine for Electronics, Technology and Computer Projects
- f nr. 3
·« fI -«~*»«
Project/
MAGNETIC FIELD DETECTOR by Andy Flind
14
Check your exposure to mains generated fields with this handheld detector
MOVING DISPLAY METRONOME by Carol Jackson
18
Mimics the traditional timekeeper by using l.e.d.s and a piezo sounder
MODEL RAILWAY TRACK CLEANER by Robert Penfold
28
Keeping your rolling-stock on the move with this dirt zapper!
BEATING THE CHRISTMAS LIGHTS by T S Christian
32
Prolong the spirit of Christmas
ERE FRUIT MACHINE - 2 by Brett Gossage and Julyan llett
45
Microcontroller design that really has a jackpot!
VIDEO MODULES-3 by Robert Penfold
66
Dynamic Noise Limiter and System Mains Power Supply - concluding modules
Sen'e/
INGENUITY UNLIMITED by Enthusiastic Readers
26
The circuit showcase for readers' designs
INTERFACE by Robert Penfold
34
The page for computer enthusiasts - fibre-optic link
ELECTRONICS FROM THE GROUND UP-4
54
by Mike Tooley B.A.
First steps in understanding electronics, with optional computer aided
design software
AMATEUR RADIO by Tony Smith G4FAI
80
EPE on ATV; Short Wave League Booklet: Young Amateur of the Year;
Happy Birthday; RARE
feature/
llprry (UlfriBtmas mh a prnspprnus
Nm f par to all nur rpaliprs | Wimborne Publishing Ltd 1994. Copyright in all drawings, photographs and articles published in EVERYDAY with PRACTICAL ELECTRONICS is fully protected, and reproduction or imitations in whole or in part are expressly forbidden.
EDITORIAL
13
INNOVATIONS Everyday news from the world of electronics
22
NEWTECHNOLOGY UPDATE by Ian Poole
24
Variable colour l.e.d.s and improving i.e. manufacturing yields
SHOPTALK with David Barrington
27
Component buying for EPE projects
ELECTRON ICS CROSSWORD Puzzle with an electronics flavour
31
FOX REPORT by Barry Fox
36
Coded TV standards - is there a future?
ELECTROMAGNETIC COMPATIBILITY by Andrew Chadwick 38 Implications of the EEC ruling
CHECKING TRANSISTORS by Andy Flind
52
Simple transistor checking using a multi-range meter
CAPTOR-VATED! by Terry de Vaux-Balbirnie
64
Solder fume captor reviewed
ELECTRONICS VIDEOS
65
Our range of educational videos to complement your studies
BOOK REVIEWS Personal views on selected books
72
BACK ISSUES Did you miss these?
73
ELECTRONICS SOFTWARE
74
Educational software - Electronics Principles II, Electronics PC Toolbox 2.0,
GCSE Electronics, and GCSE Mathematics
DIRECT BOOK SERVICE
75
A wide range of technical books available by mail order
PRINTED CIRCUIT BOARD SERVICE
78
PCBs for EPE projects - some at sale price!
ADVERTISERS INDEX
84
FREE DISPLAY NEWS (48-page Display Electronics Catalogue)
between pages 42/43
Our February '95 Issue will be published on Friday, 6 January 1995. See page 3 for details
Readers Service · Editorial and Advertisement Departments 13
Everyday with Practical Electronics, January 1995
1
Surplus always wanted for cash!
THE ORIGINAL SURPLUS WONDERLAND! THIS MONTH'S SELECTION FROM OUR VAST EVER CHANGING STOCKS
Surplus always 1 wanted for cash! |
| LOW COST PC s - ALL EXPANDABLE - ALL PC COMPATIBLE \ \
THE OFFER OF 1994 !
|
SPECIAL BUY AT 286
PC SCOOP COMPLETE
COLOUR SYSTEM
Controlled Laser Video
40Mb HD + 3Mb Ram dtcaMPiOUenoneSrMrtamsydUdeidfgegbp9Terranal0EaenaceiltDnDkddse4uAtHEwQf0phoYMGUIiretGihAsAFbrRUMeupelvAhlSrinTliaoaDAdThbGvreTEiadiloudYtinto2aedycc8droiaeaas6nrTdannkdlsyhtedkeiwsnoeretiif.dcatyvhounetRbhmsdsoOetteiaoarpansrirdagdaetNdchyll.e.te1tsSL256ocpfuM%4areRpoY0sc"phnuekitzlnf.i1ieh+£.cHIRd2oaI2eut1iMaiMnGsolebgR4nbtsoi,AfmloR9totDhdeAhpeEep.Mduymos2,sOecdy8odki6stDshOtkcweOesomrydiSnbtrshdoitv4iewabte.imr0aoadt1&nss-.
NO1.Ep4Mt2i0ob0n30a1l4E*Fthiftetlreondpepteyx(tdthriisacksk:,dtrVhivGineAo(igrnrtsawtpeihsatidecdso)fcn1aer.2tdwMorbk) card
£££234929...090050
ONLY £99 00
oTpdsArMFteniauhusStma"keidybdaDealdDy9nnesOrustiisaviSsatvu,npeorela.dalstannrc1brye,adhu26uxol9nEpakoldlaolCllenpscw,Gcc0duooot'Aarlrnrbco9bonhu0lucaneeaondricDscylXgteosaiPbTen^uoCegtPrPd.nrCdyCcamse9aDbyrwbow9lso,,elniitestssniehhsty'mouPit2sn-rsCt5g,jem69utamsot9ksttoiCatsbonacsOplfredniolLnRaaumtgrArghundpMyinristo0in,hhsu4S£eeeao'saAa9knwpr*eao9dCopyf3rO-ogl6fkod0ourM0efltk0lyou!Py!pfbfLn(lrocIPEoEiidoacpt)CTemryepda'Es!y.-.l O2npdtifolonpaplyFditrtievdeA,ebsxoptverceaisfp:yr6i5c14e40*sk3fRo6Ar0kMPCor939Vo4*ff7e2r0OkNLY. ££2299..9050
emOtTtsWhLRuhtriahSanagsrahseenr-ehtee2tmsyrPnlow3Viqfofhfn2uceueislitgsolahaltIiineNtcloepvtuivtoynTtrsirmyemospeECrVuleospRlsAasesPbutoFldtVo4tfoeAeaar1fetbramCh(n0nycagcidEsocaLoeaatmzniaiabnvits/umcnrcleeooedgrrremlepeVir.dotsltcpoairPuiisibyuaqrliel)olaoptuevleyRnfyloraaufsm,GrellspairsaCilBtvmdttaycaayLyem/hienoVaielindCuadarlnsi,b!ayO(etuwLlriemMndaaooDrlnva.Pse1cgois;O2dhI*tlPneSaboSLelwnIeaTwaniydlsEuekl)ieclssrpodVceVsnlisdIats)PdiDecs.yiariEstoiSeslbOon(ooanawamOd,choyikvUueisrcenkOThmroeisstPfiocatwfUrhottTerihiveTaoltehe--r.
BNC+SCART INTERFACE
PAL / RGB DECODER
IR+WIRED REMOTE CONTROL FAST RANDOM ACCESS
5PEC«RLI PURLHRSE only £399.00(F)
FLOPPY DISK DRIVES 3.5"- 8"
5.25" from £22.95 - 3.5" from £24.95
mgMpssiturzaeeaaetnsse.rtseadAinanv)HntteaedparpereraiuaemrrBneceIRdBhfpuAaMorlslNopy-edePDstruCeaocNstfttceEeasodWfttmra,oinnaopmdldraiaugtsrristendbatmerlny5deod.2bava(i5enerf*addd3t.aivf5snrnoh"ogdlimstplau3opgo.pwe5efpd*tspoedtrnaroirtnceibyveddrsoea!asounrnAedewlnylinotaouhfebunwsalritetaPs9esnqC0(uduu)sdai.npratld-oyess
33355*SSMM.....Dhh55522ii***55uuttass**ggtPMMuuaaaTBbbarrciiiienRttttssassaaAhh88buucs5ii0lNbboe10FMMiiDnss/iD88nhhi22*0cN-cii8851ld99EMMJu5o4U6WdG8FFu--"e366F33bd6M33S5R5l3-ei5S58n0i/CC*1ts42srpi.--Ue2udLrD7sfieb2i.cuM.8ddi0er*1se1.bKeh.rdDg4ie4isofSshMMuMrwerseedFbeilgqlig5icm&.su.0hhiLl1NtaveieBnabadospellntee3&teNon6ldNptat0EepsEKWstWootenpdly *
££E££2222399426.....9999955555(((((BBBB8))))) ££££222185595005....00000000((((EEEE))))
bDuuilatlin8"podwriveerssuwpipthly2. mIdbeyalteacsaepxatceirtiyorhdoruivseesd! in a smart ca£s4e9w9.i0th0(F)
HARD DISK DRIVES osmEpfnoehddeaedrold,fddlcaiinotsaemktpsprtaluoenrrtscaefgheweari!staheFnumdslclaaoincnoucdpaeul!s.ssBOtrtrinyamlnysedt,anrneedpwalarNcdeESsCMFDuDj2it2Isn4ut6eer8qf"uaEi8cve52a9lMe9Un.bl0tty0ral(eEh)i 58333355H*,..,.222a555555r5--''d***CCFRFdCMSUOOOUiEDsJDNNIJcIANCIINNTcMFIGSoEE9SKAECn4RRU-t2TR3Rr0CCoEM0I0B5l9PPl-32SEe.353230rT100s6235-42242f7244K4o23S00r6842mmM1R40026bb5mF00m3mMMHmMb0bbHFbbIm.IMDSDIMSMbDCEEMlFFESR/lFMMD/l,ILF/FSLRllll/(C///F(FoFlFFo/SrEFr((RRIMeo.eRqFFrqRaueEEuecLifqivutt&Lvu.eer)ibsse)RAvRttt.eeFcc)Fddo.EERrfnrFo)Em £E£1£E£EE£16698694959999.S9999........909959090S0555050(((((((jCCCCCCEC))))))))
THE AMAZING TELEBOX Converts your colour monitor into a QUALITY COLOUR TV!!
TTl m
b'omwaTutSaimlBoynouunnuAfhiAatafrtidtdotaelthstNpkNlal,ioyolomueimTYDcnrumsttro'oEoteOaecnUusialaLnoscos,etttsdHofyeaEpvnvSileiuFuiBtmvnouismOrntdiaOoiccsbodnoeNaobaloeXyngsnorrltlYd-ieeeeotoar.mfd,oaculeopnrblnorrTceCnrayoenootqthinOhlensmFvrnueemleiudioMtecesdoetefrvtctnohfgesrasrMiorceotssdrcsocmai,otinontOteoalerfaiutmpscnecslD4leraoalspapoeVOvscnsbrwarwtlrhiiHnRaleestsapaaeieinetaFEtnotnealtddtsgn.TnvnryauaaaacVieerrPulndrccoleltldedHdoetoshmcoci.o.fwiveIeopoppUTLepialroaevurEtaIHstuierfePdgmioLuatcbFrSiplMnsEetpriil,n*oluyepliBioiItctntrtTfoCcfy(OisticoTwAea.TaRlXncrE-isuVTloOAelhLadeUoMndonEaciVvfcnnNsdlhBBesoIt8mgeaGnToOmclocnoaf,EttfXounfwiipphnoColvvAeollersMyuneill.sMdsegrimBtpHesvtAtunSeooo)edYovn.oTTlwimnivterPmPrRAHeieatinEotuudcAirboRoontaRseeslFlrDrilIhdoyest----i, TTTFt'FooEEEocrLLLraoEEEbcvBBBlaeebOOOrltsXXXeyep/aSSMeshTTBysPLopfAMocearkLrsubecvltaoSt.einmTbrSdasphbniroouidepnstcpViswteieHnpsittgtvFhaiio-ctdiUenonetHdo5Tee.Fgei5nrl-oeaCponlburaostba6xpltllmyeeMT-paheekHBzlemeyssrbpohooeuonxrnuibtedloadsrnssibdpseet(cuBcinof)iencrantei£££oc363nte692.d...599055
FANS & BLOWERS MMVPEEISMAhXXEIIiHTTNR--pEESSOpOCQQUUiFAnUUBBgrKBaIUUIPPoc2ESSkn68HH11ma0212IIl09l-oxMM30fuxa3.0MMn5n83trsm8F9Fam2--c1(mD0AkUmx96)BA.mDx1AB1C8n112Ctl29mofDD*3awfmHUnaLfeasnr9nx6s1s-202t1-t(rveB9xtxa*se)Dy22t.seB5C5ts5depl0ommdes,wc0mpmsie0pefry0ce11ic122fF1i1yvvf1a0y0D1nD/211sCoC401rE00o2vxro4£££NSr02547v42tE...9o9904W55c50vk111v00C0££47£/£A//5965£££L....5469999L3295555
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kaOAswnHlrltidzetm.ceehrS.oiaundpsgepsMfloiaerTsdSWa-h.|9bPa16oElMnCe0u1MvXmte00sGceOcCe.u2o/tAO.D4lEidTH(top,mLerOhnxfodsLeEooRset7EhdrsoGrHE6iNeeAbaA8avT(lTHsm.ei,ehAnilMrToiocVmstRRnthlisTluoGiIEeitentSndoSAuooi-mrnfrw9smuge064icslld.0lcool2Ai0ramSn8cemlm/oo*VsepnSocoinuGdgdhdtfoaiAerbuettoiruno1smicpmmnn2tiiip0tenswocou).0cnhidtl)CtSuh,ewawdoylsfiimlintuAn.othh#cgwpRBst££l9srhICe11BBed0etHd53seoMCodi99AwIrwl,aM..euT00nPiyctCtA00EhtiCgtoORoD(c(tunsEEeIoMEax)1)noriiS5tnn---f' brVAEeuLGtsamoEArilsCu)oatT.rinoR95dn0OB6oHdN4taOh0CyeMrgxcsEuo.4na8EIrn0naCe.ncgMMttoeo-uoer1lsdt2i.1ui01n.sS3peB1udtUpscieto1clne2hcd.-tiCitVoiooGnmn;Ap9(ampptioinubslltsCeiisb6ywlAneitc/hmEmP£iGonC9Ano9sir..t0;oAs0r1cm5r(weEipgei)tianhn. faaCGKMKonnMMooryeamosEEalduom1s1p5u1guo0e0rs6d"re"eb2osada5hrncetiocldgkoanaAhrhnlbimyzdtcdoyiieovtgs1ifamyeoai3nn.nn.fi5pd.cAto*io9orcmR0snoxPiGordtCncdeB1aoe2AyElm*ovsrGguciyxduArhsneatimy1mocsrl1atoiea*nnsndsnogtieuetudOosecrOarc4hnsrepdl,yBeNar£Bwais£1cCti14teeh52sAt.5Ri0igtr0aGho(rtEB(imE),0';)p28^*: dot pilch NtImbyneEezeaCaexnsl-uCeharqGaituntsArigpabcm1e1t25eie*v*nnLectroefxtluwmolul1ooyr3v*ttIeeWoBdsnMteefxo-dPrr1Ciwc2bo*ibctnHhoetmdraaTpcq9hatr0uteeiadbylflareropyenlaagHtssuicotgaionhcrsasmqcnuateaestheiec ]j
Only MS.OOif) clSEeouXampkCepErslbLetyltLyelEem2wNc0aiTatdh"sleiectt.2UolemPK2uep"smroefseadainctctnueoffdnavocdirdtiut2eSirooc6enh.&"owPooIiALltphst.aVifoluSlnllhsaSo9oll0pPisdsdoE.uastyDnCadtgiesIuciAnacoopr.aLluoCntsuStl.eruebAmst,otrneaicttcoti.rvIsne, 20"....£135 22"....£155 26"....£185 if) 9" Mono cased. Black & White for CCTV Used /Tested £49.00 (C)
DC POWER SUPPLIES CPf4o5(ALsBFP1f-2r*e1na15aooaaooAsm2r2axmwmwtnts(n)v,evh1i6.h-2veeeecb5eae.5ee©l©rr05avnglvArr+p*OdOictG,v5e.AC©20a©l0nni1avo6F..-Cn51k3eLe8s/u0glo24aa)01e1lYau.0SSl0..d395+0y.AtSAPPA001·,6+p5g-1L.L.l-uv.Pl1S^12u4141t20SVoP/w3v.0avC433*0wu5r-A*i1000w01atotxai©2p.aCc-t2nx,wacv55huw1t0lht*-24i2ae6tt53n.@mls*st0e05axmv0tp.ed0f.0aoxuh2u5Swo11.fPdt*lriw7R1.wd.l-eo.-a55ys-2g5eFa.Atx3ieaIttvr.0trrES/l.dcstR.ae41e05h.e+ds0g*SFc2vSwauew1uimt.wERl5ae2lrn00aVaipbtoflFvattcxeotDc5ltdfEnhecre44hpa6e(Edodtd02a.mt..fame5ro5lawbsf+i(socur.0pivol8i5Etm/ldeteeee1ldahvwyencsd1sef.pos.ct.o©+l.04SpNeNeavr/1iews2aseee2s12stake4rwEeiwy2Vk.td)0t5dvvsc..)xtaoh.vDeS-(la14mCtmecA+a2mS.gv1o)©e2+iDdo1tv5eo££Ep££r££i.2ov.5mp22r4598+25©9@oae299955945sca,tn.....1..ev29999090+vk6c355a555002ta©'.(((i(((4,oBBxB(CCCvBn)))))))
SPECIAL INTEREST TZAVTTIFARGABNNSHCKSNrueheGEeveEPinroneeiTktkukjuoalDwtCmdnait7EooEtwsoretwrr0tn5lsLhn3Tlpneolo1bau-8eo2wuiVnOn.1yPr2SP0c5co2td8MiLKsDBPiAatkxD0dLlrS-rwlvw3APC-AoL2eaDI1D0Ad0AMRnrr-A4L54cP413Ab11i8T7113CRH61c01ry-bA6558o0005s03A2Gee6O/0j7B0v51kp0eaSnH01H10E0Wc34te0c6Vp600l1ztn30ohKsd1ei361pioegSL3dc3h458CWedHPenimPtEeAz0cnuDrpckSDPoM0ualPh4phiaUGMSHeemnltDCano0Haneacb.gLPvnuw0asitssozasea3lGoenlt1mdthtenyHmeln0l3ire6lLiritbfdsiriianglmazbr,estueapslehggedRusptsormy3mhlqeeiitarusSDslMgia4urippesoepncri/2as8eiesthnsrcaotseeu(a3n6r.ecrheanmleptA2gcrofNpososldHyir+uppemitynfeeciygaeudscaqmrwkfpMbsittrorrusuieseturmoenneimpermldqud1vinetersunes.encdcuieirptenry8hmsmdntl(R!eMaeo9F!ccu)sPrrta2opoylttbrAcael'noCorkcVrtRTveoutootceartenmtyormeravtrosgeedtuerreernt'rr)etr ££££££112££££££££31££P£1PP99159483793783159OOO77505753557555289AAA55000000005000555
BBC Model B APM Board
£100 CASH FOR THE MOST NOVEL DEMONSTRABLE
APPLICATION fdwTwbd3dtpwiebibEEBooln"ixooaroaaCPihBhmroc.itrptraoonhRrirlCOaittirceseutfktSgsshdiOs:fhrNemadeesiueMiposmndseMmrEapDowarn2dotnbolTapsyselaIo7ldeyovidytPnolcsn1eitaiatsut6oomheldhhp2arstpdmb5cddeeeratewB8tardiio0k!hmvoocpj!rlir+a2otteeeeE/vteneeyesrOc5rt.ItisgdPptssiP/hdants'tuiUtaesRheiiRcen6oefslo1nsae'sasodcOts5d3Ondnoesrro*da1adMuFdsidmerBann2w'u+ioxpDEcnatgdeBSacs1ppiahtgS'et1Cnersk2uCl,hin0najSyitrcaePtue*enouOavIeobtmcdfUm.cOseidsronlinttofIDtde.royrpNucorti/cmfB.OaocdCoenrtatRAuminehwNer.mT.pniAsitbaleLtanpCohaTpoMnBefstflrbefdlvhaoihneyeoteotcirrteye.elhduitaaahadmerucepregrntasAAc'segcidsaiter1dwteoBouPtpr.ax4fiwacnanitMpsBomu*AttaohrptrhxenlCenonaoehox,.macmaffnaittbcpoSOoroeatDq^soecpnhAjcooooaltCsetnssiAhorprnincyusdeBrlenap»5u'pstrsOVrtse0BumtehovJiaec5o-rCawiotmtect'0dnihsafornhee£slcao_rlasrtgaoototeuwospyn2mtlwoss_iesohoealimlyipuntlunet9at^eaobshotugaelrxptlhenlltsgoe.aluteeyayiemwwf9rstvscbo.tP(shstheianuBeiCt5bOitimoencum)ptuoBtnnhodas--.tf
19" RACK CABINETS
Superb quality 6 foot 40U
Virtually New, Ultra Smart
eoOnvvloeRey!^rraat?sw>c»"lol!ko«-Jld>yd.1sifm.i-CdiRfeeotnramnpscfiakpfonaslnjeesmtlesaawrtyoeuTOehrnmsri:eatwbraresohpm,cao7ltiepigatkt7trufiosicnheiss-moqmnxv1hmtdtLuniata/aesno2eaclobsdogo*ldkekioEvlimnceteefsamHysngktddiberlsceansayluxi1blqestmodat9oeoil3sufcet*dsess,gr2irhieutpdy-rpirrhhd1nraaeemalbaaee/iical2sbynclnpskedft*aemra1snylLiyllnicD2bostoHdostape.ucduesblmxuwtk.svFtiainaa.o2nUueoacnlbv2nlreyunlhf*deletyniesedstrPWt1sttdsairhfm3nbadifrrefpeatogjoraiaiuaOcenrdlc£mmtskfetpue2artoeaadlrnp9drwduekbie!ey5nooslere.sdoeorc0aUoeerrort0heqss,hicKnni:aaauekf(gtfGdinvieusbengrrydele)eyt---l
Rack 2 Rack. Less side panels
£175.00 (G)
Over 1000 racks in all sizes from stock I Call with your requirements.
LOW COST RAM UPGRADES fcIPauNobClnloT-ydvAEiseLtTei)ol'cemAnocBemftuamOlpbloVyalretEtyiebf.'oslMFtereuEcdelalmxarpddonaardnwtyadgitEehuadxna2rpdoaaMrndnEtbrseixyievottdeeen.snr dBdoefiodsmak(re2dsm8u6opFrppyulrlilooecnldene.nbsgrosItoannhrrdgPa.oCnnodC-dcXauTrdsaeindsd WHmiOtnaMeriRldnmfAEdeloorGMerwanyxsagse:bt9cihotXohSvmT8eIeMrpbR62aMiA4tt5i0M6bm9kkleecUD.omhGrOiOop5.Srr152d1y2l21e5ikumr026pniaikktng.ss:C6roa4nAodklmByesOptcelVaeptrEsed.CswMAiftoahRryDdPaaCltsaoA. LbTeDX£££uTy33s2.ee8295dx...799p9t055ao5(n(((AAAfdAills111l))i)
No Break Uninterruptible PSU's fsBrrueorpaamtlneidssdyn1lsee5tweammdaiannfcrudiotdmebsbo.DaxCteetdoenrms2iee3pis0l.eintvOMeomrlwotdasdiettehc1rlhfaKMiunslVl;UgamDcuaaMn1nsi0ueUn8.atD5elA.r-1ArpupHprtBoibxHLolel.OicmCp/oeotOwmfcre.porUmlesntUueipnnwt(peGliryt-h) tatEputTfohhinartMheetetdaieinlEbmhlgaulRaTiuenainrSthnicdtcoteOeshamftrdirrNeAnniudaasaetccktlAifcutcoiisisuCraornyeslnrCalsasteyslhtUvltefeuaecumICrBnlroelnAdMpvssceRoieeodmeflnXDmsfttatwTodanpUo/aiituoAflarhPanegTlseSloeynp,scnesoNrsobxttosesmaorotvmiacfiricpnmntd,spaedtsoteahoditwxlbanenputlepeueebarswrsvs.onei.ceosdw8WnetCeohtaBd£hnaenoi1erlntafydd0nnhpt96aiphdpos.klr0eowfvoso0wluipvefedpoerinedbrpwsgoealuitesisshmpereDdprPfeelRaCmwyCtiuAliofpertcMahndroioylew-mf!duteol-lr
Only £99.00(8) or 2 for £195(0
Issue 12 of £>isp/ai/ tyivs now available - send large SRE - PflCKEP with bargainsi
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\-ELECrR0niC5-\ as 1S t} ES2T5AYBELAISRHSED
S(usAFuncl)lbhl=ejpoe£srocs1ilct8sset,.tos0aU0tsfe.ontdori(vGwUge)Kru=saDCiMtriAiaesanLscitnoLaelu.naenndAdtdslfLl.oofooUwrcrK9aav0lpocApulduursamottyhoxesom..6rTiAetdirolelsapsgyaC-udsaAmdfroSia1nrHn7ismt.ehp5ueir%pmiscpeoViansnAcgpcTaao- iturfdoeantsfTtuotOroernrrTsdutCAeorArLpbLl£ouaL5rss0.deg.eSorbCcoaaoadsmtrilsrsaio.anugAdAnelltlls.cturrMhiragcadihhnretgiasmmergrsuaeemrs(kAeCsor)Av=redeL£tcde3Lr, taEo(AcAllkcl0'nlhg^ooEaBwoAnold^nOesadOpgsRrueiIdpdcBpee)©ls=iae/£DdcSspi^tsSoepn0cloiatfuy(iocCrEar)Sdtl-ieet£oacr8nntsrs.do5aan0ri^dc(sDCt1<)^9^^91d4f2irtToKEm)X04iGsO(ooE<vE)SO-.£aT1Ol5emrTadeXnneLdts,
Everyday with Practical Electronics, January 1995
12V, 35W PUBLIC ADDRESS
AMPLIFIER This audio power amplifier has been designed lo operate from 12V d.c. and provide up to SSWr.m.s. power. II is a public address amplifier with a line output for loudspeaker distribution systems. An output transformer is used to obtain the 100V line, offering flexibility lo wind secondaries to individual requirements. A low impedance winding for direct loudspeaker connection and two 100V secondaries for the line output are recommended. The line outputs are ^ i normally operated in parallel but if connected in series, the unit can provide 240V to function as a converter.
Four inputs are provided, each with a separate volume control. Two inputs are amplified for signals from microphones or guitar pickups, while the other two are for higher level inputs suitable lor CD players, cassettes etc. A mixer stage combines all four signals and a fifth potentiometer provides a master volume control.
The amplifier is fully discrete and uses well-tried circuitry with an output stage using MOSFETs. Often it seems that i.c.s must be used wherever possible but for a transformer output, public address amplifier, discrete designs can perform adequately, are inexpensive and usually more serviceable.
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UL TIMA TE SCREEN SA VER
Most laptop computers have sophisticatedpower management facilities, which shutdown the screen andhard disk after a period of inactivity to sa ve battery fife. Until recently these facilities ha ve not been a valiable on desktop computers. Some "Green" PCs are now becoming available, with the aim of reducing power consumption when they are notactually being used. However, ifyour existing PC is OK. spending over a thousandpounds on a new onejust to sa ve a few pounds worth of electricity does not make economic sense!
Software screen savers are available, mostly running under Microsoft Windows, but all these do is prevent a static image burning into the phosphor of the CRT. Indeed some of these are sold more on their amusement value than their original purpose!
The unit described here takes the screen saver idea to its logical conclusion. If the keyboard and mouse are not used fora presetperiod, the monitor is switched off. As soon asyou touch the keyboard or mouse, the monitor is switched back on again. This not only prevents phosphor burn, but also saves electricity. In addition it will reduce the emission of electromagnetic radiation andpositive ions, ifthese things concern you. Moreover, it costs no more than a screen saver software package.
Ifyou leave your computer on all the time but only use ittor a few hours each day, this unit could save you over £70 per year in electricity charges.
FOOT-OPERATED DRILL CONTROLLER
This project was designed as an aid to precision drilling work by hand. For example, when drilling p.c.b.s using a handheld 12Vdrill, the author has often experiencedproblems with the drillbit skating across the surface ofthe board. This causes off-centre holes, damages the surface of the board and its tracks, andean cause drill bits to break.
The efted is partly due to the high speeds at which such p.c.b. drills operate, typically 15,000 r.p.m. The jerks caused by the large acceleration when the drill starts are not easily tamed when hand-holding the drill. This project offers some relieffrom the problem.
Firstly, it uses a footswitch to start and stop the drill, thus freeing one hand to help stabilise the drill, or to hold the item being drilled. Secondly, when the footswitch is pressed, the drill speed is gradually allowed to build up to a presettable maximum speed.
EVERYDAY -. with PRACTICAL
ELECTRONICS OUR FEBRUARY '95 ISSUE WILL BE PUBLISHED ON FRIDAY, JANUARY 6
Everyday with Practical Electronics. January 1995
SURVEILLANCE PROFESSIONAL OIJALITY KITS
Mo.
for
Kits
Whether your requirement for surveillance equipment is amateur, professional or you are just fascinated by this unique area of electronics SUMA DESIGNS has a kit to fit the bill. We have been designing electronic surveillance equipment for over 12 years and you can be sure that all our kits are very well tried, tested and proven and come complete with full instructions, circuit diagrams, assembly details and all high quality components including fibreglass RGB. Unless otherwise stated all transmitters are tuneable and can be received on an ordinary VHP FM radio.
Genuine SUMA kits available only direct from Suma Designs. Beware inferior imitations!
UTX Ultra-miniature Room Transmitter
Smallest room transmitter kit in the world! Incredible 10mm x 20mm including
mic. 3-12V operation. 500m range
£16.45
MIX Micro-miniature Room Transmitter
Best-selling micro-miniature Room Transmitter
Just 17mm x 17mm including mic. 3-12V operation. 1000m range
£13.45
STX Higti-parfomianca Room Transmitter Hi performance transmitter with a buffered output stage for greater stability and range. Measures 22mm x 22mm including mic. 6-12V operation, 1500m range £15.45
VTS00 High-power Room Transmitter
Powerful 250mW output providing excellent range and performance. Size 20mm x
40mm. 9-12V operation. 3000m range
£16.45
VXT Voice Activated Transmitter Triggers only when sounds are detected. Very low standby current. Variable sensitivity and delay with LED indicator. Size 20mm x 67mm. 9V operation. 1000m range,..£19.45
HVX400 Mains Powered Room Transmitter
Connects directly to 240V AC supply for long-term monitoring. Size 30mm x 35mm.
500m range
£19.45
SCRX Subcarrier Scrambled Room Transmitter
Scrambled output from this transmitter cannot be monitored without the SCDM decoder connected to the receiver. Size 20mm x 67mm. 9V operation. 1000m range £22.95 SCLX Subcarrier Telephone Transmitter Connects to telephone line anywhere, requires no batteries. Output scrambled so requires SCDM connected to receiver. Size 32mm x 37mm. 1000m range £23.95
SCDM Subcarrier Decoder Unit for SCRX
Connects to receiver earphone socket and provides decoded audio output to
headphones. Size 32mm x 70mm. 9-12V operation
£22.95
ATR2 Micro Size Telephone Recording interface
Connects between telephone line (anywhere) and cassette recorder. Switches tape
automatically as phone is used. All conversations recorded. Size 16mm x 32mm.
Powered from line
£13.45
UTLX Ultra-miniature Telephone Transmitter
Smallest telephone transmitter kit available. Incredible size of 10mm x 20mm!
Connects to line (anywhere) and switches on and off with phone use.
All conversation transmitted. Powered from line. 500m range
£15.95
TLX700 Mlcro-minlaturs Telephone Transmitter
Best-selling telephone transmitter. Being 20mm x 20mm it is easier to assemble than [
UTLX. Connects to line (anywhere) and switches on and off with phone use All |
conversations transmitted. Powered from line 1000m range
£13.45
STLX High-performance Telephone Transmitter
High performance transmitter with buffered output stage providing excellent stability |
and performance. Connects to line (anywhere) and switches on and off with phone use.
All conversations transmitted. Powered from line. Size 22mm x 22mm.
1500m range
£16.45
TKX900 Signalling/Tracking Transmitter
Transmits a continous stream of audio pulses with variable tone and rate. Ideal for I
signalling or tracking purposes. High power output giving range up to 3000m. Size |
25mm x 63mm. 9V operation
£22.95
CD4O0 Pocket Bug Detector/locator
LEO and piezo bleeper pulse slowly, rate of pulse and pitch of tome increase as you I
approach signal. Gain control allows pinpointing of source. Size 45mm x 54mm. 9V |
operation
!
£30.95
CD600 Professional Bug Oetoctor/locator
Multicolour readout of signal strength with variable rate bleeper and variable sensitivity I
used to detect and locate hidden transmitters. Switch to AUDIO CONFORM mode to
distinguish between localised bug transmission and normal legitimate signals such as
pagers, cellular, taxis etc. Size 70mm x 100mm. 9V operation
£50.95
QTX180 Crystal Controlled Room Transmitter
Narrow band FM transmitter for the ultimate in privacy. Operates on 180 MHz and I
requires the use of a scanner receiver or our QRX180 kit (see catalogue). Size
20mm x 67mm. 9V operation. 1000m range
£40.95 |
QLX180 Crystal Controlled Telephone Transmitter
As per QTX180 but connects to telephone line to monitor both sides of conversat- I
lions. 20mm x 67mm. 9V operation. 1000m range
£40.95 |
*** Specials **
QSX188 Una Powarad Crystal Controlled Phone Transmitter
As per QLX180 but draws power requirements from line. No batteries required. Size |
32mm x 37mm. Range 500m
£35.95
DLTX/DUIX Radio Cotrtrel Switch
Remote control anything around your home or garden, outside lights, alarms, paging
system etc. System consists of a small VHP transmitter with digital encoder and receiver
unit with decoder and relay output, momentary or alternate, 8-way dil switches on both
boards set your own unique security code. TX size 45mm x 45mm. RX size 35mm x
90mm. Both 9V operation. Range up to 200m.
Complete System (2 kits)
£50.95
Individual Transmitter OLTX
£19.95
Individual Receiver DLRX
£37.95
MDX-1 HI-FI Micro Droadeactar
Not technically a surveillance device but a great idea! Connects to the headphone output
of your Hi-Fi, tape or CD and transmits Hi-Fi quality to a nearby radio. Listen to your
favourite music anywhere around the house, garden, in the bath or in the garage and
you don't have to put up with the DJ's choice and boring waffle. Size 27mm x 60mm
9V operation. 250m range
£20 95
QRX180 Crystal Controlled FM Receiver
For monitoring any of the 'Q' range transmitters. High sensitivity unit. All RF section I
supplied as a pre-built and aligned module ready to connect on board so no difficulty |
setting up. Outpt to headphones 60mm x 75mm. 9V operation
£60.95
A build-up service is available on all our kits if required.
UK customers please send cheques, POs or registered cash. Please add I £1.50 per order for P&P. Goods despatched ASAP allowing for cheque clearance. Overseas customers send sterling bank draft and add £5.00 per | order for shipment. Credit card orders welcomed on 0827 714476.
OUR LATEST CATALOGUE CONTAINING MANY MORE NEW I SURVEILLANCE KITS NOW AVAILABLE. SEND TWO FIRST | CLASS STAMPS OR OVERSEAS SEND TWO IRCS.
SUMA DESIGNS
Dept. EE The Workshops, 95 Main Road,
Baxterley. Near Atherstone, Warwickshire CV9 2LE
VISITORS STRICTLY BY APPOINTMENT ONLY
l'· · " · 1 Tel/Fax: 0827 714476
4
Everyday with Practical Electronics, January 1995
.,1
Quickroute to successful PCB & Schematic Design
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Design RGBs and Schematics quickly
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Telephone or FAX POWERware on 061 449 7101
POWERware, 14 Ley Lane.
Marple Bridge, Stockport, eKfi cnn UK
' "
Quickroute 3.0 for Windows 3.1
^'GNER E".00 ^,GcNoE"+J149 ()0
PRO £199.00
PRO+£299.00
All prices exclude post & packing, and V.A.T.
Everyday with Practical Electronics, January 1995
DEMO DISK Available
5
COMPAC ELECTRONICS
3LWEYL0ND ROAD, DAGENHAM, ESSEX RMS SAB Tel: 081 984 0831
L.O.P.T. TRANSFORMERS WIDE RANGE STOCKED.
PHILIPS, FERGUSON etc. Phone with your requirements.
Handsets: Amstrad, Toshiba, Ferguson, Philips, VIDEO PLUS handsets (seconds) £25.
Universal Remote Control, operates TV, Video, satellite.
We repair Philips hand sets, £5.00.
Video carriages - wide range stocked.
Pinch Rollers. Video figure eight mains
leads, £1.00. R.F. Video leads, 50p. SCART to SCART leads,
£2.33. SCART to SCART leads, all
pins connected, £2,95. Aerial R.F. cable, RG62,
30p per mtr. Aerial R.F. male plugs, 25p
each. TV on/off switches, £1.50,
most types. Halogen Lamps, 240V, 500W,
£2.50. Miniature Tool Kit,
comprises: side cutters knife, screwdrivers, £7.00
Amstrad Compact black cap. LNB £28.
Satellite dishes, £24 plus £5, post & carr.
Satellite cable, 30p mtr. F. Connectors, 40p each. MASPRO LNB FSS,
1 dB max., £13.33. NOKIA LNB FSS 1-3,
£13,33. NOKIA Feed Horns, for offset
antenna, £10.67. NOKIA Electromagnetic,
Polarizers, £6.67.
i.C.S SAA301 OP £3.40. TDA3654 £1.89. TDA3561A £2.85. TDA3662A£2.85.
High quality loudspeaker cable, 50p per mtr. Servicing Sprays £3.00 most types.
Please add £1.00 postage & packing, then add VAT 17-5%.
BTEC Certificated
o mmmmmm mm
A T/ OL L E E C H N
TUTOR Supported
DISTANCE LEARNING COURSES
The National College of Technology offer a range of packaged learning short courses for study at home or in an industrial training environment which carry national BTEC awards. Study can commence at any time and at any level enabling you to create a study routine to fit around existing commitments. Courses on offer include:
Analogue Electronics Digital Electronics
Fibre/Optoelectronics Programmable Logic Controllers Electronic Testing & Fault Diagnosis
Tutor support and BTEC certification are available as options with no travelling or college attendance required. These very popular courses which are ideal for vocational training contain workbooks, audio cassette lecturettes, RGB's, instruments, tools, components and leads as necessary to support the theoretical and practical training. Whether you are a newcomer to electronics or have some experience and simply need- an update or certification, there is probably a distance learning course ready for you. Write or telephone for details to:
National College of Technology NCT Ltd., PO Box 11 Wendover, Bucks Tel: (0296) 624270
OMNI ELECTRONICS 174 Dalkeith Road, Edinburgh EH16 5DX 031 667 2611
The supplier to use if you're looking for;-
A WIDE RANGE OF ^COMPONENTS AIMED ATTHE
HOBBYIST,
COMPETITIVE VAT INCLUSIVE PRICES
MAILORDER-generally by* RETURN OF POST
FRIENDLY SERVICE 1 M 1
"OPEN: Monday-Thursday 9.15 - 6.00
Friday 9.15-5.00 Saturday 9.30-5.00
V7S4
SYSTEM 200
DEVICE \
PROGRAMMER
SYSTEM Programs 24, 28, 32 pin EPROMS, EE-PROMS, FLASH and Emulators as standard, quickly, reliably and at low cost.
Expandable to cover virtually any programmable part including serial E2, PALS, GALS, EPLD's and microcontrollers from all manufacturers.
DESIGN
Not a plug in card but connects to the PC serial or parallel port; it comes complete with powerful yet easy to control software, cable and manual.
SUPPORT
UK design, manufacture and support. Same day dispatch, 12 month warranty. 10 day money back guarantee.
ASK FOR FREE INFORMATION PACK
mgp
i
MQP ELECTRONICS Ltd. Unit 2, Park Road Centre, Malmesbury, Wiltshire, SN16 OBX UK
TEL. 0666 825146 FAX. 0666 825141
GERMANY 089/4602071; NORWAY 0702-17890; ITALY 02 9210 3554 FRANCE (1)69.41.28.01; IRELAND 1-2800395; SWEDEN 08-590-32185;
Also from ELECTROSPEED UK
Everyday with Practical Electronics, January 1995
A
SELECTIONOF PRODUCTS FROM
LATEST
1995 CATALOGUE - 196 pages of regular lines at low, low prices £2.00
To obtain our latest lists, become a subscriber! Every month we'll send you our newsletter "The Greenweld Guardian", together with details of new regular & surplus products that have arrived. PLUS flyers & brochures from our suppliers listing books, records & other goods. All this for just £6 a year! or Go For Gold! - for £12 a year you receive, additionally 5% discount & half price postage!
YUASA SUPER MICROPHONES SCART LEAD
ATBARGAIN PRICES!!
All pins connected
Z5961 Shore 527B
- 1.5m long
tpmarliokcfresoswpsihrotocnnha.el Swuiptherbpuqsuhalfititsoyt
Order Code CSL20
and value with ail these
Sealed lead acid batteries
f·eDaytunraems:ic todTw'NunotpyIimlsecepuceratdf/nlaeccnxoeclreidngheavy
Z5964 Audix HM230S/ract UDM100 professional dynanr"C rmc with on/off switch and cardioid characteristics. 5m lead with XLR skt
1100+
g 1.30 £2.00 H+VAT
Individually boxed
fitted mic end. Impressive spec! Supplied with PRINTER LEAD
A number of superb batteries in excellent condition at a substantial discount on
List Price is an incredible
their new price.
£71.67!
Our Price
clip and adaptor, individually boxed.
£29.95
List Price £44,06
Our Price
1--
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re:
Z9263 6v lOAh Sze 151x101x50mm List 15.04 Z9264 12V 6Ah Size 151x103x65mm List 27,82 Z9265 12V 16Ah Size 181x167x76mm List 55,44
Z9261 12V24Ah Size 176x166x125mm Ust 56.67 Z9262 12V 38Ah Size 197x165x170mm Lst 86,16
£9.95 £10.95 £16.95 £24.95 £34.95
OUSTANDINO MONITOR OFFER!
Z9270 12" paper white monitor by Philips, model BM7542 brand new and boxed. Composite video and audio inputs. Resolution 850 lines at centre.
Z5775 Amazing deal om printer cables Brand new, individually bagged 25 way D plug to 36 way Caneyntthrionngicusp ptolu£g.6.9158mfor olonngo.f tYheosue'dOnuorrSmuaplel/rdpeaayl Price £2.00; 100 1 20; 1k+ 0.99
LOW COST STORAGE CONTAINERS
SWITCH
-
MODE PSU's
2^ Z5952 Astec SA7GA 3400 7CW urrt +5V 8A. -t-12V 35A. 12V 1A. -5V07A Price £14.95
DTTAI33CRCFn2rehuaouupasrnstgunrtoredItygtsiamilniiegPneInsumdiG aargtgtiootdteipyyrtcs1cseeeaa5tclwdpieslnmtnoaosieidIcotwntlmhlancuwdrecdT isiLtioahiytnChsdlrgOaoeDebnuM2uA tddde0ziQesAzszdtpeelrra4aoaycmL n/dmdcLpElDugM s ULTIM [ B ETER Battery and instruction manual included
Z5953 HiTRON I^G40-31 4CW i +5V 3A. 0.5A. -12V0.5A Price £4.95
AADCRDCCCesvvcicsuooutllrarttrrnssee::cnnett
0Q--2200vyi>-22000-200(0pp>00---22--222mm00k0--0-2m22m000-fm2-kr2->--2-2-220200-00020-0k(n2mX-v02>2-0M2-A-1A7--05-22020M000VAVA0»ddQacccc±±±±£00001....8.5550%%%%%
Transistor h «
0-1000 NPN/PNP
Dims
176x88x36mm
@@© ©
0600 15 Drawer storage cabinet 230x160x180mm. Only £4.60 320 16 drawer storage cabinet 220x70(158mm Only £2.95 7033 Storage box with open cxA cantde^er tray 13 compartments 210<1 TOxSOnm Only £1.99
Code No: Y122F
£29.95
Z59&4 Famefl N055P40I 55W unit »5V 64: +127 34: · 12V 24 5V 14 Price E8.96 SCOOP PmHUI OF 3.5" HO DISKS Z5987 Ex-cover disks (only two titles, one a game, Master of Magic; the other a business package, Complete Works Lite) being sold for media value only. 10 HD 3.5" disks (5 each of
two titles) for just
Z5988 New, branded (Sakura) formatted HD 3.5" disks
Siiperhl 100 for £49,95
BIG RANGE OF AUDIO BOOKS FROM TRING A
NAXOS - ASK FOR LIST. Phone Nos: SALES 01703 236363; Technical 325999; Accounts 231003; Fax (All depts) 236307; FaxOnDemand 236315* *To Obtain latest lists, info etc, iuAowsrltledld1ecirooaflmf(£e0a9n1.7df5r00op3manc2ek3Ex6pdtV3rui1Idcc5SaaeAtysfir)oio.nnmcMluaiindnatse8myeotcn-oCikV5fconare.erAre3xnemps0iTdsntm..oievMtquda(AooctsoiCybchvcnsyaceiep-tnreroSrcdesicchacshakte1e..£nasqs01.CVrdu,dg20Woieof;e0som,a0enl.POle£ooaOCfw1tarsf.5ie.oqncPi.cnidnoa&anslpPf_sstPetreh)eacuOn£ye,tc.r3mtbhfdiuOrooapeesoovnlneurmskesrrt. 27D Park Road Southampton S015 3LIQ
010 Tool & hobby case 360x310x125. Only £5.95 020 Tool & hobby case 385x285x95. Only £5.50 UOUID CRYSTAL DISPUYS
-
All with H044780 controller (and HD44100 on larger d< splays) CZO64D8E2DTPLACRMT1N62o0. 1S6IZXE2 5CXH7AR 4H.2T7 £PR6I.0C0E Z54840 ·n.CM2011 20X1 5X7 5 20 £4.60 Z5486D TLCM4021 40X2 5X7 5.20 £9.50 AApdpalitcaatsihoenentoisteisn:cAlud1e6dpinagtheebpooriWceet is available, pnce £2.00 order code Z2842
Everyday with Practical Electronics. January 1995
7
£1 BARGAIN PACKS
BARGAINS GALORE
C1 BARGAIN PACKS
- List 1
MULTI TESTER. 19 range, ex-Bntish Telecom, recondi-
> List 2
1,000 items appear in our Bargain Packs List -
request one of these when you next order.
1 x 12V Stepper Motor. 7 5 degree. Order Ref: 910
1x10 pack Screwdrivers. Order Ref: 909.
2x5 amp Pull Cord Ceiling Switches. Brown. Order
Ref: 921.
5 x reels Insulation Tape. Order Ref: 911.
4 x 14mm Bull-races. Order Ref: 912.
2 x Cord Grip Switch Lamp Holders. Order Ref: 913
1 x DC Voltage Reducer. 12V-6V. Order Ref: 916.
1x10 amp 40V Bridge Rectifier. Order Ref 889
Lightweight Stereo Headphones. Moving coil so
superior sound. Order Ref: 896
2 x 25W Crossovers. For 4ohm loudspeakers Order
Ref: 22.
2 x NiCad Constant Current Chargers. Easily adapt-
able to charge almost any NiCad battery. Order Ref:
30.
18V-0-18V 10VA mains transformer. Order Ref: 813.
2 x White Plastic Boxes. With lids, approx. 3" cube.
Lid has square hole through the centre so these are
ideal for light operated switch. Order Ref: 132.
2 x Reed Relay Kits. You get 8 reed switches and 2
coil sets. Order Ref: 148.
12V-0-12V 6VA mains transformer, p.c.b. mounting.
Order Ref: 938.
1 x Big Pull Solenoid. Mams operated. Has Ya" pull.
Order Ref: 871.
1 x Big Push Solenoid. Mains operated Has Ya" push.
Order Ref; 872.
1 x Mini Mono Amp. 3W into 4 ohm speaker or 1W into
8 ohm. Order Ref: 495.
1 x Mini Stereo 1W Amp. Order Ref:870.
15V DC 150mA p.s.u., nicely cased. Order Ref: 942
1 x In-Flight Stereo Unit is a stereo amp Has two most
useful mini moving coil speakers. Made for BOAC
p1 axs0s-e1nmgAersP.aOnerldeMreRteefr:. 2F9u.ll vision fact 70mm square
Scaled 0-100. Order Ref: 756.
2 x Lithium Batteries. 2 5V penlight size. Order Ref:
874.
2 x 3m Telephone Leads. With BT flat plug. Ideal for
phone extensions, fax. etc. Order Ref: 552.
1 x 12V Solenoid. Has good Ya" pull or could push if
modified. Order Ref: 232.
4 x In-Flex Switches. With neon on/off lights, saves
2fliexxaivn6igVncg1lAathmMinpgasis.nOsswrTdirtecarhnResdfeof:ormn9.eOrsr.dUerpRriegfh: t7m. ounting with
2 x Humidity Switches. As the air becomes damper,
the membrane stretches and operates a micro switch.
Order Ref: 32.
5 x 13A Rocker Switch. Three tags so on/off. or
changeover with centre off. Order Ref: 42.
Mini Cassette Motor. 9V. Order Ref: 944
1 x Suck or Blow-Operated Pressure Switch. Or it can
be operated by any low pressure variation such as
water level in tanks. Order Ref: 67
1 x 6V 750mA Power Supply. Nicely cased with mains
input and 6V output lead. Order Ref: 103A
2 x Stripper Boards. Each contains a 400V 2A bridge
rectifier and 14 other diodes and rectifiers as well as
dozens of condensers, etc. Order Ref: 120
12 Very Fine Drills. For PCB boards etc. Normal cost
about 80p each. Order Ref: 128
5 x Motors for Model Aeroplanes. Spin to start so
needs no switch. Order Ref: 134
6 x Microphone Inserts. Magnetic 400 ohm, also act
as speakers. Order Ref: 139
6 x Neon Indicators. In panel mounting holders with
lens. Order Ref; 180.
1 x In-Flex Simmerstat. Keeps your soldering iron etc
a1 lwx aMysaaintsthSeorleeandoyi.dO. rVdeerryRPefo:w19e6rful as Ya" pull, or
could push if modified. Order Ref: 199.
1 x Electric Clock. Mains operated Put this in a box
and you need never be late. Order Ref: 211.
4 x 12V Alarms. Makes a noise about as loud as a car
horn. All brand new Order Ref: 221.
2 x (6" x 4") Speakers. 16 ohm 5 watts, so can be
joined in parallel to make a high wattage column.
Order Ref: 243
1 x Panostat. Controls output of boiling ring from
simmer up to boil. Order Ref: 252
2 x Oblong Push Switches. For bell or chimes, these
can switch mains up to 5A so could be foot switch if
fitted in pattress. Order Ref: 263.
50 x Mixed Silicon Diodes. Order Ref: 293.
1x6 Digit Mains Operated Counter. Standard size but
counts in even numbers. Order Ref: 28.
2 x 6V Operated Reed Relays. One normally on. other
normally closed. Order Ref: 48
1 x Cabinet Lock. With two keys. Order Ref: 55.
6Yj Sii 5 Watt Speaker. Order Ref 824
1 x Shaded Pole Mains Motor. V stack, so quite
powerful. Order Ref: 85.
2x5 Aluminium Fan Blades. Could be fitted to the
a1 bxoCveasmeo. t3oYr.aOxr2dYeri Rxe1f:^8w6 ith ISA'socket pins. Order
425R6exx5f:LC8u4am5s.einso.u2sYRa oxck2Yer4
x I1* with Switches.
13A pins. 10A mains.
Order Order
Ref: Ref:
479x3.Different Standard V3 Micro Switches. Order Ref:
340.
4 x Different Sub Min Micro Switches. Order Ref; 313.
taa£inn8o.ddn5e0h2d. a0.Ov,0Ter0hd03eesrroeepRsvmeisfe:tmaa8noscuv5eerPem3r.aeAnnCCtga. earrsCnydoimnmDgapCdlceeavttesooeltwsBw.TitiDhtshCpteehmcsatiinflildpcilaraeomtidop£sn2s, TexIMtrEa ON SWITCH. Can be set anywhere from 0 to 90 Oswsss0dPvO£sAiOocCgoQh1MmMofdOS£LhUmFXVmnhheuii-2e2Oiow2aporaPELieLNrxUm2LrEIarsAracoooVt.rimdudN9nndeeEWAdsAihdAOttnmyTNkOotAuuOnIrp.-apeadrgiIsoeeeENs5D6euRCSnrllaOgTErRblnel4rrsibrHsrrBdd0VDaeemSHnt.dAKHbt,d(liRyNTaRiRwRRLbedPmOePgpaLoacIetbSEZeCOARreCAeyONebmltAeiricCaARtrntMO,pnfefaeRtflhvfXEyouofoeOkroNW:hsGl:sP:OCrlSMtRosoNdeiuaDbmIOye,ry,2N3SdE4ee2EAdLoPhcNer1ePqteI,P,oPU£BDPPxTe9HdsoLpfkCeT2aOLrirm.uwTr2n£3a1c3trn)aEVUrilC,lERiPiR5eCi.i5elcoRl26nFz1il1csnoaCitt£tIAyAE-LPebOrOt,OceP2peeKAe1aed0Onfud8enMAc1REerfCOTor.k3pWVeLotN,nr£i£;£aaaLloR.trE.1ansdiEOehrykOML2-1rt3lhn2t.nLEul18eaRscdPeei2T,ab0.E9NaAtwhgO2rE5dEiRpclr"deO,sl,Ea6dtbRtuVof0.uRa£5CeRprah1to0ORRietedrar,tLktg1sPrkb2pIh.erHWsRhnde1rSi.enedeCTO8WnVsr2Hlnrrh0om2r.rfeeAueddRod.eoo.RDmyoVodfaOrrbi£t,,iaex,uNe:onbsdou2O4CAt,um1uloRUrfiicawtgus5sPeAdgIid0:mylol2iNMrtbhSs,eofhmbdrnSPbRr3ih,oeoid58ofsclMactSaEt0£2eaR:OO0urereePcrptpeuattraF7ci23lerrWfrh3aueheS3dlgTrsdlrarpAfi.Oaaaflou6lcenteud.5roeOen:y,uwsORsyr1sLc6Rotndiaesrr,Cs,ot3seRotc,0ueA4brdeltaMrfutec.nPhocifoolxodoh5oeyRnrnRpacrtka1ruaf4mEareePreejvv(sogrMfaeb2meu,srSp1rqRdf7edrenfpret3sCloss8thm.piuoeeRbyeolidnt.obrPta5ertenisaOi1rsoepacyheo8rssbx,tvdk0lodllfeoee.iopxowqaeaagaPyadonasrsutrieuigra7l2eohehcwmmeverdilraoao6ltaParipaahe5t1eaacrilsgktoanel0tsbnn1Cuienaatnh.hs5hhttVea5aldtn,sya5Vere.fbtewicslSao8Adsltg)drlt2uadfoyGhdiraoyerfnUvibtsiDviiiswrcsr£atmpue.oaostopnokreeasCi2nmtfrtalfaa,mme.rm.entAt9mltidrycesoYaeatesa.1tiat££l£er5tgnhtnadnebd2siaoy2ct3ori40tndeoegVeds"eeesai,s..,fr...f ccctedA5bpea0CfsrpIPibiNsoimaoVournirrvaHaOCbraooarenStcmdeit-eorOr/Amdtmtb2kU.tDceyeoekri0eeNaLiitngoLrWip.fCesnVaslsbnyfEllyA!gleElagv)Tvecvrycr.TDvsiaFLea'eowifovhicOsIolnCFrInncErmOloyeaaotyylgtEogrA'tonscsrNsPpdagmsCee.gu2eoDghAglegtof0Te3oveTsfeeSro£taeNairitnTeEgal.2cosdrretRaHEerteoaiS3hdePeeelaLEwclnMhTee,wfwnoxrdsmuA:gmasEiictetMtshtmcrieTsorle1ahRttvaoioesahttfEnksE3canfeion.fi£hPdiTn£RWdlddnrtgnmOae3i25hTEg.estg£xI,c0iwirseRethTT5i,olOlr.da,trasnleiH..iuonhornigeyteraaOehmi,TpnvrhdosMmbmealartohreotRuetadlindihUiperlulocernssesuytedeessskelsafLiRtgntr.at:lisgitTswfyesesdomRl37o£etydfI,ibaeaearMkb1eog5elrrrvnefo23euioaotPwneEna:asdew.Pnn.94eniTm5arraa1cle9giatdIPfEynr8aohteox,rtced2htRb8heelv-o£s4sgoaBet.lpaefr7aio6eosulelrtzd(I.rla.uek5ebaniasceittsr0ftsfsuntrdtlioriaBeaes6itsrowqsuwnrhn£ae5Ttmnturri.idi5rmtiatntuaitepThinhttIslmnrmreldehtsleucuoaygdspelolehlegoneweeasmeengfmacgaqtcaOiofasteosidtee.innonncsKnomastcsddnoho'aeI-,lr,-tt OallrTdrhearenRgsaeefms,3ePpmr1o7eb6taebrlyburtepslaigirhatblylefauWltey,suwpilpllynodtioagprearmat,e £o3n, TOUCH DIMMERS. 40W-250W. no knob to turn, just finger on front plate, will give more, or less light, or off Silver pswlaittecdh.o£n5,wOhridteerbRaecfk:g5rPo2u3n0d., right size to replace normal 6wd2O£PLvpRre9M1HarCoehraPo8tfdlDIiW:ad,1tvtLemey3iOIsrd0LP3hiereYnPRtSAtdeoe1»5emSeerf9rEtu/rePaDasRRt1SmoenIa.5eGpw.lgHfmPHIe:feIec1TrcGeesr16oailtH8,aimmseePuPluoarAmpe2pscrRu.NlnphfeinEsToiElntpiyeoSrehLnoflOpeefganvwoarLrMlorigsitabUctlhtyeEhrytehTesgrTimoIPesalEOcAfahrnoRaiN£s-induuDsl.e1inenkp2raiitTcM.smttitt,,onOohfuOpognfmibrushNrsvdlema.oleBIe.dTiuSrsrsrwetOp£suaeRe6einpRraute9chdppt.f.cu:l,mcihnbOBe1t£aieeedu2p3lswrsaPld0eawttc,17.eiesk-ii91srdOsrtt0hwair£l6Raanldef1nneuglet5idlfdlnoer.l, co1oBbmo5nnuUaWnlldyyMktdie££8inPrn41u'ONg5sep,HdyepOGMorahOrucpdikn8ageigSihnrrP.SgeRqAOP,lueeECorfcadAEftlfrei1KSteir5ycHrEPeiRaIR1dmPen.fu.;&aKst4ItiI3PclTre5.esc7sAsTepnWotwhtnrEaoedEnn,sTdgpEteoriRrvifcc.euelslMaopprafserdaetaeulsnbefdhoenir-tsafhailfooodanurnietsdas-, adnirde.ctsiohno.uKldit citosnttraikines aanll tohbejepcat,rtsitawnidllasyeot uonffgsitnerasnhoothueldr cswsatSeaapwuHGblheooonndsOnoeoerhresllmydudwarlLadeeikaccmerncAeeAmeea.oabrorrxRotPimclcibeptsirpenpheooarcdutlpeigelhiernmncWclnlntarosaeoce,fIgsps,nOtltedeTiu,.£levskealeROgan7haesaiestwlnt.KOefcerlu,5syludditbheI0yOersroawNleidam,incesurrwcitGeas'dohstattnbrhnpaefeecglRpdslatrmrehcicpsMhilcgRe,oehtaRribtekaheeesOn:yuielsibltrfn-ltisfry:Dhtcun:gsoow7imbutpEge9rp.7iuit,5abLPilunytallPtrup59Stwbssonhtgho1y.Pai.t.suyiecree.plr2ul.bstty2eNn3smecOertcr,eftwaheocaooiircnwmsreognatirdneleuedh-niule£oslsatltslserit1wMsdda.deca4toeRnyhoheahoPrlpdaortereyrnsnthrkvfaereoiioetcbrecathiyp7aAagaeonlnvv.leetllt5nayeeauoarsiPmnrtpsreiuei3ybe3leqqlnaha£ue.ftwuukblea8ootadTieilellP.roggtsel9pehenhure£tr:5esotaHe'tt2rhtwowhipea0kotleblefel.hibeeiarmolutirtlldnyheensr-,rlt
This is the C1 Bargain Packs List 2 - watch out for lists 3 and 4 next month.
3d2 exxr
BTRuaefnt:tien3r5gy.
Model Motors, Capacitors for
tiny, medium and large, Ormedium wave radios. Order
2f2RMxoe3xrifAnxb:Fiu3cae6ihtrl2u.dra5riinWetnegg1eS2soVl8mavbeaROrleAlcHlraeoaMyrnditaiwaolcsiV.tthOswa.rlrioitOdahwebrrdmlceReuererdfRrRi:eue6nemf1:sti5csw1oto.anrvssue.mcoiIndilgesa.cloIdilef.oa2rl
loudspeaker volume control. Order Ref: 69.
427in1xgx.
vWailrueews,ou1n8,d3V5.a5r0ia.b1l0e0Roehsmisst,oyrsouirncahnoyicoef. tOherdfeorllRoewf:30A Procelain Fuse Holders. Make your own fuse
2boxar6dY,»O" rMdeertaRlefF:a8n2.Blades for 5/16" shaft. Order Ref:
8M6a/6inYsa.Motor to suit the 6Y2" blades, Order Ref: 88
1 x 4.5V 150mA DC Power Supply. Fully enclosed so
q1R105uemfie:tea1Tcs1wha6finree,WdOiarrned,desrbcRlraeecfek:n1se0md4..aOllrsdiezreRCerfo:c1o2d2iAle Clips. Order
100 Plastic Headed Cable Clips, nail in type, several
6824t4dd2bMHMsC111ei0oeexxxxxixxxozsea0grra2temd3NSiBhM1SernxRRs0id3uCdCpeuus.PEeeA3A,b.olmpffOioTS/LeO::rOn8ePMwtcSrarB11erraaurdNWRwmedii66dnnanioer46PeuutipetesarrtTtr3ombMcrfvleRH"TochbRoenRMiikereycgoSceeSmfeHrapPrfglo:fpod:ott:eGleueooe1eec2SrSrn1la2rrrPk0mdS3ito3wk81TezAiue3.wVmneeteisruR,dgart-shibmc0.bat.Mq(TchVep1iSOuehlWseo1-tiitw,8oesrttWsgeydVsOr,igR's,LteOsl8cr.YrTaOeitdhocOrdaauReShderoAinndrrosemewn,dde.ef,rR)Oiea)rrMt.RbOer1rcOrRfde2ehdRrIaerlf6t,deki:f1sdebe:redef7eu1vra2o0R8rtyel11uR1ecRmod94bfeo1ue:lfolOfer:2o:s-K11out2p25wr4oa.7eb6ln.duec.,tkoOOenmyorr----t
6plexte Sracdreiowwdoitwh ncircTueitr,mOinrdaelsr Rwefi:th247th.rough panel in-
csL1d2111ou00Cexxxi0lrDlaxe2Rftx4xHCooPVe-errSGlfumos:a2usP.ct3h0biekOO3n0-rO9gsmDMrS..dnAiipEOesnpreLlPrela1dRoSamFkeneyUerfge,T;.rnRY2rOStIeaa,6nhf"rn4s:damfse3feifrtga6roetui0srdRn,.rmseerKfsee.vfrn3sOo4o9.Tlb3rtJ,ads.uOgefserortdrRr1eeiY0rgf0«:hRW"3te2s.fip9:fb.i3ynr5oda2uls.es,weOannr--t
c1axsMeda.iOnsrdInetreRrfeefr;e8nce Suppressor. Order Ref: 21.
3 x Rocker Switches. 13A mains voltage. Order Ref: 41.
1 x Mini Uni-Selector with diagram for electronic jig-
s2axwA. OpprldiaenrcReefT: h5e6rmostats, adjustable up to 15A. Order
R1 ext:M65ains Motor with gearbox giving 1 rev per 24 hrs.
O11R%0erx"fdx:Cse2Rpre9iorR5nau.edmnfl:dei8.cP9OoWrindatevererRCKehnf;ao3nb0gs3ef.oSr wfliattcthed.
V*" spindles, Order 12-pole. 3-way with
O1 rxdeTruRbeufl:a3r0H5 and Mike, suits cassette recorders, etc.
2 x Plastic Stethosets. take crystal or magnetic inserts.
order Ref: 331.
20 x Pre-set Resistors, various types and values. Order
Ref: 332.
611R0exxfx:CR3La3ero9vnTegyrpsSienhRgafotSecwdkeiKtrcnSho.wb2ist0cAfhoerds,Voua*"sbsflleoa-rtptteeoddle.sOpoirrnd4de0lreARs,esfiO:n3rgd3lee3-r.
4poxleS, kOirrldeedr RCeofn; t3r4o3l.Knobs, engraved 0-10, Order Ref;
332ew1 5nixx5txdh.LMs.lu1ea0Omai0ndri0sndsWoe,TruOrsRaTrndReufsebo:fruoc3Rklr7ame6erfre:SrH3w8Oe5iapttceinhrgeaste,EdOleNrdmieCeranRdtseCf;wh3ai7trh3g.etre,rcmaisneadl
2 x Clockwork Motors, run for one hour. Order Ref: 389
Prices include VAT. Send cheque/postal order or ring anOdArdqddueor£st3eopcvoreesrtd£ait2nc5daprpdoascntkufirmnegeb..er.
M & B ELECTRICAL
SUPPLIES LTD
Pilgrim Works (Dept. E.E.) Stairbridge Lane, Bolney,
Sussex RH17 SPA
Telephone: 0444 881965 (Also fax but phone first)
Callers to 12 Boundary Road, Hove, Sussex.
8
Everyday with Practical Electronics. January 1995
Diiin
suf yuiif
Easy to use, low cost data acquisition products that allow your PC to be used as a range of useful test and measurement instruments, or as an advanced data logger. Easy installation via a parallel port except the ADC-16 which connects to the serial port. They require no power supply. Take up no expansion slots. Each comes with a comprehensive manual. Software drivers are included for users who wish to write their own software. Software supplied on 3.5" disk.
PiCOScope 'Virtual instrument" software. PicoLog Storage scope with trigger, timebase, rulers and offset. Real time spectrum analysis with min/max frequency and signal averaging. Multiple meters on screen (digital and bargraph). Printer and file handling support.
Advanced data logging software package. Collect store, display and print data from one sample per millisecond to one per day. Record average, min/max or scaled values (linear, equation, table look-up). Report types; monitor (with min/max alarms), y-t graphs, x-y graphs, tabulation.
NEW SJst- /6 Logic Analyser
NEW /ive- 100 Virtual Instrument
Pocket sized 16 channel Logic Analyser
Connects to PC serial port, ideal for desktops or notebooks.
Supplied with easy to use software, power supply and cables.
High Speed -up to 50MHz sampling.
S*d?4-t6 with power supply and cables £219
· Internal and external clock modes.
· 8K Trace Buffer.
MHHSi-nmtSKiH*
Dual Channel 12 bit resolution
· Digital Storage Scope
/> e o
· Spectrum Analyser · Frequency Meter · Chart Recorder
· Data Logger
%
· Voltmeter
The ADC-100 offers both a high
sampling rate (100kHz) and a high
resolution. It is ideal as a general
purpose test instrument either in the
lab or in the field. Flexible input
ranges (±200mV to ±20V) allows the
unit to connect directly to a wide
variety of signals.
/fD^-tOO with PicoScope £199 with PicoScope & PicoLog £209
/I'd e-to
/tve-11
1 Channel 8 bit
Lowest cost · Up to 22kHz sampling · 0 -5V input range
11 Channel 10 bit
· Digital output · Up to 18kHz sampling · 0 -2.5V input range
The ADC-10 gives your computer a single channel of analog input. Simply plug into the parallel port and your
ready to go.
TheADC-11 provides 11 channels of analog input in a case slightly larger than a matchbox.
It is ideal for portable data logging using a "notebook" computer.
with PicoScope £49
PicoScope & PicoLog £59
/fDC-t t with PicoScope £85
PicoScope & PicoLog £95
Carriage UK free. Overseas £6
Oscilloscope Probes ( xl, xlO ) £10 Existing ADC 10/11/12/100.users can add PicoLog for £25
ADe-t2
ADe-ie
1 Channel 12 bit
8 Channel 16 bit+sign
· High resolution
· Highest resolution
· Up to 17kHz sampling · 2Hz sampling - 16bit
· 0 -5V input range
· ± 2.5V input range
The ADC-12 is similarto The ADC-16 has the the ADC-10 but offers an highest resolution of the
improved 12 bit (1 part range, it is capable of
in 4096) resolution
detecting signal changes
compared to the ADC- as small as 40 pV. Pairs
10's 8 bit (1 part in 256). of input channels can be
used differentially to
/fDe-JZ with PicoScope £85
reject noise. Connects to serial port.
PicoScope & PicoLog £95
/ve-te withPicoLog £115
ADC-10 Simply plug into the parallel port and your ready to go.
Pico Technology Ltd. Broadway House, 149-151 St Neots Rd, Hardwick, Cambridge. CBS 7QJ
Tel: 01954-211716
Fax: 01954- 211880
wsm m
Everyday with Practical Electronics. January 1995
9
MAGENTA ELECTRON C S L T D
135 Hunter Street Burton - on - Trent ^555 Staffs. 0514 2ST mmmmm Tel 0283 565435 Fax 546932 EE151
All Prices include V.A.T. Add £3.00 per order p &p
SHOP OPEN 9-5 MOIM-FRI. CLOSED SAT -- OFFICIAL ORDERS WELCOME
EPE MICROCONTROU-ER1
1000V & 500V INSULATION rSPACEWRITER
P.I. TREASURE HUNTER'
The latest MAGENTA DESIGN - highly 1
stable & sensitive - with jiC control '
of all timing functions and advanced I
pulse separation techniques,
|
· New circuit design 1994
· High stability drift cancelling
TESTER Superb new design. Regulated output, efficient circuit. Dualscale meter, compact case. Reads up to 200 Megohms. Kit includes wound coil, cut-out case, meter scale, RGB & ALL
i |
1 | .
wuiAtpPPnhprCrniseotoBthtjigraoen,uir"crnaac1Mtloam.t6linvEWocmddanRoitaasgiyRmvvbiofeYtelopsuertoarXlhtonmnomeMndeehwgenAseos.tsaxssSlCandca"&gidog.atemeitnKtnuhlyaeigobtrpsaomeipdnpueeic+rgnaselhugsr-sald.ogeaesded
[_KIT_849_£16,9Ew
components.
12v epr"om"eraser" '
' · Easy to build I & use ' · No ground I effect, works
KIT 848
£32.95
MOSFET Mkll VARIABLE BENCH POWER SUPPLY 0-25V 2-5A
Adtil(ino4aows0tlnaie0enafsmdlegs.sAtlSeohit)qwaau.ufnaeUcitt2pioyso0msenitdmnesentireewtnarxuslhtioeneteecrnrkstfse.hoipveOrmreueplfapvyieieenrtlfaondsotter4ssesumtcEcfpor.oPponbRAlmtiiaOlelecsasMotw1waS2ironieVtrahktensadUuo-uptVtiucp.mapally-e--
I in seawater
Based on our Mkl design and
· Detects gold, I
I
silver, ferrous & I
non-ferrous |
I
metals
I · Efficient quartz controlled
preserving all the features, but now with switching pre-regulator for much higher efficiency. Panel meters indicate Volts and Amps. Fully variable down to
,
microcontroller pulse generation. zero. Toroidal mains trans-
KIT 790
£28.51
Bi MOSFET 25V2.5A
POWER SUPPLY cAcpHolumaintgspthssrstioac.plgeVfkerrfiaotorsTmir.amobTr0aolw-eni2dcofaer5lopAdmmaenasRem0iglu-sn2gmt5grheaeanVtdessorfpmslootrsawimndaedeenrrid.ctMhaitcsOeuoSrVrnFeoeEnlTttosfloaioumnutdi-rt
I · Full kit with headphones & all hardware
LKIT_847_--£63.95j
former. Kit includes punched and printed case and all parts. As featured in April 1994 EPE. An essential piece
KIT 769
£56.82
AINrelSiaUbleLaAndTnIeOat NelecTtroEniSc TtesEteRr which checks
of equipment.
DIGITAL LCD THERMOSTAT AtscwhbphFnowauroaaaievnttvthuii.hw1etivrscrn1Preeeiedshgnn0ulsaoviyghunntaemi,delcgalnntieeehletttltgi,ieselcontl.rthdm.acwiiesnetc.Meadiuprdosan.mbehinadvrsodwiCoaitnitdpasotseisutnurdpwlrasirpatlenhiteiaalouatsleytueswyleda.,sadreteeilisMnalconrnseoegdaryegtIwdsrtsNacaeg.cbteca/b.oya1Mtmlnlhnn0oesdetAAssarrb".eoXuvmeSlpitIc,onidPopmssageCnteeqbaosetrtOulerrmwoatafposlorronh,ereirraodeilotrea,nbgrewsyehlara,ouehodolawtse-iumen1ecnertidhd0ne---r
KIT 845
£64.95
ULTRASONIC PEsTSCARER Keep pets/pests away from newly sown areas, fruit, vegetable and flower beds, children's play areas, patios etc. This project produces intense pulses of ultrasound which deter visiting animals.
m
KIT 841
£29.95 · KIT INCLUDES ALL
caai1notn0sld05ule0lsgMa0ateifeoVepgnroootlorhtjesem.scoitspsT.tehcareananctuee.nboietLf reiwesaaikrbdaiangtegetaesarriynelysd.pisaoAtpawnpveclerieeraydno,cpfesosuipmpeutplctal.oer,
KIT 444
£22.37
DIGITAL COMBINATION LOCK fAablDiolsouiuegasmrrrip,tdiaendolctiipoiugalemilobrtcaekkatcemneosytwoidp-ufeitartandohmt.moeppd1ee21rrr2eaVmctkei.eorsyctDeulairykti.lel2yepId5dpe0earmaVdcl.aicstsea1E,r6ntAhitbmeerrumirnsreogehlalbeayidya-.
PORTABLE ULTRASONIC ApsaooPpuausepcttEpcptoaeiuwnsachtyliTeaairsssnlfpSeuddeatl-ueCclhe2snieadi3eAgllkddnstHreeRattzdcrntaaiEsunntsdolesgtuRf.rogucaripesMvmo.reOeuwrnmS.diFatShExgwiTeminenueetoemprunaitnstpooeguurttpfipnruduelraqstieuvwcseeonismtvchiyaa--
COMPONENTS, PCB & CASE · EFFICIENT 100V
TRANSDUCER OUTPUT · UP TO 4 METRES
· COMPLETELY INAUDIBLE RANGE
TO HUMANS
· LOWCURRENTDRAIN
KITRef. 812
£14.81
KIT 840
£19.86
E.E. TREASURE HUNTER P.I. METAL DETECTOR
MKI Magenta's highly developed &
KIT 842
£22.56
DIGITAL CAPACITANCE ApMliereEdawlTlyiEthpRraopfeusnsciohneadl alnodokpinrigntepdrofjreocnt.t pKainteils, csauspe-, p.c.b. and all components. Quartz controlled accuracy of 1%. Large clear 5 digit display and high
'COMSTEP' P C. COMPUTER STEPPING AtAaDMonnlCdluoe.OswxhescausTPilptfiiCp/nOnfld.ugyselRloappfnrestotdnwejIdeppaNcerrtniemnTsttouceEdporepnlR.eltiraeCoFddl.oAwnonfiCtebhcoEtttswhtoom2oc0too0mrsspte-uptsepmreopetador,rasldl,ierilenctpetoirorftan.c, eRnebuqomuabirrdee,rsao1nf2dsVteeap1ssAy,
KIT 846 (with 2 motors) £62.99 (Printer lead £5.00)
acclaimed design. Quartz crystal controlled circuit MOSFET coil drive. D C. coupled amplification. Full kit includes ^ PCB, handle, ^ case &
·KIT INC HEADPHONES
speed operation. Ideal for beginners - as the pF, hF and pF ranges give clear unambiguous read out of tmoatrhkoeudsaannddsuonfmpaFr.ked capacitors from a few pF up
IONISER
search coil.
A highly efficient mains powered Negative Ion Generator that clears the air by
neutralising excess positive ions. Many claimed health benefits due to the ioniser
X
·EFFICIENT CMOS DESIGN
POWERFUL COIL
KIT 493
£39.95
removing dust and pollen from the air and clearing smoke particles. Costs virtually nothing to run and is completely safe in operation. Uses five point emitters.
DRIVE
efAmpwAonaareviglrCaelimsnnroysOeefcspcoa,hhoUfneapwaanubSadiclectapoTcsrhnh,apotIemarnisCocnp,etjslseitafprcPniuortedomrdwRbeahesaOnnpincatedhnaBeemdcpnhhEpigpecliaaikntfrsrsiedaeseurev.rscpesllS,etlvhiaoinaebruglmnrynaddttohisoUnrnnosofsturesoofgbeumhyyal parkersl.
KIT 707
£17.75
AtaiOBsolnltftohAaheewsexrcTscuinnetsohlaerDletemsinnlhaiEgtsal,ctvnT(iaehrecnruEbudtmeioCteiattwnnuTis)hfnoiepOacu-uohnidsnRdsribeitibodnleluteihrncateedonsuugisuledttlrr.etyanrOsatfoipsofnoeryiurvcavnitbfadirrnreiafgoqtriueuroqasentundhmecienfirofecelnsiirekieotseonftrbaiinetnryttagewpdreeeieotssect.rn.uesLc2iein0sigtveaentnrhidntihsg1ep0torc0oirjBkceHaucttizs.t
· DETECTS FERROUS AND NON-FERROUS METAL-GOLD, SILVER, COPPER ETC.
· 190mm SEARCH COIL · NO'GROUND EFFECT-
KIT 740
£19.98 KIT 814
£21.44 KIT 81 5
£45.95
HAMEG HM303 30 MHz DUALTRACE OSCILLOSCOPES. gccAwospWaSIMCtoaonrrshsaaoEpmcedmnartObisawNriorlet2cpaecplewTiounmsiotrMto,shltnonebyVIctmfrShe.oresEi/niePtacpda,gsOurtioteiShssnuvrOvU,,prptostreesoreeTptsleberdhcNseeiSindbuisiina'Tssssaeett3dgopilEcA0,tbcriliiesMastNhvaepsN,cynsieastDitHotdhoscryttmIkresoT.zsrNm,feaenaplGondbaartlohnsinCna.8nanifeendustageI.tadHtraonQxlwolIirtasgtUsssEbiu1l,cdcAsaopt0iotuenCulLehcdlssprcrIom,itt.TiepoKsesotYodcrIrrfaorseiEgtc,pOyebSfgrerdoRueFueaaueirp-cnlwinTtptndniaiHlgotoriwihneeInwmSdtioatbmahi-IuwnmtoN1wyyiri0pStineaohn0rTtloogMeltRyvothrthneeewHUaaaedsannz-srtrl. £(C3he9qu2e.s0m0ust"Ib"fi£dB6a8.R.r6il 0 VAT INnecxlut-ddeasyFdReEliEvery
EDUCATIONAL BOOKS & PACKS
oTsAcnhhD.eoNVocollEsas.osNVsldiTecerUyribnRwogeEolklUSislbWeluyssIatTrnTaHotSemdDE, EDLiCdEuebnaCrcleaTfaniRdrsbtOuobsaNeorddoI.Ck tSfhorrouaggeho1u0t Book SiComponents £28.95, Book only £7.25 AFnUUNsbWorInTeHbooEkL, EwConTdRerOfuNllyICillSustrated in colour. ComdpheeorlnpinengBt oipsoakncke&caeClslsooawmrysp6oApngreeonj1ets2cts£o2nto,0.bo8er8,ybouBiuolntogakenrodnwklyeitpht£. 2aSd.9ou5ll-t A3CB0iomrcoSoukrOiet&sLacdCDovvoEaemnrRcapLewodEnibSdeoeSnortkasBntoR£ge3fEo0oAl.fl6oDi9wn,BtethrOBeeosAtoostR.khDeorns.PlyNRo£O2sJo.9Eld5CerTinSg
DC MOTOR/GEARBOXES
apwrIadnritoedtihaojelscmc1tsaa.f.5onnr-yM4bein5ors.VotehbpteolrDuatspsC,.tmicembcguhoetgaaongrrbiiceoasx,l Small type MGS....E4.77
STEPPING MOTORS
For computer control via standard 4 pole unipolar
drivers.
MMDD33581«- -msintainatduarred4488ssteteppssppeerrrerevv
£9.15 £12.99
10
Everyday with Practical Electronics, January 1995
MAGENTA
MAGENTA
Teach-in '93
Teach-in '93
. ·> *»
MINI LAB KITS
ALL COMPONENTS TO ASSEMBLE THE EPE MINI LAB.
Follow this exciting educational series as featured in EPE through 1993.
Full set of reprints
£3.95
Components are supplied in packs to keep ordering simple.
A full MINI LAB consists of ML1, ML3, ML5,
ML6. These are available at a special
combined price of.
£119.95
or less the p.c.b.
ML2, ML3, MLS, ML6 at
£ 109.95
The transformer unit ML4 is also needed....£22.55
MICRO LAB KITS
ALL COMPONENTS TO ASSEMBLE THE EPE MICRO LAB.
A 6502 Microprocessor trainer with many features. Accompanied by an excellent set
of tutorial articles and a manual.
Repair/fault-finding help assured when you buy your kit from us.
Full MICRO LAB kit including PC Board,
EPROM, PAL, & Manual. "
MIC 1
£155.95
(Also available less PCB etc. if required).
Full set of reprints
£3.95
KIT ML1 MINI-LAB P.C.B. + all components
inclusive of breadboard for
Part 1 (Nov. '92)
£52.45
KIT ML2 All Components for Part 1 less
p.c.b
£41.95
KIT ML3 Power Supply components £20.95
KIT ML4 Transformer unit
£22.55
KIT MLS L.E.D. Voltmeter, signal
generator, audio amplifier and
555 timer
£35.65
KIT ML6 Logic probe, display, radio
tuner
£18.85
(Note: batteries not included)
All prices include V.A.T. Add £3.00 p&p.
Tel: 0283 565435 Fax: 0283 546932
Everyday with Practical Electronics, January 1995
BUILTS TESTED
Full MICRO LAB AS MIC 1 (above) MIC IB
£189.95
Professionally assembled, inspected, cleaned and tested. Full back-up service, spares, etc available.
All prices include VAT. Add £3.00 p&p. Tel: 0283 565435 Fax: 0283 546932
II
ESR ELECTRONIC COMPONENTS
Station Road, Cullercoats,
Tyne & Wear NE30 4PQ
Tel. 091 251 4363 Fax. 091 252 2296
432223333221117777777777777777777777777777777777777E7777777777777704846802677777777777777702487777767777744444444477777777444444777777774444444447777774444777777444474444444444444444444444444444444444N444444S4L444LLLLLLLLL44444444LLLLLSSSSS4444444L44LLLLLLLLSSSSSS44444LL4LLASS44444LLLL4LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLCLLLLLLLLLLLLLLLLLWLSLLLLLLLLWWWWLWSSSSSLLSSSSLLLLWWWWWWSSSLLLLLSSWWSLSSSSSSSSlSSSSASSSSSSSSSSSSSSSSSSSSSSSSlSSSSSSSSSSSSSSSSSSS5SSSSSSSSSSSSSS889997SS778SSSSS447SSS64SSO3SSW3333SSSSS333333S333323222222222222212222GGGG221GG1GGGGG111G11111GG11II11111M111360231I4111115652731111117011081111179991171177790175000006266140077267659445o2444640999977995766667561P45555554413333340231222217359110045809032345871I580196318477z12350526714503323450708E865347236895R423562379PRLEEe£L££££££££££££££££££££££Re£££££££££££££££££££££££££££££££££11£££££££1££££££00£££££££000000£££££££00l£££££££££000000000£££££££££E00£££££00000£££££££0000000££££££000000s00000000000000000000000..000000000.00000000.00000001000000000000000609000000..2.0.0001899.018901.6677D002...22,223.....33221..21626122..1763.....33.123..1....11212..3..2..332223.331.433...24221121222740...2293324092622213734343291722521257272331115362155215022491152332424222954121211221424454442226444224200444612444541144802426112845616645050116655754444433444249303355555444555533444444444444cc44444444444444444444444444444444444m444444mmmmmmm44444444mmmmmm44444444000444444444oo0570044444444555555554444445555534444445555544444445555555555000000000000000400000000000000000000000000mm111000041820000011000067824556000000m333"mmmm3000000mmm222mmmm221000000mm1111100018999997897888775777676666555634445044451234477933346222254100222216241356011120468111121178900000060687451223801mm45789931725668235901136783450179246804234530350136789692345107TO68902345YOYFBPGFPG026789R0RSoolllli0neeerrrreaaaaennaeeCalClddsssslglneeSnoohttachooOmLLiinn££££££££gg££££££ww£££££££ani£££££i£££££ccl££££££££££££££l££££££££££££££en££££££££EnE£££££1100o££££££££££££0100e0e00£££££o000££££££££0t02000£££££££££01000oe00££0000P0L00000L10000000010000000h00gB0000000gB00000D0u00D00.000000L00001L000.000u..00000r00n000000000.d0..0.3EL.E..46L3..753.T.4193422..o3..034433.6..r...43444.4..3.9e.21..Ee.E....2437425.r4..2215331i..t25132G12.3R...22191e3231244.3422E2D2523D23E32172645230431600117248625416130z14873dz141202223342013231001281De2766D008808O686687521070727671D402948103016182D51825De69e27040e25r1868781586e6407083907edllsiesD!pnl777LLLLL77777777ZTT77ETDaBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBRAAAAAABBBBBBBBAAABBB2222222222999922222228998888MM2882222222MyM22222222II0IICTVCCCCCCCCCCCCCCCCCCCCCCCNNNCCCNNNNNN1CCCCNLN01C0CLLLCCCCNNNNNN112CCCCLLDNN0CANCCNNNCDDCNNNNNNNCCCNEN1'R33A371110111211155125411111115111111111101220111112511011IY11113C641111333335131333333331112112232233122212G1128C788888e8874777777CV2445556704235555233340311005T011607001008789992882227777773804946799900222178643d61232341237012289V3947900826662450682819D9457787808U37710009KK678292000007015470T0251125EL94ORLLLL1BBB-DDD1AC1CB762945661052345634508927643A6363BBSLILAAAAA0AA0TB££££££££££££££££££££C££££££££££££££££££A££££££££££££££££££££££££££T£££££££££££££££££00000000000000000000000000000000100000010001103000000000000£000££000S£££££0000£0000£££££00££000000£££GO.££££££.........££££.££££££.££££1..£,00.120...11000001.1..11111140..401..200000.04433332200000033.11112199111500000011563243860001613435000113501157000030221296002228201128803E88888788618131226R..6118.6...6457.......66..377562426.11747070085070604909811100090..0.67020354130.51651011685019127594335342322222329627S4454648203083090690288688488888625449503
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42404242p211112777F2200020470000007000
£££££££000100006---.---..9251311V1023300·
£££££££££2000000000_5---..41010126V1108449293
££££££££££160000000003___...4106V1111122105926003
£££££££100000000___.01211111V5027000 _ _
45_0V £££££100001042396824
_ _
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12
Everyday with Practical Electronics, January 1995
EVERYDAY I
1
WITH PBflCTICflri
ELECTRONICS INCORPORATING ELECTRONICS MONTHLY
VOL. 24 No. 1
JANUARY '95
Editorial Offices: EVERYDAY with PRACTICAL ELECTRONICS EDITORIAL ALLEN HOUSE, EAST BOROUGH, WIMBORNE DORSET BH21 1 PF Phone: Wimborne (01202) 881749 Fax: (01202) 841692. DX: Wimborne 45314 See notes on Readers' Enquiries below-we regret that lengthy technical enquiries cannot be answered over the telephone. Due to the cost we cannot reply to queries by Fax. Advertisement Offices: EVERYDAY with PRACTICAL ELECTRONICS ADVERTISEMENTS HOLLAND WOOD HOUSE, CHURCH LANE GREAT HOLLAND, ESSEX C013 0JS Phone/Fax: (01255) 850596
BACK NUMBERS We have recently been carrying out some research into readers' views of EPE. in fact the process will continue for some time yet, probably culminating in a readers' questionnaire inserted in the issue. To those selected readers who have attended meetings or interviews, organised by the research company, thanks for your assistance and forthright views.
One or two points that came out early in the process have already started us thinking about improvements to the magazine and the first noticeable change can be seen in the introduction of our Back Numbers page. It appears that some readers are not aware of the availability of back numbers for EPE. In fact we carry past issues going back about five years; although some are sold out after a year or two we can always provide a photostat of an article from any issue published in the last five years. For full information on this service, and on the content of recent EPEs see our new Back Numbers page in this issue.
HELP Another point which has come out of our research is that a number of readers are not
aware that we can assist if you have problems with one of our projects, or even if you have a query on electronics theory or circuitry in general (although there are strict limitations on this general area which 1 will point out later).
If you have built one of our projects and you are having problems we can often answer brief queries on the 'phone (see above right for the editorial address and 'phone numbers). If the problem will take some investigation we ask you to write in with full details (and an s.a.e. please), we can then give the matter some thought and/or ask the designer to make some suggestions. But, please make sure you have read the article thoroughly and checked everything carefully before contacting us, also please read Shop Talk if it is a component buying problem. On the subject of more general queries not related to published projects, we can often help with these through our Circuit Surgery column, thanks to our "surgeon" Alan Winstanley. However, it is not generally possible to produce designs to meet the needs of individual readers and we cannot undertake to answer queries on commercial equipment or on the modification of equipment or designs. We are also unable to give advice on the purchase or use of commercial products.
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EwVinETRYDAlYii
uWDvOTOHHSTTRO0Wl iT!. ·
Borough, Wimborne, Dorset BH21 IPF. Tel: 01202 881749. Subscriptions start with the next available issue. We accept Access (MasterCard) or Visa.
BINDERS
Binders to hold one volume (12 issues) are now available from the above address. These are finished in blue p.v.c., printed with the magazine logo in gold on the spine. Price £5.95 plus £3.50 post and packing (for overseas readers the postage is £6.00 to everywhere except Australia and Papua New Guinea which cost £10.50). Normally sent within seven days but please allow 28 days for delivery - more for overseas orders.
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READERS' ENQUIRIES We are unable to offer any advice on the use, purchase, repair or modification of commercial equipment or the incorporation or modification of designs published in the magazine. We regret that we cannot provide data or answer queries on articles or projects that are more than five years old. Letters requiring a personal reply must be accompanied by a stamped self-addressed envelope or a self-addressed envelope and international reply coupons. Due to the cost we cannot reply to queries by Fax.
All reasonable precautions are taken to ensure that the advice and data given to readers is reliable. We cannot, however, guarantee it and we cannot accept legal responsibility for it.
COMPONENT SUPPLIES We do not supply electronic components or kits for building the projects featured, these can be supplied by advertisers. We advise readers to check that all parts are still available before commencing any project in a back-dated issue. We regret that we cannot provide data or answer queries on projects that are more than five years old.
ADVERTISEMENTS Although the proprietors and staff of EVERYDAY with PRACTICAL ELECTRONICS take reasonable precautions to protect the interests of readers by ensuring as far as practicable that advertisements are bona fide, the magazine and its Publishers cannot give any undertakings in respect of statements or claims made by advertisers, whether these advertisements are printed as part of the magazine, or in inserts.
The Publishers regret that under no circumstances will the magazine accept liability for non-receipt of goods ordered, or for late delivery, or for faults in manufacture. Legal remedies are available in respect of some of these circumstances, and readers who have complaints should first address them to the advertiser.
TRANSMITTERS/BUGS/TELEPHONE EQUIPMENT We advise readers that certain items of radio transmitting and telephone equipment which may be advertised in our pages cannot be legally used in the UK. Readers should check the law before buying any transmitting or telephone equipment as a fine, confiscation of equipment and/or imprisonment can result from illegal use or ownership. The laws vary from country to country: overseas readers should check local laws.
Everyday with Practical Electronics. January 1995
13
Constructional Project
MAGNETIC
FIELD
J
DETECTOR «=
ANDY FUND
--=
How exposed are you to alternating magnetic fields'? Build this simple audio/visual detector to locate any "hot spots " around your home.
WE are constantly surrounded by
magnetic fields of various types and strengths. Some, like the Earth's own field or those from devices containing permanent magnets, are static in nature. Modern man. however, is ever more often exposed to a variety of alternating magnetic fields of various frequencies, emanating from the huge variety of electrical and electronic devices which now form an integral part of modern living. Over the last few years these fields have became a source of concern to some people, who feel that constant exposure to them may constitute a hazard to health. A vast amount of research on this has been carried out, much of it by the electricity authorities who are understandably concerned about the safety of their product, but to date results have been inconclusive. However, since these fields cannot generally be seen, felt or heard, a means of detecting them may be useful to those who wish to minimise their exposure to this sort of risk. The strength of a magnetic field diminishes rapidly with increasing distance from the source so, if one knows it is there, it is relatively easy to avoid spending long periods close to it.
flow through the insulator, depending upon its conductivity and the applied voltage. To
detect such a field, electrodes followed by an amplifier with a very high input impedance would be required.
Electromagnetic fields, on the other hand, are the magnetic "lines of force" surrounding the flow of current through a conductor. These are much increased in strength if the current is flowing through a coil where, in effect, the same current is flowing through lots of conductors, each adding to the overall field.
In an average house the voltages are
comparatively low, so there will not be much in the way of electrostatic fields to
worry about. There will usually be plenty of examples of current-carrying coils, however. often in close proximity to the occupants. Consequently, exposure to alternating magnetic fields, mostly of 50Hz mains frequency, is likely to be high.
Sources include motors, transformers, fluorescent lamp chokes and the house wiring itself, often surrounding the user on every side. The household electricity meter should not be forgotten either. This contains several coils generating magnetic fields for driving the aluminium disc that increments the dials, and a considerable amount of this field escapes into the surrounding space. A recent TV documentary centred upon the possible hazards of long periods spent near an electricity meter.
SENSITIVITY Most of the common magnetic fields can
be detected with this easy-to-use Magnetic Field Detector project. When brought towards a source of alternating field, it produces an audio tone of rising volume and displays a visual indication of relative strength on a ten-step l.e.d. bargraph. This
FIELD EFFECTS On being told that the author's current
project was a magnetic field detector, a number of people responded by saying "You mean from power lines?" Well, power lines do generate magnetic fields, but the chief radiation from the National Grid Company's transmission system is probably electrostatic. A brief explanation of the difference is in order before proceeding.
Electrostatic fields are produced by voltage. A high voltage applied across an insulator, such as the air between a 400kV powerline and the ground below, generates an electrical stress. Minute currents will
14
4 Everyday with Practical Electronics. January 1995
has a "logarithmic" response which compensates for the non-linear relationship between field strength and distance from source, and provides coverage of a very wide range of field strengths. It should be noted, however, that the instrument is not calibrated in terms of Tesla values.
At the low end. the instrument is very sensitive indeed. The lowest l.e.d. normally flickers as it is carried around with movement relative to the earth's force-field. When placed against a quartz analogue watch it pulsed strongly at one hertz, in time with the field generated by the watch's internal stepper motor. Since this runs for over a year on a single tiny battery, the field being sensed is obviously very weak indeed.
A useful side-effect is that permanent magnets within equipment can easily be detected. So long as the instrument and
magnet are moving relative to each other a reading appears. As soon as the motion ceases output stops. Quite small magnets can be detected at ranges of up to a foot in this way.
When setting out to design this instrument, the first decision concerned the element to be employed for field sensing. Hall effect devices were rejected as perhaps being insufficiently sensitive, leaving a coil
of some kind as the most viable cheap option.
Plenty of turns were obviously necessary and experiment suggested that for low-frequency use, something with a large iron core would be preferable. Excellent results were obtained using an old relay coil of about 500 ohms d.c. resistance but these are not, of course, generally available "off the shelf ".
A lot of 36s.w.g. wire wound upon a nail also worked, but not as well as hoped. Thinner wire might have brought improvement, but would have been difficult to handle. The characteristics of the iron from
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Fig. 1 Basic block diagram for the Magnetic Field Detector.
which nails are made may not be consistent either! Finally, a small, cheap transformer was chosen for the task.
An interesting aspect of this project has been the discovery of the extent to which magnetic flux leaks from small transformers. Efficiency in this area is not their forte! Fortunately, flux leaks into them just as well as it leaks out, resulting in a most effective sensor for field detection. They are even reasonably directional, having greatest sensitivity in line with the winding axis.
HOW IT WORKS
A simple block diagram of the project appears in Fig. 1. The primary winding of the transformer is used as the signal source, and is coupled into a high-gain amplifier with a frequency response extending well below the normal audio range. This is followed by a rectifier which drives the visual and audio output circuits.
It will be of interest to know that at one point the display was going to be a movingcoil meter. This was abandoned when it was realised that, being an electromagnetic device, the meter would give rise to all sorts of feedback instability problems! Its type and positioning would have been critical.
The full circuit diagram for the Magnetic Field Detector is shown in Fig. 2. Transformer T1 is the sensor, with the primary winding used as the input. The "detected" input signal passes through capacitor C1 to
the inverting input of op.amp ICla which is configured as an a.c. amplifier having a voltage gain of about 200 and a frequency response extending to below 10Hz. Diode D1 ensures rapid settling when the instrument is first switched on.
The output from ICla is rectified by the circuit around op.amp IClb, which senses the peak positive value of the waveform input to it. Resistors R9 and RIO give this stage a gain of two, so with an a.c. input of one volt peak-to-peak, with a peak positive value of 0-5V. produces an output of IV d.c.
Preset potentiometer VRI facilitates adjustment of "zero" to just above the negative supply voltage, close to the threshold of the first display l.e.d. Resistor R8 and diode D2 prevent large negative excursions of the input voltage to IClb which might otherwise cause unpredictable results, whilst R11 and C8 reduce ripple, noise and jitter in the output signal.
Bargraph driver IC3 is an LM3915 which is the "log-scale" version of the
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Fig. 2. Complete circuit diagram for the Magnetic Field Detector. The secondary winding of detector " transformer T1 is left unconnected.
Everyday with Practical Electronics, January 1995
15
linear LIVI3194 chip. It has a full-scale input of about l '25V, as set by an internal reference voltage generator. Resistor Rl2 sets the current to each illuminated l.e.d. to about I OmA. The ten outputs of IC3 sink the ten cathodes (k) of the bargraph l.e.d. array D4 to Dl3. which has all anodes (a) connected to the positive supply.
From Rll the signal also goes to IC4 which has a gain of about eight to produce full output from the peak input signal. The 3130 amplifier IC4 was chosen in order to obtain the highest output voltage possible, to generate maximum volume from the piezo sounder WD1 used for the audio output. The 3130 output can swing to within millivolts of either supply rail.
Preset VR2 allows the output of this stage to be adjusted to the audio threshold.
To turn the voltage into an audio signal, two CMOS analogue switches. IC5a and IC5d, connect the input of sounder WD I alternately to the output of IC4 and to the negative supply rail at a frequency of about 4kHz. This results in a signal having amplitude dependant upon the output voltage from IC4. Analogue switches lC5b and IC5c are used to form an oscillator for driving IC5a and IC5d.
Power for the circuit is supplied by a 9V PP3 battery. Regulator IC2 supplies a steady 5V to IC1 to ensure stable operation. This is also used by the two threshold adjusters to minimise drift of their settings.
CONSTRUCTION
AND TESTING All components for this design, including
the display and sounder, are mounted directly onto a printed circuit board (p.c.b.). So that the design can be fitted into a compact case, with the l.e.d. display protruding through a hole cut in the side, construction has been designed to be as "low-profile" as possible. To protrude through the hole, the display must stand slightly proud of all the other components when fitted.
The electrolytic capacitors Cl, C2, C3, C6 and C7 are all placed horizontally. Capacitor C6 would still be too high, so a square hole in the board is provided for it. Regulator IC2 and capacitor C9 can also be positioned horizontally if preferred.
Capacitor C8 is a lOOn polyester layer type. These vary in height according to their voltage ratings, so if the one to be used is too tall this may also be placed on its side. In order to maintain a low profile, sockets are not used for the i.c.s, which are soldered directly to the board.
The p.c.b. component layout and full size copper foil track master pattern are shown in Fig. 3. This board is available from the EPE PC S Service, code 923.
Construction should commence with the fitting of the link wire and the resistors, presets, capacitors, sounder WD I and the l.e.d. bargraph-array D4 to DI3. Care should be taken with the polarities of the electrolytic capacitors and the diodes, especially with capacitor C9 as the marking on tantalum beads is often difficult to read.
The anode side of the l.e.d. array, which should face capacitor C6, should be on the side of the device carrying the identity markings but constructors may prefer to check this before installation as-a mistake would take time and effort to rectify.
Sounder WD1 and the larger electrolytics can benefit from a spot of glue to secure them in place to prevent rattles!
Before any i.c.s are fitted, the circuit can be powered and checked to ensure that the supply current taken is negligible. This is
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a useful test to verify that everything is satisfactory so far. If a heavy current is taken, it could be due to shorts caused by poor soldering, or incorrect polarity of
capacitors C6 or C9. Following this test, regulator IC2 can be fitted and the 5V output of this verified as present and correct. The total drain current should then be about 4mA.
When op.amp IC1 is soldered into place, the supply current should rise to about 5mA. The voltage at pin 1, ICla output.
should be about 2-5V. The positive side of capacitor C7 will be close to 0V. but should be.adjustable by preset VRI to between 20mV to lOOmV. Touching the circuit input (the positive side of capacitor Cl) may cause a small voltage increase
across capacitor C7, depending upon the local "hum" level.
IC3 should be fitted next, noting that it is oriented the opposite way to the others, i.e. pin I at bottom right instead of top left. When the board is first powered, a dot of
I
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The completed circuit board wired to the "field" sensor transformer
16
Everyday with Practical Electronics. January 1995
m0*>
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Layout of components inside the case.
A CIRCUIT BOARD
WD i
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Fig. 4. Interwirlng to all off-board components.
light will probably flicker along the display as the circuit settles. One of the lower l.e.d.s may remain on.
Preset VR1 should be adjusted carefully so that the lowest l.e.d. just ceases to glow.
Touching the input will probably now produce a reading on the display. The onchip reference voltage of IC3, about I ^SV, should appear across resistor R12 but it is not necessary to check this unless problems are experienced.
AUDIO STAGE Progressing to the audio side, IC4 should
be soldered in next. This chip, and ICS are both CMOS devices, so the usual handling precautions are advised to prevent damage.
The output from IC4 pin 6 should be variable by preset VR2 between zero and about 40()mV, Starting at the high end. it should be adjusted downwards until it just reaches zero.
Here again, touching the circuit input at capacitors C1 may produce a rise in output voltage. The setting of preset VR1 influences the setting of VR2, so these two adjustments must be carried out in sequence.
Finally, ICS can be fitted. There should now be a "bleep" with the flicker of the bargraph when power is applied, and touching capacitor C1 should produce both audio and visual outputs. The overall supply current depends on what is being driven, but as a rough guide it will be about 10mA to 15mA when the display is not illuminated, rising to around 30mA when an input is present.
ENCLOSURE
The general layout in the case can be seen from the photographs, and the various wiring connections are shown in Fig. 4. The transformer is mounted on an aluminium bracket, steel being inadvisable as it could distort the field being sensed.
The transformer primary winding is connected to the circuit input and the secondary is left unconnected. It is essential that the secondary leads should not touch, however, as this would seriously reduce sensitivity. They can be cut short and insulated if necessary. The transformer melalwork is connected to the negative side of the input to reduce stray pickup.
A hole is cut in the case for the bargraph to project through, and the position of the p.c.b. is adjusted with four screws, one at each corner, with nuts either side for accurate height setting. A small slide switch. SI, provides the power on-off function.
PRACTICAL USE
In use, the instrument is simply switched on and pointed towards suspected sources of alternating magnetic field. Constructors will probably be surprised at some of these. Most of the small plug-in power supplies so common these days radiate strongly and can be detected from well over a foot away.
Electric fan motors produce strong fields. Some dimmer switches are quite strong sources when operating, probably because of their suppression chokes. Fluorescent lamp chokes are strong producers.
Fridges and freezers seem relatively lowlevel in comparison, probably because of
Everyday with Practical Electronics, January 1995
COMPONENTS
Resistors
R1, R2,
R6, R14 10k (4 off)
R3
2k2
R4
470k
R5. R13 47k (2 off)
R7
470
R8, R11 100k (2 off)
R9, RIO 5k6 (2 off)
R12, R15 1 k (2 off)
R16
68k
R17, R20 22k (2 off)
R18
82k
R19
1 M
All 0 6W 1' 'o metal film
See TALK Page
Potentiometers VR1, VR2, 10k horizontal preset.
(2 off).
Capacitors
01, C2,
C3, C7 lOp radial elect. SOV
(4 off)
C4, C5,
CIO 10n monolithic ceramic
(3 off)
C6
470p radial elect. 16V
C8
10On polyester layer
C9
2p2 tantalum bead. 35V
C11 1 n polyester layer.
Semiconductors D1, D2, D3 1N4148 silicon diode D4 to D13 10-segment bargraph l.e.d. array, red IC1 LM358 dual op.amp IC2 78L05+5V 100mA voltage regulator ICS LM391 5 log. bargraph display driver IC4 CA3130E CMOS op.amp. IC5 4016B CMOS quad switch
Miscellaneous
T1
6V-0V-6V 100mA sub-min.
mains transformer
WD1 piezo buzzer, p.c.b.
mounting
SI
s.p.s.t. slide switch
Printed circuit board available from
EPE PCB Service, code 923: two-part
plastic case with aluminium front and
back panels, size 153mm x 84mm x
39-5mm (w x d x h): 9V PP3 battery,
with clips: multistrand connecting wire:
aluminium bracket: mounting nuts and
bolts: solder etc.
Approx cost guidance only
<c Si *23
their steel cases, whilst the electricity meter
often basks in a field that can be picked up
at several feet. Those living in terraced
houses may find high-level "hot-spots" on
walls where their neighbours have ap-
pliances on the other side!
Of the other sources that can be detected,
it will probably be noticed that the lowest
l.e.d. flickers a little when the instrument
is carried around, even outside and well
away from any known source. The instant
it is put down, this will usually stop. The
most likely cause of this effect is movement
through the earth's magnetic field.
Magnets of any description moving
nearby will cause a strong response.
Finally, as mentioned earlier, a quartz
analogue watch usually has a stepper
motor with a coil that is pulsed once a
second, and when placed very close, instrument may be able to detect this.
the
17
Constructional Project y
MOVING
DISPLA Y METRONOME
r
m
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w
CAROL JACKSON
\
There is no need to miss your cue, its just a
matter of timing.
A pendulum effect metronome using l.e.d.s
The traditional mechanical metronome, with its weighted swing-arm provides an audio and
visual indication of beats per minute, but many simple electronic metronomes often
overlook the visual aspect, with at best, a flash from an l.e.d. on every beat.
The Moving Display Metronome described here fills this shortfall. It's based on 'a 4067 I6-Channel analogue multiplexer/ demultiplexer with a 10 l.e.d. display. When the arm of a mechanical metronome swings from side to side it appears to slow down towards the end of its travel. To
simulate this motion electronically, the
outer l.e.d.s of the display stay on for longer. This produces an effective moving dot display similar to its mechanical counterpart. The metronome "clicks" are produced by a piezo electric buzzer.
CIRCUIT
DESCRIPTION The complete circuit diagram for the
Moving Display Metronome is shown in Fig. I The heart of the circuit lies around IC3 which acts like a 16-way, single-pole switch. To achieve a pendulum motion, the outer l.e.d.s need to stay on for longer
than the ones in the middle. With 10
l.e.d.s this leaves six spare in/out positions on IC3 and these are used to delay the outer l.e.d.s.
By wiring l.e.d. D1 to outputs Y0 to Y2 (IC3 pins 9, 8, 7) and D2 to Y3 to Y4 (pins 6, 5). D1 is on for three clock pulses and D2 is on for two clock pulses. L.E.D.s D3 to D8 are on for one clock pulse and D9 and D10 are wired the same way as Dl and D2. Thus it appears that the metronome is
slowing down at the end of each travel. The l.e.d.s are incremented by applying a
4-bit binary count sequence to IC3 inputs AO to A3 (pins 10. II, 14 and 13). A 4516 4-bit binary up/down counter, IC2, is used for this purpose.
After IC2 counts up to 16, the count must be reversed to change the direction of the l.e.d.s. This is achieved by using half of IC4. a 4013 dual D-type flip-flop, which
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18
Everyday with Practical Electronics, January 1995
is wired to provide a toggle action when clocked.
When the count reaches 16, pin 7 of IC2, goes low for one clock pulse. This pulse is inverted by f.e.t. transistor TRI and fed to pin 3 of IC4a. This toggles the flip-flop and sends IC4a pin I low. Pin 10 of IC2 is now low for the next 16 clock pulses, therefore providing the down count. When the count reaches 0, pin 7 of IC2 goes low again for one clock pulse, which toggles IC4a pin 1 high, causing the count to change direction again.
COUNTING SPEED
The speed of the count sequence is controlled by IC1, a 7555 low power CMOS timer. This configuration provides an equal mark-to-mark space astable output.
Assuming the output, pin 3, of ICI is low and capacitor C1 is at half the supply voltage, C1 will continue to discharge through resistor R1 and potentiometer VR1. When the voltage on C1 falls to a third of the supply voltage, trigger input, pin 2, sets an internal flip flop and pin 3 goes high. Capacitor Cl now charges up through Rl and VR1, until two thirds of the supply voltage. The threshold input, pin 6. then resets the internal flip flop, where Cl will once again discharge, thus creating a square wave output.
By varying potentiometer VRI, the clock frequency, and therefore Beats Per Minute (BPM) increases or decreases. With the components shown the BPM ranges from approximately 20 to 270. The range is slightly larger than a normal metronome's to allow for component tolerances.
* %
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HMIJIII
Comparing the old pendulum type metronome with the new I.e. d. version.
The metronome "clicks" are produced through a small solid-state buzzer WD1. When D1 or D10 are illuminated, a pulse is sent to pin 11 of IC4b, via diode-OR network, Dll, D12 and resistor RI4. IC4b is configured as a positive edge triggered monostable.
When pin 11 of IC4b is triggered the Q output (pin 13) is set high and capacitor C2 starts charging through resistor R15 until the voltage on C2 is high enough to reset pin 13. When this happens, C2
is rapidly discharged through diode DI3. This ensures that the pulse width of the metronome "click" is constant, regardless
of the clock pulse width. Pin 13 of IC4b is fed to WD1. via transistor TR2.
Capacitors C4 to C6 provide power
supply decoupling. The average current consumption of the unit is 7mA. An ordinary 555 timer can be used in place of the CMOS 7555 (ICI). If this is done, the current consumption will rise by 3mA.
COMPONENTS
Resistors
Rl, R14 10k (2 off)
R2, Rl 5
100k (2 off)
R3
4k7
R4 to R13 Ik (10 off)
All 0-25W 5% carbon film
See TALK Page
Potentiometer
VRI
220k min. rotary carbon, lin.
Capacitors
Cl
1 p polyester
C2
470n polyester
C3, C5, C6 10On monolithic ceramic (3 off)
C4
470p radial elect. 16V
Semiconductors
DltoDIO 3mm red l e d. (10 off)
D11 to D13 1N4148 signal diode (3 off)
TRI, TR2 VN0610L n-channel f.e.t. (2 off)
ICI
7555 CMOS timer
IC2
4516 CMOS 4-bit up/down binary counter
ICS
4067BEY CMOS 1 -of-16 analogue switch
IC4
4013 CMOS dual D-type flip flop
Miscellaneous
B1
9V PP3 battery, with connecting clips
WD1
low-profile p.c.b.-mounting buzzer
SI
sub-miniature s.p.d.t. slide switch
Printed circuit board available from EPE PCS Service, code 925; plastic case to choice; 8-pin d.i.l. socket: 14-pin d.i.l. socket; 16-pin d.i.l. socket: 24-pin d.i.l. socket: l e d. clipsoptional (10 off); solder pins (4 off); multistrand connecting wire; p.c.b. mounting nuts and bolts: solder etc.
Approx cost guidance only
£20
Everyday with Practical Electronics, January 1995
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Layout of components on the completed printed circuit board.
19
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IC2 WwwBvWS
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TR1
a <1 f ·+N «a
0 .^i R3
a3Bm^' r ti
V
0 J
I U
I
Fig. 2. Metronome printed circuit board component layout and full size underside
copper foil master pattern. Note: the insulated link is soldered to the copper track side. Also shown (right) are thepinouts for the l.e.d.s, diodes and fe ts.
CONSTRUCTION The Metronome circuit is built on a
single-sided printed circuit board (p.c.b.). The underside copper foil master pattern and component overlay are shown in Fig. 2. This board is available from the EPE PCB Service, code 925.
It's not critical which order the components are fitted, but you will probably find it easiest to fit the smallest parts first i.e. seven wire links (insulated link inserted
later), resistors and diodes and so on. Transistors TR1 and TR2 should be fitted last.
Make sure components such as diodes and l.e.d.s are fitted the correct way round. Pinouts for these and the transistors are also shown in Fig. 2. Transistors TRI. TR2 and ICl to IC4 are CMOS devices and the usual handling precautions should be observed. Buzzer WD I is a low profile p.c.b. mounting type, with the polarity marked on the underside of the casing.
PP3 BATTERY CUP NEGATIVE (BLACK 1 ~a--EZTPOSmVEIREDI
JJl
Tor-
+W·D 1
ies
-·
VR 1
CIRCUIT BOARD
SHAFT FACING FORWARD
|EEt$260 I
Fig. 3. hterwiring from the battery dip, beat control VR1 and on/off switch SI to the p.c.b.
FLAT L_
STANDARD 3mm l.E.D.
VIEWED FROM BELOW SODGURARATCINEE
Once all the components have been fitted, place an insulated wire link from the drain (d) of TR2 to the negative side of the sounder WD I on the track side of the p.c.b., see Fig. 2. Next, wire the slide switch SI. PP3 battery clip and VRI to the p.c.b. as shown in Fig. 3.
TESTING
Before you switch the Metronome on.
check that the components and i.c.s are
insterted correctly and there are no solder
bridges or splashes on the underside of the
p.c.b.
With the battery connected and the sup-
ply switch on, the l.e.d.s should appear to
move like a pendulum. If nothing happens,
disconnect the battery, and check your
wiring. If any of the l.e.d.s don't illuminate,
they're probably the wrong way round.
Check the fe d. pinouts. shown in Fig. 2,
When the two outer l.e.d.s light a click
should be heard from WD1. If there is no
sound, check the wire link from the drain
of TR2 to the negative (- ve) side of WD I.
If this is OK. WD1 might be the wrong way
round.
Adjusting VRI in a clockwise direction
should increase the speed of the display. If
the opposite VRI.
is
true,
check
the
wiring
to
20
Everyday with Practical Electronics. January 1995
EXPRESS COMPONENTS
fMAINS IONIZER KIT Very useful kit that increases the flow of negative ions, helps clear cigarette smoke, dust, pollen etc. Helps reduce stress and respiratory problems. £15. kit, £20 I built. COMBINATION LOCK Electronic 9 key combination lock suitable for alanns, cars.houses etc. easily programmable. Includes mains 2Arelay o/p. 9v operation. £10 kit, £14 built. VARIABLE POWER SUPPLY Stabiized, short circuit protected. Gives 3-30v DC at 2.5 A, ideal for workshop j or laboratory. £14 kit,£18built. 24VAC I required. LEA D ACID CHA RG ER. Two auto-
I matic charging rates(fast and slow), 1 visual indication of battery stale. Ideal J for alarm systems.emergency lighting, I battery projects etc. £12 kil,£16 built. PHONE LINE RECORDER.Device that connects to the 'phone line and I activates a cassette recorder when the I handset is lifted. Ideal for recording I 'phone conversations etc!. £8 kit, £12 I built. ROBOT VOICE. Turns your voice | into a robot voice! answer the phone I with a different voice!. £9 kit, £13 I built. PHONEBUG DETECTOR Thisde1 vice will warn you if somebody is I eavesdropping on your'phone line. £6 I kit £9 built. ] PHONEBUG. Small bug powered by I the telephone line. Only transmits when I the phone is used. Popular surveilL lance product.£8 kit, £12 built.
STROBE LIGHT. Bright strobe light with an adjustable frequency of 1 -60hz. (a lot faster than conventional strobes!) £16 kit, £20 built. 4W FM TRANSMITTER. 3 RF stages, audio preamp. 12-18vDC. Medium powered bug £20 kit, £28 built. 3 CHANNEL LIGHT CHASER 3x 800w output, speed and direction controls. can be used with 12 led's (supplied)orTRIACS formains lights (also supplied). 9-15v DC. £17kil, £23 built. 25W FM TRANSMITTER 4 stage, a preamp will be required (Our preamp below is suitable) £79 built.(no kits). SOUND EFFECTS GENERATOR Produces any thing from bird chips to sirens! add sounds to all sorts of things £9 kit £13 built. FM/AM SCANNER Well not quite.you have to t urn Uie knob yourself but you will hear things on this radio (even TV) that you would not hear on an ordinary radio! A receiver that covers 50-160M HZ both AM and FM. Built in 5w amplifier. £15 kit, £20 built. CAR ALARM SYSTEM. Works on vibration and/or voltage drop from door etc being opened Entry and exit delays plus adjustable alarm duration. Low cost protection! £12 kit, £16 built. 15W FM TRANSMITTER 4 stage, high powerbug.You wilI need a preamp for this (see our preamp below which is ok) £69 built, (no kits). 1W FM TRANSMITTER. 2 stage including preamp and mic. Good general purpose bug. 8-30VDC £12 kit.£16 built
50 I/C's for £1.50 Nice mix of chips at a bargain price! CERAMIC CAPACITOR PACK Good mixed pack of 100 capacitors
for just £1.00 ELECTROLYTIC PACK 1 100 small mixed electrolytic
capacitors just £1.00 ELECTROLYTIC PACK 2 50 larger electrolytic mixed
capacitors RESISTOR PACK NO 1 250 low wattage resistors, ideal for most projects etc. Just £1.00 RESISTOR PACK NO 2 Hi wattage pack, good selection of mixed wattages and values 50 in all, bargain price just £1.00
PRESET PACK Nice selection of 25 mixed preset
pots for just another £ 1! RELAY PACK NO 1 6 mixed relays for £1, thats just 17p
each. CONNECTOR PACK 10 different connectors, again for £1
FUSE PACK NO 1 40 mixed 20mm fuses, ideal for repairs etc, or just to stock up the
spares box! Just £1.00
FUSE PACK NO 2 30 mixed 1.25" fuses again ideal for
spares etc. Just £1.00 WIRE PACK
25 Metres of insulated wire for just £1.00, good for projects etc. SLEEVING PACK
100 assorted pieces of sleeving for connectors etc. Yours for just £1.00
DIODE PACK 100 assorted diodes for just £1.00
LED PACK 20 light emitting diodes for £1.00
TRANSISTOR PACK 50 mixed transistors, another bargain
at £1.00 BUZZER PACK 10 things Uiat make a noise for just
£1.00! POT PACK 10 pots for £1, (5 different types) a snip at £1.00 DISPLAYS 10 seven segment displays for
£1.00 ORDER 10 PACKS OR MORE
AND CHOOSE ONE FREE PACKII
FREE COMPONENT CATA LOGUE WITH EVERY ORDER!!
BULK PACKS
KITS 'N MODULES
PREAMP MIXER 3 channel input, about a month on one independent level and tone controls. 1.5v battery. Frequency is
Post LIQUID LEVEL DETECTOR low a telephone conversation withoutl Useful item, can be used to detect holding the handset to your ear! £11 kit I
Ideal for use with the hi power FM set to drive away mosquitos etc. £7 kit, tluid levels in watertanks, ballis, ponds £15 built.
transmitters £15 kit, £19 built.
£11 built.
TREMBLER ALARM Designed for 3 CHANNEL SOUND TO LIGHT.
bikes etc, adjustable sensitivity, preset Can be used anywhere as no connection
fishtanks etc. Could also be used as rain alarm with an easily constructed sensor. £5 kit, £9 built.
SWITCH PACK 10 switches for just £1 00
alarm time, auto reset. Could be adapted is made to hi fi. Separate sensitivity FM TRANSMITTER Miiu FM trans-
for all sorts of "borrowable" things £12 controls for each channel,
kit.£16 built.
1,200WpowerhandIing. Microphone
ULTRASONIC RADAR A project included £14 kit. £19 built.
that can be used as a movement detector MINI METAL DETECTOR Detects
in an enclosed space. Range about 10 pipes,wires etc up to 20cm deep Use-
mitter 2 transistor, comes with FET
m mature mic and is tuneable from 63 to 12v FI X)U RESCENT A useful kit that I
130MHZ. £7 kit, £11 built
will enable you to light large flourescent I
FUNCTION GENERATOR Gener- lubes from your car battery etc. 9v mains I
ates sinusoidal, saw tooth and square transfonner required. £8 kit, £12 builtT
metres, 12vDC. Good basis for ful before you drill those holes! £8 kit.
car.shed,caravan alarm etc.£ 14 kit, £ 19 £12 built.
built.
0 5 MINUTE TIMER Simple time
wavefomis from 201iz up to 20kliz. Separate level controls for each waveform. 24vac. £15 kit. £20 built
KNOB PACK 10 knobs for just £100
PHONE CALL RELAY Very useful switch adjustable from 0-5 mins.will 5 WATT SIREN Powerful siren kit
kit that incorporates a relay that oper- switch 2A mains load. 12v op Ideal for ates when the phone rings. Can be used laboratory, photographic projects etc.
with an impressive 5 watts output. Ideal
for alarms etc. £6 kit £10 built
REMEMBER! YOUR FREE COPYJ
to operate more bells, signalling lights £7 kit. £11 built. etc. Good for noisy enviroments or if 7 WATT HI FI AMPLIFIER. Useful, you have your headphones on! £10 kit, powerful amplifier 20hz-15hz, 12-
TELEPHONE AMPLIFIER Very OF OUR CUT PRICE COMPOsensitive amplifier which using a 'phone NENTS CATALOGUE SENT pickup coil (supplied) will let you fol WITH EVERY ORDER!!!
£14 built.
18vdc. Good for intercoms, audio sys-
PORTABLE ALARM SYSTEM tems, car etc. £7 kit £11 built.
Small 9v alann system based on a mer- INCAR SOUND TO LIGHT Put How to place your order
cury switch. The alann contitues to some atmosphere in your cor with this sound until disabled by the owner. kit Each channel has 6 led's that create
By phone
0273 771156
Buzzer included. £11 kit £15 built. a beautiful lighting effect! £10 kit, £14 By FAX
0273 206875
800W MUSIC TO LIGHT EFFECT. built.
Add rhythm to your music with.this VOX SWITCH. This is a sound acti- By Post . PO box 517 Hove Sussex BN3 5QZ
simplesound to light kit £8 kit, £12 vated switch, ideal for use on transmit- Payment by ACCESS,VISA, CHEQUE OR POSTAL ORDER.
built.
ters, CB's, tape recorders etc. Adjust- Cheques and postal orders should be payable to Express Components
MOSQUITO REPELLER Modem able sensitivity, built in delay. Mic in- ALL PRICES ARE SUBJECT T099p POST AND VAT. Some ofourproductsJ
way to keep the midges away! Runs for put. £7 kit, £11 built.
I be unlicensable for use in the UK (particularly the FM transmillers )
Everyday with Practical Electronics. January 1995
21
milAIVAtlAIM A roundup of the latest innowaiions 'wsss?
SNORERS AND SUPER-COOLERS
More safety for marriages,
motorists and microchips?
-- by Haze! Cavendish
Willyjohnson, of Microsharp Wonder Screen fame, and Sean Martindale have invented an electronic cure for snorers. Called Shnor-
nomor, it makes use of a new microchip designed by the pair in a device resembling a miniature hearing aid, and is intended to be worn by snorers when they retire to bed.
Activated by a small microphone, Schnomomor picks up the low note of the snore and converts it into a high frequency note which sounds an alarm in the brain, making the sleeper move his or her head slightly, which disturbs the relaxed muscles causing the snore.
Willy Johnson has countered the possibility of a person becoming used to such a sound by ensuring that the random bleep ranges through different frequencies, is irregularly timed and varies in volume, so that if snoring recurs it will be diverted by a different sound.
"We have done a great deal of testing, and the device has been psychologically proven," says Johnson, who claims that the advantage of the joint invention is that it does not actually wake the snorer, who continues in a deep and undisturbed sleep - no doubt to the intense relief of a spouse.
"Sean and I believe our invention could be of very real benefit to mankind, as snoring is said to contribute to many a marital break-up", says Johnson, a fact confirmed by Chest Physician John Stradling, who runs the Sleep Apnoea Clinic at the Churchill Hospital in Oxford. He says he has 20 people referred to him with a snoring problem every week of the year.
"I can categorically say Johnson will make millions if it is successful", said Dr Stradling.
He recalls, though, that an earlier invention of an electronic wrist watch, which gave a sleeping person a small electric shock when snoring, failed its objective trials because the snorer got used to it. Johnson's repost is that a shock to the wrist makes the hand move and not the head.
Another application of the invention is intended to keep sleepy drivers awake on the Motorways, as the slightest relaxing of the muscles indicating the onset of sleep could be checked by a shrill bleep alerting the drowsy driver - and could save many lives.
'
INSTANT COOLING
Johnson is also working independently on an electronic instant cooling
system likely to prove valuable in the new "electron-squeezing" technol-
ogy, and in a fast retrieval situation.
"We have microwaves which heat things up quickly, so I am now
experimenting with a simple way of cooling things down equally quickly'',
says Johnson. Although the real value of this invention will be in cooling
electronic systems rapidly to give greater power, it should also prove a
boon to wine waiters as it should be possible to cool bottles of wine, or
indeed Martini
cans of cola, in chilled it is true,
just 30 but they
seconds. should be
"pTlehaesyanwtlyillconoolttobetheAmpaelartiec,»a·n'-'
says Johnson.
The one unfulfilled ambition Willy Johnson cherishes is to s&e his inven-
tions bought and manufactured in Britain. "I know now that I will have
no difficulty finding companies abroad to take them up, but I would like,
more than anything, to contribute' to the British manufacturing industry
and see an invention of mine benefit my own people."
FUNNY MONEY FINDER Funny Money rife in High Street," a local newspaper recently announced. If you feel at risk of loosing money by accepting forged banknotes then this clever unit from Maplin could let you sort out the fakes from the bona-fides. It simply shines UV light on them, and whereas genuine notes absorb UV light, forgeries reflect it. If the note is genuine, very little light is reflected when it is held under the ultraviolet tube. A fake note, though, lights up with a bright violet colour. The mains powered bank note checker is supplied in a rugged black plastic housing that is designed for desk or counter use. The unit is fitted with a top mounted on/off switch and approximately 1m of mains lead, complete with 13A plug. Its dimensions are 180mm x 120mm x 75mm, and, it costs only £7.99, including VAT. It would be good if a portable version were also to be introduced for shoppers! For further information, contact any of Maplin's nationwide shops, or phone their head office on 0702 554161.
MERSEY GAMES The UK has notched up its latest inward investment success as Japanese electronic giant. Sony, has recently decided to locate on Merseyside. The project, which will create 250 new jobs, was secured with the help of a £1.75 million DTI grant. Sony Electronic Publishing Limited (SEPL) will site its software development and support centre in the Wavertree Technology Park in Liverpool. The centre will carry out product development for the whole of the company's computer games market in Europe.
22
HAPPY BIRTHDAY BULL! It is Bull Electricafs birthday! They have been selling electronic "goodies" for fifty yearsl They have also produced their biggest ever catalogue, 100 pages in the latest 1995 issue If you did not get a free copy with last months EPE then one will be included with your next order, or alternatively just send them 45p in stamps and they will post you a copy.
For further information, contact Bull Electrical, Dept. EPE 250 Portland Road, Hove, Sussex BN3 5QT. Tel: 0273 203500, Fax- 0273 323077.
Everyday with Practical Electronics. January 1995
IMPROVED MOTOR
CONTROLLERS
International Rectifier has introduced a new family of intelligent power modules that uses a new architecture to offer greatly reduced motor controller complexity and cost compared to either discrete components or existing modules.
IR's integrated driver technology eliminates input opto-isolators, and three of the four isolated power supplies required by existing intelligent power modules. The higher level of integration in these multi-chip power modules increases efficiency and performance by packaging the latest-generation IGBTs and HEXFRED K diodes together with an IR2130 power integrated circuit driver on an electrically-isolated, thermally-conductive base.
The initial products in the family, the IPM1560 and IPM2060, are 15A and 20A, 600V devices. They comprise three-phase bridges of IGBTs driven by an IR2130, which provides both high-voltage isolated drive and fast protection functions. These devices target one and two horsepower motor controllers. Other modules are scheduled for introduction in early 1995.
For further information contact International Rectifier, Holland Road, Hurst Green, Oxted, Surrey RH8 9BB. Telephone (0883) 713215.
·'
PLEASE TAKE MOTE
Stereo HiFi Controller
July/Aug'94
August issue pages 630 and 633: The type number for IC12
used in the Expansion and Display circuit should be LF353 and
not LF347. The components list is also incorrect. Resistor R46 should be removed and a link put in its place. If
not removed, it forms a potential divider to a.c. signals with
C20 and R49. This effectively reduces the sensitivity of IC3/IC4 in detecting signals, and will therefore not stop the expansion board counting from 0 to 3. In an otherwise faultless board the unit will still work, but not as well.
SMART BANK Schlumherger signs smartcard development contract with Visa, signalling fundamental shift in international hanking card practice. First world-scale smartcard application, conforming to international hank standards developedjointly by Visa, Mastercard & Europay. Visa International has sleeted Schlumherger Smart Cards & Systems as a technological partner to develop a smartcard-based customer card. The new card will provide Visa with enormous potential to develop its range of financial services, coupled with a much more secure platform for electronic payment compared with conventional magnetic stripe technology. The design will additionally conform to new international banking transcation standards developed by a working group composed of Visa, Mastercard and Europay (VME). This, it is claimed, will make it a potential worldwide smarcard application. The contract covers the development of the software architecture for a powerful microprocessor-based smartcard chip, possessing a very high degree of flexibility for the creation of future financial service applications.
TEL-GUARD FOR YOUR HOME A young, Surrey based company called ComTel Ltd have come
up with a fresh concept in home security using the existing BT telephone network. Currently the installation work, is carried out by Gate-A-Mation Ltd of Woking Surrey, supplier and installer of automatic gate, door and barrier systems.
By using the existing telephone network, it is claimed that TelGuard enables the user to remain in control of their property from anywhere in the world. It permits instant reliable communications between an automatic entrance and any number of locations where a telephone is installed - your home, your office, or even you car - in fact, up to 1.000 locations from a single TelGuard. Access can therefore be gained from any call point programmed into the system, be it Birmingham, England or Birmingham, USA!
It is also claimed to be less costly then large hard-wired audio entry systems which require expensive cable runs and often costly regular maintenace, TelGuard is a virtually circuit-free system that uses the existing BT telephone network to activate the command, whether it is "open gates", "open doors," "turn on light", or a range of other commands that can be activated simply by pressing a series of buttons on your own telephone.
Provided the system is linked to BT"s DTMF telephone network, a variety of commands can be programmed.
The visitor enters the correct reference number on the key pad and then presses the "call" button. This instructs the system to secretly dial a specific telephone number, enabling the visitor to hear the connection. The occupant answers the telephone and screens the visitor. They then press a code number on their own telephone, followed by a # for the gate or door to open (e.g. 1 #). TelGuard automatically activates the command, returns a short constant tone of its own and then disconnects the call. This is confirmation to the occupant that the instruction has been accepted and carried out.
Each resident has a 4-digit PIN number, which, when entered into the keypad, allows instant access. For further information contact either: Gate-A-Mation Limited, Unit 1, Boundary Business Centre. Boundary Way, Woking, Surrey GU21 SDH, (Tel: 0483 747373) or CommTel Ltd. P.O. Box 192, Dorking, Surrey, (Tel: 0306 877889).
Everyday with Practical Electronics. January 1995
PLANE TALKING
In-flight holiday makers may well have heard cabin announcements to the effect that the use of mobile phones on
the aircraft is prohibited and possibly dangerous to flight safety.
Now there may be a remedy for at least some inveterate cordless chatterers cut off from their addiction. A new inflight telephone service, has recently been announced by Trade and Technology Minister Ian Taylor.
BT has been granted a Telecommunications Act licence to
operate ground stations in the UK to provide Terrestrial Flight Telephone System (TFTS) services, TFTS will enable passengers to make telephone calls from aircraft during flights.
Mr Taylor said; "This innovative and UK developed service will add a vital link in our communication infrastructure and shows how government is exploiting the radio spectrum to promote the introduction of new technology.
Mounted in a wall or on a plinth, one TelGuard unit can serve an entire estate.
· mmammmmwrnmrn-mmmrn
v /v Hi, > -
s
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«9« «PH mmwm
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New Technology
Update
Varaible colour /. e. d.s are becoming a distinct possibility and seismic servo techniques are set to improve i.e. manufacturing yields.
Light emitting diodes have been available for many years now. Standard red
l.e.d.s are widely available for just a few pence. They are used in vast quantities as cheap and reliable indicators, replacing the incandescent bulbs which were almost the only option a number of years ago. In addition to this they also find widespread use in alphanumeric displays, although other less current hungry devices are tending to dominate this field now.
limitations
Despite their widespread acceptance there are still many limitations to l.e.d. technology, One of the most obvious is the limited range of colours which are available. Red is the most common and the easiest to produce. Other colours including orange, green, yellow and blue are available, but they are often more expensive. In fact it was a number of years after the first red l.e.d.s were introduced before any other colours were available.
This shows some of the difficulties which have been encountered in developing and manufacturing these new colours. Different processes are needed in the manufacture of these variants. However, a new development which is being undertaken at the University of California has made significant progress in streamlining the manufacture of different coloured l.e.d.s and making devices which can change their colours.
Organic Colours
The new l.e.d. is based around a structure which contains two different types of layer. One consists of an organic substance called p-paraphenylene vinylene and the other is an inorganic substance called cadmium selenide. In the new structure it is found that the cadmium selenide layer will emit light when a forward bias around four volts is applied. The colour is dependent upon the size of the cadmium selenide crystals, and varies from red to yellow. This means that exactly the same process can be used to manufacture l.e.d.s of differing colours; only some of the conditions need to be changed.
Of more interest, however, is the pparaphenylene vinylene. It is found that as the bias increases, this layer starts to emit light, and eventually becomes the dominant light source. This emits a green light, and purely by changing the bias on the device the colour changes.
This work is still in its early stages of development, and a number of problems need to be overcome. At the moment the device only has a limited life when it is running since the efficiency falls. Currently the p-paraphenylene vinylene layer has the
shortest life falling away to nothing leaving only the cadmium selenide layer active. Despite this problem it does show the way in which l.e.d. developments may progress in the future.
I.C. Manufacturing
Imnrovements The sizes of components in i.c.s are falling
at an amazing rate. Dimensions not thought possible a few years ago are now commonplace with today's i.c.s. To achieve this has not been easy. Many new techniques have had to be employed, and many millions of pounds have been spent in research. Manufacturers and designers alike have had to overcome various limitations in the basic processes of lithography, diffusion, and etching which are used in the manufacture of these devices.
Whilst the spotlight has fallen on methods of improving these techniques there have been many other areas where equally important work has been undertaken. This work may not have received the same amount of publicity, but it has been just as crucial to the development of the smaller i.e. technologies.
Bad Vibrations
One of these areas is in the limitation of vibration, particularly during the photographic processes. When the first CDs were manufactured there was a lot of publicity given to the fact that they had to be manufactured under conditions of minimal vibration. However, it is not always realised that micro-inch displacements on a chip undergoing lithography or ion implantation can have disastrous effects. Unfortunately all areas of the world are subject to some degree of vibration, and this can be a major factor affecting the yields of i.c.s during manufacture.
As a result of this, manufacturers have to go to vast lengths to mechanically isolate the relevant pieces of their equipment. Critical items are often placed on suspended floors which are themselves mounted on shock absorbing pillars. Even then areas where there are low levels of vibration have to be sought. This requires .expensive geological searches to be performed and it usually results in having to set up the facility in a remote location away from any sources of vibration.
Once the location has been found, building and running the facility is more costly than if it could be located in a more convenient place. Accordingly, any methods of reducing vibration, and enabling more convenient sites to be chosen would be welcomed by i.e. manufacturers.
Phased Compensation
To help overcome this problem a
company called Barry Controls based in Brighton, Massachussetts, U.S.A. has
developed an active compensation system. This senses any external low frequency vibrations and generates vibrations in the opposite phase to cancel out any movement and keep the work piece absolutely still.
The system employs two methods of vibration limitation. Both passive and active techniques are successfully combined to give an improvement of a factor of four or five over anything else which is currently available. In fact it is effective in limiting vibrations between 0-3Hz and 200Hz and it is quoted as giving an isolation level of 99 per cent.
The system is based around a central computer controller which analyses the data presented to it and generates signals to operate the active system. The first input to the system is taken from geophones embedded into the floor. Careful thought has gone into the development of these sensors so that they exactly detect the vibrations in all three planes.
Pedestal Power
Floor movements are analyzed by the controller and the resulting information is used to generate control signals for
the three pedestals on which the work floor is mounted. Each pedestal contains
five transducers which perform the active vibration isolation. They use the piezo-
electric effect to convert the high voltage
signals from the controller into mechanical displacements to counteract the vibrations. The pedestals also carry additional
sensors which are used to feed back additional vibration information to the controller.
The system is so versatile that even vibrations created on the work area itself
are detected and eliminated. This is
particularly vital because the high speed
movements needed to make many of the
processes like ion implantation viable create their own vibrations. In fact the new system is so successful at eliminating these vibrations that many of the machines are able to operate faster than they would normally be able, making the system even
more cost effective.
The new Barry Controls system is likely
to be a major contribution to the cost
reduction in the manufacture of large i.c.s.
It may be of particular benefit because
it might allow fabrication plants to be
located in areas manufacturer.
more
suitable
for
the
24
Everyday with Practical Electronics. January 1995
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Everyday with Practical Electronics. January 1995
25
o, m
Our regular round-up of readers' own circuits. We pay between £10 and £50 for all material published, depending on length and technical merit. We're looking for novel applications and circuit tips, not simply mechanical or "electrical" ideas. Ideas must be the readers' own work and not have been submitted for publication elsewhere. The circuits shown have NOT been proven by us. Ingenuity Unlimited is open to ALL abilities, but items for consideration in this column should preferably be typed or word-processed, with a brief circuit description showing all relevant component values. Please draw all circuit schematics as clearly as possible.
Send your circuit ideas to: Alan Winstanley, Ingenuity Unlimited, Wimborne Publishing Ltd., Allen House, East Borough, Wimborne, Dorset, BH21 1 PF. They could earn you some real cash!
Audio Cable Tester
- s®mls ©oafi
tsyflir®©
The circuit diagram shown in Fig. I can
be used to test most audio and hi-fi cables
for open and short circuits, in one simple
operation. The design is based around
three l.e.d.s D3 to D5 in series, which are
connected in parallel with the cable under
test via the two "test" sockets SKI and
SK2. These connectors could be phono or
jack sockets for instance.
Under normal conditions, D3 and D5
are shunted by the core and screening
shield respectively, while D4 passes current
between the two and is therefore normally
illuminated. However, if either the core or
the screening shield are open circuit, or
there is a short between the two conduc-
tors, the pattern of l.e.d.s will change,
which will indicate the problem instantly.
The remainder of the circuit, based
around transistor TRI, forms a simple
10mA current sink. This is required to
maintain a constant current through the
rfESTl
SKI
ivfl
BC109
IN 4148 . -m401428
UNTDOERCATBELSTE
t EE45370 |
F/g. 1. Audio Cable Tester circuit diagram.
light-emitting diodes no matter how many l.e.d.s, if any, are actually in circuit.
To test a cable, connect the suspect lead into both sockets and press switch SI, The status of the l.e.d. display indicates the condition of the cable according to Table 1.
Table 1: L.E.D./Cable Status Condition
on D3
off
core is open circuit core is OK (*)
on D4
off
core-shield is OK (*) core shorted to shield
on D5
off
shield is open circuit shield is OK (*)
(') indicates cable PASS condition
As well as audio cables, this circuit can test twin-conductor cables, including BNC and aerial leads. The type of cable simply depends on your choice for SKI and SK2, or test leads could be used instead.
Neil Johnson, Camberley, Surrey
Simple D.C. Servomotor Controller - im^dlsD^s, if®Qj)®iln(es ®(lSo
My second circuit diagram, see Fig. 2, will drive small d.c. servo mechanisms such as those used in radio control models. It consists of ICI, a 741 or similar op.amp configured as a comparator and driven from a split ±I2V supply. ICI monitors the voltage set at its non-inverting input (pin 3) ,b(y the Position control VRI, and the voltage at the inverting input (pin 2) is determined by the servo position potentiometer VR2 which is coupled mechanically to the servo motor shaft in the normal fashion. The output drives a complementary pair of driver transistors TRI/ TR2 via the preset VR3 which should be trimmed to the minimum required for driving the transistors satisfactorily.
Resistor R5 provides a degree of current feedback: if the motor is under a heavy load it passes more current which consequently increases the voltage drop across R5. This reduces the voltage across the motor. Negative feedback passes via R4 to the inverting input which therefore causes the drive signal to be increased.
Ck?
|1 POSITION |1 > V1R0k1 vR2
4k7
IEEt53BGI
100k w TRI
22n
I7C411C 10 k
VR3 Sen
VR2 INTEGRAL WITH SERVOMOTOR
--\A^A-- TR2
TR1.TR2 SEE TEXT
Fig. 2. Circuit diagram for a Simple D. C. Servomotor Controller.
Since this circuit evolved from my junk box, the use of preset potentiometer VR3 enables the circuit to be fine-tuned to almost any npnjpnp pair, e.g. BFY5I/
BFX40. The rest of the circuit component values are not too critical.
Neil Johnson, Camberley, Surrey
26
Everyday with Practical Electronics. January 1995
900Hz Audio Line-Up Oscillator - snnn® wanw® sngimaDl] soonff©®
The circuit of Fig. 3 was originally designed to be incorporated into a Fourchannel Stereo Mixer to provide a source of constant amplitude tone, to help set the recording level on tape recorders. It could equally be adapted as a signal injector to check that an audio project works properly.
It was designed to be powered from an existing ± 15V d.c. split supply and comprises a square wave oscillator followed by a low pass filter. The total assembly cost is approximately £5.
Since a square wave consists of the fundamental frequency plus all odd-numbered harmonics of that frequency decreasing in value by the reciprocal of the harmonic number, if the low pass filter has a sufficiently large attenuation at the third harmonic, then a fairly'good sine wave will result.
A dual low-noise op.amp (type TL072), IC1 and associated components form a 900Hz square wave oscillator. For convenience, the ratio of resistor R2 and R3 was chosen for the ± 15V supply to make the output frequency approximately equal to:
f =
1
u-
CI(R1 + VR1)
The rest of the circuit is a 3-pole 3dB passband ripple Chebyshev low pass filter, chosen for its steep roll off. Values were calculated so that the largest capacitor would be under IpF. The off-the-shelf values shown deviated from the theoretical values by just ± l -2%
The combination of resistors R4. R5 and R6 effectively form the filter input resistor. R4 and R5 attenuate ICla square wave
output to approximately 2V. If the output impedance of ICla is zero, then R4 and R5
are paralleled to produce 3k 1. This is increased to 1 Ik by adding R6, actually 6k8 and Ikl resistors in series. With the three "series" resistors equal to Ilk, the cut off frequency is 928Hz.
The output of ICIb is fed through resistor R9 and trimmed by control VR2. R9 preventing instability with capacitive loads (e.g. cable capacitance) when VR2 is at its maximum setting. The output is about I -4V r.m.s.. and it was assumed that a d.c. blocking capacitor would be present in the equipment under test.
Since the actual cut-off frequency of the filter depends on the actual capacitance values. I recommend setting the oscillator frequency to match that of the filter as
R310k V1R0kI -vsA-^/yv--
ITCL0I72^^
Fig. 3. Circuit diagram for a 900Hz A udio Line- Up Oscillator. IEE^S3kG1
follows: set preset VRI to minimum resistance and connect a suitable meter to the output. Slowly increase VRI to reduce the frequency, and observe the output increasing to a maximum. Then decrease VRI so that the output falls slightly (say IdB). VRI could then be replaced by a fixed value of the setting so found.
Stability and frequency depend solely on the voltage regulators in the power supply. After eight hours use there was no discernible change, distortion was about 0-5% which is more than adequate for this application. Since ICla generates a 28V p-p square wave, careful power rail decoupling is needed, as shown. Mount capacitors C5, C6 and C7 near to ICla pins 4 and 8.
B.J. Taylor, Rick mans worth, Herts.
1 6C830 n |1 1R1fkl
-H5V ^^6
5 TL072^>--
-15V
1R090
ii 3C940 p V1L0ROkG2
i uo>H
mh100 n 1
m 1C070 n
Sib ---L1i 0C06n
SHOP HMrAiL K with David Barrington
EPE Fruit Machine Due to postal delays, we only received
news of a change of address for some of the "special" items needed to complete the EPE Fruit Machine project after our "printing date".
The ready programmed PIC16C57 controller chip is available from the authors, price £12. They also have a consignment of the 0-8in 7-segment, common cathode, displays and are offering a set of three for the sum of £5: this seems a very fair price. The coloured, self-adhesive front panel overlay is also available from the same source for the sum of £2.
All orders (Strictly Mai! Order Only) should be sent to the following address: Mr, B. Gossage, 119A Victoria Road, Ruislip, Middlesex HA4 9BN. All monies should be made payable to B. Gossage. Please add 50p for UK p&p and £2.50 for Overseas postage and packing.
Finally, please note that the servo motor is the Futaba FB.S148 type. The printed circuit board is available from the EPE PCB Service, code 914. Magnetic Field Detector
Ideally, the case used to house the Magnetic Field Detector should be an all
plastic one and certainly must not be a steel type. However, the one chosen does have aluminium front and back panels. This was picked for its compactness and rigidity. (The "ali" does not have an effect on the "field".).
The case is from the Vero series 200 and was obtained from Maplin. code LL08J, This is fairly expensive and no doubt most of our component advertisers will be able to offer an alternative.
For those readers who do not wish to search for a suitable "field sensor" transformer, the one used in the model is a sub-miniature mains transformer with a 6\/-0V-6V secondary 100mA output. This was also purchased from the above named source, code WB00A, The same applies to the p.c.b. mounting piezo sounder, code JH24B
Make sure you order the "log" bargraph display driver i.e. The 10-segment l e d. array is now widely stocked by our component advertisers. The printed circuit board is available from our EPE PCB Service, code 923. Model Railway Track Cleaner
Only one item is likely to cause concern when ordering up parts for the Mode! Railway Track Cleaner and that is the step-up transformer. It is a ready made type based on
a ferrite pot-core intended for use in ionisers. It was purchased from Maplin, code JL94C (lon.Tran).
A suitable mains transformer would be the same one as listed for the Magnetic Field Detector mentioned above. The printed circuit is available from the EPF PCB Service, code 923 (see page 79). Moving Display Metronome
We have been unable to locate a source for the VN0610L n- channel f.e.t, used in the Moving Display Metronome. We cannot see any reason why the 2N5459 f.e.t. should not be used instead (not tried on model). However, the pinout is different i.e. reading top to bottom in Fig. 2 inset, it should be gate, source and drain. The low profile buzzer is the one listed by Maplin as code KLffiSN
The printed circuit board is available from the EPE PCB Service, code 925. Beating The Christmas Lights
You may have some difficulty in finding a three watt wirewound resistor that matches the value shown in the table for the Beating The Christmas i/gr/rts project. You can, of course, use one with a higher rating providing it is of the correct value.
Video Modules We do not expect any component
buying problems to arise when shopping for parts for the Dynamic Noise Limiter or System Mains Power Supply, the last of the Video Modules. The printed circuit boards are available from the EPE PCB Service, codes 919 (DNL) and 920 (System PSU).
Everyday with Practical Electronics, January 1995
27
Constructional Project
MODEL RA/LWA Y
TRACK
T
v 7tl CLEANER
0 ROBERT PENFOLD
Don't delay, keep your model
trains running on time.
Most model trains operate well at high and medium speeds, but are often less convincing when run at
slow speeds. The train controller is often the main culprit, and very basic types do not provide good speed regulation. This tends to give erratic speeds, particularly when the train is running very slowly. Worse than this, before too long the train usually comes to a sudden halt.
There can be several causes of this problem, but the most common one is simply grease or other dirt on a small length of track. This gives a poor electrical contact and a momentary loss of power to the locomotive.
If only a very short length of track is affected, the momentum of the train, even at slow speeds, will take it over the dirty piece of track. The train will continue on its journey, but will give a noticeable and unrealistic shudder.
Due to its lack of momentum a slow moving train is likely to come to an abrupt stop if more than a few millimetres of track are affected. High quality controllers are less prone to this problem than very basic types, but if a significant length of track is affected, contact will always be lost with the train, and it will come to a halt.
LD/HT ZAPPING
The best solution to the dirt problem is to simply keep the track scrupulously clean, but this can be quite time consum, ing. Also, it can be difficult to get every millimetre of track really clean, particularly
when some of the track is far from new. An alternative approach is to keep the track as clean as reasonably possible, and to use an electronic track cleaner to "zap" any remaining small amounts of dirt on the tracks.
This "zapping" is done by applying a high voltage across the tracks when the train loses electrical contact with the tracks. Although a thin layer of dirt may act as an effective insulator at the low voltage used to power the train, it will not do so at a higher potential of around 200V. The high voltage therefore breaks down the film of insulation, and restores power to the train. Where the train would otherwise have come to a standstill, it instead carries on with no more than a momentary hesitation.
Although using a high voltage across the tracks might seem to be dangerous, this voltage is at a high impedance. The available current is therefore very low, and the equipment is unlikely to give even a moderate electric shock. The maximum output current is a matter of microamps rather than milliamps.
HOW IT WORKS The block diagram of Fig. 1 shows the
simple arrangement used in this Model Railway Track Cleaner. The circuit is powered from a simple non-stabilised mains power supply unit, or a 9V battery supply can be used if preferred.
The low voltage d.c. supply is stepped up to a high voltage a.c. type by an oscillator
OUoT.PcU. T
1 I
'dSiWreITcCtiHon
MPA.SIN.US .
OSCILLATOR
STTREAP-NUSP.
MDIIOXDERE --(
fgfe^1S6|
A D.C. ^ INPUT
Fig. 1. Block diagram for the Mode! Railway Track Cleaner.
operating at a high audio frequency, and a step-up transformer. The latter is a readymade type based on a ferrite pot-core. It provides an unloaded output of around 200V r.m.s.
On the face of it some sensor circuitry is needed in order to determine whether or not the train is in contact with the track, and to switch on the oscillator if it is not. In practice this is not necessary due to the high source impedance of the high voltage signal.
Take Care Extreme care must he exercised when constructing this project as it involves making mains connections, any reader who is unsure of heing able to make a safe connection must seek the advice ofa qualifiedperson. Also, the circuit MUST be built in an Earthed metal case. Although the output from the Mode! Railway Track Cleaner is far from lethal, it does provide a high voltage, and might give a noticeable electric shock to anyone coming into contact with it. It is best to avoid contact with any high voltage sources, even high impedance ones.
If the high voltage supply is permanently connected to the track it will normally have no significant effect. The electric motor in the train will provide a very low impedance across the tracks which virtually short circuits the output from the transformer. The voltage across the tracks is only a fraction of a volt, and the current flow through the motor in the train is under one milliamp.
If the train loses electrical contact with the track there is an extremely high impedance across the tracks, and the output from the transformer almost immediately jumps to its normal level of around 200V. It then breaks down the film of insulation, contact is restored with the motor in the train, and normal operation is restored.
In practice things are not quite as simple as this. There will not necessarily be a high impedance across the tracks when the train is not connected across the them. This is simply due to the fact that the output from the train controller will still be connected to the tracks, and will probably place a low impedance across them.
The presence of the controller will almost certainly quench the output from the transformer. If it does not there is the risk of the high voltage from the transformer finding its way into the controller circuit, where it could obviously cause a lot of damage.
28
Everyday with Practical Elec tronics, January 1995
DIOOE MIXER
In order to overcome this problem it is merely necessary to use a simple diode mixer to combine the outputs of the train controller and the track cleaner. Basically all the mixer does is to connect the higher voltage source through to the output, while preventing one source from forcing a current into the other.
With the model train in contact with the track the controller provides the higher voltage and powers the track. With the train out of contact with the track the transformer provides the higher voltage, and breaks down the film of insulation. Thus the circuit automatically switches between the two voltage sources in the required manner.
<" EQ
INS REVERSE
Front panel controls of the completed Track Cleaner.
ON/OFF Sla 2iOV
M24A0IVNS
Sib
1ND41002 *w*-
1No042^00ik2
100FmSAlQ
470p
lEEtS16G|
Ck 7 IC1
NE555N I
1^SK2
10k
^<SK1
11
1oNw40k07 1N4007
TT
\ ( '
j·I*iIIIl!1ilOooooeool>
10R0S-kC^ S2a LP1
* SEE TEXT
Fig. 2. Full circuit diagram for the Mode! Railway Track Cleaner. The neon indicator LP1 flashes when a high voltage is present on the track.
A neon indicator is connected at the output of the diode mixer, and this flashes when the high voltage signal is connected to the track. This provides confirmation that the unit is being brought into operation, and it also helps to identify any stretches of track that are contaminated with grease or dirt.
For the diode mixer circuit to work properly it is essential that the polarity of the input voltage from the train controller is correct. The direction of the train is altered by changing the polarity of the voltage across the tracks. The track cleaner is therefore fed with a voltage of the correct polarity from the controller, and the direction of the train is governed by a polarity switch at the output of the track cleaner circuit, not by the controller's direction switch.
CIRCUIT
OPERATION
The full circuit diagram for the Model Railway Electronic Track cleaner appears in Fig. 2. The mains power supply is a conventional full-wave type having pushpull rectification provided by diodes Dl and D2,
As the current consumption of the main circuit is only a few milliamps, the loaded supply voltage provided by a 6V 100mA mains transformer is approximately 9V. It is possible to power the circuit from a fairly high capacity 9V battery (e.g. six HP7 cells in series). SI, Tl, Dl, D2, and FS1 are then omitted, and the battery is connected across capacitor C1 via a s.p.s.t. on/off switch.
The oscillator stage utilizes a 555 timer IC1 in the standard astable mode.
Potentiometer VR1 is used to adjust the operating frequency of ICI to obtain optimum efficiency from the step-up transformer T2. It is not advisable to use a low power 555 for ICI as many of these have relatively low maximum output currents, and they might not work well in this circuit.
Oscillator ICI drives the primary of stepup transformer T2 via capacitor C3 and current limiting resistor R3. The drive level has to be something of a compromise. If too little drive is used the unit will be ineffective, but with too much drive there is a risk of the unit delivering a significant electric shock. A value of 22 ohms for resistor R3 was found to give a high enough output voltage to counteract dirt on the track, but gives an output signal of high enough source impedance to keep the unit safe.
In normal operation the input signal from the controller is fed to the output
sockets (SK3 and SK.4) via diode D3 and direction switch S2. Diode D4 prevents the controller from forcing a high current through the secondary winding of T2.
If the train loses electrical contact with the track, the high voltage output from T2 is half-wave rectified by D4 and fed to the track via S2, Diode D3 and resistor R4 then prevent the controller from quenching T2 output, and also prevent the high output voltage from being fed to the controller.
LP1 is the neon indicator, and this should be a type having an internal series resistor for 240V mains use. Resistor R5 provides further current limiting which prevents LP1 from drawing too much of the available output current from T2.
COMPONENTS
Resistors R1,R2 4k7 (2 off) SHIOIP
R4
m
TALK
R5 100k
Page
All 0'25W 5% carbon film
Potentiometer VR1 47k rotary carbon, lin.
Capacitors
C1
470p radial elect. 10V
C2
In polyester
C3
330n polyester
Semiconductors Dl, D2 1 N4002 100V 1A rect. diode (2 off) D3, D4 1 N4007 1000V 1A rect. diode (2 off) ICI NE555N timer i.e.
Miscellaneous
LP1 mains panel neon having
j jx-. internal series resistor
FS1 100mA 20mm anti-surge
fuse
51
rotary mains switch
52
d.p.d.t. toggle switch
11
mains primary, 6V-0V-6V
100mA secondary
12
"Ioniser" transformer
SKI to SK4 4mm socket (4 off)
Printed circuit board available from
fPf PCS Service, code 924; metal in-
strument case about 203mm x 127mm x
52mm: mains lead and fused (2A) plug:
8-pin d.i.l. socket: pair of 20mm fuse-
clips; wire: solder: etc.
Approx cost guidance only
£30
Everyday with Practical Electronics, January 1995
29
CONSTRUCTION The printed circuit board (p.c.b.) com-
ponent layout and the actual size copper track pattern appears in Fig. 3. This board is available from the EPE PCB Service, code 924.
Construction of the p.c.b. is largely straightforward. Fuse FS1 is mounted on the board via a pair of 20mm fuse-clips. FSI should be an anti-surge fuse, and not a quick-blow type (which might "blow" at switch-on as capacitor C1 charges up).
Step-up transformer T2 has a polarising pin, so it is not possible to fit it to the board the wrong way round. This component is fairly expensive, and it is made from a very hard but brittle material. It should therefore be treated with due respect. Dropping it onto a hard surface could easily result in the ferrite pot-core smashing.
Make quite sure that the four rectifier diodes (D1 to D4) and electrolytic capacitor Cl are fitted with the correct orientation. Also be careful to fit IC1 the right way round (with pin 1 towards the bottom edge of the board). In order to fit into the component layout easily capacitors C2 and C3 should be printed circuit mounting types having 7-5mm (0-3 inch) lead spacing.
CASE DETAILS The unit is housed in an instrument case
of all metal construction. For reasons of safety the case must be a type that has a screw fitting lid, not a clip-on type.
The three controls (SI, S2 and VR1) and LP1 are mounted on the front panel of the case, with SI well towards the lefthand end of the panel. Sockets SKI to SK4 are fitted on the rear panel of the case. Four millimetre sockets are used on the prototype, but it is acceptable to use another type if it fits in better with your controller, etc.
A hole for the mains lead is made in the rear panel of the case, roughly opposite on/off switch SI, This hole should be fitted with a grommet to protect the cable.
Transformer Tl and the printed circuit board are mounted on the base panel of the case, with Tl towards the left-hand end of the unit. A chassis connection point is required, and this can be provided by a solder tag mounted on one of Tl's mounting bolts.
I
-SI
al a D11 | D2 R1
IC1
k k
o
0
0
t EE4517G |
VR1
EATRATGH
asa
I
Rt I-- Q« k
LP 1 vl V
Fig. 3. Printed circuit board component layout and full size copper foil master pattern.
The p.c.b. must be securely fixed in place, and in this case it is recommended that M3 or 6BA screws rather than plastic standoffs be used. Spacers about 6mm to 10mm long are used over the fixing screws so that the underside of the board is kept well clear of the metal case.
Once everything is installed in the case the hard wiring is added as shown in Fig. 4.
This is very straightforward, hut as the dangerous mains supply is involved it is important to proceed
more carefully than normal. The mains lead must be a three-core type, with the Earth lead reliably connected to the chassis connection point. The mains plug should be fitted with a 2A fuse. Double check all the wiring, particularly that to SI and Tl, before testing the unit.
TESTING AND USE
Commence testing by first checking that the unit is passing the input supply through to the output. It will only do so if the input supply has the correct polarity, but the right polarity can be found by trial and error if necessary (with the Track Cleaner turned off). Remember that with the Track Cleaner in use the direction of the train must be controlled using switch S2 on
the unit, and not using the appropriate control of the train controller. With the train removed from the track, switch on the Track Cleaner. Neon indicator LP1 will probably light up when
v
The completed Mode! Railway Track Cleaner with the case top cover removed to show some of the component positionings and wiring. For safety, the case must be all metaf have a screw fixing Iid and be securely Earthed - see Fig. 4.
30
X
January 1995
M2A4I0NVS N
2A0V · ·
ON/OFF )3t
CIRCUIT BOARD
©
vR 1 @
NPUT SK2 SKI
OUTPUT SK3 SKA m m
a b
DIRECTION
LP1 [ CEtSieG 1
m
*
4*
wm « nm wm Layout and wiring inside the metai case. The mains lead and transformer primary connections to the on/off switch should be covered with insulating sleeving.
Fig. 4. Interwir/ng between the various components andp.c.b.
the unit is switched on, although it will probably not light up very
brightly. By adjusting VR1 it should be possible to find a setting
that gives reasonably brightness from LP1 with no flickering.
Once VR1 has been given the optimum setting it will probably
not need any readjustment unless alterations are made to the track
layout. Putting the engine in place on the track should result in
LPI switching off. If power is then applied to the train it will
probably be found that LPI flashes each time the train passes
problem pieces of track, but this obviously depends on the cleanli-
ness of the track.
Although the output from the Mode! Railway Track Cleaner is far
from lethal, it docs provide a high voltage, and might give a notice-
able electric shock to anyone coming into contact with it. It is best to
avoid ones.
contact
with
any
high
voltage
sources,
even
high
impedance
ELECTROhllCS
CROSSWORD
ACROSS: 1. Sailors measure conductance, we hear. (6) 4. Connections, end to end. (6) 7. This takes charge. (9) 9. None confused over this indicator. 10. A prefix for 1012. (4) 11. In a state of flux? (5) 13. A line of repetitive networks. (6) 14. You've got me there! (6) 15. Locked up with a 5-electrode valve - without the poetry. (4) 17. Study transport. (5) 19. A good one is often needed between electronic systems. (5) 21. No current flows in this circuit. (4) 23. A man from 12 down? (4) 24. Everything's in tune here. (9) 25. A forceful scientist? (6) 26. An adjustment in 7 across that produces 24 across. (6)
DOWN: 1. Carries the information. (6) 2. Second part of 6 down. (4) 3. Try always to make your projects this. (6) 4. Can be used in place of 11 across for some jobs. (6) 5. First part of 6 down. (4) 6. A measure of alternating quantities. (4,4, 6) 7. Earlier name for 7 across. 8. X marks the opposition. (9) 11. Two in the colour code. (3)
Everyday with Practical Electronics, January 1995
12. Pole discovered in neither this nor that. (5) 15. It's a part of the nucleus. (6) 16. The French fool in a salt water lake, (6) 18. Fixing hardware with I06 ohms looks spicy. (6) 20. Graphic plan, for example. (5) 22. Derogatory name for a haphazard circuit. (4) 23. Observe the trace. (4)
(Solution on page 35)
31
Constructional Project BEATING THE
1 m
CHRISTMAS LIGHTS
W /
T.S. CHRISTIAN
Longer lasting fairy lights can keep the festive spirit aglow beyond twelfth night.
Why is IT that just because we have a technical hobby, we are expected to be able to fix everything around
the house - instantly? You only have to be able to tune a radio to more than one station to be hailed as the saviour of every piece of electrical gear in the house!
In our house, the worst time is Christmas. Not just all those presents that require plugs, or the new toys that demand inexhaustible supplies of batteries (when they work, that is). No, the problems peak before the gifts are unwrapped: doomsday is when they get the fairy lights out.
LOOK FIRST
Admittedly, we have more than a fair share of the darned things. They dominate the Christmas decorations. Some are inherited, some donated and some even purchased. Every year, the first of the festive duties comprise untangling, servicing and maintaining them and, as with any seriesconnected arrangement, fault-tracing can be a nightmare.
True, an initial inspection will generally reveal those screw fittings that are loose and those push-fittings that have parted company. However, finding the opencircuit lamp in a forty-lamp string.
carefully entangled in a structure assembled from sections of green lavatory brush precariously hung with fragile glass ornaments, is a tedious process not at all helped by the exhortations of the assembled family to "mind the decorations".
USEFUL LIFE The life expectancy of the type of mini-
ature tungsten filament lamps that comprise these abominations is about 50 hours at full power: about two days if they are left on overnight. Moreover, as Fig. 1 shows, their life is strongly dependent on the current passed; a five per cent change either way can affect life expectancy by a factor of three.
Thus, the type of lamp that obligingly fails short-circuit so you can find it, simply increases the voltage on, and thus current through, the rest of the string of lights, with a consequent decrease in their life expectancy.
THE FIX Some reduction in the stresses and
labours of Christmas was achieved initially by operating fairy lights from lamp dimmers. Since these can be more expen-
500.0% LIFE AND BRIGHTNESS
450.0%
400.0%
350.0%
300.0% 250.0%
200.0%
150.0%
100.0%
50.0%
0.0%
96% 98% 100% 102%
106%
LAMP CURRENT
Fig. 1. Curve of life expectancy against current for series-connected miniature tungsten filament lamps. (Source: Handbook of the American Illumination Engineering Society.)
sive than the light sets themselves, and someone will always turn them up full when you are not looking, an alternative approach was sought.
This resulted in what is now the standard modification to all "authorized" fairy-light strings and their relatives: the ballast resistor box. Every lamp string includes a small plastic box enclosing a wire-wound resistor of ample rating connected in series with the lamps, as shown in Fig. 2.
MAINS SUPPLY
R -AAAT0 DROP 5% OF VOLTAGE
Fig. 2. A resistor in series with a string of lights not only reduces current but also switch-on surge. As Fig. 1 shows, there is hardly any reduction in brightness for the 5% reduction in current suggested
Table 1; Ballast resistor values for fairy lights.
No. of Usual Ballast Resistor lamps current ohms watts
5 0 06A 180
3
7 0 1A 120
3
12 0 15A 82
3
20 0 05A 220
3
40 0 05A 220
3
Note: 5-lamp and 7-lamp data are for continental-style bridges.
Resistor values depend on the rating and number of lamps in the siring, but are chosen to drop about 5% of the operating voltage (12V or so for UK mains). Values for commonly available lighting strings are given in Table 1.
BOXING OA Y Choose the plastic box with care, and
make all connections carefully and safely. Standard project boxes are probably quite suitable. Use a 5A terminal strip bolted to the base of the box for internal connections and for supporting the resistor(s) clear of the plastic, as in Fig. 3. Since dissipation is low, the temperature rise is small.
32
Everyday with Practical Electronics. January 1995
For decorative bridges, or where several chains of lights are used, the resistor and connections can usually be fitted inside one box. A suggested subsitute for a plastic box is a modern electrician's ceiling rose screwed to a piece of 10mm plywood. There are usually sufficient screw connectors inside for all connections required, and to mount the resistors securely. Moreover, both insulation and fire resistance correspond to National Standards.
It is good practice to run 3-core cable to the box. so that an Earth is present. Fit cable clamps or clips so that wires won't pull out. Check the safety of the light string while you are at it, examing it for breaks, chippings and chafings, and the like.
STOTRLIANMGP
5A TERMINAL BLOCK
Fig. 3. Series resistor and connections can be made inside a plastic project box using terminal blocks, as shown, or In a standard ceiling rose. Make sure that connections are tight and cables securely damped.
i
A completed "two string" lights protector. The resistors must be proud of the case-floor. Never remove the Ud if the unit is still plugged into the MAINS and use a proper cable damp for the mains lead..
CHRISTMAS SPIRIT
These simple additions have transformed my experience and perception of Christmas for the last three years. Failure rate has fallen dramatically: more than predicted by Fig. 1, since the initial switch-on surge is also limited by the resistor.
A twelve-lamp string that could once be relied upon to fail at least three times in the Twelve Days has not failed in three years. Thus not only is the cost of the ballast unit more than defrayed by the savings
i-k > v-
Approx cost (excluding case)
Guidance ^ on/y <£ #
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3? INTER
Robert Pentold
THIS month we conclude our look at serial data transmission via fibre-optic
links with an f.s.k. (frequency shift keying)
--R11a\5-- 60
<-9 lo 12V
system that will operate at up to 19200 baud over a range of at least 20 metres using any reasonably good quality cable. We will not consider the basic way in which an f.s.k. system operates, since this was covered in the Interface article that appeared in the November issue of EPE. The system featured here is a conventional type using two tones to represent the two logic levels of the serial
R5k160
R31k63 220p
PIM1 P4
1C00Ju 4Cn47 1RM92 II -» vW-
SfHTRJSJ O TR® 4 BC549
LB-CIR5® S49
signal.
3
The use of an f.s.k. system inevitably
results in circuits that are substantially
more complex than those used in the direct coupled link described previously. However, there is a major advantage in an f.s.k. system in that it will work quite happily if only a relatively weak light signal is present at the receiver.
Apart from giving a greater maximum operating range, this also gives better reliability over shorter ranges. With the direct coupled system everything has to be just right if it is to function properly. If (say) the cable of an f.s.k. system is not fully pushed "home" into one of the photocells, it will probably go on working flawlessly!
Two Timing
The circuit for the transmitter appears in Fig. 1. It is based on a 4046BE CMOS micro-power phase-locked-loop (p.l.I.). In this case it is only the voltage controlled oscillator (v.c.o.) that is utilized, and no connections are made to any of the other sections of ICl.
The output from ICl is a good quality squarewave signal at normal CMOS logic levels. This signal drives l.e.d. D2 via an emitter follower stage based on transistor TR2. Resistor R7 is the current limiter for the l.e.d., and it sets the "on" current at approximately 40mA. This gives an average l.e.d. current of about 20mA.
F/g. 2. Amplifier and monstable stages of the receiver.
Capacitor C2 and resistor R6 are the timing components for the v.c.o. Resistors R3 and R5 provide a control voltage to ICl that is normally about 3V. This gives an output frequency of typically just over 70kHz.
A high input level results in transistor TRI switching on, and resistor R4 being shunted across resistor R5. This reduces the control voltage to only about 2V, and reduces the output frequency to a little over 40kHz. As the input signal switches to and fro between the low and high logic
levels, the output frequency of the transmitter switches back and forth between
these two frequencies. It is important that this circuit is powered
from a reasonably accurate 5V supply. A different supply voltage would result in the l.e.d. current being altered. More importantly, even a small change in the supply potential would substantially alter the two carrier frequencies. This change to the carrier frequencies would almost certainly
prevent the system from functioning. A different supply voltage should only be used if the values of the relevant resistors are changed to suit this supply potential. The current consumption of the transmitter circuit is typically a little over 20mA.
Pulse Counting
The circuit for the amplifier and monostable stages of the receiver is shown in Fig. 2. The photocell is a phototransistor (TR3), and its collector to emitter leakage is used to provide a light dependent resistance. The pulses of red light from the transmitter produce an increase in the leakage through TR3, which results in small negative pulses being generated at TR3's collector. No connection is made to the base terminal of TR3, but this terminal can be wired to the 0V supply rail if there are any problems with stray pick up here.
The amplifier is a two stage common emitter type having capacitive coupling. It provides about 80dB or so of gain at 40kHz to 70kHz, which is sufficient to drive TR5 into clipping even if only a relatively weak input signal is present. The monostable is a CMOS 4047BE used in the positive edge triggered mode. Capacitor C6 and resistor R14 are the timing components, and the
specified values give an output pulse duration of approximately six microseconds. This gives an average output voltage of a little under half the supply voltage with the carrier frequency at 70kHz, reducing lo only about one quarter of the supply voltage with the carrier at 40kHz.
In order to extract the average output
10c0i u
1R53k
39C02 p
voltage from IC2 it is merely necessary to use some lowpass filtering. With a 19200 baud input signal the maximum input fre-
i2l
quency is 9-6kHz (i.e. alternate "marks" and
"spaces" give a 9.6kHz squarewave). This is
FU 27k
TR2
4046BE
BFY51
obviously not that far removed from the minimum carrier frequency of just over
SiKnI 3Rk19 (S v/w-
TRI
LL
BC547
R567
40kHz, making it essential to use some high slope filtering in order to obtain a glitch free output signal.
01 1N4148
3Rk29
22K
02 10k SrH750
0V
The circuit diagram for the filter and output stages is detailed in Fig. 3, Originally a fourth order (24dB per octave) filter was
tried, but this was found to give a slightly
Fig. 1. The frequency shift key (f.s.k.) fibre-optic transmitter circuit.
jittery output signal. Much better results are obtained using the
34
Everyday with Practical Electronics, January 1995
final circuit which has two third order (18dB per octave) filters connected in series. This gives a total attenuation rate of 36dB per octave, and together with a cutoff frequency of about 14kHz to 15kHz this gives over 50dB of attenuation at the lower carrier frequency. This seems to be more than adequate to provide glitch-free operation.
The output stage is an operational amplifier (1C4) used as a straightforward voltage comparator. Preset potentiometer VR1 provides an adjustable reference voltage to the non-inverting input of 1C4, and the output of IC3b is fed to the inverting input. VRl must be adjusted to provide a reference voltage that is half way between the two input levels from IC3b. The output from 1C4 will then accurately reflect the mark-space ratio of the input signal to the transmitter, even at high baud rates.
Although it might seem to be a mistake to feed the signal from IC3b to the inverting input of IC4, this is actually correct. High and low input levels at the transmitter produce low and high carrier frequencies respectively.
These are converted to low and high voltages by the demodulator at the receiver, requiring an inversion through IC4 to give an output signal of the same polarity as the input signal. IC4 provides an inversion that revokes the inversion through TRI at the transmitter.
Negative Thoughts
Apart from increasing the switching speed of the output signal, op.amp IC4 also provides level shifting. An RS232C signal does not operate at normal 5V logic levels, but instead operates at about plus and minus 12V. Minimum loaded signal voltages of plus and minus 3V are acceptable. IC4 must therefore be powered from dual balanced supplies so that it can provide a negative output signal. In practice most RS232C inputs can be driven properly using a signal that has a minimum output potential of about 0 to 0-5V, provided a fairly short connecting cable is used.
Therefore, the circuit will usually work perfectly well if pin 4 of 1C4 is connected to the OV rail and the negative supply is omitted. If your equipment is fussy about signal levels, and will only work when fed with an RS232C signal at the correct levels, a negative supply must be used for IC4. An easy way of providing this supply is to use the negative supply generator described in last month's Interface article.
The SFH350 phototransistor and SFH750 l.e.d. are available from Electrovalue. These are designed for use with standard 2.2mm cable having a 1mm diameter core (available from Maplin Electronics). They each have an orifice into which the end of the cable is plugged, but there is no built-in method of clamping the cable in place. If necessary, the
RtOI5k R101k6 R101k7
ICic4s == CrArs3s1s4N0E
4V7Pk t
R10Ik8 R101k9 R102k0
OSuKfp2ul
i 1 COO7 u
C9 2n2
1Cn85
ICS1O0p
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Fig. 3. Filter and output stages of the receiver.
-9 to 12V
constructor must devise a simple method of fixing the cable at each end of the system, but be careful not to clamp it too tight so that the polymer filament becomes damaged.
Clean Cut
I think that it is worth repeating the warning given last month that fibre-optic cables are usually supplied with neither end of the cable prepared for use. The cable might work well enough as supplied, but it will probably be necessary to trim it at both ends in order to obtain good efficiency.
It is merely necessary to trim off a few millimetres from each end of the cable using a sharp modelling knife. Use plenty of pressure so that you cut through the cable cleanly in one go. The cuts must be at right angles to the cable.
Obviously due care must be taken not to cut yourself or the worktop. If you do not have a proper cutting board a thick piece of card is a good substitute. Provided the ends of the cable are cut cleanly there should be no need to bother with polishing the ends of the polymer filament.
Preset VRl must be given a suitable setting before the system will function correctly. The easiest way of finding the correct setting for VRl is to feed the input of the transmitter with a 10kHz squarewave logic signal. Then monitor the output of the receiver using an oscilloscope, and adjust VRl for an output signal having a 1-to-l mark-space ratio. In the absence of suitable test gear it is just a matter of feeding an RS232C serial signal through the system and using trial and error to find a setting for VRl that gives good results.
In Use
The prototype worked well using a cable 20 metres long. I only tried it at 9600 baud, but it can handle a 10kHz squarewave signal properly, and should therefore work properly at 19200 baud. 11 should also work properly at any lower baud rate. Refer to last month's Interface article for RS232C port connection details, and tips on getting reluctant ports to transmit data.
O
O
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Everyday with Practical Electronics. January 1995
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35
CD
D
J)
by Barry Fox
CODED TV STANDARDS At the International Broadcasting Con-
vention in Amsterdam in September, a panel of industry experts asked themselves; Is MPEG-2 future proof? Is there anything better around the corner?
First let's recap on the current state of play. MPEG is the technology which makes all the new digital video and television systems possible, and makes the government's plans to waste valuable u.h.f. frequencies on an analogue Channel 5 all the more absurd. More accurately, MPEG is the standard for digitally coding pictures by Discrete Cosine Transform compression. This involves throwing away redundant information and rebuilding the pictures by predicting where moving objects should be. If the prediction fails, for instance where there is random motion such as smoke or downhill race skiers weaving between posts, the picture can dissolve into a mosaic of coloured blocks. For a good example of this look at the music Video CDs recently released by PMI. When Kate Bush moves fast she turns into a multi-coloured chessboard. MPEG confusingly stands for the committee that set the standard. The Moving Pictures Expert Group is part of ISO, the International Organisation for Standardisation, usually called the International Standards Organisation.
FIELD SAMPLING Digital expert John Watkinson has a
much more accurate but unofficial definition of MPEG: Motion Predicted Educated Guesswork.
The MPEG-I standard covers low bit rates, around 1.5MBit/s as used for Video CD. MPEG-2 is for higher bit rates, around 3MB/s to 20MB/s, and is used for broadcasting One difference is that the MPEG-I bit rate is constant. The MPEG-2 rate can vary, depending on the picture content. And MPEG-1 saves bits by working at reduced resolution.
It does this by taking each full picture frame, halving the number of lines which make up the picture, and coding only those lines. So it codes at 25 pictures a second. On replay, the decoder reconstructs pictures with half the normal number of lines but displays each picture twice over to make up the full TV picture speed of 50Hz, So there is no flicker, but some clarity is lost and there may be some motion artefacts, e.g. judder when the camera pans past vertical objects like lamposts.
For MPEG-2, each field is coded and decoded separately, at 50Hz, to deliver an interlaced display, like broadcast TV.
MPEG-3 was originally intended to cover HDTV. Now it has been absorbed into MPEG-2 which covers data rates high enough for HD.
Until the MPEG-2 standard is finally set, and chips are ready, the broadcasters are using MPEG-1 at higher bit rates. And even with the MPEG-2 standard, there is still need for a further set of standards to define the modulation techniques used. This is why 140 electronics companies and broadcast organisations in Europe have got together to form the wholly voluntary DVB, or digitial video broadcasting group. DVB is doing, for free, the kind of job the EC Eurocrats in Brussels are paid to do.
Philips' Theo Peek describes the spirit of collaboration amongst the DVB Group as "almost Japanese ".
The DVB Technical Committee or "Module" agreed a standard (MPEG-2 with QPSK, Quadrature Phase Shift Keying) for satellite broadcasting in December 1993 and for cable (MPEG-2 with 64 QAM, Quadrature Amplitude Modulation) in January 1994. The Committee expects to agree on a standard for terrestrial broadcasting (MPEG-2 with COFDM, Coded Orthogonal Frequency Division Multiplex) before the end of this year. Audio decoders will be flexible, to cope either with stereo Musicam, Dolby AC-3 or Musicam multi-channel. These standards go first to the DVB Steering Board, and then to the European Standards Organisation ETSI for rubber stamping.
CODING RATES Things are moving fast. Philips and
Pace/NTL were both receiving DVB satellite broadcasts in Amsterdam, with consumer receivers based on chips made by Thomson. At the Live '94 Consumer Electronics Show held at Earl's Court in London a few days later, the UK Widescreen Forum stand was receiving digital TV broadcasts made by the NTL from a 70 watt transmitter at Croydon, on UHF channel 34. The data rate was 15MB/s, MPEG-1, using ODFM to spread the data over 512 carriers with 16 QAM modulation. Reception was on a standard 18 element domestic aerial.
The future MPEG-4 will cover coding at much lower rates, under 100 kilobits/second, e.g. for telephone transmission or disc and chip storage of motion pictures. Fractal compression has been tipped for MPEG-4. Whereas DCT breaks the picture into blocks, fractal coding works by analysing the tiny component shapes from which all images are built.
Dr Michael Barnsley of Iterated Systems, the company behind fractals, was billed as a late entry to the IBC panel. But he never appeared. This was a pity because Chris Birch of Scientific Atlanta, Canada, was very dismissive of fractal technology for MPEG-4. He was equally dismissive of wavelets compression technology. This is a variant of DCT coding. Whereas DCT coding works with fixed block sizes, wavelets technology varies the block size to suit the signal.
Birch suggested that that one way to achieve super-low coding rates may be to use "image synthesis". This compares with MIDI sound coding.
Whereas a MIDI decoder stores wave tables, which are digital snatches of musical instruments which are then moulded by the playback unit, image synthesis would store basic images, like the President of the United States. But the tables would need updating, "George Bush would not want to be confused with Bill Clinton", says Birch.
CALCULATIONS Dr. Leonardo Chiariglione, of Italy is
the dynamic Chairman of the MPEG committees. He had nice way of answering a suggestion from a member of the audience that new technology such as wavelets might be better than MPEG.
"The last time I calculated, a year ago, it had taken 600 man years to put together a working MPEG standard. If you can find 600 man years and put together a working system, I am sure you will find some buyers".
Chiariglione confirms that the MPEG-2 Committee is now extending its scope to new areas which include the control of remote storage media, non-backwards compatible audio coding and 10-bit video coding. The final draft for MPEG-2 should be ready by November 1995.
Paul Ratliff of the BBC Research Department in the UK predicts that the broadcast industry may have to move to programmable software decoding, as currently used by the computer industry. The decoder is just a powerful processor and memory which works with whatever decoding algorithm it receives.
Says Chiariglione "We will still need to categorise the algorithm, always within limits. For MPEG-4 we are considering this, perhaps with the decoder storing a range of different algorithms, so that the program just tells it - Use algorithm 25".
As the seminar Chairman reminded in his summing up: "Anyone who thinks we do not need standards should just try putting a MAC disc in an IBM PC, and see what happens".
36
Everyday with Practical Electronics, January 1995
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Everyday with Practical Electronics, January 1995
37
Special Feature
ELECTROMA GNET/C
COMPATIBILITY
ANDREW CHADWICK
=
The implications of the new EMC
regulations, although not yet fully
clear, will have a profound effect
upon the electronics industry,
and even, it is claimed, upon some
aspects of the hobbyist market.
Electromagnetic compatibility, or EMC, is defined as "the ability of a
device to function satisfactorily in its electromagnetic environment without introducing intolerable disturbances to that environment or to other devices therein."
Despite the seemingly academic definition, manufacturers of electrical and electronic equipment are currently taking a great deal of interest in the subject, mainly due to the necessity of meeting new legislation which came into force in 1992.
The problem is not new. In 1933 international organisations held a meeting in Paris to discuss radio interference, which led to the formation of the Comite International Special des Perturbations Radioelectriques or C1SPR. Since its inception the CISPR has produced a number of reports and standards, mainly on radio interference. Many of these have been adopted by CENELEC, the organisation responsible for electrical standards in Europe. In the UK the main legislation on the subject has been contained in the Wireless Telegraphy Acts of 1949 and 1967.
HARMONISA TIOPJ However, in recent years the situation
has become far more complex. The development of mobile phones, personal computers and microprocessor-controlled household appliances has brought with it the risk of detrimental interference to all kinds of electronic appliances, not only to radio receivers.
A growing awareness of this led to recognition of the need for the more wideranging concept of compatibility. Standards on EMC were written but these were limited to certain product groups and were often specific to a particular country. Recent legislation has changed all that and imposed EMC requirements on virtually all electrical and electronic equipment intended for sale in the European Community.
The new legislation on EMC, known as the EMC Directive, is part of the effort to remove the physical, technical and fiscal barriers to free trade in the European
Community. Conforming to differing technical standards in member states leads to increased manufacturing costs and delays the marketing of innovative products. The process of removing these sorts of restraint has acquired the rather charming title of harmonisation. It will hopefully lead to the practical realisation of the single internal market, which was established, in principle, at the beginning of 1993,
STATUTORY
REQUIREMENTS The EMC directive was adopted in 1989,
and became part of the British legislature in the form of what is known as a Statutory Instrument, entitled The Electromagnetic Compatibility Regulations. The essential requirements are that apparatus should be constructed so that:
"The electromagnetic disturbance it generates does not exceed a level allowing radio and telecommunications equipment and other apparatus to operate as intended.
"The apparatus has an adequate level of intrinsic immunity to electromagnetic disturbance enabling it to operate as intended."
These two separate aspects of the problem are usually referred to as emission and immunity, respectively.
The term electromagnetic disturbance covers not only radio frequency effects but also other unwanted signals such as transients on the mains and control cables, electrostatic discharges and magnetic fields. However, nuclear electromagnetic pulses are excluded!
TRA NSITIONA L
COMPLIANCE Although deceptively simple in sum-
mary the scope and implications of this directive are very wide-ranging. The original intention was that it should come into force on 1st January 1992. However, as a result of widespread protest by the industry at the impossibility of achieving this, the directive was delayed until 28th
October 1992 and an amendment was agreed giving manufacturers until 1st January 1996 to comply. In the current transitional period manufacturers may either comply with the new directive or with the regulations at present in force in the state concerned.
Like any other legislation there must be a method of enforcing the EMC directive, and penalties for those who contravene it. Each state in the European Community can choose its own method of enforcement. Britain has opted for a complaint-driven system using the existing trading standards organisation. Although the maximum penalties of a £5000 fine or a threemonth prison sentence may not seem very harsh, the main deterrent is likely to be the possibility of a product being excluded from the market.
The scope of the EMC directive is very wide, and effectively applies to all equipment produced since 28th October 1992. Where a manufacturer has taken advantage of the transitional period and currently only complies with existing standards, he will still need to meet the directive by the 1996 deadline if the product is to remain on the market.
EXEMPTIONS There are some exemptions to the legisla-
tion. Equipment for use outside the EC countries and secondhand equipment are two examples. Equipment that is unaffected by electromagnetic disturbances and does not emit unwanted electromagnetic disturbances is described as "benign", and is also excluded.
In the hobby field, radio amateur apparatus which is not available commercially is exempt, but CB equipment is not, as it is classed as consumer electronics. Designs for projects appearing in the hobby electronic press are obviously not within the scope of the directive as there is no commercial supply of equipment.
General electronic components are also excluded as they have no "intrinsic function intended for the end user". However, kits of parts supplied commercially will have to conform, as they are sold for the purpose of constructing a specific piece of equipment. This is likely to have serious implications for companies specialising in this area.
There are also certain product groups, such as active implantable medical devices and motor vehicles, where a general directive has already been implemented which includes requirements for EMC. These then take precedence over those in the EMC directive.
38
Everyday with Practical Electronics. January 1995
NEARLY
UNIVERSAL
Despite these exceptions most electronic and electrical equipment is affected.
The basic method of showing compliance with the directive is for the manufacturer to demonstrate that a product conforms with the relevant EMC standards. This involves either the manufacturer or a third-party specialist company testing the product in accordance with the standards.
One of the difficulties of achieving the original 1992 deadline was that the scope of the standards which existed was restricted to certain aspects of EMC, in a limited range of equipment. The situation now is that there are a handful of product and product family standards and two generic standards.
EN 55014, which is issued as BS 800 in this country, is an example of a product family standard, and deals with emission (of an electromagnetic kind!) from household appliances. Most of the current product standards are harmonised versions of those which were in existence before the EMC directive came into force. Work is being carried out on a wide range of new product standards but it may be some time before these are issued.
The generic standards are intended to cover a wide range of equipment in a particular environment and apply when no suitable product standard exists. The two currently available are EN 50081-1 and EN 50082-1 which deal with emission and immunity in residential, commercial and light industrial premises. Similar generic standards for industrial environments are in preparation.
TECHNICAL
COMPLIANCE
The other way in which a manufacturer can demonstrate compliance is by means of a technical construction file. This is a collection of drawings, descriptions of EMC provisions and calculations relating to these, and the results of any tests performed. The technical construction file is submitted to a "competent body" for approval.
So far about 30 competent bodies have been appointed in the United Kingdom. Some are divisions of existing manufacturers and research organisations but many are specialist companies specifically set up to handle what promises to be a rapidlygrowing (and lucrative!) demand for EMC expertise.
One exception to the above is equipment incorporating a radio transmitter which must be submitted to a notified body for testing. There are four of these bodies in the UK each dealing with a different type of equipment.
Once compliance has been demonstrated, the manufacturer must make a Declaration of Conformity describing the equipment and citing the evidence for compliance. The CE (Communaute Europeene) symbol may then be used on the equipment, allowing it to be marketed unhindered in any state in the European Community.
The CE marking is not specific to EMC, but simply shows that a product complies with relevant "new approach" European directives. Consequently if other directives apply to a product it must also comply with these before the symbol can be used. Readers may have seen the CE symbol on many toys, showing they comply with the Toy Safety directive.
ENCLOSURE PORT
APCORPTOWER APPARATUS EARTH PORT
D CPOPROTWER
PORT
(EE<.531G |
Fig. 1. The five emission ports recognised by EMC standards.
RADIATION
Some of the radiated emission will travel directly to the antenna and some will be reflected from the ground, as shown in Fig. 3. The amount reflected is very dependent on the condition of the soil, and so for consistent results it is usually necessary
to install a conducting ground plane, consisting. for example, of a metal mesh with dimensions as shown in Fig. 2.
It is also necessary to adjust the position of the antenna and rotate the EUT to obtain the worst-case readings. The other major problem with an OFTS is masking of emissions from the EUT by ambient noise such as transmissions from local taxi radios!
PORTS The extent of the testing required to
OABNTTAEINNNMAA,XAIMDJUUMSTSAIGBNLAEL TO
demonstrate compliance can be seen by glancing through the residential, commer-
DIRECT
9
cial and light industry generic standards.
EUT
EN 50081-1 and EN 50082-1. In these
6
standards a piece of apparatus is con-
sidered to consist of a number of "ports"
REFLECTED
as shown in Fig 1.
GROUND PLANE OR EARTH
The standards recognise five categories of "ports" which are capable of transmit-
[EEt5330 I
ting electromagnetic disturbances to and
from apparatus. A mains cable, for instance, would be classified as an a.c. power port.
Fig. 3. Direct and reflected paths for radiated emission.
The generic emission standard speci-
The generic emission standard also speci-
fies the maximum electromagnetic radia- fies limits for continuous conducted inter-
tion from each of the ports and gives a ference from the equipment to the mains
reference to another basic standard which supply, the mains "port", over the fre^
details the test method. The electromag- quency range 150kHz to 30MHz. This is
netic field strength from the enclosure port, measured using the set-up shown in Fig. 4.
for instance, must not exceed 30dB (pV/m)
The artificial mains network provides a
at 10m over a frequency range of 30- constant standard impedance to the EUT,
230MHz, or 37dB over the range 230- and attenuates signals from the mains
1000MHz. This is an example of a radiated that could interfere with the measure-
emission requirement and would normally ments. It may also be necessary to
be checked using an Open Field Test Site or provide additional mains filtering or per-
OPTS.
form the measurements
in a screened enclosure
2d
to eliminate outside interference.
Harmonic com-
ponents of the mains
current in the range 0 to
2kHz produced by the
equipment must also be
limited. A low value
resistor in the supply or
a current transformer is
1-7d
used to monitor the current, and a spectrum
ANTENNA GR0UND (EPQLUAINPEMENT UENuDETR TEST 1
analyser identifies and measures the harmonics. During the tests the
mains supply must be
maintained within two
per cent of the nominal
voltage and 0-5 per cent
of frequency.
Fig. 2. Minimum dimensions of an Open Field Test Site
Limits are also set on discontinuous inter-
and gr ound plane.
ference, such as clicks
when, for example, a
thermostat operates, and on voltage fluc-
An OFTS is an elliptical piece of flat (to tuations.
within SOmpi) ground whose dimensions are defined as shown in Fig 2. Even for a
IMMUNITY
distance d of 10m this requires an area of STANDARDS
20m by 17m. Furthermore, there must be The generic immunity standard is more
no large reflecting surfaces, such as build- extensive and includes specifications for
ings close to the perimeter of the site.
immunity to RE electromagnetic fields over
The equipment under test, or EUT, is a wide frequency range, electrostatic
placed at one of the foci, and a receiv- discharges, magnetic fields, high voltage
ing antenna at the other. The antenna is transients, voltage dips and variations.
connected to a suitable instrument, such
Each specification has an associated
as a spectrum analyser or receiver, which performance criterion of A, B or C.
is capable of measuring the field strength Performance criterion A means that the
over the appropriate frequency range.
equipment must perform as intended
Everyday with Practical Electronics, January 1995
39
TYPICAL ARTIFICIAL MAINS NETWORK
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(M5TS0UPEENA0CESTIAUMRBRPULIENEMDGARANIENNCCSAEETLIRVYUESRME)REWNOITTRH
Fig. 4. Measuring conducted interference using an artificial mains network.
during the test. B that it should operate as intended after but not necessarily during the test, and C that there may be a temporary loss of function that is recoverable either automatically or by means of the controls.
The simplest set-up for testing immunity to radiated R.F. fields is shown in Fig. 5. The field strength at the EUT is specified by the standard as 3V/m over a frequency range of 27-300MHz. This is monitored by field probes on or near the EUT as the frequency is swept over the range. The tests have to be carried out in a screened chamber to prevent the strong electromagnetic fields that are generated interfering with
the monitoring and other equipment in the immediate surroundings.
Results using this method of testing can be misleading due to reflections and standing waves set up in the screened chamber. More recent draft standards, which are
likely to come into force soon, extend the range of frequencies at which tests must be carried out up to IGFlz, and include modulated fields. The preferred test setup has been revised to an anechoic chamber or absorber-lined shielded enclosure to avoid the problems of reflections and nonuniform field strength.
The electrostatic discharge tests are designed to simulate the effect of the equipment being touched by a charged person. Simply walking across a synthetic carpet can lead to a build-up of charge, resulting in potentials as high as lOkV. Contact with a piece of equipment
produces a rapid discharge to earth with peak currents of maybe 10A.
The test method uses a discharge generator which incorporates the electrical equivalent of the human body, as shown in Fig. 6. In the air discharge test the capacitor is charged to 8kV and the dis-
TARNATNESNMNIATT^ING
SCREENED METAL ENCLOSURE
MINIMUM 1 M
, FIELD PROBE
ft 0-0 IT
WOODEN TABLE
(EEt535G | ARM.-- EPPLOIFWIEERR<1 GESINGENRAALTOG RV--X
FIEMLEDTESRTRENGTH
Fig. 5. Testing for radiated immunity.
BUFILLKTHEERAD- TYPE
charge electrode brought near to the EUT until a discharge occurs. This is repeated at other points on the accessible surface and to nearby conducting surfaces.
UIMCERTAIIM
IMPLICA T/OnUS
The above brief descriptions should give an idea of the extent and complexity of the testing required to demonstrate compliance with the EMC directive. It is difficult to judge the full implications of the legislation at the moment, particularly as many of the standards are still only available in draft form. However, it is apparent that there will have to be a good deal of investment in specialised test facilities, equipment and training.
Many of the larger manufacturers of consumer electronics, domestic appliances and telecommunication and IT equipment already possess EMC test facilities of some sort, and for them the new legislation may only involve an extension of current practice. Smaller companies whose products are subject to EMC requirements for the first time will be affected more severely.
. 100MQ Ir-
HPOIGWHEVROSLUTAPGPLEYj|III I I I I I
150A VvA-!hnio<;rn
150p
( EE*,536G |
OEFQUHIVUAMLAENNTBCOIDRYCUIT
Fig. 6. Simplified electrostatic discharge generator.
For example, compliance testing by a
third-party test house might typically take
three days, one day for emission and two
for immunity, at a cost of £600-£1000 a
day. With an anechoic chamber costing
maybe £500,000, investing in your own
facilities is out of the question. However
there is likely to be a market for low-cost
DIY test rigs that will give a rough indica-
tion of whether equipment is likely to
comply, before it is submitted for a full
test.
Many people regard the EMC Directive
as the most complex and far-reaching
of all the Directives aimed at achiev-
ing a single European market. Hopefully
the benefits in terms of compatibility
and unrestricted worthwhile.
trade
will
make
it
all
EVERYDAY[ trV/TH PRACTICAL ELECTRONICS
SUBSCRIPTION ORDER FORM AOnnvuearlsesausbs£c3r0ip(tsiuornfarcaetems a(i1l)99£44/75.)5;0U(Kair£m24a.i0l)0.
Allen HoTuos:e,EEvearsyt dBaoyrwouitghh.PWraicmtibcaolrnEel,eDctororsneict sB.H21 1 PF Name Address.
40
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enclose
payment of £
(cheque/PO in £ sterling
payable to EveArycdceaysswoirthViPsaraNctoic. al Electronics
only).
Signature
Card Ex. Date stPhclreeiapsnteieoxsnutpaapdvldyarielnsaasbmlseehoiaswnsdnueab.dedFloroerwsbsaSocfkucbnausrmcdrhbiopelrtdsieosrneeisf tdhcieaffneErdeointnotlryfiarolsmptaagtrhete. wsuitbh-
.DZH Everyday with Practical Electronics, January 1995
"Electronics Workbench
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is the best simulator to
design and verify circuits."
Gordon MacDonald Production Engineer Tedmickin
Electronics Workbench is a higltK productive bench where you design and verify' circuits in a fraction of the time. Connections arc always perfect.Wires route themselves. And the simulated components and test instruments work just like the real thing.
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It's faster than building widt actual components because you change connections and component values instantly. And since die simulated components are free, you don't need to replace burnt-out parts or keep an extensive inventory. The result; You save precious time and money. Guaranteed!
The standard tor simplicity and power for over six years. Electronics Workbench is the most popular tool of its kind. It lias gained worldwide acclaim as die ideal complement to any test bench. Fact: Over 90% of our customers recommend it to their friends and colleagues.
Electronics Workbench
I e (h n o I o g y in [ d u c a t i o n CSU95 NATIONAL HALL, OlYMPIA, LONDON
Electronics Workbench
· II ·
^
electronics lah in a computerTM
Just £199 For IX)S, Windows or Mac Version. vtsa ^
Call: 44 0203 233216
Robinson Marshall (Europe) PLC
Nadella Building, Progress Close, Leofric Business Park, Coventry. Warwickshire CVS 2TF
FAX: (44) 0203 233210
-gll
30-day money-back guarantee.
mmSott
SA··lhWitpripatidhnegtmhceahrapkrusgreacsrhea-sthUeeKofp£rE4ol.pe9ec9rtrt.yoAnolilfcpsthnWeeieorsrrkeabsrepenecpchltui.vsOeVffo.Aewr.Tnv.earlisd. until October 15. 1994.
owpSSr
AyV 1 INTERACTIVE
fri
WHETHER ELECTRONICS IS YOUR HOBBY
OR YOUR LIVELIHOOD... YOU NEED THE MODERN ELECTRONICS MANUAL
----^orderno^
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4/8.2
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The essential reference Work
·Easy-to-use format ·Clear and simple layout ·Regular Supplements ·Sturdy ring-binder ·News of latest developments
. ^ \
·Full components checklist · Extensive data tables
· Detailed supply information
·Ready-to-transfer RGBs
EVERYTHING YOU NEED TO
·Comprehensive subject range · Detailed assembly instructions
KNOW ABOUT ELECTRONICS! · Professionally written
If the fascinating and fast-changing world of electronics is your livelihood, your study subject or simply your passion, the revised edition of THE MODERN ELECTRONICS MANUAL is the reference work for you to have at your side.
The Base Manual contains information on the following subjects:
BASIC PRINCIPLES:Symbols, components and their characteristics, passive component circuits, power supplies, acoustics and electroacoustics, the workshop, principles of metrology, measuring instruments, digital electronics, operational amplifiers, timers, physics for electronics,
CIRCUITS TO BUILD:Construction techniques, radio, telephony, microcomputing, measuring instruments, vehicle electronics, security, audio, power supplies, electronic music (over 25 different projects).
REPAIRS AND MAINTENANCE: Basic circuit operation for radio, television, audio/hi-fi, telephones.
DATA:Diodes, transistors, thyristors and triacs, digital and linear i.c.s, microprocessors.
The Manual also covers Safety, Specialist Vocabulary with Abbreviationsand Suppliers.
OVER 1,000 pages,with over 900 diagrams and photographs, A4 looseleaf format weighing over 3.5kg. ALL-IN-ONE AND EASY-TO-USE: A sturdy ring-binder allows you to use the Manual on your workbench. The looseleaf format also means you can slot in the regular supplements as they arrive - so all your information is there at a glance.
EXTENSIVE GLOSSARY:Should you come across a technical word, phrase or abbreviation you're notfamiliar with-simply turn to the glossary included in the Manual and you'll find a comprehensive definition in plain English.
iiuuuiiui (SUAiS ANcTiEiE mjuuui^^
H Our 30 day money back guarantee gives you complete peace of mind. If you are not entirely happy i}j| 0} with the Manual, for whatever reason, simply return it to us in good condition within 30 days and we K m will make a full refund of your payment- no Small print and no questions asked. || (Overseas buyers do have to pay the overseas postage charge).
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Now - at last - the most comprehensive reference work ever produced at a price you can afford, the revised edition of THE MODERN ELECTRONICS MANUAL
provides you with all the essential information you need.
Issue No. 13
Selected Distribution
Display Electronics - The Big Move
Another bumper issue of Display News, this time a massive 48 pages of selected goodies. Many bargains are scattered amongst the pages, hopefully something to interest a wide spectrum of our customers from the electronics hobbyist to the industrial user. Remember we are most happy to serve ALL customers large and small. Our technical staff are always ready to answer your questions to their best ability.
Big News - We have finally outgrown our current 20,000 sq feet location and will be moving to a new 40,000 sq feet site in South East London, early in 1995. The new premises will offer many advantages to our customers - such as off street parking, London Transport buses pass the door and two Southern Region stations are situated close by. Plus you can look forward to the Largest walk around Surplus Electronics Outlet in the UK perhaps even in Europe I! Complete with Coffee machine ! Check out our regular adverts for more information soon.
<£i
Win a Bottle of Champagne !
To mark the occasion of our forthcoming move we are offering a quality bottle of champagne for the best five suggestions to fill 'Big Dave's' text bubble. What could he be saying ??? Send entries to our regular address, we will publish the best ones in our next flyer - good luck. Finally, a Very Merry Christmas and Happy New Year to you all.
9
DISPLfly ELECTRDfllCS N
So_jvr m
vVJi
CS? o*0
· ·
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· · ·
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· · ·
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· · ·
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·
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· · · · ·
· ·
· ·
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· · · · ·
··· · ···· ·
-sisciRonics-
All Mall & Offices 32 Biggin Way, Upper Norwood,
London, England SE19 3XF
VISA
ESTABLISHED 25 YEARS
0181 679 4414 24 Hour Fax Line 0181 679 1927
Shop & Showroom for callers (no mail to shop) 215 Whitehorse Lane, South Norwood, London Open Monday to Saturday 9.00 to 5:30. Opposite Selhurst Park Football Ground.
On 68A London Transport Bus Route. Near Selhurst & Thornton Heath Rail Stations.
© Display Electronics 1995
Display 9{ews Issue No. 13
tt
Rack Cabinets And Accessories
C^S 00°
py c* 5^
MASSIVE REDUCTIONS - VIRTUALLY NEW
Ultra Smart - Less Than Half Price!! DISCOUNTS AVAILABLE FOR QUANTITY ORDERS - CALL
For your information, a V is a standard rack measure. 1U = 1.75"
3U 19" Quality General Purpose Rack Case
Free standing, smart case with integral 3U 19" rack mounting lugs. Made of high quality aluminium
extrusion with removable two tone grey steel covers, with side and bottom ventilation slots. Fully
,
featured, the rack has 6 position mounting slots for standard cage nuts, fitted left and right both front
and back. Internal recessed carrying handles and modern construction make this a very smart rack indeed
Supplied in "as new" little used condition. The overall dimensions are 20%"W x
x 16-5/8"D
Order as: 3U RACK CASE Only £39.95 (C)
7U Heavy Duty Desk / Floor Equipment Cabinet
Superior quality heavy duty equipment cabinet made from steel and alloy, finished in two tone grey
colour scheme. Front fitted vertical fixing struts accept standard clip in 'cage nuts' and the rear mounting
frame is ready drilled and tapped for a 20" x 13-3/8" blanking or mounting panel. Both the top and bottom
of the rack are fitted with fully perforated panels to allow maximum convection cooling and superior elec-
trical screening. The top section is double skinned over with a solid steel sheet to prevent spillage of liquids
or foreign objects from falling through the top mesh. An all round side 0.7"
ventilation gap provides highly efficient cooling. Complete with side mount-
OCO
ed recessed fold away carry handles. External dims. 16" H x 20%" W x 18" D. xJlliy
wD (D)
A superb rack at a superb price!! Supplied in "as new" condition. Order as: DESK CAB 1.
. 14U
14 & 16U 19" Desk / Floor Standing Ideal unit for either desk or floor standing equipment. All steel construction finished in two tone light brown with 8 fixed vertical cage nut fixing strips mounted 4 front and 4 rear which allow for any combination of fixing or support. Excellent ventilation is provided by slotted vents in the bottom section and on the removable back panel. Supplied in good slightiy used condition complete with 2 fitted flush carry handles and 4 rubber feet. Dims: 14U 291/2" H X 16.5" D X 20" W. Front to back vertical fixing strut dim: 16%" Dims: 16U 29,/2" H X 16.5" D X 20" W. Front to back vertical fixing strut dim: 16"
Steel shelf support angle brackets for 14U & 161) racks £3.95 per pair
Special Offer - Either type Only £49.95 (o
16U
32U - High Quality - All steel cabinet
Made by Eurocraft Ltd to the highest possible specification this free standing rack cabinet features all steel construc-
tion with removable side, front and back doors. The front and back doors are hinged for easy access and all are lock-
able with high quality 5 lever barrel locks (key supplied). The front door is constructed of double walled steel with a
'designer style' smoked acrylic front panel to enable status indicators or leds to be seen quickly through the panel, yet
remain unobtrusive. Internally the rack features full slotted reinforced vertical fixing members to take the heaviest of
equipment and movable vertical fixing (two supplied as standard) struts pre punched for standard 'cage nuts'. A mains
distribution panel internally mounted to the bottom rear, provides 8 I EC 3 pin Euro sockets and 1 x 13 amp 3 pin
switched utility socket. Overall ventilation is provided by fully louvered back door and double skinned top section with
top and side louvres. The top panel may be removed for fitting of integral fans to the sub plate etc. Other features
include: Fitted castors and floor levelers, prepunched utility panel at lower rear for cable / connector access etc.
Supplied in excellent, slightly used condition. _
,,
.
,
r\r\
Ext. Dimensions 64" Hx 25" Dx 233/4" W. A SUpefD buy 31 Ollly t I 95.00 (G)
39U VERO - Budget 6 foot
Made in the UK by Vero Enclosures these open front and back racks feature steel and alloy con
struction finished in a very smart two tone light grey colour scheme. Removable side panels allow easy
access to the 4 vertical fixing struts which are fixed 18" apart (front to back). The struts accept standard clip
in "cage nuts" for mounting all types of 19" rack equipment, panels etc. Overall external dimensions: 77" H x 23" D x
I*
22%" W. Internal inside dimensions: front to back 18", maximum vertical fixing area 68V2". Supplied in good used condition,
Order as: VERO 1
Only £155.00 each (G)
ALL ADVERTISED RACKS PLUS A LARGE RANGE OF SPECIALS MAY BE VIEWED PRIOR TO PURCHASE AT OUR SOUTH LONDON CASH & CARRY WAREHOUSE
0181-679-4414
1
Fax: 0181-679-1927
^ ^ ^ «%>
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^ ^^
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(Display 9^ezvs Issue No. 13
40U 'Optima' High Grade Extra Deep
Top quality 19" rack cabinets made in UK by Optima Enclosures Ltd. Units feature designer, smoked acrylic lockable front door, full height lockable half louvered back door and removable louvered side panels. Fully adjustable internal fixing struts/ready punched for standard 'cage nuts' for any configuration of equipment mounting, plus ready mounted integral 12 way 13 amp socket, switched, mains distribution strip make these racks some of the most versatile we have ever sold. Racks may be stacked side by side and therefore, if purchased in multiples, require only two side panels in total. Overall dimensions are IIV2 H x 321/2" D x 22" W. Call for shipping cost.
Complete rack inc. 2 removable side panels. Order As: OPT RACK 1
£335.00 Call for shipping cost Internal heavy duty shelves for above with fixing kit. £18.95 each
Rack complete as above but LESS side panels Order As: OPT RACK 2
£225.00 Call for shipping cost Top mount, twin fan cooling assembly occupies no space in rack. £39.95 each
WOTS A U ? A rack Standard of Measure = to 1.75" So, now you know!!
CAGE NUTS Clip in nut used for fixing panels or equipment
to rack frames 10 For £3.95
Less than Vi MAKERS PRICE !!
42U 'Eurocraft' All steel cabinet
Another fine Eurocraft UK made cabinet. Made to the highest possible specification this free standing rack cabinet features all steel construction with removable side, front and back doors. The front and back doors are hinged for easy access and all are lockable with high quality 5 lever barrel locks (key supplied). The front door is constructed of double walled steel with a 'designer style' smoked acrylic front panel to enable status indicators or leds to be seen quickly through the panel, yet remain unobtrusive and away from unauthorised fingers I! Internally the rack features fully slotted reinforced vertical and horizontal fixing members to take the heaviest of equipment and shelf supports. Two movable vertical fixing struts pre punched for standard 'cage nuts' are prebolted to the fixing members. A fully enclosed mains distribution panel internally mounted to the bottom rear, provides 8 IEC 3 pin Euro sockets and 1x13 amp 3 pin switched utility socket. Overall ventilation is provided by fully louvred back door and double skinned top section with top and side louvres. The top panel may be removed for fitting of integral fans to the sub plate etc. Other features include; Fitted castors and floor levelers, pre punched utility panel at lower rear for cable / connector access etc. Supplied in excellent, slightly used condition. External Dimensions 79.5" H x 25" D x 23%" W. Call for shipping cost Q p |y £299 00 (^0
A host of options can be supplied with all of our rack cabinets these include: fans, brackets, blanking panels,
shelfs, shelf supports, power distribution etc. Please call our technical staff for more Information.
-STOP PRESS-
Just arrived as were going to print!! call for more info.
OPTIMA 'GIANT' 44U 19" rack cabinets same spec as rack OPT1 (top of this page)
As new condition complete with side panels etc. ONLY £435.00 - shipping call
Slim Line (1U) Triple Fan Trays
Measuring only 1U high (1 %") this unit, Vero part number 28-43201E or equivalent, encas-
es three 120 mm quality fans to provide a large degree of air movement / cooling in the min-
imum of space - very quiet running. Supplied fully tested with 90 day guarantee. Specify when
ordering 110 o.r 240 volts AC.Order as: 1U FAN TRAY.
r*AC OC
z.4o.yo (c)
2U Alloy Vented Blanking Panels
f / -·
OoO · : .oOo..
OoO
.vcO<_i" oCo.V
o: C o
OO"·
Ooo' o
·:oc"O
'::oo0 q;
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Standard 2U x 17" vented blanking panel - ideal for fitting towards the top of a rack cabinet to allow natural cooling by convection or as a draft exit for forced air cooling. Made of 0.125" alloy plate and finished in a light brown colour. Easily painted to suit your own colour scheme IRFE 0n|y ^ ^ ^ 2 j gg(A)
0181-679-4414
2
Fax: 0181-679-1927
'Display D^WS Issue No. 13
No Break Uninterruptible Power Supplies
Brand new and boxed model MUD 1085-AHBH from Densei, 240 volts AC 1 kVA (4.2 amps). The batteries in this unit are housed in a separate case. This model also features a constant voltage constant frequency output. Indicators include charger running, inverter running and inverter alarm. A buzzer alarm is also provided. The unit
supplies output signals to an AUX terminal to indicate that there has been a power failure. The three signals at the terminal are the On battery signal. Inverter on/off signal ^ and the Alarm signal. Typically these signals are taken to CMOS gates for processing if required. Provision is also made for external switching of the inverter. Supplied complete with operation manual. Order as MUD-UPS
Only £575 each (F)
1 kVA SMI
INPUT:
SPECIFICATIONS
Phase= Single
Voltage= 240v ± 15%
Frequency= 47-53hz
Capacity= 1.8kVA
OUTPUT: BATTERY:
Phase= Single
Voltage= 240v ± 2% Frequency= 50hz ± 0.5% Capacity^ 1 .OkVA
Current= 4.2 A max Instantaneous voltage variation = ± 10% or less. Setting time 100ms or less
Sealed lead acid
Time available from interrupt = 15 minutes at full load
Emerson 'Accucard' Internal PC UPS
A brand new 8 Bit half length PC compatible card for all IBM XT/AT compatibles. The % length card provides DC power to all internal system components in the event of power supply failure. The Accusaver software provided uses only 6k of base RAM and automatically copies all system, expanded and video memory to the hard disk in the event of loss of power. When power is returned the machine is returned to the exact status when the power failed, even if you ; were in the middle of an application ! The unit features full self diagnostics on boot and is supplied with full fitting instructions, software and manual. Normal price £189.00.
Only £69,00 each (B) 2/£120.00 (c)
Chubb High Security Barrel Lock
10 lever very secure steel lock, as used on cash registers, alarm systems, banking equipment, and Welsh John's wallet. Spare keys are not available or copyable by locksmith's and must be obtained direct from Chubb Ltd. Each lock is supplied with two keys and every lock supplied has an individual combination. The key is made of solid brass and is particularly unobtrusive measuring only 44mm in length. The barrel lock is mounted via a 19 mm hole and threaded ring (supplied) and has a 9 mm square shaft and lock nut to accept a host of tounges. The key turns the lock through 90 deg and remains captive in the turned position.
Only £3.99 w 10 / £25.00
mm
Relays
These are all fully shrouded "Continental" type relays. Contacts typically rated at 5 amps. Dimensions only vary slightly - about 11A"H x 1 "W x 5/8"D. PLEASE ORDER RELAYS BY THE PART NUMBER LISTED.
CR-1 6 vdc. 52 ohms. 2 c/o CR-3 12vdc.185 ohms. 4 c/o CR-5 12vdc.250 ohms.1 c/o.10 A CR-7 12vdc. Latching. 2 c/o CR-9 24vdc. 700 ohms. 2 c/o
£2.25 £2.25 £2.95 £3.25 £2.25
CR-2 12 vdc. 185 ohms. 2 c/o CR-4 12vdc.200 ohms. 1 c/o CR-6 12vdc.260 ohms. 1 c/o.16 A CR-8 12vdc. 330 ohms. 6 c/o CR-10 48vdc. 1700 ohms. 2 c/o
£2.25 £1.95 £3.95 £3.25 £2.25
Shipping for all relays is (A)'
Jumbo High Voltage Capacitor
It's not often you see a non electrolytic capacitor of this size and voltage - and especially at this price I Made by General Electric USA, Cat Ref 28F2011 and rated at 8 mf at a massive 4,250 V DC this item will deliver a massive amount of energy in a fraction of a second! . Normally used in high voltage pulse circuits such as radar or for the firing of Xenon flash tubes or pulse type lasers. Completely hermetically sealed with electrical connections made by two bolts mounted on top of the two porcelain insulators. A push on tag connection is provided to safety earth the all metal casing. The unit is supplied with a shorting link to prevent static electricity in the air from self charging, possibly resulting in an electric shock hazard - this must not be removed until required for use. Dimensions: 5" w x 6" h x 8 "
Only £14.95 each (B)
Please be warned that electricity and high voltages can be dangerous and lethal. If at all in doubt seek expert advice before purchase or use of this item.
0181-679-4414
Fax: 0181-679-1927
'Display 9\(eu's Issue No. 13 Floppy Disk Drives
"US
Note: We supply only first grade floppy disk drives of well known brands. Unless otherwise A stated, all are new or removed from new equipment and are totally standard in every way, y
C
SVa" 720 K or SW 360K £24.95 ,b, or 3/E69 <0
51/4" 720K
£22.95 <6, or 3/E65 (c,
31/2" 1.44 M or 51/4" 1.2 M
£29.95 ^ or 3/E84 (c,
Laptop Floppy Disk Drives
Ultra compact 1" height 31/2" 1.44 Mb drives for use in laptop computers. Such drives differ from the more normal desktop drives in that
no separate power connector is provided. The power for the drive goes up two of the wires of the data cable. This cable is supplied and
terminates in a 34 way female IDC connector.
__ _
* rtrtrt r\r-
£36.95 (B) or 3 for £99.95 (C)
SVa" 1.2 Mb External Floppy drives With PSU's
Brand new and boxed external SVa" 1.2 Mb floppy disk drives complete with integral povyer supply. These are Teac FD-55GFR which is one of the state of the art 96 TRI floppies which will read and write double sided, double density plus high density with equal ease. Comes complete with all necessary cabling. Your existing data cable is replaced with the one supplied, which has an extension to a slot plate bearing a 37 way female D socket, as does the drive itself. 37 way connecting cable included. This drive was in fact made as an add on to a Zenith range of laptops but is equally at home with any PC compatible which supports 1,2 Mb drives. Measures 12"L x 6"W x 2-%"H. Two tone grey metal case, extremely sturdily made. Complete with installation and user manual.
Only £49.95 each (C)
WITH
Last Chance! To Buy a 720K
3V2" External Floppy Drive For Your
Zenith Minisport Laptop!
--
Brand new Zenith packaged SVz" 720K external floppy disk drive made for Zenith's Minisport laptop com-
puter. Would probably work with other laptops if the sub-miniature 20 pin D plug were changed, as internally the drive is a standard
Panasonic with a standard 34 way connector and separate power socket.
^
mm
Comes complete with installation manual. Measures 7-%"D x 4-%"W x 1-1/8"H. _ .
.
To the best of our knowledge Zenith have ceased production of these drives and Ljniy
63Cn (B)
we have only limited quantities - so buy now or forever hold your peace!
'
51/4" to 31/2" Disk Drive Conversion Kit
Another most useful item, Converts your 5V4 disk drive bay on a standard IBM or compatible system to accept a S'A" floppy disk drive. Kit even comes complete with screws and adaptor cables to change the data and power connections to the different format used on SVa" floppy disk drives. Makes that upgrade job a breeze !
£7.95 each w
%
0181-679-4414
4
8" FLOPPY DRIVES BY
SHUGART TANDON MITSUBISHI EX STOCK CALL FOR DETAILS
Fax: 0181-679-1927
(Display (Mezvs Issue No. 13
·o"Hard Disc Drives
All our Hard Disk Drives and controllers are new or removed from jequipment and extensively tested before shipment to you. We have ofvveerl
65 different types Ex Stock so please call us with your requirements
CAPACITY TYPE
FEATURES
PRICE
10 megabyte 20 megabyte 20 megabyte 20 megabyte
30 megabyte 40 megabyte 42 megabyte 45 megabyte 85 megabyte 160 megabyte
ST-506 MFM interface ST-506 MFM interface ST-506 MFM interface ATA (IDE) interface
ST-506 RLL interface ATA (IDE) interface
ST-506 MFM interface SCSI interface SMD interface SMD interface
Tandon TM-502 full height 5Va" NEC Model D5126 half height 51A" Fuji FK-309-26 half height 31/2" Conner CP-321 half height S'/s" (or equiv.)
Seagate ST-238R half height SVa" Conner CP-3044 1" high SVi" (or equiv) CDC Wren II 94205-51 half height SVa"
Rodime RO-3057S half height SVi" BRAND NEW NEC D2246 full height 8" BRAND NEW Fujitsu M2322K full height 8"
HARD DISK CONTROLLER CARDS
£39.95(C) £54.95(C) £59.95(C) £69.95(C) £69.95(C)
£89.00(C) £69.95(C) £99.00(C) £299.00(E) £195.00(E)
TYPE
8 Bit XT Type 8 Bit XT Type 16 Bit AT Type 16 Bit AT Type 16 Bit AT Type 16 Bit AT Type MCA (IBM PS-2)
INTERFACE
ST-506 MFM interface ST-506 MFM interface ST-506 MFM interface ST-506 MFM interface ST-506 RLL interface ATA(IDE) interface SCSI interface
FEATURES
Short card for 1 or 2 hard drives only Full length card for 1 or 2 hard drives and floppy drives 3/4 length card for 1 or 2 hard drives only 3/4 length card for 1 or 2 hard drives and floppy drives 3/4 length card for 1 or 2 hard drives only Short card for 1 for 2 hard drives and floppy drives Adaptec AHA-1640, Current RRP £275
PRICE
£34.95(A1) £49.95(A1) £29.95(A1) £44.95(A1) £34.95(A1) £24.95(A1) £129.00(A1)
Outstanding Deals on 5Va"
Floppy Disks!
" ···-.
Maxell MD2-D double sided double density Gold Standard 5Va" floppy disks at an
unheard of price. Brand new and boxed, straight from the manufacturer! 100% Certified! We
bought up an entire surplus stock from
a big user and are passing the savings
j
OO A CZ
on to you. Buy whilst we still have DUX OT I U ~ L/niy
(A)
some left!
1.2 MB
Brand new and boxed high density 5V4" 1.2 megabyte floppy disks at an unbeatable price.
These diskettes are made for Victor by a brand name manufacturer. Box contains 10 disks
with all the necessary labels. At this
Jt
price you just have to buy!
QqX Of 10-OnlyE4.99 (A)
150/250 Mb External SCSI Tape Streamer
Brand new and boxed Archive VP series model 250e external extra high capacity tape streamers for all who need large backup storage either on their own machines or for multi-user networks including Novell and the popular versions of Unix. Suitable for PC-XT-AT and PS-2. Uses DC6150 for 150 megabytes and DC6250 for 250 megabytes, or equivalents, 1/4" industrial type cartridges for total reliability and security. Requires a SCSI interface card or Archive's own 402 (PC's) or 409A(PS/2) controller. Suggested software is QlCstream 4.0, PCTools version 8 or Norton backup utilities. The data transfer rate is 112 Kb per second and reliability is less than 1 error in 1010 bits. Fully recommended for high reliability and/or network use.
a Only £299.00 each (D)
40/80 Mb External Tape Streamers Brand new and boxed XL series model 5240. It has 40 Mb capacity (80 Mb compressed if the driving soft-
ware supports Data Compression) or 60 Mb with extended length cartridges (120 Mb compressed). Suitable for PC-XT machines. Uses Maynard 340 (for 40 Mb), Maynard 1120B (for 60 Mb) or equivalent tape. The interface required is PC compatible floppy. Data transfer rate is 1.2 Mb per minute. Suggested software is QlCstream although other utilities may well support this drive.
Only £99.00 each (D)
0181-679-4414
5
Fax: 0181-679-1927
'Display O^ezvs Issue No. 13
immiinttmumiunnuim
Qume Daisywheel Printer For Parts Or For Use As Is
------
Brand new and boxed Qume LetterPro 20 printer complete with
Elite 12, 96 ASCII character daisywheel, ribbon and 120 page man-
ual. Uses the QS-3 parallel interface. A gift if you use that interface
or can convert it to Centronics, but most people will want it for the
wv.-..
treasure trove of brand new parts. The platen motor alone costs three times our price for the whole machine! Hundreds of parts for
ms*'
DIY, taking
robotics and hobbyists. It's worth the money just for the fun of it apart! Contains several DC motors with precision optical
>PLRV use
1, As is 2, McxJIy 3, For parts DEAL
positioning mechanisms. The manual supplied is very full and describes the Centronics, Serial and QS-3 inter-
fsatacneds awlhoinceh faulrley einnsctaalsleedd sinwidtcifhfemreondt empoodweelsr soufptphliys pprroinvtiedri.nAg+ls-o16invcDluCdeasnda
fs ,, i.. Q_ OA- QK --
+5 vDC. In summary - a gift!
vyniy
(D)
General Purpose Oscilloscope Probes
General purpose passive oscilloscope probes. BS-100 is switchable 1:1 and 10:1, BS-010 is 10:1
only They both come with a full complement of accessories: spring loaded test hook, IC test tip, insulating tip, BNC adaptor, compensating tool for trimmer adjustment, 20 cm ground lead and probe tip. Both also feature nice "ultraflex" cable 1.2 metres long. Specifications for BS-010 and BS-100 in 10:1 position are the same.
Attenuation Bandwidth
Rise Time Input resistance Input capacitance Working voltage
1:1
DC to >25 Mhz
14 ns
1 MQ (scope input)
90pf (+ scope input)
200 vDC including
pk AC
derating with frequency
Attenuation
Bandwidth
Rise Time Input resistance Input capacitance Working voltage
1:1 and 10:1
DC to >250 Mhz <1.4 ns 9 MQ +/-1% (10 MH for scopes with 1
16pf 500 vDC including pk AC derating with frequency
input)
Bs-010 £14.95 (A)
Bs-100 £19.95 (A)
SURPLUS WANTED ££££
TOP CASH WAITING! Display Electronics has a constant requirement for quantities of surplus / obsolete and redundant stocks. All kinds of electronic / computer / test equipment / power supplies / components / connectors / semiconductors / IC s / printed circuit boards / radio equipment / motors / racks / relays etc. always wanted. We are able to give a fast quote on lists of items available, or by viewing 'that pile in the corner1. We are also happy to negotiate a Confidential Reward' for any information leading to a purchase. Distance or quantity no problem - Fax or call Dave Fisher or Gavin Mac for further information now!!
1 in 3 out X 15 Video Distribution Amplifiers
MM
1^1$! y-r « iilpP
Professional Video Distribution Amps (VDA's) made in the USA by the DI-TECH Corporation type number 113 as a card or 1130 as a complete rack system. The video amp on the single card features a full
bandwidth (ideal for colour) input with on board adjustment for gain and frequency response with electronics to give up to three individual buffered outputs for driving direct into 75 ohms at 1 v peak to peak. All connections to the PCB are via a 15 way 0.15 gold Dialed edge connector. The single board unit board features two on board regulators to control the wide range + and - 14.5 to 24 volt dc rail inputs and LED status indicators for both the DC rails. A complete 2U (3.5") rack chassis mounting unit complete with edge connectors is also available to accept up to 15 x 3 output VDA's with all inputs and outputs terminated on the rear panel via BNO sockets, qivinq a total of 45 outputs. Module dims. 190 mm x 70 mm x 20 mm. Rack dims 485 x 70 x 20 mm. Current requirements 100 Ma per1VDA. Supplied in fully tested condition with data. Order individual boards as VDA-PCB and complete rack unit with 15 off VDA as VDA-R.
VDA-PCB £29.00 each w
VDA- R £375.00 (D)
0181-679-4414
6
Fax: 0181-679-1927
Display 9{ezus Issue No. 13
s* *0
£300 off manufacturers price!! 1024 x 1024 Resolution
Fully PC / Amiga / Mac Compatible
In our quest to find the most interesting value for money surplus items, this must rate as close to #1 as any I State of the art technology at prices you can now afford !! The MicroTouch, touch screen system consists of a flat clear glass panel measuring 11.75" x 9.25" which is invisibly divided into 1024 x 1024 x and y (almost 1,500,000) touch points I! When connected to its accompanying controller board an RS232 serial connection constantly outputs two ASCII numbers giving the exact X,Y location of a finger when touching the screen, this X,Y number is computed in amazingly less then 8 milliseconds giving virtually instantaneous response. Simple software which can be written in Basic, C, Pascal or assembler etc can be used to decode these real time numbers for a host of applications where keyboard input is not practicable, possible or desired. The mechanics of the touch screen offer some most useful features such as unaffected by dirt or grease buildup, fully protected against radiated interference and electrostatic voltages up to 25KV, impervious to liquids, may be written on with felt tip pen, metallic objects ignored. Plus many more too numerous to mention here. Just a few of the 1000's of possible applications include;
ispsmsa Point of Sale Terminals. Multiple answer response when used with the touch screen placed in front of a monitor or over diagram / plan - eliminates need for keyboard skills or fragile mouse.
Control Panels and Automation. Use with or without a video monitor, coloured card or lighted panel may be placed behind touch screen, just imagine a control panel with 2,000 switches in a space only 11" x 9" I!
Disabled Persons Computers / Controllers. Any area from a few pixels to a whole screen can be defined for touch response, ideal for machine / computer interface for persons with limited co-ordination / movement or computer training. For instance use of a finger in Windows instead of a mouse or even direct 'finger painting' onto CRT.
The applications for this item are only limited by your imagination !!
Unit supplied complete with mounting frame, data sheet, fully assembled controller PCB which connects direct to touch screen via 9 way 'D' plug. Controller outputs data via serial RS232 connection which is connected direct to PC serial port. Supplied complete with fully enclosed power supply. RFE Fully Tested & Guaranteed for 90 days.
Normally over £420! Our Price Only £145.00 (B)
Touch Screen; Overall panel dimensions: 11 %" x S'/a" Analogue output to controller via 9 way 'D' plug. Controller: Fibre glass PCB dimensions 714" x S'/a". Touch screen input via 9 way 'D' socket, RS232 serial data i/o via 25 way 'D' socket. Power supply requirements +5v DC 200 ma ±12v DC 100 ma. each rail.
FREE MicroTouch
To enhance the use of the MicroTouch touch screen system, a full suite of software and drivers with accompanying documentation is available, including the latest patches and drivers for other computers such as Amiga & Macintosh - call the MicroTouch bulletin board on (USA) 0101 508 683 0358 up to 9600 baud supported.
TouchWare. Software system compatible with DOS, Windows and Windows NT, provides full mouse emulation via touchscreen.
TruePoint Touch Monitor. Full demo software, Diagnostic, Configuration etc.
DrivePoint. TSR software program to greatly simplify custom programming. The drivers functions can be called (via software interrupt 17h) from programs written in Basic, C, Pascal, or Assembler.
Pad Manager. Full utility for a programmer to easily define touch zones or pads (up to 2048 on one screen !!). Pads and zones may be
defined as buttons or menu options. Use of the Pad Manager saves performing tedious calculations and drastically reduces implemen-
tation to a few commands.
Complete PC Software Pack
The complete software pack (4 disks) tor IBM PC with printed manuals is also available from us: with full manuals £29.00 w
0181-679-4414
7
Fax: 0181-679-1927
(Display 9{ews Issue No. 13
The
"Telebox"
Computer type video monitors, are by necessity, constructed to a much higher standard than domestic television receivers. Better electronics and far higher definition CRT tubes are chosen to give long term reliability and superior picture quality. Very often costly computer type monitors are under-utilised by being dedicated to a particular computer system - and then only being used for computer purposes. The Display Electronics TELEBOX will enable the same dedicated computer monitor to be used for a host of other audio
visual applications, giving more effective use of equipment, for instance - connect direct to a composite video monitor and you instantly have a quality 7 channel colour TV !! The TELEBOX consists of an attractive fully cased mains powered unit, containing all electronics ready to plug into a host of video monitors made by manufacturrs such as MICROVITEC, ATARI, SANYO, SONY, COMMODORE, PHILIPS, , ATUNG, AMSTRAD and many more. The composite video output will also plug directly into most video recorders, allowing reception of TV channels not normally
receivable on most television receivers (TELEBOX MB). Push button controls on the front panel allow reception of 8 fully tuneable 'off air1 UHF colour television or video channels. TELEBOX MB covers virtually all television frequencies VHP and UHF including the HYPERBAND as used by most cable TV operators. Composite 75 O and RGB video outputs are located on the rear panel (RGB outputs on RGB version only) for direct connection to most makes of monitor. Measures 153/4W x SVaD x 31/4H For complete compatibility - even for monitors without sound - an integral 4 waft audio amplifier and low level Hi Fi audio out-
put are provided on all models. Also ideal for low cost video / audio source for Desk Top Video applications.
TELEBOX ST Standard unit with composite video and audio outputs.
£34.95
Order As:
TELEBOX STL TELEBOX MB TELEBOX MBR TELEBOX RGB
As ST - with fitted integral loud speaker.
£37.50
As type ST but fitted with Multiband tuner for VHF, UHF and Hyperband. £69.95
19" Rack mount PRO version of MB, BNC video output. XLR Audio, etc. £175.95
As MB but with added RGB and composite sync outputs.
£89.50
All Teleboxes are shipping code (B)
RGB Telebox also suitable for IBM type multisync monitors with RGB analog & composite sync inputs down to 15.625 kHz. For sync on green / over-
seas and custom versions VHF and UHF please call. SECAM / NTSC versions not available. Colour CRT required to see a colour picture. Cable outlet required to receive signals in Hyperband. Unit will not make tea!
SPECIAL OFFER
FOR NON SIGHTED PERSONS. A special version of the TELEBOX is available for use as a TV sound only tuner'. Complete with internal speaker It
is offered at a concessionary price inclusive of shipping and VAT
£45.00. Available to sight Impaired persons only.
Order as: TELEBOX B-ST
SCART / PERITEL CABLE SPECIAL
As used on most types of video recorders and televisions. These cables enable direct connection of audio and video signals from equipment to equipment. Far superior pictures and sound quality can be obtained, especially when copying from tape to tape. Both types fitted with phono plugs and 1.5 Meters long.
SC1 2 Video and 2 Audio connections £5.95 (A)
SC2 2 Video and 4 Audio connections £6.95 (A)
TV & Satellite Front End Tuner Modules
m
BIG DISCOUNTS FOR QUANTITY - CALL
Used in a host of applications including most TV's and VCR machines. Front end tuner units take care of the wide band television signals which are constantly in the atmosphere (when being transmitted)! The TV aerial or satellite LMB output signal is connected directly to the tuner and the internal electronics and selectivity, by various means tune to the particular frequency required. Two methods of tuning are generally used, Varicap and Phase Lock Loop. Varicap tuning simply uses a DC control voltage via a variable resistor, and as the voltage decreases or increases so the tuner linearly tunes through the required frequency spectrum. The phase lock system uses external digital logic which counts the output frequency (normally supplied by an internal -^256 divider) and enables stable locking of the required frequency via a digital method. The outputs of the following tuners are at a standard IF frequency of 38 Mhz. All tuners are supplied with data sheets on request.
PHILIPS U341 LO Covers the UK UHF TV frequency band, (431 to 855 Mhz) varicap tuned by external DC voltage 0 to 32 volts. Signal input via co-ax cable, Operates on 12 V dc. Dimensions 18 mm W x 55 mm H x 87 mm L Tested NEW RFE £8.95 (A)
PHILIPS UV615S. Most versatile tuner, varicap tuned with a frequency coverage from the bottom end of the VHF to the top of the UHF TV spectrum in 4 DC switched bands, (48.25 to 11"2.25 Mhz, 119.25 to 294.25 Mhz, 303.25 to 423.25 Mhz and 431.25 to 855.25 Mhz) this includes the mystical HYPERBAND as used by most cable TV companies and not receivable on most TV sets, indeed, the very same tuner as used in the MB TELEBOX. The Printed circuit mount tuner requires 12 volts to operate with a DC
voltage spread of 0-32 fortuning. Dimensions W 19 mm, x H 55 mm x L 85 mm. Co-Ax socket input. Brand New £16.95 (A)
PHILIPS U743/600 Covers the UK UHF TV frequency band, varicap tuned by external DC voltage, signal input side mounted via long reach (32 mm) co-ax socket. Operates on 12 V dc. Tuner case Dimensions W 20 mm, H 38 mm case L 66 mm + 33 mm connector snout, Brand New £9.95 (A)
SHARP BSFA75G08 Standard tuner for satellite receiver applications. Frequency coverage from 950 to 1750 Mhz. Phase lock loop tuning. Requires 12v dc , Input via screw type 'F' connector socket. Dimension 13 cm L x 1.7 cm W x 4.6 cm H LARGE QUANTITY & BIG DISCOUNTS AVAILABLE - Brand New £10.95 (A)
0181-679-4414
8
Fax: 0181-679-1927
'Display 9{eu>s Issue No. 13
LARGE QUANTITIES AVAILABLE - CALL FOR VOLUME PRICING
8088 XT PC-99 COLOUR
A perfect entry machine with 8088 processor and CGA colour monitor in good used condition and guaranteed for 90 days. Fully IBM PC compatible.
·
High Quality - USA made
' " --
·
256K RAM fitted - expandable to 640K
·
360K double sided 5%" floppy
·
2 serial and 1 parallel ports
·
MS-DOS 4.01 included
·
High quality keyboard
Complete with 12" CGA colour monitor
mwi* ij'jj t
Optional Fitted Extras - and they really are optional - the basic PC-
99 above is fully operational on its own.
·
640K RAM
E39.00
·
Second 5Va" 360K floppy (or 720K)
£29.95
·
20 megabyte internal hard drive with controller £79!oo
£99.00 (E)
Ik
HIGRADE 286
mvu wmamrxttji m\\m
For the serious home user or small business. Supplied in good used condition
and fully guaranteed, just compare this spec:
3MB RAM installed 12 Mhz Landmark speed 1.2 meg SW floppy 40 megabyte hard drive Complete with MS-DOS 4.01 EGA video board fitted 2 serial ports 1 parallel
Co-processor socket for 80287 Complete with high quality keyboard
Optional Fitted Extras for the HIGRADE 286 256k VGA graphics card 1 mb SVGA graphics card 1.4Mb S'/a" Floppy Drive (instead of 1.2 Mb) NE2000 Ethernet (Thick, thin or twisted) Maths Coprocessor 80287 FITTED Forefront MTS-9600/S or/H SVGA - SAVE
£29.00 £49.00 £25.95 £49.00 £29.95 £10.00
pnrinmt.7 Croommpes^rcnompnl^etfef6wu/i»th.W11h0.|1<fhKdeeyfieens hitasnpcreidcekaenydboreaarldly, manaddewtiothla3st with_all metal construction and small desktop foot
Megabytes of total memory you have room to spare with all your applica-
t'ons. What's more you can save £10 on the purchase of a Forefront
MTS-9600 SVGA multisync monitor when purchased together with the
HIGRADE 286 system. Display Electronics - unbeatable for value !!
£149.00 (E)
0181-679-4414
9
Fax: 0181-679-1927
'Display 9{ezVS Issue No. 13
Solid State Relays
International Rectifier type D2402 thyristor output solid state relay rated at IVi amps in the range 48 to 280 vac. Minimum control voltage is 3 vdc at 2 ma with a maximum of 32 vdc. Single pole, normally open. Normal input impedance is 1500W. The 1 second RMS overload current is 5 amps and the peak blocking voltage is 500 volts. Solid state relays have many advantages over the magnetic type, particularly reliability, no contact bounce and zero voltage point turn on and zero current point turn off. Screw (not supplied) terminals and brand new. Dims: 2VL x 1%"W x %"H.
£6.95 each (A) 5 for £26 (B) 50 for £235 ()
Sub Miniature 7 amps - 240 vAC
Measuring only 2-1/2cm x 1-1/2cm x 1cm this miniature single pole single throw solid state relay by Sigma
l j
type 226RE-2-12A1 exhibits an enormous switching capability of 7 amps at 240 v AC. Encapsulated in plas
tic on a metal mounting plate which bolts down to the chassis or heatsink in TO-3 spacing. Needs 12 vdc at
13 ma to energise. Use solid state for nil bounce!
£6.95 each (a)5 for £34 (b)50 for £225 P)
High Power Solid State Relays
25 Amps - 240 vAC
Only slightly larger physically, than the Sigma yet able to switch a load of 25 amps at 240 volts AC. Control voltage can vary between 3 and 30 volts DC. At 3 volts it draws 2 ma, at 15 volts about 10 ma. Mounting holes are 1-3/4" apart. The body of the relay measures 1-1/8"L x T'W x %"H. Screw fixing. Brand new prime stock from Grayhill model 70S2-03-C-25-S.
30 Amps - 240 vAC
Cordos Model GB2600-602 very high capacity solid state relay with a rating of 30 amps at 240 vAC. Trigger voltage is 20 vDC at about 8 ma. Connection is standard 0.25" push on or solder connectors. Measurements are t-WLx 1-V4"W x 1"H.
£12.95 each w 5 for £57 (B)
£8.95 each (A) 5 for £43 (B)
HEATSINKS RECOMMENDED WHEN USED WITH HIGH POWER
Dual-in-Line Reed Relays
Lovely little dual-in-line single pole normally open dry reed relay. DILR-5 is nominally 5 volts and DILR-12 is nominally 12 volts DC. Both have an operational spread of about 20%. Coil impedance is 500 and 550 ohms respectively. The circuit diagrams of DILR-5 and DILR-12 are the same except that the c.oil of DILR12 is connected to pins 2 and 9 rather than 2 and 6. Dimensions, of course, are the same as for a 14 pin dual in line integrated circuit. An overstock position permits us to offer both of these relays at the same price - and you may mix or match!.
3/E3.95 10/E9.50 25/E19.95 w 100 for £75 (bi
KEYSWITCH Time Delay & Flasher Relays
Keyswitch Model SZA 20 time delay before energising relay. Delay is adjustable by a knob on the face between
100 and 1000 seconds.The supply voltage is dual, 220 vac or 24vdc. Relay contacts are rated at 240vac and
15 amps maximum. Standard 48 wide DIN case. Similar to above, Keyswitch SZSD 20. Delay is adjustable from
3 to 30 seconds. The supply voltage is 110 vac or 24 vdc. Keyswitch Flasher Relay Model SZB 20. The unit
i);
will accept three different supply voltages: 24vdc, 24vac or 220vac. Choice of flashing times: 1 or 2 per second. It will flash loads up to 3 amps. Ideal for "Piccadilly Circus" lights, attention getting displays and all sim-
ilar applications.
Either type only £5.95 (A) each or 3 for £16.00 (B)
12v DC Coil, 15 amp Sealed Relay
High quality ARROW relay type MSA30-40 fully enclosed in clear acrylic case. Two separate changeover silver tungsten contact pairs rated at 15 amps AC /10 amps DC are brought out to solder tags which will also accomadate standard 0.25" lukar push on tags. A neat feature is the pre drilled nylon mounting lug which allows the relay to be fixed at any angle on almost any surface. The 12v dc coil is ideal for all automotive and general alarm applications or just as a general purpose relay for the spares box or repair kit. Overall dimensions inc lug length 6.3 cm H x 3.5 cm W x 4.8 cm D
Only £3.75 each w 3 / £9.50 (A)
0181-679-4414
10
Fax: 0181-679-1927
'Display 9{e.TVs Issue No. 13
Voltage Sensing Relays
Plug in voltage sensing relays designed to monitor voltages. The user sets a voltage on the front panel dial,
when that level is reached, the relay contacts changeover. They release when the triggering voltage drops
by 10% or is removed. A resistor may be wired between pins 8 and 9 to increase this hysteresis by about
75%. Shorting these pins causes the contacts to latch when energised. The supply voltage is 225-250 vac
at 2 5 va consumption. The sensing voltage range is 50-500v ac(peak)/dc. Contact ratings are 10 amps to
380vac, 10 amps at 25vdc and 1 amp at 250vdc. A front panel LED is provided to show when the relay is on. Dims:3:' x 3" x 1-3/8". The octal type base is 11 pin. R S Components Ltd number 348-605. Data sheet
included. Ideal for all voltage sensing and
_
control applications.
£19.95 ©aCh (A) 3/E55.00 (B)
«
240 VK BASE
PIN OUT
Moving Coil Meters
FERRITE
US ;N»T" I\ & t
i V
VOLTS /*>
TUBES
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Centre reading milli-volt meter full scale 100 mv dc. The face measures 70 cm square, face in
front of panel is 13 mm and 40
mm is required behind the panel
300 vac full scale with built in shunt resistor. 70 cm square face, 13 mm thick. A removable rubber gasket is also included.
Needs 40 mm behind the panel.
1 ma basic meter dual scaled 15 and 3 vdc. Requires external 15K and 3K resistors if scales
are used as is. 60 mm square face 10 mm thick, 20 mm required behind panel.
£7.95 (A) 3/£21 (B)
£7.95 (A) 3/£21 (B)
£3.95 (A) 3/£11 (B)
Used for a host of applications incuding simple chokes, RFI, TVI and general interference suppression etc. Dimensions 17mm long x 9.5 mm diameter with internal bore of 6.5 mm.
Pack of 16
Only £1.99 w
Large qty available
Ruggedised 25 ma Panel Meter
Direct reading 0-25 ma 65mm scaleplate. Made to the highest spec for BT this fully ruggedised and
hermetically sealed edgewise panel alone or panel mounted via 70 X 33
meter lends mm cutout,
itself to a host gg Q0
o^ f app3lic/a£tio1ns.8Ma(By)be
used
stand-
imminr
Ultra High Precision Hybrid Lens
Perfect for all sorts of DIY and experimenting jobs! Delta 20 lens assembly from US Precision Lens I Inc as used in high quality projection TV systems. Focal length is two inches and the lens diameter
is three and three quarter inches. Complete with four integral mounting brackets and adjustable focussing ring which can be locked in place with a butterfly nut. Illustrated without lens hoods. Brand new must have cost a fortune to make - but our price is
Only £15.95 each (B) 2/£31.00 (q
Colour Coded Jeweller's Screwdrivers
N
Jeweller's precision type screwdrivers in either Philips or slotted and each one has a colour coded plastic grip for easy identification. Slotted in six sizes from 1 to 3.5mm; Philips #0-4 to #1-1. Order PH for Philips or SL for slotted.
Either type £2.49 each or both for £4.50 w
Infra-Red Remote Controls
ENTER O/K) CANCEL
Brand new state of the art infra red remote controls for use with TV's, VCR's Stereo's and si other appliances. Almost all of the electronics is contained in a D6124 CMOS LSI chip. The transmitted frequency depends on a ceramic resonator with a frequency between 400 and 500 kHZ. Gomes with a 455 kHZ one installed which may be easily changed; the final frequency is the resonator frequency divided by 8 and by 12. Only measures 5-3/4"L x 1-1/2"W x 1/2 'H. A very complete data shee3tt 1for the D5i6124 is included on request.
LARGE QUANTITY AVAILABLE
Only £3.95 each w 5/£15 m 25/E50 (B) 100/E175 (ci
0181-679-4414
11
Fax: 0181-679-1927
(Dispfay 9{ews Issue No. 13
Liquid Flow Transducer
CTNRMHAEMAKNSTDCBEUOMCWEeNRT FLO O/P
"irG V
Here's an interesting one for the handyman or the experimenter. These transducers convert the amount of flow of non-corrosive liquid into output pulses. For instance a flow
of 10 fluid ounces through the transducer will give 200 pulses out. Output pulses fol' low the flow rate proportionately. Maximum pressure 80 psi and the unit uses 5vdc
supply. By the simple addition of a 1K pull up resistor on the output, the unit will inter-
face direct to CMOS or TTL etc. These transducers are hand made by Pektron and each one is indi-
vidually calibrated. Wire colour coding is noted on the body of the transducer. Overall measurement of the body is 4"L
and 1.5"D at the thickest point. Both inlet and outlet pipes are fitted with a standard BSP threaded coupler. Brand new
of course and regularly priced at about£150.
i.. i · i 11^
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Only £22.95 each or 3 for £60.00
IEC-1 IEC-2 IEC-3 IEC-4 IEC-5
IEC-7 IEC-9 IEC-10
IEC and Mains Plugs/Sockets/Cables
As used on most computers and printers.
All are rated at 240 volts AC.
Standard rewirable 3 pin male in line plugs. Screw fitting. 10 amps Standard rewirable 3 pin male in line sockets. Screw fitting. 6 amps Standard chassis mount male sockets with integral 20 mm fuse drawer. 6 amps Chassis socket as above with built in DPDT rocker switch
El .50 (A) £1.25 (A) £1.20 (A) £2.25 (A)
Quality moulded 13 amp mains plug on 2 metres of cable terminated in standard IEC moulded female plug 2 metre IEC extension cord. Straight female socket to shrouded male plug Chassis mount IEC socket with two integral fuses Right angled re wireable 3 pin cable mount socket with grommet.
£3.95 (A) £2.50 (A) £2.20 (A) £1.99 (A)
MIX OR MATCH DISCOUNTS 10 to 49 = Less 5% (B) 100 up = Less 10% (D)
Automatic security Time And Date Document Stamper
Heavy duty automatic time and date security stamping machine. Facile Model 33. Often used on clock cards or for Security stamping of documents where a reliable and secure time and date can be stamped on to a document or form, rather than hand written. Time and date can only be set via a security key and lock (key supplied) The date may be set in either DD-MM-YY or MM-DD-YY formats and the time is in 24 hour format. 220-240 vAC 50 Hz operation. Attractive two tone beige. Replaceable ribbon. || Measures (at highest point) S' H x 8"L x 5"W. Excellent used condition - fully tested & guaranteed.
Regular price is £345 - our price Only £149.00 (B)
'CROC LEAD KITS A must for every bench or toolkit! Kit comprises of 10 x 10" long coloured clip leads each end terminated with an insulated crocodile clip - save hours on hookups / experiments etc.
£2.99 per pack of 10 (A)
0181-679-4414
1/2 Price - High Grade BNC Sockets Greenpar Ltd. D84-16. Chassis mount 75 ohm BNC socket with PTFE inner and gold plated inner. Supplied complete with solder tag and lock nut. Order as GNBNC.
70p each or 10/£6.25 w
Amphenol 31-10. ISOLATED chassis mount 50 ohm BNC socket. Socket features solder tags for both the inner and outer connections. Supplied complete with nut and locking ring. Order as AMBNC.
90p each 10/£7.50 w
LARGE QTY AVAILABLE CALL FOR PRICING
12
Fax: 0181-679-1927
K:>$i?> !>?
Tfispfay 9{ews Issue No. 13
111 illiliil ^"* M ./· ?i".:-?£· .i?:<·(>& ^>··s;>-j:. #v.xi'
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Aluminium Grill Piece Remember those times you said to yourself "why don't I have a piece of that?" - usually on a Sunday when everything is closed! Just such an item is aluminium grill sheeting. These handy sized sheets measure 9-1/2" x 5" and are 1-1/2 mm thick. The holes are 1/8" diameter. One side is polished so it is ideal for dress up jobs. Buy while you think about it!
2 sheets for £1.00 10/£4.50 (A)
Unbreakable !!! Plastic Sheet
Incredibly strong and only 2.5 mm thick. - strong isn't the word - the test we gave it was to hit it with a 5 Kg sledge hammer from above ones head !!! It didn't break, mark or crack !! Just the thing for those very secure applications. Makrolon sheet is polycarbonate based and amazingly strong - and therefore expensive. These particular panels were cut drilled for a particular application to cover some high voltage equipment. Cut up and O chpptQ fni* CQ Q** rA-n use for your own application Tinted'see through finish'16.5" x 17.75 Brand New ^ OllCClo IUI 2_C7.^0 t«';
K
E
Y
P
A
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Hundreds of applications lend themselves to the following items: Alarm Systems, Data Entry,
Security, Car Alarms etc etc. And at these prices
High Quality Miniature Hexadecimal
Grayhill 83BC1. Lovef^ifff^tefaSi^fWifayflew miniature hexadecimal keyboards with a straightforward connection. Each key has one terminal common to them all and one brought out to its own individual connector. Connection diagram on request. Perfect for any project which needs hexadecimal input. Black keyboard body and bright white keys with black lettering. The keyboard measures 2" square and stands 3/8" above the mounting panel or printed circuit board. Pads are sculpted and measure 3/8" square. Nice firm key action - a beautiful piece of brand new surplus.
2 e
D C
£7.95 each w or 5 for £37.95 (ai) or 50 for £350 (c)
Heavy Duty 10 Digit Keypad
As used in pay type telephones, this versatile heavy duty general purpose 10 key keypad arranged in the
matrix shown in the sketch (the connections to the PC board are also illustrated,) lends itself to a host of
applications. The keyboard is mounted on, and forms part of, a 6" x 3" printed circuit board which also con-
tains a transistor, red LED, resistors and PC board connectors. The keys feature full travel action and are 3/8"
2580 369
high above their mounting assembly, so there is plenty of
room for them to pass through a panel. The keys them-
3 selves are legended 0 to 9, in bright white on black and ,, measure 3/8" square. The great advantage of this key-
» board is the simplicity of the matrix, making it ideal for
100's of applications such as digital locks, access or
security systems etc.
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£3.95 each w or 5 for £14.95 (B)
12 Button Telephone type Keypads
Top Grade keypad made by ALPS type 11KE013A. 12 full travel keys, double shot moulded with large legends 0 to 9 and * and # all mounted on a very strong ABS white plastic moulding, with four fixing holes for front or rear mounting. Internally the normally open pushbuttons are protected by an all over rubber shield making the keypad impervious to dust and liquid splashes. For long term reliability the switches are constructed on a gold plated printed circuit board for good conductivity and low contact bounce. Electrically the switches are on a 4 x 3 matrix with all outputs brought out to 7 solder pads on 0.1" pitch. Overall dimensions 2%" L x 314" W x %" D.
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£1.95 each w 10 for £17.00 (B) 100 for £150.00 (c)
Five Outlet Mains Distribution / Extension Block
High quality 5 way 13 amp socket mains distribution blocks, not the type sold in your local hardware store. Unit features 5 top
quality MK 13 amp flush mounted shuttered sockets manufactured to BS
1363, all housed in a heavy gauge, plated steel, totally enclosed box with
4i||. - JUV.
v- Jn cable entry at rear. The box is earthed. Sockets are mounted on a 45 degree angle so that the plug cables flow neatly away from the block. Overall dimen-|
sions 13"L x 3"W x 1-1/2"H. Hundreds of uses for workshop, garage or qual
ity equipment racks etc.
£12.95 each (B) or 3 for £35.95 (Q
0181-679-4414
13
Fax: 0181-679-1927
Display tyzvs Issue No. 13 rN
o
h o
M IVU
20" SVGA Multisync Monitor
For those who think size really matters! The Microvitec 20H727E 20" Multisync monitor can accept CGA, EGA, VGA, SVGA and the Archimedes, Amiga and the Atari. Its large area makes all your applications larger than life. Scanning frequencies: Horizontal 1536KHz, Vertical 45-100Hz. 0.31mm dot pitch. Measures ISV^'W x lOV^'D x 16%"H. Supplied in good used condition (possible minor screen burns). We have limited stocks so hurry!
....................... mm
Only £375.00 each (F)
SVGA Multisync / Multimode 14" Monitor
A beautiful monitor: the 14" Forefront Model MTS-9600 SuperVGA multi"sync with resolution of 1024 x 768 and 0.28 dot pitch. This monitor features a multisync capability, down to 15Khz, not found in many other types of monitor, this feature 'enables direct connection to a host of computers such as all types of compatible IBM PC's, CGA, EGA VGA & SVGA modes, BBC, ARCHIMEDES, ATARI, AMIGA (Inc A1200), SIN-
CLAIR and with the 9600/H model the high resolution monochrome mode of the Atari. A "Text" switch is provided for word processing, spreadsheets and other text based programs plus an overscan switch. The modern case styling and the deep etched non-glare screen makes this monitor particularly restful on the eyes and convenient to use. Contrast, brightness and On/Off controls on the front with horizontal and vertical sizing and vertical positioning controls on the rear.Scanning frequencies: Horizontal 15.625-37KHz, Vertical 50-70Hz. Measures 14"W x 14"D x 12"H. Supplied In excellent used condition (possible minor screen burns) and guaranteed for 90 days. Probably one of the best buy in monitors that we - and certainly you - will ever have!
Order as 9600 / S for IBM, COMMODORE, BBC SINCLAIR etc.
Order as 9600 / H for all above computers + ATARI HI RES Custom switchbox unit for ATARI ST to switch between colour and mono hi res modes Tilt & Swivel Stand for Forefront
£129(E)
£149 (E) £25 (A) £15 (A)
12" VGA Multisync Monitor
The Electrohome ECM-1211SBU VGA multisync monitor with resolution of 640 x 480. Multi input
selection; 9 pin CGA/ EGA type connector; 15 pin Hi-density VGA type connection or 5 BNC con-
nectors. 0.31 pitch. Front panel controls are for brightness and contrast, A "Text" switch is also pro-
vided for word pro use. Compatible with PCs, Amiga, Atari and oth-
ers, Measures 12"W x lA'/fFD x 12"H. Supplied in good used condition
(possible minor screen burns). Full 90 day guarantee.
Only
x? xx (E)
9" VGA Multisync Colour
An incredible feat of design; The KME17M1005 9" Colour VGA multisync monitor has multiple
inputs: 9 pin CGA/ EGA type connector; 15 pin Hi-density VGA type connection or 6 BNC connectors. 0.28mm Dot pitch. Front panel controls are for brightness and contrast, horizontal and vertical
> i
size. A front flap conceals adjustments for height / width for all the different types of input. Ideal as
a second screen for CAD / CAE or just where size is important. Scanning frequencies: Horizontal
15.625-40KHz, Vertical 40-90Hz, Measures 1014"W x 12V2"D x 10"H. Supplied in good used con-
dition (possible minor screen burns). Guaranteed for 90 fiays.
Only £195 each (E)
And another 9" VGA Multisync ! NEC Model CMV103NE. 9" Colour VGA multisync monitor has a single 9 pin 'D' connector. Will accept VGA signal with supplied adaptor, and CGA and EGA with normal 9 pin connection. Will also accept an RGB input with the sync on green, dual BNC connectors allowing 'Daisychaining'. Measures lOVW x 91/2H x 14"D. In good used condition (possible minor screen burns). Guaranteed for 90 days.
Only £ | /9 each (E)
0181-679-4414
14
Fax: 0181-679-1927
(Display 9{ezus issue No. 13
Lynwood 14" SVGA Colour
; Lynwood model Ml4C A very modern case design along with a high resolution tube make this monitor an absolute bargain! It has a tilt and swivel base and side mounted controls for contrast and brightness. The tube has a 0.28mm dot pitch. Input is via a 15 pin high density VGA type connec:i706/8oT(Ilhnltsenrl?a0cne,dt0).rhRaesadrucaolsnctraonlsniand9ju,srteqhuoerinzcoinetSal0af3nd1-v5eartnicdal 3w5i.d5thKaHlzo.ngMwaixtihmoutmherreasdojluutsitomne1n0ts24 Ixn | excellent hardly used condition and fully guaranteed for 90 days
Only £129.00 (E)
9" VGA Monochrome Black & White Monitor
A delightfully compact unit. Resolution is standard 640 x 480. Standard 15 pin Hi-density connector This
unit was manufactured for a point of. sale system and is completely standard apart from the tilt/swivel base
under which the 240 v AC power and signal cables emerge. The brightness control is on the front. The power
switch, contrast, vertical size and horizontal adjustment are on the rear. Measures 9"W x
x
10"D.Supplied in good used condition (possible minor screen burns). Full 90 day guarantee
Only £69 (E)
14" CGA/EGA Monitor
By Philips the 9CM073 14" EGA/CGA monitor. Features both horizontal and vertical shift controls together with the normal contrast and brightness, all front panel accessible. This monitor also has a text mode switch and both amber or green text is selectable, ^ making it ideal for users who do a lot of word processing or spreadsheet work yet still need 640 x 350 graphics capability. Housed in an attractive modern style cream case. In good used condition
(possible minor screen burns) with 90 day guarantee. Measures 14"W x 12"H x 13,/2"D. Input is via a standard 9 pin male socket.
The perfect choice with
the HIGRADE 286,
Only £99 each (E)
10" EGA Monitors
A super deal on state of the art 10" EGA monitors by KME model 15M10004, featuring a high resolution tube for superb clarity. Connection is via a standard 9 pin female D connector. Front panel controls are brightness and contrast, rear panel are focus and sub-brightness. Link selectable at rear for 100/120/220/240 vac. Housed in an attractive two tone brown metal cabinet which matches nicely the dark etched non-glare screen. Measures 12"L x 10"W x 10"H. A tremendous buy in high
resolution monitors. In excellent used condition with a 90 day ^ , OQO
guarantee.
Qflly
ESCh (E)
£49 !! 12" CGA Monitor Bargain
That s right - you read it correctly - a 12" IBM- PC CGA high resolution colour monitor for only £49! How can you refuse that offer! Runs straight off any PC or compatible with a standard CGA card. Housed in an attractive two tone grey plastic case with a useful anti glare escutcheon which doubles at the top as a carrying handle.. Three unobtrusive controls on the lower front - Contrast, Brightness and Power. Also features a degaussing control plus vertical and horizontal holds on the rear panel. Measures 16"D x 13"H x 13"W. Supplied fully tested with a full 90 day guarantee. The cosmetic only front trim has been removed for contractual reasons, possible minor screen burns. Buy whilst we still have stocks!
Large Quantity Available - Call for pricing
Only £49 Each (E)
Barco 26" FST RGB
+ Composite Monitor
Model OCM 2840R. This beautiful professional grade large screen monitor is ideal for presentations and for those who need a high quality screen. The unit has an FST tube with a glass coyer (Possible minor screen burns). Has both RGB and composite video inputs, with in / out connections for daisychaining. All the controls are discretely mounted on the rear of the unit. Has internal modular constuction for ease of servicing. Fitted with side mount threaded bushes for bracket mounting or ceiling suspension Ideal for use with the Philips Laservision player VP410 featured in this issue or any other high quality video application. Measures W24" x H20" x DIS'/a. Limited Quantity Available.
0181-679-4414
Only £399.00 (G)
15
Fax; 0181-679-1927
'Display 9{eius Issue No. 13
Sony Trinitron NTSC TV / Monitor
Usual Sony quality item, Model KT20TR22. This 20 inch monitor is a high quality NTSC
VHP/ UHF television with a standard NTSC composite video input with sound. The mains
input voltage is 110 volt 50 or 60Hz, it can of course function on 240 v mains with a suitable
step down auto transformer if required. Front panel controls adjust for brightness, volume,
contrast and preset tuning. With a Trinitron Tube and very modern case styling this mon-
itor that
is perfect for Karaoke (Most Karaoke requires the NTSC television standard.
Laserdiscs Measures
aWre20N%TSxCH) 1o9r1/a4 nxyDo1t9h"e.r
application Supplied in
excellent used condition with our standard 90 day warranty.
SPECIAL - Only £199.00 (e )
24 inch Green Screen Monitors Huge 24" screen size (diagonal) monitors but with a case size of only 22" x 18" x 16". Perfect for clubs, shops, airports and other applications with a large viewing audience or where the screen is to be watched from a distance. Standard composite BNC 75 input with a loop through socket for daisy chaining. In good used condition, some units may have minor screen burns. Housed in a sturdy metal case with inset carrying handles. Fully tested and guaranteed for 90 days.
Only £65.00 each (E)
Probably Europe's Largest Range of LOW COST video monitors for all applications we have over 5,000 monitors ex stock at any one time. If your needs are not covered here, please call our sales office. New products arrive daily.
Super Deal on Analog RGB Monitors
Perfect for Amiga & BBC
£89.00 (E)
Plus most computers which use analog RGB and combined 15.625 Khz sync (but not M the Atari). These are excellent resolution colour monitors at an excellent price. They :'W were manufactured for console use but are free standing and enclosed so make a very economical buy as a quality monitor for these machines. The 12" laser etched CRT provides particularly high contrast and clarity and the phosphor persistence is such that they are ideal for games and and word processing etc. They measure 14"D x 12"H x 12"W and are supplied complete with a data cable for the above machines or with 4 BNC female sockets for others. A termination switch is available on the rear so that the monitor may be used alone or as part of a daisychain. Supplied in good used condition (possible minor screen burns) and fully guaranteed for 90 days. Please specify whether Amiga, BBC or BNC connections required.
20", 22" & 26" LOW COST Composite Colour Monitors
Another bulk purchase of this superb Rediffusion Mk 4 UK made colour monitor enables even further price reductions on our last advertised price!! Features an integral PIL tube with fully isolated chassis utilising state of the art electronics. Features include auto degauss circuitry, auto colour balance and full internal modular construction for which we hold a vast amount of spares for long term technical support. Housed in-attractive teak finish type case to suit any surrounding - home or office. Standard 75 ohm composite video input connects to all forms of video equipment, ideal for use in Schools, Shops, Disco's, Churches, point of sale and all AV applications. Supplied in excellent slightly used condition with full 90 day RTB guarantee. Dims.(cms) 62W x 46D x 41H. Other available options, integral audio amp, call for pricing.
20 "...£135 (E) 22"...£155 (E) 26"...£185
"3 0181-679-4414
16
Fax: 0181-679-1927
'Display 9{ews Issue No. 13
Philips 12" Black & White Data / CCTV Monitors A recent bulk purchase brings you this very compact high resolution video monitor. Made bv Philips type number BM7542 /05G this monitor will find itself at home for a host of video applications including; video camera and surveillance monitors, data computer displays or point of sale equipment etc. A standard composite video input at 15,625 Khz (+ - 600 Hz) is provided plus a low wi·thf1 tfh0e C2^0y]Muhazubdal0ndiwnpiduttht,08a5n0inlitneegrraelsoaluudtiioonaamnpdliofiuerr parnicdespanedakyeoru. Choamvebianneoththeeser fDeiastpulraeys Electronics bargain !! Inputs are via standard Phono type sockets on the rear panel with all main controls under a neat drop down flap to the front. Supplied BRAND NEW complete with mains cable and 36 page user manual in 99 languages I! (well almost I) Dims mm 305 W x 303 D x 280 H
Brand New - Only £69.95 (C)
Bargain 12" Monochrome Displays
12 green screen by NEC, Model JB-1201M(E). Standard 15 khz with composite video input Output also provided for daisychaining, both via phono or BNC sockets. Normal brightness,contrast, on/ off/ volume controls on the front with vertical linearity, height, both holds and sub-brightness on the rear. Unusual for a professional use monitor, these also have a sound input and integral speaker. Very attractive swept back case construction in off-white or cream colour. These second user units may have screen burns but carry a three month warranty and are fully tested prior to despatch. Overall dimensions 14"W x 12"H x 12"D.
£29.95 each (oor 10 for £250.00 (G)
9 inch Green Screen A/EC Monitors
Model 901
These are brand new and boxed 9 inch composite video green screen monitors made by NEC. They have deep etched screens for eyeresting non-glare use and the cases are made of tough plastic. Standard composite 15.625 KHz 75 Q video inputs and a switch to optionally route to a
high impedance circuit so that a number of monitors can be
daisy-chained on one line. An output socket is provided for the optional daisy chaining. Both input and output sockets are standard BNC connectors. The monitors are powered by 220/240v AC by way of a standard I EC male chassis plug. I EC cable supplied. Internal links permit 115v AC operation (902 only). The 901 is two tone grey and its dimensions are 11" x 11" x 11" The 902 is black and measures 9" x 91/2" x 10". Superb quality at a knock down price I!
Model 902
Model 901: £44.95 (0
Model 902 : £49.95 (C)
High Resolution CCTV Monitor
A super deal on brand new Merit 9" black and white monitors for CCTV or any other monitor application. Resolution is in excess of 750 lines! 4
composite 0.5 - 2V p-p video inputs are provided via 4 x 5 pin DIN sockets. ^ Individual inputs may either be permanently selected, programmed or automatically sequenced via the front panel switches. A continuously variable speed control on the front panel allows variable 'dwejl' time for each input. Provision is also made for VCR either input or output, a switch is supplied for Record or Play. A DC supply to power up to four cameras is also provided. Measures only S'/a" x SVi" x 9". Many other features including integral audio
· · BW
oafITC,/PC/^TnVc' wsPoerakkseurc- hBeaasutsiufurlvlyeimllaadneceinosftubradbyytwroootomnse, bsrtoowrens,mpeatraklicnagsaeraenads, isdheaolpfsorplaullstyhpuensdreds of other similar applications. Limited quantities - Note - illustration may differ sliqhtlv to
product described. _
^
^
_
Only £99.00 each (o 3/£285 (p)
COMPUTAR" 16 mm fl.3 TV Lenses
To complement any TV video camera system, this top of the range auto iris lens Computar MCA1613APC will enhance any video camera. Standard screw thread 'C mount with ' focusing ring and lock nut. The lens features ND filter, remote control and integral electronics ^ with fast acting auto ins system to compensate for all light levels to give the best possible pictures ^ in very dark and very bright situations. Connections to the lens enable the composite video signal to automatically control the aperture, with either average or peak light weighting. Requires 8 to 16 v DC at < 30 ma to operate. Supplied complete with instructions. BRAND NEW & BOXED.
Current list price £185 - Our Price Only £95.00 ibi
0181-679-4414
17
Fax: 0181-679-1927
'Display 9\[ezVS Issue No. 13
Multiport Expansion Cards
Four way Multiport cards from Arnet Model Multi4 which expand your PC-AT or compatible by adding four serial ports to it. Brand new and comes with all necessary software, including diagnostics, on both 720k SVz" and 360k 5-1/4" floppies. Output is via a 62 pin D connector. Comes with mating connector and a split cable terminated in four 25 way D female plugs. An Operators Manual is included which gives very full data on port addresses and so on.
Fully Configurable I/O Card
Only £59.95 (A1)
Suitable for your IBM, PC-XT or PC-AT computer, it will expand your computer to add an additional two serial ports and one parallel port. Short card with one of the serial and the parallel connectors on the end plus a flying leading and mounting plate for the second serial. Comes complete with software, including diagnostics and a full data sheet. In as new condition, fully tested and guaranteed for 90 days.
£14,95 (ad each or 2 for £28.00 (B)
Memory Upgrade Cards Will increase your PC or PC-XT base memory by either 256k or 512k in 64k steps. They may also be used to fill in RAM above the 640k DOS limit, for special application programs. In as new condition with a full data sheet and fully guaranteed for 90 days.
256k £32.95 ·"> 512k £48.95
- <
Intel 'ABOVE' Memory Expansion Card
m
·>-
INTEL 'ABOVE' Memory Expansion Board. Full length PC-XT and PC-AT compatible card with 2 Mbytes of memory on board. Card is fully selectable for Expanded or Extended
(286 processor and above) memory. Full data and driver disk supplied.
· · i'
Fully tested and guaranteed. RFE. Windows compatible. Qn|y £50 05
PC Digital Input / Output Card
This is a general purpose digital input and output card, providing six 8 bit parallel I/O ports and
six counter timers plus serial data facilities, all under the control of software. Three 65C22 VIA
interface devices are used, each of which provides two 8 bit ports with two control lines per
port. Three of the ports have facilities on the card for high current output buffers enabling thou-
sands of different types of external equipment to be driven directly, including relays, motors, valves and LEDs etc. The card fits a short IBM or compatible expansion slot and the con-
BBS
nection to the outside equipment is via three ribbon cables which plug into the card and pass
out of the computer through the slot aperture of the PC. The beauty of this card is that, whilst
it can be controlled by short programs in any language, it lends itself to Basic programming
and, in fact, all of the examples in the comprehensive manual are in that language.
This card is ideal for all applications where a PC user wants to interface his computer with the outside world. Brand new with full loose leaf binder manual.
Only £59.95
each
(B)
ROM Expansion/Boot Board
Not to be confused with RAM memory expansion cards, these cards will
enable the ROM of an original PC or a PC-XT, or compatibles, to be
expanded by up to 64K. Comes with a BiPolar ROM type TBP28S865
which defines the principle operations. For specialised applications a new
device could be programmed. Control circuitry is provided onboard
for the erasure and writing of EEPROMs. and as supplied,, the board is
configured for use with seven 2764A 8K x 8 EPROMS and one 52B13 2K x 8 EEPROM. The main and important feature of the board
is its versatility. DIP switches are used to set the starting memory address, the I/O port address and to define the board's configuration.
The starting memory address may be set in 2K increments anywhere within the normal 1 Mb PC address space. The I/O port allows
software to read the configuration and status of the board. Additionally, each ROM socket has an area of links so that alternative ROM
types may be used. Ideal for installing specialist BIOS code, diagnostic routines and many other types of programs which are best
sited in ROM. May also be used for converting PCs into diskless systems for dedicated process control and industrial control applications, possibly storing important variables and constants in
OCQ QC /m
the EEPROM etc. A data sheet on the board is supplied.
VJfliy
^ '
IBM PC Graphics Cards CGA EGA VGA SVGA etc
CGA colour / Mono (Composite) graphics card. Suitable for IBM XT. Full length Card. 9 pin D socket output and phono / BNC for composite - RFE Tested. Hercules / CGA graphics card. % length card switchable between Hercules (monochrome) and colour (CGA). Both outputs are via the same standard 9 pin D socket. NEW EGA graphics card. Full length card with 256K on board. 9 pin D socket output - RFE tested. EGA graphics card. Half length card with 256K on board. 9 pin D socket output - NEW VGA graphics card. Half length card with 256K on board. 15 pin Hi Density D socket output. - NEW SVGA graphics card. Half length card with 1Mb on board. 15 pin Hi Density D socket output. - NEW
£19.95 (A1)
£24.95 (A1) £29.95 (A1) £35.95 (A1) £39.95 (A1) £49.95 (A1)
0181-679-4414
18
Fax: 0181-679-1927
'Display tyzos Issue No. 13
12 Kv Compact EHT Power Supply
Dual output, 12 KV and 400 vdc, with only 24 vdc in and the case only measures a handy 4"L x 3"W x 1Vfc"H
plus both output voltages are adjustable! The nominal 12 KV is adjustable from 11 KV to 13 KV and the 400
vdc from 400 to 600 vdc. Rated load is 400 ma into 500pf; load regulation, no load to full load, at nominal
input is 12 vdc (0.1 /o). Line regulation on the 400 vdc output is 0.1 vdc (200 ppm) @ 500 vdc. Brand new
this supply was originally intended for the EHT power for a cathode ray tube; the handy totally enclosed unit
makes a very versatile EHT bench supply or for inclusion in all types of equipment. Mounting is by way of
two screws on the base. ### WARNING; MUST NOT BE USED AS CAR ANTI THEFT DEVICE ###
£24.95 (A) each 5 / £110 (B)
(lift JIP
/ ·
Transformers TR-10-16 Dual primary, wire for 120 or 240v. Dual secondary windings of 10v and 16v Maximum load 30 and 20 va respectively. 3" x 2.5" x 2.5".
TR-15015 240 v primary. 12-0-12v secondary. Max 1 amp. 2.75"x2"x2".
£4.95(A) £4.95(A)
TanRd-M24T0Mvu. l2ti.5ta"pxa3u"tox t3r"a.nsformer. 10 taps at 100, 110, 115, 120 127 200 225 230
TR-MP This is a miniature power supply as it includes integral diodes and supplies 12 vdc full wave from 240vac in. The transformer is split bobbin construction, permitting the ultra miniaturisation. 1.2 va rating. 1.75" x 1.25" sq.
£9.95(B) £3.95(A)
Tsi5d"eToFf.Tthheiswtirnadnisnfgoramnedrhinascluad1e5s vaonltisnsteegcroanl dthaeryrmwailthfuasne 1(111vDaErCa)tinogn. tVheie2w4in0gvforlotmmtahienstoinpput
pin 2 and 4 is the primary input via the fuse, 3 & 4 is direct to the primary. Pins 2 & 4 at the bottom
is the secondary. PCB mount or can be used stand alone with bolts.
£4.95(A)
TR-20 Miniature mains transformer, 20 volt secondary unloaded. 1 amp capacity. Windings are internally shielded with the shield brought out for grounding. Flying leads and bracket
construction. Dims 2-1/4"L x 1-1/2"D x 1-1A"H,
£4.95(A)
TR-VAR Multi output. Primary 0-220-240. Triple secondaries: 8-0-8v 15-0-15v @ 600ma. Dimensions 3"L x 2"D x 3-1/2"W overall.
1 550ma,19-0-19v @ 700ma £6.95(B)
TR-POT Ultra compact potted printed circuit board mount. Twin primaries 0-120vAC & twin secondaries of 9vAC 4 VA. Both may be connected in series or parallel. RS Components Ltd catalogue number 208-254. Measures only 2" x 1-3/4" x 3/4" above PCB board.
£4.95 (A)
Profusely Shielded Mains Transformer
An unusually well made and generously shielded 220/240vac fully shrouded mains transformer with'thole secondaries giving 9 volts @ 2A, 18 volts @ 1 amp and 24 volts @ 1 amp, all continuous - increase by about 50/o for intermittent applications. 60 va. The secondaries are all fully isolated Flying lead connections: white, purple and red for neutral, 220v live and 240v live respectively on the primary and yellow, orange and red for 9v, 18v and 24v on the secondaries. Dimensions; 3-3/8"L x 2-3/4"W x 2-3/8"H Sony part number 1-450-530-11. Part replacement cost is normally £601!
Only £9.95 Pior 3 for £27.00 (C)
Fully Encased Dual Secondary A fully encased transformer by Racal-Milgo model 4415X302A, ideal in applications where safety is a factor. 230 vAC primary (2 metre 3 core cord ) with two centre tapped secondaries- 15-0-15 (yellow, black, violet) at 1 amp and 11-0-11 (red, white, orange) at 1.5 amps. 25 va capacity. The secondary leads, and a ground lead, exit from the bottom of the transformer, the mains input from the top. Mounting is by four screws to the bottom. Overall measurements are 2!^" square by 3" high.
Only £5.95 (b)3/£16.50 (q
Fully Encased 'Hy Grade' Mains Isolator* and Filter
Very high efficiency mains spike and noise filter. A 1:1 massively built toroidal transformer providing 240 vac in and the same out is capable of acting as an isolator by the "removal of one internal link. Nominal capacity is 1.04 amps; the output is monitored by a circuit breaker which breaks at 1.88 amps. Filtering is provided by two off of 2 mfd 450 vac capacitors which form a resonant circuit with the secondary winding. This being tuned to 50 hz provides additional filtering to give excellent protection against mams spikes and dips. The input lead is terminated with a quality 13 amp mains plug. Output is taken x 4 H,axn'O"'/,zfW9.raIll.lu13straamtepd swoicthkecto. vIenrgroeomdouvseedd. condition fully guaranteed for 90 days. Measures 8y2"L
Only £49.00 each (D)
0181-679-4414
19
Fax: 0181-679-1927
'Disptaif '\l'U's Issue No. 13
ADAPTORS / PSU'S
Protected AC Adaptor
This adaptor has an input of 240 vac at 45 va and an output of 19 vac at 1.6 amps. The internal transformer
(which can be accessed by overdrilling the rivets) has double protection. On the secondary is a 5 amp glass fuse
complete in a cup holder. The primary is protected by a PC-Tron subminiature super fast fuse rated at 3 amps.
These devices have current limiting capabilities, enabling them to go open circuit before the full short circuit is
applied, providing excellent dims: SVi x 2!/2" x 2,/2".
overload
protection.
Complies --
with
BS6301
and _
manufactured to BS 415.
-
e\ r^r-
Overall
£9.95 each (B) or 2 for £18.95 (B)
3 %
Regulated Multi-Voltage Adaptor
This handy regulated power adaptor simply plugs into the mains and supplies switch
selectable outputs of: 1.5, 3, 4.5, 6, 7.5, 9 and 12 volts DC. Output current is 500
ma (200 ma @ 3 or 4.5v settings). No less than 6 output connectors are sup-
plied: both sizes in miniature jack plugs and power together with a 1.1mm
Walkman type powerplug and a PP3 battery snap. All the voltages and all the connectors
Si'n/Vo'nxe2lu/n2"it!x C2o,/n2"troovlserinalcll.ude
a
voltage
select
slide,
a
power
slide
and
power ,
on
indicator. ^ ,,
Measures __
£9.95 each (B)or 2 for £18.95 (B)
BT Approved "GEC" Adaptor GEC D143640 BT Approved. 240vac input, 15vdc 150ma output. Bare wires in and miniature 3.5mm plug out. Dims: SlV'L X IV^H x 1%"W.
£3.95 each (a)3/£10.95 (b)
Heavy Duty 9 vdc 1 amp Adaptor
This is a 230 volt ac mains adaptor delivering 1.3 amp peak, 1 amp nominal at 9 volts DC on the output
under load; off load it outputs 12 volts. Full wave rectification is utilised and integral spike suppression
is featured negative.
The The
input is by flying wire adaptor measures
and the 3%"L x
o2u1/t2p"uWt
to x
a 2.5mm 2"H. A
power plug with the centre connection high quality adaptor complete with
ventilation vents.
£5.95 each (A) 3/£16.95(B)
9 VAC Adaptors
230 vac mains adaptor with 9 vac 300 ma output at 2.7 va. Plugs straight into a normal mains wall socket. The extra long two metre lead is terminated with a 2.5mm power plug. Measures 2'/2"H x 2"W x 2"D.
£3.95 each (a)3/£10.95 (B)
w
Multi Output Adaptor
A particularly versatile adaptor because the DC outputs are ideal for feeding into a regulator to get + 12 vdc, + 5 or 6 vdc and - 5 or 6 vdc. The actual outputs are + 16 vdc.@ 100 ma, + 8 vdc @ 500 ma and - 8vdc @ 40 ma. Tandata model SA 195WALU PA. Plugs straight into the normal 13 amp mains socket; the 1-1/2 metre output lead is terminated in a 4 way DIN plug. Measures 31/2"L x 2"D x 2"W.
£5.95 (A) 3/£16.95 (bi
Fully Enclosed 9vdc 220ma PSU Made for Visicorp for continuous operation of their pointing devices. Rated at 240 vac input and 9vdc 220ma output. Flying leads on the input cable and miniature jack plug on the other. Measures a compact 3" x 2" x 1V2". Ideal for replacement of most 9 volt PP3 battery applications.
£4.95 each (a)3/£13.95 (b)
0181-679-4414
20
Fax: 0181-679-1927
"Display 9{ews Issue No. 13 Mains Suppressors and Filters
622C10
3EZM4S
L2127
SD5A10
FS203D
APF 300C
Potter Model 622C10 high capacity mains suppressor rated at 250 volts AC at 10 amps. A number of pieces of equipment can be protected with this unit to give protection against surges and transient spikes. Fully enclosed so it does not have to be mounted inside the
ffllyuinignlneSados. /Cir,cul,i.tPd~iategcratsm wFlh*iicnh9.ilns,dJbiycawteasyt°hfe,wco0nbn0e]c{thioonlessisonpreinatresdaot nthtehebotottpomof othf ethuensituppressor and electrical connection via
Measures 514"Lx2%"H x 2"W.
£10.95 (B) each or 3 for £29.95(C)
Corcam Model 3EZM4S This unit is perfect for computers suffering from mains borne interference and transient spikes. It has a
i1n0n0, T12o0r,^2o2n0 andi 2o4^n0 vAIrC. and raStne{dj at r2oacmkeprss^@,'tc2h40tovgAeCthaenrdwi3thaminptesgr@al 1fu20sevAs Cac. cTeshseibmleaifnrosmcotnhneefcrtoinotn. Iits iastlitnhke sreelaercbtavbwleavfor
of push on connoctors. Mossuros 4 x 3" x 1 ovorsll.
£6.95 (A) or 3 for £19 95(B)
Bel|ing-Lee type L2127 mains RFI filters rated at 250 volts 3 amps maximum. Comes complete with a built in mains cable (English
coding), and a three pin miniature non-reversible socket. A mating plug, which goes to the equipment is also supplied. Ideal for those
who are bugged by RF m erference and who require a particularly compact suppressor yet which has sufficient capacity to cover most
applications. Dims 3-1/8 x 2.5" x 1.5".
£4.95 (A) each or 3 for £12.95(B)
?3/^pr^SSilQ"\A?eVcifQ®uTyPie^D5.u10 Rated ]15/250 vAC ancl 5 amPs- This is a single bolt compact suppressor measuring only .trali in andJ out. and earHthe.xcTlhuidsinisg athpeamrtiocuunlatirnlgy beoalstilayndmcoounnnteedctiaonndtacbosm, pwahcitchsuaprpersensasporc-onpneerfcetcotrswahsenshsopwanc;ethisesreesatrriectleivde. and neu-
ITT Type FS203D. Rated at 250 vac and 6 amps. Bolt down can type with flying leads exiting at the top of the can. They are'llr tonq.
Measures l-7/o n x 1-3/8 D
£4.95 (A) each or 3 for £14(B)
cWapimacpietoyr-sDaunbdili6e8r 0TmypheinAdPuFct3o0rs0.CM. Pearisnuteredscoirncluyit1b-o3/a8rMdLmxo1u-n3t/1mGa'Winsxsuppressor
rated
at
250
vAC 3A. Contains £4.95 (A) or 3
a network of 4700pf for £12 95(A)
Single/Three Phase Extra Heavy Duty Suppressors
Very high capacity and versatile mains suppressor. May be wired for Delta or Star three phase config-
m
uration and will handle up to 30 amps or may be used for single phase. Voltage capacity is 120-208 vAC or 240-416 vAC, 47/63 Hz, Has shielded barrier strip screw down input and bolt fixing output connections
Measures 6" long including connectors by 4" square.
Only £39.00 each (C)
UHF Video & Audio Modulator
High quality unit made by ALPS part number MDLK5D for incorporation into video recorders players or any application to provide a UHF modulated signal from a monochrome or colour composite video and low level sound source. Fully encased in tin plated box, unit features co axial input and output sockets to give a 'loop through' function thus when used with a domestic type television set there is no need to unplug the standard aerial input. An internal switchable 'boost' amp gives 3-4dB of gain to the UHF off air signal right across the 47 to 854 MHz spectrum. Another nice feature is the incorporation of a tuning switch - when activated a black and white bar is modulated on to the UHF output to aid tuning to the correct channel. Standard 75 ohm video signal with lOOmv 10k ohm audio input. Printed circuit or solder tag connection. Unit comes pre tuned to UHF channel 38, a pre set pot allows adjustment of video output channels 30 to 39. Operates on single 5vDC rail at 70 ma. Dimensions mm 44 W x 50 H x 28 D. Supplied complete with data sheet.
(«
»
Only £6.95 (A) 10/£65.00 (bi 50 / £55.00 (c) 100 / £495.00 ()
ill.
Hi
Modol K-101
lonisation Smoke Alarms
Kidde Models KSA-300 and K-101 are UL and BS 5446 PL1 approved battery pow ered smoke alarms. Both are lonisation types for superior performance and have advanced design single ionisation chambers for the prevention of false alarms and particularly triggering from atmospheric pressure and humidity changes. They also both feature self lest buttons so that the alarm can be activated to make sure that iljs operational, exceptionally high intensity alarms and easy two screw installation. Model KSA-300 has an integral escape light. KSA-300 measures 6" diameter by 1'/?" high and uses two PP-3, 9 volt batteries."K-101 uses one PP-3 and is 4%" diameter and the same height Both types arc brand new, packaged and come complete with a full instruction booklet.
Model KSA-300
Model K-101 £8.95 w
Model KSA-300 £11.95 w
0181-679-4414
21
Fax; 0181-679-1927
'Display 9{evJs Issue No. 13
Single Board
^ ^ -Diy.^. L 9 · i A- ~ i
Piai
"Professional" BBC B Type
r ^i i #
Computer
Only £29.95 III Plus the chance to win £100 cash !!! A major purchase allows us to offer you the PROFESSIONAL version of the BBC
computer at a parts only price PLUS the chance to WIN £100.00. Used as a front end graphics system on large networked systems
, the architecture of this board has so many similarities to the regular BBC model B that we are sure that with a bit of experimenta-
tion and ingenuity many useful applications will be found for this board!! The board is supplied complete with an input/output connector
panel which brings all the I/O to 'D' and BNC type connectors - all you have to do is provide +5 and ae12 v DC. The Professional con-
sists of a single PCB with most major IC's socketed. Three 27128 EPROMS contain the custom operating system on which we have
no information. On application of DC power the system boots and provides diagnostic information on the video output. On board DIP
switches and jumpers select the ECONET address and enable the four extra EPROM sockets for user software. The main IC line up
includes 6502 or 6512 CPU, 8 x 4564 Ram IC's, 2 x 6522 pio's, SAA5050 teletext ic, (that's worth £10.00 on its own !!) 6845 screen
controller, 68B54 Econet controller, 3 x 27128 EPROMS, 3 x ACORN ULA type IC's plus approx 62 other IC's, Inputs and outputs
on the connector panel are labelled ECONET, ANALOG RGB OUT, PARALLEL PRINTER, COMPOSITE VIDEO OUT, RGB OUT, KEYBOARD IN, KEYBOARD OUT, IS IN, IS OUT, and SERIAL PRINTER. Dims: main board 13V2" x 914", I/O board 141/2" x 31/2", front panel
2" high. Supplied tested and complete with circuit diagram and
competition enlr, form
Only £29.95 Or 2 for £53 W
FRWEIEN C£01/H0P0ECTA'TS'2 H'f
We will award £100 cash to the person or establishment who offers the most novel\ application, which must be demonstrable with this amazing board. We will be the
sole judge of the winner and reserve the right to publish the winning entries. An entry form with details and conditions comes with each board - buy 10 and make
10 entries!
12V DC Miniature Push Solenoid These solenoids are brand new and made for a well known daisywheel printer manufacturer. It is the hammer solenoid which strikes the letter on the wheel to force it against the ribbon and paper. They 1 are therefore powerful little solenoids with a throw of about 5/16", so are capable of very high oper-
ating speeds. They require 12vdc and their pulse consumption is 3 amps. The actual consumption will depend on the pulse frequency and width, in other words how many times the solenoid is used and for how long.
SOL-12: £3.95 (A) or 5 for £17.95 (B)
Various Terminal Blocks Three different types of barrier strips. BA1 is a 12 way professional type with leaf
'fV»,#'Vx &tokyv:.v&r,,vi
springs to prevent conductor damage by the clamping screws, rated 20 A 440vAC. BA2 is a 12 way right angled block rated at 15 A 750 vAC and BA3 is 3 way, totally shrouded
S BI*** 9f*WMM
by a cover with moulded sequential markings, rated at 36A 500 vAC and 600 vDC. R.S.
f Components Ltd. numbers are 423-598 = BA1, 423-374 = BA2 and 424-563 = BA3. At
a fraction of normal cost:
BA1...E1.49 BA2...E0.85 BA3...E1.25 w Discounts (mix or match): 10-99=10%
Drawing Files & Carrying Cases
An unusual item for us but a very useful one if you want to store or carry large documents, such as drawings, music, blueprints and so on. They are made of durable cardboard and the two halves are kept closed by Velcro buttons so that everything doesn't fall out! It opens out as shown in the sketch on the right and then the inner pocket, also secured with Velcro, opens. In its closed or carrying position it measures 241/2" high by 121/2" wide by 11/2" thick. When first opened the width doubles and with the inner pocket opened the width is 34". The maximum size of document therefore is 34" x 24".
Box of 5 for £10.95 (B)
0181-679-4414
22
Fax: 0181-679-1927
'Display yjeivs Issue No. 13
OPTOELECTRONIC
tt SALE · ·
4 1
3 2
1 = Sensor transistor collector 2= Sensor transistor emitter 3 = Xmitter LED anode 4 = Xmitter LED cathode Pin 1 is indicated by a dot on top of the case. Pin 4 by a shorter lead. Above is the bottom view.
Infrared Reflex
Transmitter/Sensors
Type OPB 706A reflex transmitter sensors from TRW Optron. Similar in size to a TO-92 plastic transistor, these reflex opto devices consist of an infrared transmitter and sensor in the same case. Any reflective surface sends the transmitted beam back to the sensor, interruption of the beam can therefore be sensed. The transmitter is a light emitting diode and the sensor a photo transistor.Specifications are as follows:
Transmitter LED:
Maximum reverse voltage
= 3 volts
Minimum Output current Maximum forward current
Vce Distance to reflective surface
= 500 ma = 20 ma-
= 5 volts = 0.05"
£1.95 each (A) 5 for £8.95 w
i r;
LED Assortment Sale Two assortments of LEDs. Red, amber, clear, green and infra red. Many sizes and shapes - round and rectangular 3mm, 8mm, 10mm etc. Fill up your stock box whilst we have excessive stock! All brand
new and unused
25 for £2.95
100 for £8.95 (A)
10 Bar Dual In Line LED Array
Siemens RBG1000. Ten individual red LED elements housed in a 20 pin dual in line package forms a very
compact linear bar display, which may be end stacked for extended lengths. Ideal for bargraphs, level displays mm ftf.38 K and solid state meter movements. Each LED element is intensity matched to give an excellent uniform appear-
ance overall. Typical power requirements per
. ._ , __ _
LED: 2 volts at 10 ma. Maximum 6 volts and £2.95 63011 Or 1 0 fOr £26.00 (A)
25ma.
One red and one amber LED arranged in a holder, one over
Red and Amber LED Pairs
the other. Extremely useful when you need a "stop and ready" display. The LEDs are standard 5 mm and are eas-
ily removable for separate use if requiredI and can therefore be interchanged. Come with the red on top.
Four pairs for £1.99 (A) 10 pair £4.50 (A)
7 Segment Dual Numeric Displays
Matsushita type LN526RA dual 7 segment LED numeric displays with right hand decimal points.
9/16" character height 3/8" width including the decimal point. Normal dual in line pins.
Feature low power dissipation with high luminosity. Red colour. The modules are end stack-
able so that any number may be used. Common anode with all segments and decimal points
separately addressable.
^ _
,
_ , _ ._ _
£2.95 each (A) 5 for £13.95 (A)
Gap Type Opto Detectors
Two different types of opto detectors: Texas Instruments TIL 143 and TRW Optron OPB 813. They
are virtually identical electrically - detector current 200 ma at 10 volts and 20 ma but differ slight-
i m
ly in the gap size. TIL 143 has a gap width of 2.6 mm width and 6.5 mm length whilst OPB 813 is
3.3 mm and 8.7 mm. Either type mix or match
5 for £2.95 (A) or 10 for £5.50 (A)
0181-679-4414
23
Fax; 0181-679-1927
(Display (l\[eu'S Issue No. 13
T
5 volt DC
Fluorescent Display
mPm
Modules
You read right a compact Vacuum Fluorescent Display Module that needs only a single 5 vdc supply - how? - there is an integral DC to DC voltage converter on board which boosts the 5 vdc to the 100 or so volts required by vacuum fluorescents. This results in highly readable, bright (typically 175 fl) blue-green alphanumerics which, if required, can be filtered to blue, green, aqua, ye low or red. The characters are arranged on a two line by twenty format utilising a 5 x 7 dot matrix so that lower case letters, numerals, symbols
and punctuation may all be used; indeed, the entire ASCII 96-character set can be displayed. In addition, the distinctive characters of the General European, German and Scandinavian fonts, as well as a selection of scientific symbols, can be produced under software control. This IEE-FLIP 3600-44-040 also includes an improved on board microprocessor which features advanced control features enhanced serial data interface and a faster display refresh rate. Most of the ASCII control functions are supported, including carriage return line feed, advance and backspace cursor, character blink fields, visible or invisible cursor, blinking or non-blinking underbar and so on. Four end of line modes are also supported, including horizontal scrolling from right to left on the bottom line after it has been filled. The brightness of the display may be controlled by software in tour steps and interfacing is extremely simple, it may be either parallel or 1200 baud serial. Little if any extra hardware is required. In parallel mode the display module is addressed as two RAM memory locations in a memory map I/O configuration. For serial interfacing a complete asynchronous receiver with TTL comoatible input is built in. Complete descriptions of the two interfaces are included in the data sheet provided. Data may be entered in
the normal left to right mode or randomly with the addressable cursor. Power rating of the module is 5.5 watts, in other words it draws about 1 1 amps Overall it measures GViL x 2"W x 1'/2"H without the connectors on the rear, which are standard edge connectors -
one for power and reset, the other for data. The 3600-44-040 is an amazingly versatile display featuring a high degree of user friendliness both in its interfacing and power requirements. It may be used with ease in virtually any application for which it is suited. They
are brand new, are supplied with a complete data and application booklet and normally cost about £139 each. ^30 00 each (A) 3 fOT £30 00
Miniature 16x2 LCD Display
Hitachi model LM052L 16 characters by 2 line standard ASCII LCD display panel. The ASCII controller HD44780 is built in. Only a single +5 vdc supply is required and typical current draw is a minuscule 1 ma! Resolution is excellent with a maximum 40 dots per character making the total
screen capacity 1280 dots. One useful function is that data may be sent to the module in either 4 bit parallel two operation mode or 8 bit parallel single operation, so that it can be interfaced to either 4 or 8 bit MPUs. The LM052L is therefore very easy to use - you simply enable, select write and send the data. In addition to sending data, instructions may be sent to the module in order to con' trol the cursor, to issue clear display commands, cursor direction commands and so on. The data sheet supplied contains details ot how to issue instructions to the internal register. Brand new and unused. See the May to July 1990 issues of Practical Electronics for a general description of the applications of almost identical displays!
£8.95 each w 3 for £25.00 w 10 for £80 (B)
CS CS
s
Large Back Lit Liquid Crystal Point of
Sale Displays
Super bright back lit LCD displays of the type that you see at supermarket checkout tills. Both made by Alps - LDSEA3022B features VERY LARGE 12 mm characters organised as 2 lines I by 16 and is supplied in the smart case illustrated. LDSCB2021B is a single line of 24 LARGE 7 mm characters and is the top illustration. Both have characters made up of a 5 x 7 matrix. Both units feature Hitachi inbuilt driver IC's and are driven by a simple 8 bit parallel interface by way of a 20 way male IDC plug provided. The displays require a single +5vdc rail to operate and a separate voltage to power the filament type lamps which provide the backlighting. As supplied the miniature flange type push in bulbs are rated at 24 volts but can be easily changed to suit your own voltage requirements. The viewing area of the larger display is 65/8" x 1-5/8" and SVa" x 5/8" the smaller. Overall the displays measure 8" x 2V2" and 7Vz" x I1/2". The case in which LDSEA3022B is housed is swivel and tilt, stands SVa" high is 8%" long and 21/2" thick. These displays are particularly recommended where a high degree of legibility is required at a distance. The orange type backlight gives a very readable but unobtrusive effect. Both displays brand new with full data.
LDSC....£19.95 (ad LDSE...E39.95 (AD
11.5" Backlit LCD 640 x 840 VGA Flat Displays
A masterpiece of engineering the SHARP LM64048Z VGA LCD backlit display is the same type used on laptops, data displays etc. Unit features all internal drive electronics to obtain a pixel.resolution of 640 x 480 with a dot pitch of 0.33. All connections to the display are made via a 14 way ribbon cable. The backlighting is achieved by a unique internal optical system whereby a miniature white fluorescent tube light is evenly distributed across the entire screen face. Panel display area measures diagonally 11.25" vertical 7" horizontal 9.25". Overall the unit measures 12" W x 9.5" H x 1" deep. Supplied with full manufactures data. Removed from NEW equipment- Guaranteed
\:r~
LARGE QTY AVAILABLE
Only £125.00 (B)
0181-679-4414
24
Fax: 0181-679-1927
(Display 9jeius Issue No. 13
Extra Strong Equipment / Brief / Suit Case Deal Originally made as special equipment cases, these are a perfect size to be used as an equipment case - or a brief case- or even a suitcase! Inside is a built in 10" square leather pocket (ideal for probes, papers or shirts!) and a Vz" thick piece of foam plastic glued to one side to provide safety to that valuable equipment - or the shirts! Press down automatic locks for security and a key is also supplied. The moulded handle is sprung loaded so that it lays flush when not in use. The case has extra strong hook and rod hinges and reinforced metal fittings. The case is made with immensely strong dark brown ABS with extra strengthening in matching matte black ribbed metal - yet it weighs only 2 kg!!. Measures 20"W x 15"H x 6"T. Brand new with four sturdy feet and complete with 2 keys. Whether you want to carry equipment, tools, papers or clothes this case will do the job and at this price how can you lose? Brand new surplus. DON'T MISS THIS ITEM !!
£24.95 each (B) 2 for £48 (c) 5 for £108(0)
Laptop Computer, Equipment, Carry-On, Holdall
A terrific buy in high quality holdalls by a household name manufacturer, originally intended for carrying laptop computers or other equipment. They are of superior quality to the normal holdall which can be bought in baggage stores because they both have a multiplicity of pockets and pouches and use stout zips. Velcro fastening and very generous padding throughout. Both types are brand new and come to us in original manufacturers' packaging. As can be seen from the photographs they are very similar to each other with slightly differing features, so we will describe them individually: Hold-1: This is the one in the top photograph on the left. It measures 17"H x 14"W x 5"T overall without any contents. The main pouch has a stiffener around the inside so it will not lay totally flat, on the other hand clothes and such like would get less creased. The shoulder strap may be used or removed and is adjustable in length. The handle is in two parts, when used the two sections attach with Velcro. The main pouch contains a padded divider which can be attached to one side of the pouch; built into that side of the pouch, and therefore covered by the divider, are three pockets. The secondary pouch is padded and does not contain extra pockets. Both pouches are secured with high quality zips.
Hold-2: Measurements are an inch or so greater than Hold-1 all round, the handle and shoulder straps are virtually identical. The main pouch, like Hold-1, has a padded divider but instead of the three pockets of Hold-1 there are 6 small ones, provision for pens and an owners label, and a large secondary internal pouch. A removable padded retaining "bar" is also provided. The outside pouch is secured by a Velcro fastened front flap which covers the whole pouch, rather than a zip. Also has large stout rubber feet on the bottom. In summary Hold-2 is a little larger and has more internal pockets than Hold-1, on the other hand Hold-1 benefits with the main pouch stiffener, particularly if it is intended that the holdall be used for clothes.
Hold-1: £12.95 b)2/£23.95 (C)
Hold-2: £13.95 b. 2/E26.95 c
Call for further generous discounts on quantities of holdalls!
Micro Miniature R-T Curve Matched NTC Thermistor
When we say Micro Miniature, we mean it ! Just the size of a pinhead !! This NTC 10K ohm thermistor RS part number 151-237 exhibits A VERY closely matched spec from device to device over a wide temperature range. Nominal resistance of 10k ohm at 250C with a temperature range of -80° C to +150oC. Tolerance over range 0°C to +70oC is ±0.20C. Epoxy encapsulated with long 75 mm leads. Ideal for a host of applications including accurate temperature measurement etc.
Normal price £3.50 Each - Our Price £1.95 10/£18.00 100 / £165.00 (A)
[|j Betamax Tapes Industrial Grade Intelligent Barcode Wand
For those of you who still appreciate the superb quality of the now defunct Betamax video recorder system (as does the writer!), this may well be one of your last chances to
obtain BRAND NEW tapes for this machine. Tapes are top quality 'Scotch 3M' brand and have a run time of 1hr and 5 minutes.
Only
£2.95 (A)
4/£10.00 (B)
Only
£19.95 (A)
A Masterpiece of engineering this heavy duty barcode wand has to be seen to be appreciated. Externally the wand is made of high impact ABS plastic with a very durable lens system mounted to one end. Inside a complete fibre optic system concentrates a high output red LED into a pin light source, when swiped across a barcode, internal optics reflect the light source back into the wand and convert these into serial data output fully TTL 5v compatible logic levels, equivalent to the barcode read, for interfacing with computers etc. Requires 12 V dc at 100 ma Supplied fully tested complete with 4 foot curly cord & Data sheet.
0181-679-4414
25
Fax: 0181-679-1927
'Display 9^ezvs Issue No. 13
7 Segment And Dot Matrix
LED Displays
LA 2511-21 8 LA 2521-21 13
LA 5622-11 11
1 m. m
LTL 2820G
LTL 2720Y
wX:
LTL 2620HR
LJ 2021-21 12
Illustrations shown approximately actual size
LJ 2041-21 12
LA 2311-41
A "once in a lifetime" buy of various brand new surplus display boards
BRIEF SPECIFICATIONS OF THE DISPLAYS Heights refer to the actual digit size. Luminous Intensity in mcd @ lOma
LA 2311: Jumbo sized 2.3" high, red 7 segment dis-
from a well known leisure company enables us to bring you a fascinating assortment of boards to be used as is or for the valuable displays they contain. A full data sheet is provided which gives pinouts and operating data for all of the displays and notes on the operation of some of the boards - at press time we are still accumulating further data! The IC s on
plays with decimal. Common anode. Grey face.
the boards are all MM5450N which are 34 segment LED drivers accepting
Regular price £6.26 each, LJ 2021 (green) 2 mcd LJ 2041 (orange) 2.2 mcd,
a serial clocked data input signal. Data on this chip is included in the data pack. We don't have roomTo describe the boards in full but a brief
jumbo sized 35 dot matrices with X-Y selection. 2" x 1- description of each follows:
3/8" display area. Side stackable and locking to give any display length. Grey face. Regular price £4.24 each. LA 2511: Large red 1" 7 segment with decimal. 1.0 mcd. Common anode. A black face provides exceptionally high contrast. Regular price £3.22 each. LA 2521; Large green 1" 7 segment with decimal. 3.3
Board A: Contains 14 off LA 2521-21 green 1" 7 segment displays mounted in a cross
formation, IC's and several transistors. 10 way IDC connector on rear. 8"H x 10,/2"W.
Order #877
E9-95 (B)
Board B: 6 off LJ 2021-21 large green 35 dot matrix displays, 8 off LTL series LED
Bar Arrays (4 green, 2 yellow and 2 high intensity red), 4 IC's and several transistors.
1 each of 26 way, 10 way and 20 way IDC and 1 off 8 way header connector. 13"W x
mcd. Grey face. Regular price £3.22 each
eVz'H. Order #875
£12.95 (B)
LA 5622: Dual "normal" size 0.56" green 7 segment displays. Common anode. 1.85 mcd (each). Approx. regular price £2.87 each. LTL series in high intensity red, green and yellow. Each package contains 8 LEDs in 4 bars of 2 LEDs each. All diodes may be individually lit. Appx. regular price £1.80.
Board C: 6 off LJ 2041-21 large 35 red dot matrix displays, 2 off IC's. 10 way IDC and
8 way header on rear.14)4" x 2-1/8". Order #874
£12.95 (B)
Board D: 4 off LA 2511-21 red 1" 7 segment displays with 1 off 16 way IDC on rear.
A'/zT x 2-3/8"H. These are ideal if you just want a four digit display as all connections
for the displays are simply taken to the IDC connector on the rear. Order #873
E6-95 (B)
Board E; 4 off LA 2311-41 huge red 7 segment displays, a dual LA 5622-11 green 7
segment display with a 16 way IDC on the rear. 7%"L x SVH. This is a fascinating
u
· ·"
board; for one thing the jumbo displays have to be seen to be appreciated, they are so large. Also the inclusion of the green provides a distinct method of displaying seconds
A
in a clock or hundredths in a counter. Like Board D the display pins go straight to the connector, providing a very simple interface for clock, counter or other circuitry. Worth
the price just to look at the size of them!
XSi,-
Order #872
E9-95 (B)
Any 10 boards less 10% discount.
D E
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DISPLHt USE
n 231... FAMosordJi8pfyarts
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0181-679-4414
C 26
£2 Fax: 0181-679-1927
(Dispby yfews Issue No. 13
Intel Maths Co - Processors for PC's
The most economical way of speeding up your PC is to install a Math Co-Processor in your PC-XT, 286 or 386
in!
machine. It speeds up applications such as AutoCAD, Lotus123, Excel and many more. Please check with your PC
manufacturer the type of unit you require before ordering.
TYPE
SUITABLE FOR
PRICE
8087-
80287-10 80C287-12 80387SX-16 80387DX-25
IBM XT 8088 MACHINES (RFE) DIL PACKAGE
IBM AT 80286 MACHINES 8-12MHz (RFE) DIL PACKAGE IBM AT 80C286 CMOS CHIP MACHINES 12-16MHz DIL PACKAGE IBM AT 80386SX MACHINES @16MHz. PLEASE STATE PGA OR PLCC PACKAGE IBM AT 80386DX MACHINES @ 25 MHz. PGA
£34.95(A)
£34.95(A) £39.95(A) £44.95(A) £44.95(A)
30 pin, 1 Mb 80 ns SIMMS
BRAND SPANKING NEW - FULLY GUARANTEED FOR IBM PC XT AT TYPE COMPUTERS
1 Mb x 9 80 ns SIMM 3 chip
£23.50 each (a)
1 Mb x 9 80 ns SIMM 9 chip
£22.50 each (a)
Apricot 31/2" Disk Drives for Spares and DIYers
Brand New Sony V/i" disk drive type OA-D31V-04, made specifically for an early Apricot computer. The
drive is for single sided use as it has only one head. We imagine that it is 40 track, although there is a tiny
little slide switch on the back which looks suspiciously like a 40 / 80 track selection switch. Quality madei
item and apart from its obvious use as a spare drive it also offers a major source of parts for the hobbyist
including miniature stepper motor, hall effect 300-400 rpm brushless motor and a precision rack slide assem
bly plus IC's and many other useful components. We have no data on it and
because of this it is going at a knock down price. Measures 5" x 4" x 2"
f\
Only £10 (B)
Super PC-Kwik Disk Accelerator Software
Super PC-Kwik (version 3.53) from Multisoft is one of the best known, and most efficient, programs around for speeding up your computer's access to floppies and hard disks. After installation, a dramatic improvement in the speed of your computer, regardless of its existing speed, will be seen. The exact
percentage of improvement cannot be stated as it depends totally on the type of work for which you use your machine. As a general rule of thumb, if your applications access the floppies or hard disk a lot you can look for a doubling in apparent machine speed. PC-Kwik works by creating a cache in RAM.
In that cache it stores the sectors of the media which you use most. When you call for a file or data that is cached then PC-Kwik goes to RAM for it and thus saves a disk access, which although seemingly fast is in fact one of the main operations in slowing down a system. Brand new in original packaging - supports expanded and extended memory - at under half its normal price.
Only £7.95 each (A)
Quarterdeck QEMM-386 Expanded
a?
Memory Manager
The Quarterdeck Expanded Memory Manager - 386 (QEMM-386) version 6,02 is a memory manager for
386, 486 and Pentium PCs and PS/2s. And more. QEMM-386 manages all of your PC's memory- how-
<2
ever you want to use it. As such, QEMM-386 is not only an expanded memory manager, but it is also
an extended memory and a high (640-1024K) memory manager - all in one! QEMM-386 is compati-
ble with all the current industry memory specification standards. With QEMM-386 you can load drivers (for example, a network), TSR'S, and DOS resources in any available high memory. The benefit to
,
*
you is more memory below 640K for your DOS program. QEMM-386 sets up your memory as opti-
mally as it can -automatically with its Optimize feature. The goal, of course, always, is to give you the
maximum utilisation of your most precious PC resource, memory-in the easiest way possible. This software
is on SYz" media, brand new at a bargain price.
m a.
^
Only £24.95 each w
Microsoft Compatible Three Button Serial Mouse
This new ergonomically designed mouse fits efficiently and neatly into your hand making your work more easy and productive. Assembled in the Far East by Z-Nix Inc, this state of the art mouse comes complete with all software on 3-V4" disk only. The limp type cable is terminated in a 9 pin D connector and a 9 to 25 way D connector adaptor is also supplied, for those with a 25 way male socket on their serial ports. Fully compatible with the Microsoft mouse standards, including ballistic acceleration. All parameters may be set by the software, which also includes as a bonus Pop-Up menu software allowing you to enhance programs such as Lotus 1-2-3, dBase and many other programs which do not usually support a mouse.
Only £14.95 each (A1)
0181-679-4414
27
Fax; 0181-679-1927
'Dispfoy 9{eivs Issue No. 13
Nickel Cadmium Batteries
Super Ni-Cad Sale!
We have been able to obtain quantities of ni-cad battery packs which
have been retired from a large user of cellular phones and 2 way
radios. The majority have been declared surplus for cosmetic rea-
sons, dents and scratches on the cases and in some cases the
demise of a single cell. This makes them no longer usable in the
equipment for which they were made. We have tested a cross
section and the actual batteries inside seem to have plenty of life
.r--
left in them. They come in inside. At this price we are
all shapes and sizes, with unable to select particular
all types sizes or
toyfpceesllaasrnd
they are sold as is.
5 for £9.95 (a')1 0 for £16.50 w
C Size Cells
Sanyo "Cadnica" stick of five standard "C size rechargeable nickel cadmium batteries, model number 5N-1800CR. Designed for Victor laptop computers. Nominal voltage 1.25 volts per cell and 6 volts 1.8 amp hours for entire stick. A thermal cutout is incorporated with a temperature sensor strapped to the case of one of the cells. May be used as is or very easily divided into the separate cells as shown in the lower photograph. Measures 26mm diameter and 250mm long.
Per bar
£8.95 each (A)
3 Volt Lithium Backup Batteries
Size 2/3A (33mm long, 16.6mm diameter) industry standard size lithium batteries. Used main- smm
ly as backup batteries for CMOS memory and clock support in IBM PC's and other applications.
Rated at 3 volts 1.5 amp/hour. Printed circuit mount or solder to the PC tabs. Brand new, made
by Panasonic.
3V
£1.95 each (A) 5/E9.00 (A)
12v 24 Ah Rechargeable Sealed Lead Batteries
A super deal in BRAND NEW sealed maintenance free rechargeable lead acid batteries. Rated at 12 vdc
at 24 amp hours these compact high energy sources have a wide range of applications including standby
power systems, robots, golfcarts, etc etc.
m **
7.5"H. Supplied complete with nut / bolt £24.95 each ») 2/E48.00 <0 connection kit.
Automatic 12 v, Lead Acid Battery Chargers
Specifically designed to charge 12 v DC sealed lead acid batteries (as on special offer above) for an electric golf cart, unfortunately the golf cart company went broke and we bought the entire stock. Quality made in an all steel louvered case with dimensions of only 7 W x 4.25" H x 5" D. The unit will completely charge a 12 volt 24 Ah battery in approx 16 hours. The nice feature about this unit is that internal electronics constantly monitor the state of the battery so when the charge is complete it switches into a 'trickle' mode just enough to maintain the battery in peak condition and for an infinite period, ready for use. Many other types of charger on the market tend to 'cook' sealed lead acid batteries grossly shortening their life. Supplied BRAND NEW with maker's instructions and 2 crocodile clips.
Knock Down Price Only £16.95 each (B)
Chloride "Powersafe" High Current - 6 V 100 AH Batteries
Made for BT by Chloride, type 3VB11 specifically for standby power systems where the batteries are trickle charged for long periods of
time and therefore have to be particularly reliable. We came across a large quantity of these driving a massive inverter in a London
financial institution - all are relatively new and in excellent condition. Batteries are totally enclosed and maintenance free and rated at
100 amp hours, they are also capable of giving an extremely high current for short periods of time and therefore all normal safety measures must be taken to avoid short circuits which could result in severe burns or a fire. Many uses include standby power sys-
ttehmresa,dehdiglhugcsu. rSreunppt lsieodurfuclelys,tetsrtaecdtiownithd9ri0vedsayetgcu.aTraenrmteeinaantidonatisa cvuiarrtewnot CQQ Q ^ R^ Parh (C) 2r\/V ir\n r*5r U r\U r\ (D)
list price of over £135 each, the Bank's loss is your gain !!!
1-0^7.^0 CdUi I £.1
.\J\J
Dimensions: 9" H x 8" D x 8" W
0181-679-4414
28
Fax: 0181-679-1927
'Display tyzUS Issue No. 13
Apart from a vast range of current product, many obsolete and discontinued items are listed in the
Display Electronics "Semiconductor HotList" Send £2.50 for your own personal copy or £7.50 for 3 issues.
IC's, Transistors, Regs, Diodes, SCR's, Opto
FROM STOCK
SAVE
THIS MONTH - JUST A SMALL SELECTION FROM OUR VAST RANGE
6802 68A21 80C31 8085 Z80BSI0-2 2732 2764 27C64 27C256 27512 HN27C101G-25 6264P-15
Central Processing Unit Peripheral Controller CPU with serial I/O Central Processing Unit Input/Output Controller 32K EPROM 64K EPROM 64K EPROM LP * 256K EPROM * 512K EPROM* 1 meg EPROM (131 k x 8. Packaqe=32 pin OIL) 8K Static memory
£2.90 each. £3.00 each. £4.75 each. £3.00 each. £4.50 each. £1.00 each. £1.20 each. £1.50 each. £2.90 each. £4.90 each. £5.50 each. £2.35 each.
10 for £24.00
10 for £24.00 10 for £41.00 10 for £23.00
10 for £39.00 10 for £8.00 10 for £ 9.95 10 for £14.00 10 for £22.00 10 for £45.00 10 for £50.00
10 for £22.00
LM7812V 12 Volt positive 1.5 amp regulator
Why pay more ??
^ 38p 10/E3.50 y
INTEL 486-DX33 * 33 Mhz CPU IC
with integral math co pro. Heatsink fitted.
v
£99.00
y
LM78H05 12 Volt 5 AMP regulator in T03 CASE Loadsa Amps - and only
v £3.50 10/E32.00
'
NEC V20-8
The well known NEC speed up CPU * Speed up your PC!
£12.95
y
D8271 The disk controller IC necessary to get the BBC
B to use disks. Now obsolete. Don't get caught out!
v
£32.00
J
D8748 Microprocessor with 1K x 8 bit UV
erasable EPROM built in.
ly £5.95 10/£50
SAA5050
^ f
Philips Teletext integrated circuit. Now obsolete.
£7.00 10/E55
SAA5243/E Current Philips Teletext IC
£9.95 10/E80
^ ®
D8751
MPU With 4k x 8 bit integral EPROM +Serial UART
s £22.00 10/£190 y
D87C51
CMOS Version of this very versatile micro, integral 4k x 8 EPROM + Serial UART
A80386-16 16 MHz
Ever Popular PC or controller CPU
'
LM1881N
N
Versatile Video / Sync stripper IC many uses - 8 pin OIL pack
£24.95 10/E220 4164
Specials!
41256
411000 1M X 9 1M X 9 1M X 9
£12.95
64K DRAM
300 nanosecond or better
200 nanosecond or better
150 nanosecond or better
120 nanosecond or better
256K DRAM
150 nanosecond or better
120 nanosecond or better
1 MEG DRAM
120 nanosecond or better
120 ns SIMM modules for IBM PC, XT, AT etc
80 ns SIMM modules 3 chip for IBM PC, XT, AT etc
80 ns SIMM modules 9 chip for IBM PC, XT, AT etc
£2.45 10/E21
9 for £6 or 18 for £11.50 9 for £10 or 18 for £18.50 9 for £16 or 18 for £29.00 9 for £18 or 18 for £32.00 9 for £20 or 18 for £37.00 9 for £22 or 18 for £40.00 9 for £40 or 18 for £78.00 £19.50 each 2 for £38.00 £23.50 each £22.50 each
256K RAM SIPPS - Special Offer
These are brand new 256K dynamic RAM SIPPS containing 9 off Texas Instruments TMS 4256 or equiva-
lent and their associated decoupling capacitors. Although the chips are absolutely standard, as used in
thousands of computers, these SIPPS were manufactured for a specific application and the pinout of the module is therefore not as per a stan-
dard SIPP package. The chips are surface mounted with full length formed leads and may be very easily removed from the PC board.
Alternatively the module may be used as is or modified. A very cheap way to
buy256Kdyn.micRAMI
£9.95 per SIPP (A) 4 fOf £32 (A)
0181-679-4414
29
Fax: 0181-679-1927
'Display 9{ezvs Issue No. 13
Inkjet Printer
A*
«r
; We bought another MASSIVE quantity of these printers at a very advantageous \ price, we are passing this price straight on to you, on a we need the
space basis'. Therefore, a massive reduction brings you this printer for only
£34.95 ! Naturally at this 'No Time To Test Price' all units are 'sold off the pile'
un-tested and without guarantee. For those of you who 'smell a bargain' here
is the specification of the printer. Mannesmann Tally monochrome inkjet print~ er Model MT90, featuring high speed, high print quality and quiet operation using
bubble jet technology. Choice of draft or Near Letter Quality modes using bidirectional operation in text mode and unidirectional in
graphics mode. Printing speed is 220 cps in draft and 110 cps in NLQ. Standard RS-232C serial interface. Paper feed is fanfold, roll
or single sheet, ink is via ink cartridge Mannesmann part no 040-858. Print width is 8 inches, normal characters print at 80 column,
enlarged at 40 column. Condensed versions of both at 132 and 66. There are four modes of graphic printing: 480, 960, 1920 and 1440 bits. Dims: 153/4"Lx 11-5/8"W x 4,/2"H.
WAS£119.00- Now To Clear £34.95 !! (D)
Another Display Printer Bargain
We seem to be getting quite a name for high qualify, brand spanking new printers at well under half price! We sold out of the Hazeltine Esprints and then the Epson MX-SO's. Now we have a deal better than both, the Centronics 152 in both parallel and serial versions shining bright in manufacturer's cartons, original packaging, complete with manuals at a fraction of the original price. The 152 is a full width (5 to 15 inches width paper) printer with a choice of tractor, fan fold or single sheet feed. Both versions of the 152 have the following specifications in common:
Print speed: Print format: Printing: Dot matrix: Input code: Paper advance: Print buffer: Country codes supported:
150 characters per second
10 cpi/16.36 cpi Bidirectional impact 9x7 96 character ASCII 6 lines /inch. 13 line feeds /second 768 characters plus one line England, USA, France, Germany, Italy, Denmark, Sweden
The 152-2 is standard Centronics parallel interface, the 152-4 is standard RS-232C serial. The latter is factory preset for 1 start bit, 7 data bits,1 even parity bit and 1 stop bit. 8 data bits may also be selected and the parity may be disabled or made odd. Baud rate is switch selectable from 200 to 9600 in the usual steps. Measurements 21 "W x 15"D x 7"H.
152-2 or 152-4: £129.00 each. (E)
Superb 24 Pin Printer
If you need a quality 24 pin Dot Matrix printer that is up to any job then look no further! The NEC P9XL is an advanced printer featuring letter quality printing and high resolution graphics, giving a maximum 360 DPI output. Print speeds range from 140 characters per second Letter Quality to 400 characters per second Draft. Standard Centronics parallel interface. Can also emulate Diablo / IBM. Comes with Feeder as standard. Measurements 24!4"W x 15"D x 14%"H. A real heavy duty printer. Supplied in good used condition.
Only £199.00 (E)
Colour Inkjet Printers
Canon Model PJ-1080A Colour Inkjet printers for high quality, and quiet, print and graphics production. Both standard (80 column) and enlarged (40 column) characters are available. The seven colours are Yellow, Magenta, Cyan, Green, Red, Blue and Black. Uses four nozzles orientated horizontally, the additional three colours are obtained by combining two, for instance, yellow and cyan for green. Characters - full HwI'Wrr yASjoCrII sectoplulmusn64Rsepsoelcuitailon- aisre64p0rindtoetds opnerali5nex. 7ThdeotPmJ-a1t0ri8x0Aforw8il0l accocluemptneiatnhder1s0inxle sheet up to A4 or roll paper up to SVa" wide, maximum diameter of the roil is 2%". Also perfect for overhead projection film up to t,4 size. Dual cartridge ink supply, tri-colour and black with 3.2 million and 4 million character capacity respectively. In excellent used condition with full 90 day guarantee.
Only £199.00 (D)
0181-679-4414
30
Fax: 0181-679-1927
'Display 9{ezvs Issue No. 13
Ultra Fast Full Size Printers The Newbury Data Model 8840 high speed full size (15.5" paper) printer buzzes along at an amazing 240 cps. An excellent buy enables us to bring this printer to you at a saving of over £1000! Newbury products are famous for their quality and the 8840 is no exception. It features an integral fully adjustable paper tractor giving exceptionally fast accurate paper han- ( dling and copes with multi-part forms and precision printing with ease. There are 10 selectable built in type fonts providing up to 226 printable characters on a single line. Many high quality printer features are standard including convenient electronic horizontal and vertical tab setting. It has the normal form and line feed buttons on the front panel together with reset, hold and on line. The ribbon cartridge has a 15 million character expected life. RS232 serial interface. For little more than you would normally expect to pay for a desktop, you can buy this full size professional printer! Sold in superb tested condition, with a 90 day guarantee.
Only £295.00 (E)
Y
B
O
A
R
D
Jj
U
11
PC-XT/AT Switchable & PC-XT Keyboards
30 Function Key Switchable XT/AT
A vesry nice brand new and boxed switchable XT/AT enhanced keyboard featuring no less than 30 function ke;ys making 115 keys in all. In AT mode it will power up as a true AT, that is with the Numb Lock on, unless the machine software directs otherwise. This is a UK keyboard with a pound sign as well as a dollar sign. The backslash, ampersand and other keys which sometimes give a placement problem, are all in their correct places for the UK. Good clicky feel with the normal three LED indicators built into the keys.
JtiLkkk;
r
fJiX I
£49.95 <b,
mm a
Switchable XT/AT Brand new and boxed keyboard for use with the PC XT and AT, switch selectable. 85 keys with the usual 3 LED indicators. 10 function keys along the top of the keyboard. Made by NCR. Complete with template for user slogans.
£32.95 .B.
XT Keyboard
Unique keyboards made by Honeywell for Bull. Even though they are enhanced they are still compatible with the XT and compatibles together with the original PC. What's more it comes with an assortment of keys so that you can make it into a UK or US keyboard! It has LED indicators for CAPS and NUMB plus features no less that 94 keys, with the 10 function keys on the left. A handy pencil ledge just above the top line of keys is provided. Nice two tone grey, measures 20" L x 9" D. Normal retractable tilt legs, curly cord and 5 pin DIN plug. Plus the ultimate in convenience: the cord can be exited from the left, centre or right of the rear of the keyboard!!
x, 1 fI 1J i t ! £29.95 (B)
rr? mm
High Quality - Low Cost XT / AT / PC Keyboard Made for a major rental user of computer systems, we have the contract to purchase all of their ex-rental equipment. Quite often the equipment is only in use for a few weeks and is returned to us in virtually new condition! One of these 'goodies' is this quality keyboard - fully configurable for all systems via a DIP switch on it's underside, it features light pressure double shot moulded keytops, a generous length curly cable terminated with a standard 5 way DIN plug. All keys are standard except for the exception of a key with a UK '£' sign. Supplied fully tested & guaranteed at a snip price of only....
£19.95 b, 5 \ £85.00 c,
Educational Keyboards ?? We are often asked to supply keyboards for use in schools and nursery groups. Forward thinking teachers could do no better than to familiarise children with the look and feel of a keyboard - after all its most likely that whatever field of employment or lifestyle they adopt in the future, a keyboard of some description will probably be encountered. Display Electronics have vast stocks of keyboards ideal for this application, quite often brand new or hardly used, but electrically non compatible with the current PC trend. We are able to supply these units as Educational Keyboards at a price well below their original cost and ideal for the purpose described.
Order as KB-ED £5.95 each m or 5 \ £25.00 (C)
0181-679-4414
31
Fax: 0181-679-1927
Tfisplay 9\[eiOS Issue No. 13
Hi Quality Chassis Box
Built to BT's highest standards this box was made to house a num- i
I ber of printed circuit cards and mains power supply unit, which slide ;
in the front door, which hinges upwards. As supplied there are i
four 40 way 0.1" card edge connectors at the back, all those used
have gold plated contacts. The box is made so that these sockets
can be moved and new ones added as required. The probable
maximum of possible cards is twelve. Complete with power cord and a standard 25 way D female connector. Even a
spare D connector male plug is supplied. Dims 16"L x 14.5" W x 6"H. Very ruggedly manufactured and makes a perfect enclosure
for hundreds of different projects.
, _ ._ __
_ , r\r>r\ r\r\
Only £15.95 (C) or 2 for £30.00 ()
General Purpose Chassis Box Ex BT general purpose chassis boxes, complete with rectifiers, two 12 volt TO-3 cased regulators and a 2N3055 transistor, all mounted on a large heat sink at the rear of the case. Two 25 way 'D' sockets, one ^ male and one female, also mounted on rear. Internally there are two bays (one optionally divided into two) stretching the length of the case which can be left as is or removed. At the back of the bays are 3 gold plated 40 way edge connector sockets. The front of the case hinges upwards for easy access. Steel chassis with aluminium Only £10 95 (C) OT 3/£29 95 (D) cover and front panel. Measures 16" x 11W x 2,/2".
Combination Desk Top Case Beautiful desskk top enclosures from Vero type 65-5033K suit!aabblle for hundreds of different projects.
The unit has a sloping front with a removable panel of attractive matt anodised aluminium which comes with a peel-off protective plastic cover. The case itself is made of high impact black and light grey plastic in two parts which screw together. Seven fastening bosses are supplied inside on the base so that chassis or printed circuit boards may be mounted. Dims in mm are 228L x 215W x 76H (at the back 50 mm at the front). The slope of the anodised alu-
minium panel is 70E, the flat top is 65mm wide and the anodised aluminium panel measures 200mm x 130mm. Fixing hardware is supplied. A super case which will dress up any project.
£9.95 each w 3 for £27.00 (B)
Instrument / Keyboard Case An attractively styled sloping back black moulded case suitable for hundreds of applications. The two aluminium plates are removable for ease of drilling and the case itself is in two parts for simple accessibility. The back aluminium plate slopes at a 45E, the front one is horizontal. Measures 7-3/8" long by 4-1/4" wide. The height at the front is 1 -5/8" high and SVa" at the back. The back aluminium plate is 3%" x 2Vi and the front 3%" x 414.
£3.95 (A) each or 3 for £11.00 (B)
Half Width Euro Rack
Useful item for constructors of modular RGB equipment. Made from all aluminium extrusion this mini rack lends it's uses to a host of applications. As shipped the unit is fitted with 8 x DIN 4162 64 way socket connectors (half populated) these have long solder spills on so can be re-used or as they are only held in by two screws may be replaced. The connectors are 'Bus Wired' and terminate on to 3 x 24 way connectors on the rear panel. Card guides comform to the standard 100 mm vertical spacing for Eurocards. Overall Dims are mm 355 W x 235 D x 132 H. Supplied in used but in good condition.
Only £14.95 (B)
Signal Isolation Transformer
WANTED
To complete a personnel collection of test equipment manuals, we would very much like to locate the following manufacturers catalogues: TEXTRONIX Test Equipment catalogues for 1980 & 1989 HEWLETT PACKARD Test Equipment catalogues for 1977 & 1989
Please contact Dave Fisher at Display Electronics Naturally a suitable reward could be considered.
S9S0^^ RMaidniioatuSrpeadreosubplaertwnouumndbetrra2n1s7fo-8m26er.
I MHB specifically made for audio / data trans-
liB^H'^1 fearch.ieAvnedisboylathtieodnouvbolletawgoeunodf
4kv is bobbin
which is also wound to give a 1-1 ratio with an
input and output impediance of 600 ohms.
Connection via solder tags.
Dim. mm 45 H x 44 D x 46 W Order as RS-IT
Only £3.95 w
0181-679-4414
32
Fax: 0181-679-1927
(Display (h[eu>s Issue No. 13 tAl^.
We had a bit of luck! A certain well known company uses extra high grade VMS tapes - mainly 120 minutes, by Fuji Super High Grade, BASF, TDK etc. for a precision film application. Because of the special application they can record them only once. Their loss is your gain. At these prices you can't even buy such quality direct from the manufacturers! This is one of the best deals we have ever been able to offer (mail order only) - first quality at a lowest ever price - and you don't often see that!
10 for £14 (B) 25 for £33 ra 50 for £65 ra 100 for £125
Very Versatile 'G' Clamps
Extremely versatile because not only may they be used
as an ordinary clamp, they have threaded holes on the
rear so that they themselves can be attached to other
1
objects, in this way, almost anything can be made capa-
ble of being clamped to any protruding surface. Has a jaw
height of 2V2". Thousands of uses in any workshop or
household.
Telescopic Aerial
A standard heavily chromed telescopic aerial for portable radios and other applications. Screw (supplied) fixing at the base. It has 7 sections and the length varies from 4-5/8" to 17". Base diameter is 5/16". Makes a handy pointing tool as well!
Only £3.45 each w 5/£15.95 w
3 for £3.95 (A) or 10 for £10 (ad
High Quality Video Cables
'Gold Dubbing Cable' 6 ft long, ideally suited cjjp for connection of two video recorders - features jr1' GOLD plated phono connectors for ultra low noise. Connectors on each end of cable are clearly marked 'Audio' and 'Video'.
Heavy gauge 3.75 m, 75Q RG59U video cable assembly fitted with
high quality moulded nickel nectors terminated one end plug and PL259 plug the
owptlihathteerBd. NcBColan>c---k*'1TM11*
_
cable. Must have cost a fortune !
General purpose video cable terminated one end with moulded BNC male connector, _ the other end being Phono / RCA Jack) plug. 1.5 m long in Black finish.
Satellite 'F' to 'F' connector cable 26" long. Industrial grade RG59 75ii cable terminated at each end with a crimp type 'F' plug as used on most satellite equipment.
Telescopic Aerial with Angled Mast
Six section versatile telescopic aerial YOKOWO type 1300-01. Side bracket fixing and the ability not only to extend to 42" but also to be placed in any angle up to 45 degrees from the vertical. Heavy chrome finish. Closed length is 8.25".
£1.75 (A) each or 5 /£7.75 (ad
40mm Submin Speaker
Radio Spares part number 248-476. High quality miniature speaker for general purpose use in audio or tone generator applications, ideal for direct RGB fixing. Solder tag connections. 8 ohm coil rated at 200 mW
£2.25 each or any 3 for £5.99 w
Only 99p 10/E7.95 (A)
Audio Cassette Mechanisms Brand new complete stereo audio cassette mechanisms, including stereo play and electronic erase heads. The motor is 12 vdc. Six piano type control keys for Record, Fast Forward, Rewind, Play, Eject and Pause. First grade well engineered quality on a sturdy metal chassis and heavy duty motor. The assembly is of normal cassette machine size - < ff approximately 7"L x 5"W x 2-,/2"H. Just needs the electronics and its ready to go! Also very useful for spare parts. Shown with the plastic cover removed for ease of illustration.
£9.95 each w 3 for £27.95 (B)
Sticky Number Sheets
(D @ (5) (4) @) One of those useful items that's always handy to have around. A large sheet of 84 very durable PVC permanent self adhesive peel off numbers, numbered 1 to 84, Each number is circular die cut and 5 mm across. Ideal for numbering parts, IC's on prototype boards, stock locations, in fact any numbering job that comes to mind !!
10 Sheets £1.95 m
TT 0181-679-4414
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Fax: 0181-679-1927
'Display 'J\(eu's Issue No. 13
Pressure Gauges
Three different types of pressure gauges to choose from;
PG-1 Three scales. The red outer 0-30 Ibf/in2; the middle black is 0-2 kgf/cm2 and the inner black is 0-2
bars. Stainless steel case measuring 1-7/8" diameter by 1%" deep overall. The bushing is 15mm diameter.
PG-2 Two scales; the inner in red 0-4 bars and the outer in black 0-60 Ibs/in2. Black metal case with heav-
$
ily chromed surround. Dims: 2,,D x 1%" including the screw bushing connector, which is 10mm diameter.
PG-3 Two scales both coloured black. The outer 0-4 bars and the inner 0-60 Ibs/in2. Stainless steel case
measuring 2" diameter by 1%" deep including the 10mm diameter bushing.
Any type £4.50 each w 3/E12 (B)IVIix or match!
Quality Bargain Parcels
Bargain packs or bags are not uncommon in the surplus industry but sometimes they prove to be disappointing when received. Because we know this, we go to a lot of trouble to select quality contents for our parcels and that is why they are different. We make certain that our customers not only get the very best value for their money but also receive real quality material and an excellent mix of parts. The only similarity between our parcels and others is that they are sold by weight. You can buy our parcels with total confidence that you will get a very nice surprise when you open them! They contain hundreds of different types of electronic parts and equipment ranging all the way from semiconductors and optoelectronics to potentiometers and complete sub-assemblies. The majority of the contents are brand new! We regret that we cannot fill orders for specific parts.
5 kgs £8.95 (B) 10 kgs £14.50 (c) 20 kgs £22.50 ()
Parts Boards Bargain Parcels We have thousands of parts boards from all types of equipment - computers, televisions, modems, RF boards, memory banks and so on. Most of them are new spares and some are from, again new, equipment. Rather than sort them all out and prepare data sheets we are selling them in parcels of various numbers of boards for parts stripping. The board sizes vary from about 4": 6" up to jumbo size. We cannot say what actual sizes are in any parcel but each will have a good mix. The components on the boards are mostly IC's and other semiconductors, relays, DIP switches, connectors etc. The IC's may be socketed or not. The one thing certain is that you can save an awful lot of money in component costs!
5 board parcel £4.95 (ai) 10 board parcel £8.50 (B)
Bundles
"Bundles" are assortments of various types of the same basic component, A bundle of relays for instance
would contain the stipulated number of relays, of differing voltages, contacts and sizes. The majority of ^
a
parts in a bundle are brand new, only a few are ex-equipment and only when they would present an extra-
ordinary value to the customer. Bundles must be distinguished from Grab Bags which might contain any
type of part.
Relays You never have the right relay at the right time. Stock up at these prices! May be any mounting style. Single and multi pole, DC and AC, high or low voltages. But definitely a good mix I!
Integrated Circuits
10 for £9.95 (B) or 100 for £90 (c)
A massive pool of ICs of all types makes this one of our most attractive bundles. Mostly dual in line, plastic and ceramic - digital and analogue, many to military specifications. Op-amps and other linears, CMOS, TTL, LSI and others. Mostly regular types with some house numbers. All fully guaranteed NO FALL OUTS. How can you go wrong at these prices?
Small Semi's
100 for £11 - or - 200 for £20 (b,
This bundle contains small semiconductors of all types. May contain small signal silicon transistors, LEDs of
all shapes and sizes, diodes, character readouts and so on. All brand new of course.
!
Passives
100 for £7.95 - or - 500 for £35 (A)
All types of passive components including pots, PC board mount resistor trimmers, variable and fixed capacitors, chokes, coils and many others. These passives are sold by weight. Very approximately 100 passives is equivalent to a half pound. Added bonus - six microswitches thrown in outside the weight!
1/2 kg for £7.95 or 1 kg for £14 (B)
^7
Crimp Connectors Regular type crimp connectors, solder tags, solder lugs, spades, butt joiners open and closed ended etc - sold by the item in many car accessory shops for around 20p each !!! Our price
200 for £3.25 - or - 400 for £6 (A)
0181-679-4414
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Fax: 0181-679-1927
CDisptay 9{ezVS Issue No. 13
Crouzet Geared and Ungeared Dual
Low Speed Synchronous Mains Motors
/op 03
Type U82265 super precision high quality geared motor from Crouzet which may be used with either
115 or 230 vac as required. It consumes only 12 watts yet gives torque you can hardly hold. The ; speed is a useful general purpose 30 RPM The gearbox is precision engineered in bronze and steel \CS3IS
0
ftPW
with a beautifully smooth working. The shaft is %"L x V4"D. The overall dimensions, including the gear ^ box but excluding the shaft are 2-5/8" diameter by 2,/2"H. A brand new top quality geared motor at ^
a fantastic price - ideal for hundreds of applications.
£19.95 each{B) or 3 for £55.00 (C)
Mains 3A HP Motor with Brake
Doerr motor Model LR 22132 delivering 3/4 horsepower and 2900 RPM from 220 / 230 vac 50 hz. Rated for continuous operation with a consumption of 4.1 amps. Features automatic thermal protection and pre-lubricated ball bearing action. The motor has a coil operated brake on one end which locks the shaft dead. It requires 12 vdc at Vz amp. The drive shaft is Vz" and comes with a belt drum fitted which may be taken off by unscrewing a couple of Allen screws if required. The diameter of the body is 6" (excluding the thermal trip and capacitor protrusions) and the overall length is 16". Removed from equipment and in excellent condition, fully guaranteed for 90 days.
Only £49.95 each (F)
« B 10 11 1Z W 14 w
Fantastic Miniature DC Motor Selection
High Torque 40 RPM DC Geared Motor Radio Spares part number 330-799. Quality totally enclosed reversible 6 to 12V DC steel geared, high torque motors - try and hold the shaft and it will take your fingers off!. 40 revs per minute at 12 volts, 30 revs at 10 volts. Draws 15 ma at 12 volts, no load. 6 mm diameter drive shaft 15 mm long. Length including shaft is 90 mm, diameter at widest point is 40 mm. Front flange mounting via 4 fixing holes. Brand new and high quality for continuous duty. Order as MHT-2.
rBEliNjTW, MCSEwmBrp-
RS Price £40!! Our price only £19.95 (ad
Crouzet type 82/180. This is the same motor as Miniature Swiss precision DC motor and gearbox by ESCAP type
above without gears. The shaft is 1/8" diameter by C11.210-5. Undoubtedly one of the best quality geared motors ever
%" long. The overall diameter is 2-5/8" and the to come our way. Completely tubular measuring only 53mm long
height without the shaft is 1 Vz".
by 24 mm diam.'Unit features a 12 stage gearbox
giving a final speed on the 2.7 x 6 mm drive shaft
MM-1 £3.90 or 4/£10 (A)
'of 90 rpm @ 6v and 180 rpm @ 12v. VERY HIGH TORQUE. Ideal models, lens control, robot-
We call this the Pancake motor because of its ultra slim 9 mm thickness. Precision made by the Japanese NAMIKI Co,
ics etc. At a current manufacturers price of £55 each, these motors should not be missed.
this motor was made to direct drive tape cassette reel hubs
in high quality digital tape decks. The motor features RARE EARTH magnets giving it incredible power for it's
MM-5 £14.95 each (A)
small size - so powerful that it is virtually impossible to
stop the 1.5 x 6mm spindle with your fingers when run on only 6v!! Nominal speed on 6v DC 1200 rpm. Dim 9 x 42 m
This is a little jewel of a precision geared motor ideal for all appli,cations where real "Swiss Made" quality and preci-
sion is needed. The torque has to be seen to be
MM-2 £1.99 or 3/£5
believed and it fairly sings as it goes! It needs
ll2v DC to give about 1500 rpm and it gives
Heavy Duty 6-24 v DC Computer Tape deck
proportionately lower RPM voltages down to
reel motor dimensions 15 x 8.1 cm. Fully about 6 volts. Dims, only 3L x 2.5Dcm. The gear may be removed
enclosed construction with front flange from the shaft if required leaving Va"L x 1/16" shaft for any appli-
= mount and 30 x 8 mm spindle. High torque cation! A beautiful piece of craftsmanship - must normally sell for
with typical no load speeds of 2400 rpm @ around £50!
24v and 1200 rpm @ 12v. Continuously
rated, even under stalled condition. Complete
MM-6 £6.95 each (A)
with flange mounting plate. RFE.
MM-S £10.95 each 3/E29.95 to
6 to 12v dc motor with integral gearbox very high _^..torque. Runs down to 2 vdc. Revs range from
60 to 240 rpm from 2 to 12 v dc. 4.5 x3.5cm with 15x3 mm drive shaft. IDEAL MODELS ETC.
A nice little general purpose motor running at 3750 RPM at 12 vdc with very high torque. It has lower revs at 6vdc but we recommend this motor for 12 volt applications. The motor is reversible with the same strong torque. Measures 1-1/4" diameter by 1" deep.
The shaft is 1/16" diameter by Vz" long.
MM-4 £6.55 each (A)
MM-7 £3.95 or 3/£10 (A)
0181-679-4414
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Fax: 0181-679-1927
'Display 9\[ezvs Issue No. 13
High Reliability Printer Mechanisms
Star model DP824-12-F miniature high speed matrix printer mechanisms for normal paper. Brand new and boxed. Uses standard ribbons, friction feed paper and 7 pin head. Full 40 character per line width on normal 114mm (4") paper. Fast ten lines per second paper feed and «- one line per second print speed. Requires 12 vdc and driver electronics. Built for high reliability applications and sold at a fraction of its normal price.
Only £49.95 each (B) 3/£139 (C)
Credit Card Swipe Reader System
Now's your chance to see what is actually on your credit card !! ICL 136720/01 compact stand alone card reader features all internal
electronics to output a decoded TIL level serial data stream containing all the data recorded on track 2 which is the industry standard
track for data on credit cards etc. To complement this unit our engineers have written a BASIC program
to run on a standard PC - when coupled to the reader via the serial port, each time a card is
'swiped' the number is displayed on the screen in ASCII and HEX. Hundreds of other appli-
% cations include security, entry control systems, Point of Sale data capture etc. Supplied test-
fiCLl
ed, in as new condition, complete with Full Data sheet & Basic program,
i Requires +5 & +- 12v DC.
f
Limited Quantity - Only £49.95 (B)
Star DP8340 40 Column Point of Sale Slip Receipt Printer
Star stand alone printer type DP8340 RM. Manufactured for use as a receipt label or ticket printer for a host of applications. Totally enclosed unit with standard RS232 serial interface with selectable baud rates from 150 to 9600. Printer excepts plain paper rolls fed from the rear from its own roll holder. Internal micro processor electronics control the 9 needle head to give an exceptionally high throughput of approx 2 lines per second. Many other features, to numerous to list here are fully covered in the 50 page manual. A few of this printers outstanding points are: 40 column printing, block graphics, two colour ribbon, software controlled peripheral output to drive cash draw, paper cutter, software handshake, etc. An exceptionally well built device which will provide long term service and reliability. Requires 12 V DC power at approx 2 amps. Supplied BRAND NEW with full manual. Manufacturers current price is over £200. Our price only
Only £145.00 (b)
ibiWMO zzz LJ D
Multicore Cable Bargain
BICC type H6900 cable assembly- one end terminated with a 15 way 'D' type plug, the other with a 15 way 'D' socket. Each connector is moulded on in heavy duty plastic and there are 9 pins connected. Remove these connectors if not required and you are left with a profusely screened multicore cable in a bright blue outer colour. Cable length is 6.5 mtrs long and with overall outer diameter off 11 mm. The inner is composed of 4 twisted pairs of individually coloured 7/0.2 mm cables. Each pair is individually screened with an aluminium foil wrap and all 4 pairs are overall screened by a heavy woven tin copper braid. A separate 7/02 mm bare screen or drain wire runs up the centre core. Ideal for all low voltage applications where extremely good screening, quality and durability is required.
Only £5.95 (A) 10/ £48.00 (ai)
BACK IN STOCK AGAIN!! Isolated BNC Connector Boards
This is a front panel for a distribution board and contains 34 high quality female BNC connectors. They are chassis isolated, that is to say the outer shell is insulated from the mounting hardware and chassis. Panel measures ISVfe" x 2". You won't buy them anywhere else at under 20p each! As a matter of fact they are normally £1.57 each!
Only £7.95 each w
wmm ii»
15 Amp Solid Brass Switch Sockets
Top quality product from one of
Britain's best electrical accessory mak-
ers, MK Ltd. Rated at 15 Amps 240 V
#
to accept the heavy duty round pin 15
amp un-fused type plug. Solid brass brushed
front panel with white switch and trim - must
cost a fortune !! Order as MK15.
13 amp Qaa//fy Switch Sockets
Stainless steel front plate, High Grade 13 amp switch socket. UK made by Dorman and Smith for the MOD, so best quality. Removable front plate therefore ideal for flush or surface mount with additional backbox.
inly £3.50 (A) 5/£15.00 m
Only £2.25 /At R/QQ OR
0181-679-4414
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Fax: 0181-679-1927
'Display tyzvs Issue No. 13
BT Approved Push Button Phones By Philips
BT approved push button telephone - an improved version of the standard BT "Statesman" with "Recall" button. Two tone brown colour with a matte stout plastic finish rather than the shiny lighter weight plastic of the "Statesman". Built to a high specification by Philips. Complete with a standard telephone plug on a long 3 metre cord ready to plug into your wall socket. Tested good used condition 90 day guarantee.
Order as PHDP for pulse dial
or PHMF for tone dial.
Only £12.95 each (A) 5/E59 (B) 10/£99 (C)
Quality Aerosol Electrical Products
AE-1 Freezer. A rapidly cooling chemical, ideal for locating those
frustrating intermittent components and testing thermo sensitive
devices. Nett weight 228 grams.
£1.35 (A)
AE-2 Switch cleaning lubricant. A special formulation for cleaning
contacts and commutators and leaving a thin film of oil to reduce
contact wear. Nett weight 226 grams.
£0.99 (A)
AE-3 Solvent degreaser. A fast and efficient solvent for general pur-
pose cleaning including PC boards, tape heads, relays and most plastics and paint surfaces.
£0.99 (A)
^ - .< -T
AE-4 This is The famous Ambersil anti-static foaming cleanser, versa-
tile deep cleaning formula for virtually all electronic equipment, plastics
and cabinets. Removes grime and grease as you have never seen before !!
£2.50 (A)
DIN Rail Components An international standard defines a metal strip (honest it's true), called a 'DIN' rail. This metal strip is normally bolted onto a chassis or into an enclosed box. On this strip can be mounted (usually clipped ) a virtual host of electronic / electrical devices and connectors. The whole concept is to provide a logical, quick and easy method to build / modify or service control panels and electronic systems We have some large quantitys of these devices as follows:
Klippon SAK 16/35 terminal connector rated at up to 600v at 35 amps, upto 16mm2 cable entry.
Klippon SAK S3/32 in line cartridge fuse holder with clamping lugs. Rated upto 440v at 15 amps.
Only £6.50 for 10 (ad
Pi
Only £12.50 for 10 (ai)
Quality Handtools for Electronics
SC-1 High quality US made diagonal side cutters by Hunter for electronic applications made of extra high quality semi-polished steel. 3/4" blade length with 3-1/2" insulated handles Maximum jaw width at tips is 3/4". SC-2 Exactly the same as the above but miniature, 5/16" blade length with 2-1/2" insulated handles Maximum jaw width at tips is 5/8". The nose is more tapered than SC-1. SD-1 US made quality slot head screwdriver from Challenger. High qrade chrome plated steel round blade with flared tip. Yellow plastic grooved handle 3/4" diameter for a"solid grip. The blade is 3-1/2" long. CT-1 Heavy duty precision hand tool for crimping 50 and 75 ohm connectors to RG-58/U, RG-59/U and RG-62/U coaxial cables. Manufactured from high grade steel with one movable and one fixed jaw plus ratchet release for ease of use. Normal distributor price for this precision tool is £60!
£7.95 each (A) £9.95 each (A) £1.00 each (A)
£29.95 each (A)
Air Valves & Switches Two different types of air flow valves from Martonair, types S/666 and S/560. The first, shown in the left hand photograph, is a low profile push button switch type with a firm spring return. There are three apertures, an inlet port, a cylinder port and an exhaust port. At the rest position the inlet port is sealed and the cylinder port is connected to the exhaust. When the button is pressed, and for as long as it remains pressed the inlet port is connected to the cylinder port, sealing the exhaust. In electrical terms it is a normally closed momentary operation single changeover switch. The valve body measures 2"H x 1-1/4"W x 3/4"T. The panel hole required is 1-1/8". Type S/560 (right hand photograph) also has three ports as described above but the changeover is controlled by air pressure at two pilot ports, one at each end of the valve. A momentary air pressure at one pilot port whilst the other is evacuated changes the valve over where it stays until a momentary pressure is applied at the other, whilst the first is evacuated. A single changeover toggle switch. The air supply pressure rating for both switches is 10-100 psi and all ports are 1/8 " B.S.P. Air pressure on the pilot ports of S/560 is 30 psi minimum to ensure changeover and it measures 2-1/2" long by 1-1/4" square. These valves are brand new and packaged in the manufacturers original boxes and S/560 is supplied complete with mounting bracket and screws. S/666 is panel mounted and is supplied with shrouding and mounting nuts.
S/666; £8.95 each or 3 for £24.95 w
S/560: £17.95 each or 3 for £49.95 ·
0181-679-4414
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Fax: 0181-679-1927
'Display tyzvs Issue No. 13
pan®
For
^ppiicatio";
Axial Cooling Fans Please specify 110 or 240fva for AC fans
Size
Model
Description
60 mm 80 mm 80 mm 80 mm 80 mm 92 mm 93 mm 120 mm 120 mm 120 mm 120mm
60 mm 80 mm 120 mm 120 mm 120 mm
MMF06D12
AT300 126LF/8850 MMF08C12 8978 MMF09B12 99 XU 2984 WR341 Var.
AT500 812/814 8312 FB-12C12H CUDC24K4 4124X
DC 12V 0.84 watts. 25mm thick. Mitsubishi AC 38 mm thick AC38 mm thick DC 12V Mitsubishi 2.04 watts. 25mm thick AC 240v Papst Slimline 25 mm thick. Low noise DC 12V Mitsubishi 2.64 watts. 25mm thick AC ETRI Slimline - only 25 mm thick AC dual voltage 110/240v. 38 mm thick AC 38 mm thick As above RFE and fully tested 115 volts AC. 38 mm thick DC Slimline 25 mm thick. Order no.812 for 6/12v or 814 for 24v DC Slimline 30 mm thick. Papst 6-15 vdc. 1.8 watts DC 12v 12 watts. 38 mm thick. High throughput DC 24v 8 watts. 25 mm thick DC 28v 5.5 watts. 38 mm thick
Brand new Mitsubishi 60 X 25 mm Fan Scoop Attention all manufacturers using 60mm 12 volt DC fans! We have a HUGE quantity of these brand new fans, Model MMF06D12. Specifications : 12v DC, 0.84 watts input. 11.6 CFM at 24dB(A). Measures 60mm square by 25mm. Buy now before they all go!
Large Quantity Available - Call for pricing
Price £6.95 £8.50 £ 8.50 £8.95 £ 9.95 £5.95 £ 9.95 £10.95 £ 9.95 £4.95 £9.95 £15.95 £12.95 £12.50 £14.50 £10.95
MM
Only £4.95 each w 3/£13 w 10/£42 (Q 100/£400 (E) 1000+/CALL
Special Offer
A beautiful little ultra slimline from Densitron model DPF92B012 high performance 12 vdc 3.12 watt axial fan. It uses an electronically commutat'ed brushless motor to give long life, very low noise and extra high efficiency operation. Measures only 92 mm square by an incredible 18 mm thin!
An incredible buy at only
£8.95 w
2 for £16 (B) 10 for £75 (c) 100 for £590 (Q)
Exactly the same physically as the above Densitron ultra slimline but Model DPF92B230FS for 230/240 vac mains voltage at 8 watts.
Only £9.25 each w 2/£18 w 10/£85 (c) 100 for £620 (n
5 VDC 3 Watt Papst Fans Super fans for all applications where only a 5 volt rail is available - not necessary to have a separate fan power supply! Papst System model 8105 G. Measures only 80 mm square by 38 mm thick. RFE in almost new tested condition - only
£9.95 each w 2/£18.00 (B) 10/£85 (C)
6 inch Round Fans For High Air Flow Papst type 7450 230 volt AC round fan for extra high air flow. Has high size/air flow ratio with 5 large fan blades. 6" diameter (6-3/8" mounting hole to mounting hole) by 2-1/8" thick.
£12.95 each (B) or 3/£33.00 (c)
Fan guard grilles for standard 4,/2" fans. 4,/2" between mounting holes horizontally and vertically, 5 13/16" diagonal. Made of hardened plastic in black matte. £1.25 each or 10 for £9.95 (A)
*Ef 0181-679-4414
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Fax: 0181-679-1927
'Display tyzvs Issue No. 13
Mains Voltage Shaded Pole Motor Fan
Gould type JB-3AR, this fan has all the advantages of being driven by a 220/240 vac shaded pole motor rf and tv
Interference free. The fan blade diameter is 3" and overall depth is 2-V2". Height is 3V2". Connection is by two fly- I M
ing leads terminated in push on connectors. A nice brand new exceptionally quiet efficient fan for all mains appli-
cations, at a give away price!
m
-
£4.95 each w or 3 for £12.95 m
Similar to the above with five unenclosed 4" diameter blades. Attachment is by way of 4 stout chromium plated spider legs The mounting holes are at the corners of a 4" square. Rated at 230 vac 14 watts. Made by Howard Industries model number 3-90 8449.
£6.95 each wor 3 for £19.95 (B)
Brushless 12 vdc Miniature Fan Buhler brushless fan model MF-55. These miniature fans are designed for optimum air flow and aerodynamic rating together with a small size coupled with very low electrical and magnetic interference, which is achieved by a match box size controller supplied with the fan. The pack is nominally 12 vdc input. The operational range is 8 to 16 vdc with a pro-rata fan speed. The rotation direction is reversible with reduced performance ratings. The MF-55 measures only 2-1/2" square and has nine blades. The power pack measures 2" x 1-V2" x '/a".
£4.95 each w 5 for £19.95 (B)
BEg» mi w
Superb Sub-Miniature Fans
Sanyo Pico Ace 25 Model 109PO6125S402 - a beautiful little sub-miniature fan with an amazing volume of air flow. Runs on 12 volts DC @ 0.21 amps. Measures only 2-3/8" square and 1" thick.
NEW COMPACT
SIDE BLOWER
LARGE QTY AVAILABLE
£7.95 each w or 3/£22.00 (B) Would you believe it - only 1 Va" square yet with seven blades and it moves that air! Made by Omron for Epson type D0412. Rated at 12 vDC at 150 ma. Mounting holes are 11A" apart square and it is only 3/4" thick. Ideal for all miniature work, model making, trains etc.
£8.95 each (A) or 3/E25.00 (B)
DSG 390
TORIN 4" x 1.5" Side Blower Just the job for those compact units that require a good blast of air. Torin type DSG380 features a very compact unit - the air intake to the blower is on the large flat side with the output ( see arrow) on the thin side. The air output aperture measures 30 x 64 mm and can be left as supplied or coupled to hosing etc. Quality made in ABS plastic on a cast alloy chassis. Three hole fixing with flying lead connections 240 v AC 20 watts. Overall dim 125 mm square x 40 mm thick.
Only £12.95 m or 3/£33.00 (B)
High Density Snail Blowers
Four inch diameter blower powered by a high quality 220 volts AC motor by Fasco Industries (Torin) type U62 B1, complete with integral starter capacitor. Draws 0.36/0.44 amps. RPM 2770/3350. 1/20 HP class B. Features thermal protection and sealed ball bearing. Brand new surplus made for IBM. Perfect for applications requiring the high speed movement of air, particularly for cooling medium to larger items of equipment. Overall measurements; 11 "L x 5"D x 5"H. Outlet duct: S'/a" x 2". Motor shaft; approximately 3" long and 5/16" diameter. At these prices they are worth buying for the motor alone' Order as BLOW 1
£22.95 (D) 3 for £66.00 (E)
This is similar to the above but the motor has its shaft extended from both ends and it drives two blow-
ers. 220/240 volts AC at 0,6 amps. RPM 2825/3350, 1/20 HP. Thermally protected Requires a 4 mfd capacitor. Model number JF1E007N. Measures 16"L x 5"D x 5"H. Outlet ducts: 4" x 2,/2" each.
Ideal for applications where the ratio of air movement to power consumed needs to be verv hioh
Order as BLOW 2
' a'
£24.95 el 2 for £48.00 (E)
This is an extra high capacity snail blower by McLean Engineering 7162-1254 Type U62, for 220 volts AC at ^ quaB lity baallsbeianrtienggralcostnasrttrinugctcioanpacaintdor istoisyoruatceadn fjourstcpolungtininuoanuds gdou.tyIt. aRlsPoMfeaistu2re8s5t0h/e3r4m0a0l. pCroSteActiaonnd Underwriters Laboratories approved - of course. A really nice blower capable of movinq an enormous amount of air for those critical jobs. Order as BLOW 3
0181-679-4414
Only £29.95 each () 2 for £55.00 (E)
39
Fax: 0181-679-1927
'Display 9(ews Issue No. 13
i
li
as
The world of electronics has many
facets. Components, in particular,
have been used for many things
other than their intended function.
Jewellery made from IC silicon
wafers, discrete parts made into
intricate sculptures and now core
memory panels for you to frame!
A long (!) time ago, core memory
came not in the form of silicon
chips but in panels containing miles
of copper wire almost as fine as
i
human hair. This wire was weaved m into a criss-cross pattern forming a
Magnification of one "square" in photo opposite.
matrix of horizontal and vertical wires. Where each wire crosses another, they pass through a tiny
ferrite ring, so small that a microscope is needed to see it. It is, or
rather was, the charge existing at this point which was either "on"
or "off" constituted one bit (not byte!) of memory. The combination
of the colour of the woven wire and beads, plus the fact that gold
plated connectors are used makes for a beautiful piece of memo-
rabilia from the early days of computers, which if framed, will form
a talking point at many a party! Originally four are concertinad
together to give about 256K. We have separated the individual pan-
els which measure 19" x 14" each.
One panel £19.95 (B)
Four (still connected) £59.95 (C)
Digital Thermometer and Clock
SS
Here's a prime piece of surplus to take advantage of! A brand new and packaged indoor/outdoor digital Thermoctock - a thermorneter and clock combined which may
be used inside or outside, complete with a self-adhesive water resistant thermoprobe
THIRflldcflRE
for outside use, on a 3 metre lead. The Thermoclock may be switched for either func-
tion and whilst in one mode a button may be depressed to display the other. In other
words whilst functioning as a clock, pressing the button will give a temperature reading. Inside and outside use
is also switch selectable. When inside is chosen an internal thermosensor is used and the external probe is
ignored. Features a jumbo sized liquid crystal display (3/4" high) for high legibility even at a distance. A
12 hour clock is displayedl complete with AM/PM readout. An extremely wide temperature range of -50EC (-58EF) to +70EC (+158EF) is available. The Thermoclock is powered by a standard
l_R44 (or equivalent) button cell which is easily replaced in a slide compartment. Measures only 3!4"L x 21/4"H x 5/8"T and comes complete with a foldaway back stand for desk use. Ideal for
Water Resistant
household, car, office, greenhouse and almost everywhere else!
Outside
Only £11.95 each (A)
SURPLUS WANTED
TOP CASH WAITING! Display Electronics has a constant requirement for quantities of surplus / obsolete and redundant stocks. All kinds of electronic / computer / test equipment / power supplies / components / connectors / semiconductors / IC's / printed circuit boards / radio equipment / motors / racks / relays etc. always wanted. We are able to give a fast quote on lists of items available, or by viewing 'that pile in the corner1. We are also happy to negotiate a 'Confidential Reward' for any information leading to a purchase. Distance or quantity no problem - Fax or call Dave Fisher or Gavin Mac for further information now!!
0181-679-4414
40
Fax: 0181-679-1927
(Disptay 0\[eiVS Issue No. 13
Miniature Portable Frequency Counters
v:-\ ***3lfSX
Brand new Kaise frequency counters models SK-6710 (frequencies to 250 Mhz) and SK-6720
(frequencies to 1 Ghz) which literally are pocket sized and are powered by either six AA bat-
teries (not supplied) or a mains adaptor. Either of the 9 vDC adaptors shown on page 18 of
·Display'Mews Issue No.11 would be fine. The readout on both models is by way of bright 7mm
mm i
red LED displays, the SK-6710 has 5 digits (99999) and the 6720 has 4'/2 (19999). Both have overflow indicators and an internal frequency standard of 3.2768 Mhz. The Gate Time
(the gate inputs the frequency to be measured and the standard frequency and outputs to
the counter) is front panel switchable between 0.01 sec and 1 sec. The front panel also
houses the range selector. They have a foldaway support as shown in the photograph and with it retracted measure 5"L x 4-3/8"W x 11/2"H. The sturdy case is of steel and brushed alu-
minium. Both are supplied with a shielded input lead with a BNC plug to fit the socket on
the counter at one end with two crocodile clips at the other.
Ranges Lo range 1Hz to 2MHz Hi range 1 Mhz to 250MHz
SK-< 5710
Gate Time Resolution
1 s
1 Hz
0.01s
100 Hz
1 s
100 Hz
0.01 s
10 KHz
Accuracy ± 50 ppm ± 1 count
Note: Input sensitivities vary slightly over the various ranges but lay between 30 mV rms and 50 mV rms for them all.
Ranges
1 M range 1Hz to 2MHz 100 M range
1 Mhz to 160MHz 1 GHz range lOOMhz to 1GHz
SK-67J20
Gate Time Resolution
1 s
1 Hz
0.01s
100 Hz
1 s
100 Hz
0.01 s
10 KHz
1 s
1 KHz
0.01 s
100 KHz
Accuracy ± 50 ppm ± 1 count
SK-6710-£89.95 (B) SK-6720 - £125.00 (B)
MS-DOS
MS-DOS version 4.01 on 31/2" 720K floppies
£9.95 (B)
MS-DOS version 4.01 on 5%" 360K floppies
MS-DOS version 5.0 on SVz" 720K floppies MS-DOS version 6.0 on 31/2" 1.44Mb floppies
£8.95 (B) £14.95 (B) £22.95 (B)
Notes: All of the above versions support large hard drive partitions - unlike 3.x and earlier. They also all include the important utilities which usually come with MS-DOS such as CHKDSK, SMARTDRV, FORMAT and so on. However MSDOS used by OEM's can differ in small respects as to content. For instance the 5Va" above includes GW-BASIC, the 3M" do not. If any of the OEM optional utilities are critical for you please call to check before ordering. All are brand new, sealed and un-registered, so presumably can be updated to new versions of MS-DOS when released.
IBM PC Card Mount
/ Blanking Plates
Often hard to find item. Plated pressed steel with two right angled tapped mounting holes which may be used for mounting a custom PCB or hardware to be secured by the card guide frame on all types of PC, AT or XT computers. May also be used as blanking plate to ensure correct operation of your computers cooling system when unused cards are removed, thus causing incorrect airflow and possible overheating. Don't be without them - Overheating can be VERY costly!
£1.25 each
or 6 for £5.00 w
19" 24 Port Network/Comms Distribution Panels
MiiStS rw li r-
27
T ~
iiailfci rar w fei ssr :
tim. W.WMJ
Professional USA made by ORTRONICS # OR-811044521 24 port 8 wire 'Quad' frame patch panel on 19" 2 U rack mount panel made for network or signal distribution patching, all 8 way RJ45 8 way sockets are pre wired to Krone strips on the rear of the panel for use of simple IDC connection techniques. Each krone strip has write on panels on for clear cable pair identification. Fully UL & CSA approved product. Typical current price of this unit is around £125. Surplus buying brings this to you BRAND NEW,
0181-679-4414
Only £85.00 (B) 41
Fax: 0181-679-1927
(Display 'Hews Issue No. 13
Computer
Controlled Laser
Video Disk Player
m
One of the most amazing surplus deals that we ever been able to offer
our customers! The Philips VP410 LaserVision player, in a used/tested
condition, which plays disks which are, in effect, 12" CD's. The VP410 may
be operated and controlled in two different ways. Firstly by an infra red remote control, obtain-
able from Philips part number either VP131 or VP410 and secondly by computer via a standard RS-232 port. It will play enter-
tainment disks with startling visual and audio quality in two channel stereo or mono, or when controlled by a computer, it may also be
used as a versatile high quality storage/retrieval medium. It will play back either LaserVision CAV (active play) or CLV (Long Play) discs
(which covers all commercially available video discs). With the former, special LongVision effects may be used, such as still, slow-
motion, reverse play, fast forward, fast reverse and goto picture or chapter number. The disk has a maximum capacity of 54,000 pic-
tures per side (approximately 36 minutes of play at 25 pictures per second). The CLV disc offers continuous forward play only but with
time and chapter search, plus the added advantage of increased playing time of 1 hour per side. Here is a brief list of the major fea-
tures of this incredible machine:
·
RGB output/PAL-RGB decoder: Employs a specially designed PAL-RGB decoder for incredible picture quality - even in non-
standard playing modes, such as still and slow-motion. A full 5 Mhz video bandwidth is supplied in all playing modes making high res-
olution pictures such as maps and small text crystal clear.
·
Sync Pulse Generator: An internal sync pulse generator is employed so that freshly generated line and field sync pulses
are available at the player's output at all times for a rock steady and shimmer free picture.
·
Genlock: A feature which enables the field and line sync pulses from the player output to be synchronised with an external
reference signal. It ensures correct overlay of video signals.
·
CVBS output/RGB-PAL encoder: The VP410 contains an RGB-PAL encoder. This takes the RGB output from the player
and encodes it into a CVBS signal, using fresh sync pulses from the internal generator described above. The signal at the CVBS out-
put is therefore totally stable.
·
Electronic Timebase Corrector: A charge coupled device timebase corrector is employed to provide timing correction. This
replaces the more usual mechanical methods providing a far superior optical system.
·
Instant Jump: The radial mirror which points the laser beam at the correct track to be read is so manipulated that a search
for a required picture can be virtually instantaneous. Very useful when one picture "connects" with another - rather like the pages of
the A - Z map!
·
Fast Random Access: Special circuitry results in phenomenal access times, that is to find any particular point on the disc.
Typical times to search an entire disc are 1 second for CAV discs and 5 seconds for CLV.
·
Wired Remote Control: If an infra red remote is being used, it may be that the player is located out of the necessary line of
site and a control computer is not available. For such circumstances provision is made to hard wire the remote to the player.
The VP410 will drive either RGB or CVBS monitors. Output for RGB is via a Scart socket (which also outputs an additional CVBS sig-
nal), CVBS is via a BNC. BNC's are also used for other signals such as syncs; audio in and out is via phono sockets and the RS-232 via a standard 25 way D female socket. Baud rates for the RS-232 are set at 1200, 2400, 4800 or 9600 by way of a DIP switch on the back panel. One of the most attractive features of the VP410 is the ease with which it is computer controlled. Virtually any language may be used to write a short control programme, it lends itself particularly to friendly interface high level languages such as Quick Basic, Visual Basic and so on. Communication is by way of an integral "instruction set" called F code. F code commands when received from the computer produce a reaction similar to the receipt of an infra red signal from the remote control. All the software has to do therefore is to
send an F code down the RS-232. If a user friendly environment is not needed then a program would not be required. Any software
that is capable of sending user definable code and receive acknowledgments back would do. There are ab,out 40 commands in the F code set, the decimal, character and hex values of each are listed in the data supplied, together with a full description. Outstanding clarity and quality of both picture and sound plus choice of either computer or remote control (neither supplied!) adds up
to one of the best deals we have ever been able to bring you. We don't anticipate being able to get another buy like this one so we seriously recommend that you buy as quickly as possible if you are interested.
Only £399.00 (F)
AMPEX W'Audio Mastering Tape
AtVlPESX
Still one of the best and un-complicated mediums on which to record high quality audio , try and edit sound cuts on a cassette ! AMPEX Pro Grade type 407 mastering tape polyester based, the best of the cream as used by many studios and discerning audiophiles. You don't have to be one of them to use this tape - only the difference is, that they are probably paying twice the price than you can buy here!! Complete with library case.
7" Spool, 1800' Only £4.75 (A) or 5 / £21 (B)
0181-679-4414
42
Fax: 0181-679-1927
'Display 9{ezvs Issue No. 13
Modems
With oil modems - ProComm communications soFtiuore. Very
extensive doc on the disk!
A deluxe top of the line modem from Acer Model 2424, V22 1200/2400 baud asynchronous full duplex. Stand alone external, total-
ly Hayes compatible and complete with internal speaker. Front panel switches for selecting: Talk/Data, Originate Answer,
1200/2400 and Normal/Test. Features MNP Level 4 error control. Front panel LED indicators (see below):
EF HS AA CD OH, RD, SD, TR and MR. Auto answer and auto dial facilities. The back panel contains
a configuration switch, an RS-232 25 way female connector to link to the serial port of the host computer, J
RJ11C female jack to go to the line and the same for your phone should you wish to run your telephone
through the modem, rather than use a "Y" connector on the wall jack. A cable is supplied for connecting
the modem to the line wall jack. Unlike some (very annoying) modems, a power switch is also locat- m
ed on the back panel. Very attractive styled metal case in light beige, to match the standard PC
colouring. , with ribbed decor and offset front
m*s. nr-
panel. Measures 10"L x 6%"W x 1%"H. Brand
Olll V £49.95 (B)
new and boxed.
*
V32 MNP5 9600 Baud Multimode 'WorldPort' Modems
I 9600B»!n
% IWSSWi 1H:,,¥! iiiiii
Technology strikes again!! Made by US ROBOTICS leaders in modem technology, this very handy, pocket size portable modem will communicate with virtually all types of data networks and Bulletin Boards including: Internet, Compuserve and most others currently in existence today. The size of this unit for an external modem has to be seen to believed ! Hardly bigger than a pack of cigarettes and when operated on it's own internal 9v battery truly portable. The unit will function at all data rates from 300 to 9600 baud with full error correction to level MNP 5. Fully Hayes compatible with 4 status LEDS and a 25 way 'D' socket for connection to any standard PC serial port. Supplied complete with utility cable to match PCs or laptop computers with either 9 or 25 way serial communication sockets, phone patch cable for standard BT type socket, 240v AC mains adaptor and operating guide. Dimensions mm, only 117 L x 26 H x 70
W. Brand New but as OEM packed (and at our price) supplied without manufacturers original box. Limited quantity available. Battery not included.
APPROVED
Only £79.00 (bj
PS/2 Internal Modem Made by ACER and fully Hayes compatible internal modem is designed for use with the IBM PC type PS2 bus. Usable up to data rates of 2400 baud V22 Bis. Ideal for all communications to bulletin boards and network services. Supplied with connection cable and a free copy of Procom. Brand New
Only £39.00
V22 1200 Baud BT Approved Modems
Ever popular Master Systems 2/12 microprocessor controlled V22 full duplex 1200 baud modem. Fully BT approved unit, provides standard V22 high speed data comm, which at 120 cps, can save your phone bill and connect time by a staggering 75%! Ultra slim 45 mm high. Full featured with LED status indicators and remote error diagnostics. Sync or Async use; speech or data switching; built in 240v mains supply and 2 wire connection to BT. Units are in used but good condition. Fully tested prior to dispatch, with data and a full 90 day guarantee. What more can you ask for - and at this price!!
Only £49.00 (C)
r»D »V» 9 <9 VV" * ***
wit xi em e*»* etl
Racal-Milgo "OMNIMODE" 96 Pro High Speed Modem
Industrial specification modem designed for synchronous data use at speeds of up to 9600 baud (CCITT V29) over a dedicated 4 wire leased line circuit. Fully compatible with MPS9601 & MPS9629 modems and protocols. Many features (to many to mention here !!) are included in the 90 page manual, eg: soft strapping, continuous duty, full local and remote test, non volatile set up storage etc. etc. Original cost over £700 each. Supplied BRAND NEW and boxed.
BRAND NEW SURPLUS Only £169.00 (C)
iwiMM
0181-679-4414
43
Fax: 0181-679-1927
'Display 'Mews Issue No. 13
Ball Point Pen Printer/Plotters
This is a full 40 character per line ball point pen printer plotter using standard 114mm wide i8 paper. If is a high quality mechanism from Alps/ DED Ltd and comes complete with an 8
page data pack which includes the circuit diagrams for the simple electronics used to drive
the stepper motors and pen control solenoid. It has two stepper motors to accurately control
both paper and pen movement in either forward or backward directions enabling graphics and
plotting to a resolution of 1/5th of a millimetre! Text printing is achieved by the mechanism low-
ering and raising the pen onto the paper then drawing lines in 0.2mm steps, giving extremely leg-
ible characters. Again this is carried out by the two stepper motors. Condensed characters can be print- vl-- '
ed at twice the number of characters per line giving 80 characters per line on paper only 4-1/2" wide!.
Scaled enlarged characters are printed in a similar way. An additional feature of this model is that an integral sensor detects when
the pen is at the carriage return position and closes a normally open switch, the contacts of which are available for external use. Typical
print speed is 12 characters per second and plotting speed is 52mm per second in both
AS RECOMMENDED IN
j horizontal and vertical mode. Along a 45 degree vector the speed is 73 mm per second. Paper feed is approximately 6 lines per second. A single +5v DC is used for power, using
EVERYDAY ELECTRONICS under '/a amp.
FOR THEIR SEISMOGRAPH PROJECT!
£49 each (M) or 3 for £120 (B) Pens: Box of 4 for £5.50 w
Hi-Gain Indoor TV Aerials Brand new and boxed indoor TV aerials for both colour and black and white receivers covering all UHF TV channels. British made by Mercury Telecraft - model ST02 - with many de-luxe features. The aerial may be adjusted for either horizontal (as shown) or vertical orientation. A wide loop dipole is used for extra gain and a double alloy reflector for anti-ghosting. Extremely light in weight, which is useful if used with a portable or hand held receiver, yet of sturdy construction with a one and a half metre co-axial cable terminated in a normal TV aerial plug. Overall measurements are 13"L x 11 "W x 8"H.
Only £4.99 each 3/£14.50 (B)
Zero Insertion Force Sockets
Zero insertion force sockets from Texttool. Socket action is controlled by a lever: when open the IC or other device may be dropped into the socket, when the lever is flipped the leads are firmly gripped. Z-28 is a 28 pin IC socket and has pretinned leads. Z-32 is for 32 pin in line boards or devices with .1" spacing. Ideal for speed testing or wherever permanent contact is not required.
mmmn
Either type: £5.95 each or 5 for £27 (A)
iiVfOff V
Latching Push Switch Banks
rIiiiv<>V.osfhe.)i »·i>.mjm. y\Ti T^«
rr5 These are two types of latching push button banks. The first {SWB-1) contains 7 DPDT switches, one of which is a dummy, to release the others. All are mounted on a PC board as shown. At the back of the board is a 12 way terminal block and on the side is a 2 way block. The
switches are wired so that one terminal of the side block is routed to any one terminal on the
back when the switch controlling that terminal is pressed. At rest, there is a similar arrangement
but the routing is through a capacitor, which can be shorted out if required. The mounting of the
switches on the board provides a very versatile and adaptable arrangement as 3 other termi-
nals are provided in addition to the blocks, so almost any arrangement can be used. The sec-
ond bank (SWB-2) is not on a PC board and is a simple bank of 4 DPDT switches. Both types have black plastic push buttons, the
first round, the second square.
SWB-1: 2/E2.50 (A) 5/£5 10/E9 (B)
Handy Portable Vacuum Cleaner
This is an extremely useful portable 220 vac vacuum cleaner for service engineers, jobs around the house, car, garden and even the computer! Quality made by / for IBM, and supplied to their service engineers for cleaning laser printers and photostat machines - so it has to be good qual-
ity. It has a beefy 175 watt motor which gives very strong suction and has a re-usable and washajble!filter. Uses a standard 1" diameter hose (not supplied). Measures 11" long by 5" diameter at its widest part Comes complete with a generous 3 metre long two core (UK coloured) mains cable.
Only £19.95 each (B) or 3 for £58 (D)
0181-679-4414
44
Fax: 0181-679-1927
Display C\(ezvs Issue No. 13
Perspex Sheets Two useful sheets of Perspex. PS-1 measures 12"L x 4-3/4"W x 1/8"T, has square corners and is very slightly black tinted. Two of the corners of PS-2 are rounded and the other two have small indents and drilled holes, obviously to fit hinge pins. There is a larger hole (probably a fingerhole) drilled towards the rounded corner side; the sheet was probably made as a hinged flapdoor for some equipment. PS-2 measures 9"L x 5""W X 1/4MT.
Either sheet: 2 for £1.50 (a) 10 for £6.00 (B)
Low Profile High Dissipation Black Anodised Heat Sinks BLANK Super low profile black anodised heat sinks with a lot of dissipation yet only 1/2" high! They are undrilled so that you can make it fit your own particular application. The high dissipation rate comes from the large number of fins, 14 in all with 7 on each side. The blank area is 6" x 1-1/2" on which to mount any i case size of semiconductor. Overall measurements are 6"L x 3-5/8"W x 1/2"H, Order as BHS-1.
£3.95 (A)each or 3 for £10.95 (B)
Space limitations this issue of Display News prevented us from printing our 2 page listing of power supplies, We have over 10,000 power supplies of all types ex stock - call our sales line for more information or a full list.
Low Profile Heatsink Very nice brand new blank heat sinks. The unique design provides double fins and also a large area of flush contact with the mounting base. RS Components Ltd stock number 401-497. Measures 4"L x 2-1/2"W x 1/2"H. Blank mounting area is 4" x 1-1/4".
£1.49 each (A) 5/6.95 (A) 10/£13 (B)
TO-220 High Dissipation Heat Sinks
Extruded black anodised sinks for TO220 or similar cases. May be mounted horizontal-
ly by the devices mounting screw or vertically with self tapping screws (not supplied) as
shown. This is an excellent quality sink from Redpoint. Dims; 2-3/8"L x 1-1/4"W x
^
5/8"H. Order HS-22200--11.TThhe same as the above but without self tapping screw hooiles. Order
HS-220-2.
75p each (A) or 3 for £1.99 (a) 50 for £26 (Ai)
NOT BEEN GETTING IT LATELY ?? Then maybe your address is not correct on our mailing list, if you have moved house, changed job etc. then don't forget to notify us
DON'T MISS THOSE BARGAINS
0181-679-4414
45
Fax: 0181-679-1927
'Dispfaij '\eu's Issue No. 13
The most efficient and easiest way to have an instant range of electronic components at your disposal for a fraction of their vds L normal costs - not even considering the inconvenience factor
of not having that crucial part - just when you want it!! The following boards contain an exceptionally good mix of all types of analogue and digital components, keep them handy and you will using them for years to come !!
Jumbo Parts Board
This is the entire brain of the 16 bit 8088 system from Future Computers. It measures a whopping 14 inches square! We have no data so it is sold as a parts board and is not guaranteed to operate
II
as a computer board or to be fully populated. It contains about 200 ICs. The logic is TTL-LS.
Included are eighteen 64K RAM chips,which are scarce nowadays! and a NEC D765A disk con-
troller and 7220 graphics IC plus normal support LSI packages. A ni-cad battery is provided for cal-
endar support and a nice low profile relay. Three crystals of 24, 25 and 8mhz are included plus
a buzzer. We believe that these boards are ex working equipment so if you can get it going its a
gift but anyway its a gift for the parts!
Only £9.95 each <6)3 for £25.50 (8)
Massive Discretes Board This is a video distribution board and consists of 32 individual circuits on the same board - yielding a massive parts count as follows: 96 off Tantalum bead capacitors 47mfd @ 16v. 32 each of: Bourns trimpot 100 W; transistor NPN 45v 200ma BC183; transistor PNP 45v 200ma BC213; transistor NPN 40v 500ma BSX20. Plus hundreds of resistors and capacitors, not listed. Note that the two complementary transistors may be matched pairs and should be removed from the board accordingly. There are also 32 hard to get plastic shrouded linking clips as used on disk drives and other equipment. The board measures 12" x 9".
Only £6.95 each (B) 3 for £19.95 (b)
General Purpose Parts Mix!
This one is a real mixture and includes close to 100 transistors some of which are complementary
pairs; Bourns trimpots, 18 ICs - all 74LS series, tantalum bead capacitors and hundreds of resistors.
The reverse side of the board to that shown, holds 5 edge connector sockets. The transistors are
BC183, BC213, BFY50 and BSX20's. The ICs include 6 off 74LS244 octal 3 state buffers. The board
measures 12" x 8-1/2".
<?:
£5.95 (A) 3 for £16.95 (B)
c" ">~ j:r W. W'Vi!
, :! ^ #f **
Super Opto-Coupler Parts Board
What a tremendous buy for those of you who want some very high isolation voltage opto-couplers! These boards hold 16 off OPI 110's which have an isolation voltage of 10,000 volts. Input is to a photo emitter diode, output from a phototransistor - all in the same case of course. Ratings for the output are maximum 30 volts and 40 ma. The diode's input ratings are 1.5 volts and 20 ma. Rise time is 2 ms and overall package dissipation is 100 mw. In addition to the opto-couplers the board has 16 off 47 mfd @ 63 vdc electrolytics, 16 off BY206 diodes and various resistors.
iffint
£4.95 (B) per board
3/£13.00 (b)
Complete Monitor Board Made by Weir Electronics
Although we sell this board for the parts it contains, it is in fact a complete board from a 12" working monochrome monitor based around the well known TDA1170S and TDA1180 ICs, with a BUV48 as the line output transistor. Complete with video input stage and BNC connector, amplification and driver stages and line output with EHT tube connector. A CRT octal base socket is also provided on flying leads. The board tapers from front to back but the overall measurements are 8-1/2" x 8". We have no data - but it should not be hard for you to sort it out or strip for parts!
Only £7.95 each (ad 3 for £21.00 (bj
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Constructional Project
ijy> /trr f=-
EPE FRUIT
WIa
MACHINE /(
BRETTGOSSAGEandJULYAN/LETT - Part2
A coin operated fruit machine that really pays out!
Operating principles of fruit machines and the design approach adopted for the EPE Emit Machine
were discussed last month. Also, the full circuit description and construction of the circuit board were covered. This month we conclude with the mechanical construction, checking and operation.
MECHANICAL
CONSTRUCTION Building the coin detector and payout
mechanisms is not difficult, but should be carried out with reasonable accuracy to ensure reliable operation. Most of the parts are simple rectangles which can be cut from the plastic sheet using a Stanley knife or large modelling knife.
Score the plastic down to about half its depth, then simply snap the plastic apart by
bending. Be extremely careful as these knifes are very dangerous, NEVER cut towards your fingers. Don't use the knife to cut the pipe, use a junior hacksaw, and clean up with emery paper.
A number of circular holes have to be cut. For the small holes, a drill can be used. For the larger holes, start by drilling a 3mm to 4mm pilot hole, then use a reamer to take the hole out to a larger diameter, and finally, for best results, use a Q-max hole cutler.
This project needs only one hole cutter, size 20mm. but they are rather expensive. The 21mm holes can be punched initially to 20mm and then enlarged using fine emery paper, but care should be taken not to let the hole become eccentric.
The plastic parts should be glued together using "Plastic Weld" or a similar
solvent glue. This substance isn't really glue at all. it dissolves the plastic, welding it together. It was found best to apply plenty of glue using a fine paint brush then hold the parts together for several seconds until the plastic starts to re-set.
It takes much longer, however, for the plastic to set hard, hours rather than seconds. It may be a good idea to experiment with the glue and a few offcuts of plastic, in order to establish a good technique for making these welds. The author's first attempts resulted in some rather fragile joints!
All the plastic parts required are detailed in Fig. 5, Fig. 7 and Fig. 12. Check the details carefully as although most parts are made from 80 thou' white plastic sheet, there are a few exceptions.
Side and underside views of each of the mechanisms are shown in Fig. 6 and Fig. 8. The letters can be used to cross-reference the drawings with the parts in Fig. 5, Fig. 7 and Fig. 12, These figures should be used in conjunction with the photographs when fitting the various parts together.
The completed circuit board, minus the controller i.e. The link J1, used when "testing", is positioned just left of the Hold switch. Everyday with Practical Electronics, January 1995
t
m. <·5
COIN DETECTOR Glue together all parts of the coin detec-
tor mechanism, then glue the infra-red l.e.d. and phototransistor (TRW) into the small plastic pipe pieces. Unfortunately, these two devices look identical, although the l.e.d. may have much longer legs than the transistor. Check carefully the wiring from these devices to the 4-pin connector (SK4), details are given in Fig. 11. Solder wires to the legs of the devices and insulate with heatshrink sleeving.
PA YOUT
MECHA NISM Glue together all parts of the coin payout
mechanism. The specified Futaba servo motor comes with rubber mounting blocks which are first pressed into the holes on the servo chassis. M3 bolts should be used with suitable length spacers to mount the servo onto the payout mechanism base-plate.
I
The completed coin detector mechanism is giued behind the coin cutout slot in the top of the case. Ribbon cable is used to connect the infra-red l.e.d. and phototransistor back to the p. c. b. - see Fig. 11.
hmm 11^-
PthaotutswKhtiotePpclaustticfrosmhee8t0.
8 mm
poiPnluaasrtisstdtiieQdcedcpi(uaifpmtceaf.emrtoeemrte)r6w(3mhimtmem
0e .i
Fig. 5. Plastic parts for the coin detector mechanism.
The connecting link which connects the coin slide to the servo actuator arm 'requires special consideration. The actuator is initially supplied with four arms, three of which should be cut off as shown in Fig. 8. The arm should then be used to find the mid-position of the servo shaft's full range of travel.
Leaving the servo shaft in its mid-position, remove the arm from the shaft. Link the coin slide and the arm with the metal link and then press the arm onto the splines of the servo shaft so that it is perpendicular
%
to the direction of travel of the coin slide as shown in Fig. 8.
The coin slide should now be half way between its extremes of movement. This alignment is necessary to ensure the best possible range of travel of the coin slide. Finally, screw the arm firmly to the servo shaft using the screw provided.
TESTING Turning now to the p.c.b. and servo, ensure that the microcontroller chip (IC1) is NOT fitted. Connect just the battery pack
Fig. 6. Coin detector mechanism. The infra-red l.e.d. and phototransistor are glued in the small tubes either side of the coin slot.
to the p.c.b. (PL I), and link the two pins of PL2 (on/off switch connector). If possible use an oscilloscope to check for the servo control waveform on IC2b pin 9. (See a in Fig. 9). Fit the link J1 and the servo control waveform should change to that of h in Fig. 9.
There should also be an approximate 50Hz square wave signal at IC2a pin 5. If these signals are not present, disconnect the battery and check the polarity of the supplies and the connections.
The payout mechanism showing the coin collection tube and the servo motor plugged into the p.c.b. connector.
46
Underside of the servo mechanism base-plate showing the modified servo actuator arm and coin slide linkage.
Everyday with Practical Electronics, January 1995
The mechanical adjustment of the servo position needs to be quite accurate so that coins are dispensed correctly. With the coin mechanism disconnected from the rest of
the unit, and the servo link (paper clip) fitted to the coin slide of the payout mechanism, manually push the servo arm round to both end limits, and check for smooth movement of the slide.
Next, fill the coin tube as much as possible (by now you should have saved lots of 5p pieces!) and holding the mechanism approximately upright, rotate the servo arm
to and fro and see if the coins are easily dispensed.
Empty the coin tube and connect the battery and servo to the p.c.b. The servo should move to one end of the travel, the "payout" position. Adjust preset VR1 so that the hole cut-out in the slider has moved about one millimetre further than necessary to "payout" the coin.
Fit the link Jl. Now adjust preset VR2 so that the same condition occurs with the other fixed hole cut-out at the bottom of the coin stack tube. This is the "collect"
App«o« 2--mSH»|nIr*,-
nUr lC2b Pm 9
>PP'0» 20mS
n. -n
- Appron I,mSc-Jou
IC2b
Pm
9
11U (Lmk Jl
FittAe2dP0)Pn'0S*
n^tJ
·iJUUUlJUMIUllimiUlUlMJE luS ---- ICI Pin 27 (CUC)
F/ff. 9. Servo control waveforms.
15n
10 mm I ;03fT i
--0T0-- 3mm -0'03--mm
" 28 mm H 021mn^
4mmcu*t2o.u/5tmm
01 Smm
L
PthaorutswAhtioteFplcaustticfrosmhee8t0. PwahritteGpcluasttifcrosmhe6e0t thou Pmailrdt Hstemelad(beefnrotmpa1pmermdip) Poi(nouasvrtiestdireJdfledcoiuwdatimapfmreiopteemetr)e.rp2,l1am1s9tmimc mpipe
1 5 mm SO mm
i
U 21 mm -- Fig. 7. Plastic parts and servo link dimensions for the coin payout mechanism.
h-
J)
fr D, E
Fig. 8. Construction details of the coin payout mechanism. Everyday with Practical Electronics. January 1995
position. Preset VR1 must be adjusted first as it affects both end position adjustments.
Finally, place some coins in the mechanism and operate the servo by fitting and removing the link Jl with the battery connected. Disconnect the battery. Insert 1C1 and switch on, all three of the 7-segment displays should instantly light with the BAR or symbol (segment g), and, after a short delay, the eight yellow "Feature" l.e.d.s should sequence through a repeating flashing pattern. If this is not the case, check the CLK signal to ICI pin 27, and see that it matches c in Fig, 19, i.e. a clock signal of 1 MHz.
The first sign of battery failure is when the displays become dim, and the servo does not operate. This will not really be noticed until a win is achieved during "play."
CASE
CONSTRUCTION The basic cutouts required for the case of
the Fruit Machine are shown in Fig. 10. These are mostly made in the front of the
47
cutouts by occasionally fitting the completed p.c.b. into the box, by pushing the I.e.d.s through the holes (this should give a tight fit). Take your time doing this. Although a lot of mishaps may be covered up by the stick-on front panel, its nice to get an accurate finished result.
Note that all the dimensions given in Fig. 10 are in inches and tenths of an inch. This is purely because component sizes (notably the i.c.s) on the p.c.b. are based on imperial measurements, and it was easier to lay them out using these.
The five mounting screws (M3) for the
p.c.b. were glued to the inside "front" of the box on the prototype using an epoxy resin such as Araldite. This was to avoid having screwheads showing on the front, even though these would be covered by the stick-on front panel facia.
As the p.c.b. position is held quite firmly by the eight "Feature" I.e.d.s, the mounting screws can be first attached firmly to the p.c.b. with nuts either side, and then adjusted so that the p.c.b. height is correct in relation to the front of the box, allowing a 2mm to 3mm protrusion of the start and hold switches.
t
MB6 plastic box (the bottom of the box, not its lid), with the coin slot and on/off switch cutouts in the "top" of it.
Drilling small pilot holes around the rim first and then using a square file was found to be the most effective method of producing the square cutouts. Using a file which had a slight radius on each edge rhade it easier to get neat square cutouts with tiny rounded corners. One word of warning though - don't try this on the new carpet, as the flecks of filed plastic have tremendous static charge, and tend to stick to everything, including your clothes!
It may be advantageous to drill the holes for the eight "Feature" I.e.d.s first, and then monitor the progress of the other
*>
0 20mm /
1.2-
(apCptruhotixct.kon0ce.o0sms75-) 1.8-
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&
(S40eeH3mTolemexst)
mi -
PCS outline
View from FRONT of box
4.1*
Positioning of the p.c.b. guard and siting of the payout servo. Also shown are the coin sensor andpiezo sounder.
48
15-V Ftg 10. Case front cutout dimensions and drilling details. The dotted outline shows the position of the circuit board behind the "front" of the case. The coin slot and on/offswitch cutouts are made in the top - see above.
Everyday with Practical Electronics, January 1995
t . ·· * I.
o
SK5
Piezo
?OOnvn
Led (aoode) TM(c=., SK4
e* c Coin
S3
Servo
JKBLACK SK3
The p.c.b. connectors mounted on the track side.
Switch
j--i r J L Battery
SK2
140111^1 D± SKI
Fig. 11. Interwiring ribbon cable runs from the piezo sounder (top), coin detector, coin payout servo mechanism, on/off switch and battery holder (bottom) to the printed circuit board connector piugs.
K.
Jsm" [Si
HI5' Ppfrlaoarmsttsic8R0sthotehUeotu.cuwthite
PtshhaoerutetVb.lcacukt fprloamsti8c0
1mcmut«ou6tmm 7mmcu*to1u2tmm
\ Fig. 12. Plastic parts and dimensions for the coin chute/battery compartment and coin mechanism support.
FINAL ASSEMBLY
A guard for the back of the p.c.b. will be needed to protect it from damage or short circuits caused by coins dropping into the "money-box" portion of the machine (if
the coin stack overflows). This can be made out of cardboard or stiff paper.
First cut out a piece the size of the p.c.b. and then make cutouts for the holes, capacitors and connectors. Mount the p.c.b. in the empty case with the guard flush to it, not forgetting positioning of the red display filter. This can either be glued to the inside of the finished box, or glued to the p.c.b. assembly.
Now make up the five wiring assemblies
as shown in Fig 11. Glue the coin detector to the inside top of the box, in line with the cutout slot for the coin, and make sure that the "trailing" cable runs out of the way of any coins. The coin detector may be attached with two screws for easy removal, for instance, if there is a problem with the infra-red l.e.d. or opto-transistor.
Fit and connect the on/off switch, and the connector to the battery pack. Glue the piezo sounder to the upper middle right hand side of the box, and connect it to the uppermost connector on the p.c.b. (PL5).
Place, or glue the two square pieces of plastic "T" & "U" (See Fig. 12) as low as possible, into the bottom sides of the box, ensuring correct orientation (50mm high, 53mm deep). These hold up the coin mechanism at the sides. Glue the two runners "R" & "S" above the pieces just fitted, allowing a 2mm gap for the coin mechanism to slide in between them. Connect the servo to the p.c.b. and slide the completed coin mechanism into these slots.
Finally, push the black coin tray slide (V) into place at an approximate 45 de-
gree angle, into the space below the coin mechanism. When the lid is fitted to the box, the angle of this slide is fixed, and it also holds up the coin mechanism at its centre, giving the construction extra rigidity.
Fit the battery pack into the area at the base of the box with Velcro or double-sided sticky pads, and connect it to the battery clip. Cut a little slot into the right hand side
of the black coin slide, to accommodate the wires for the battery clip, so that the lid does not trap them when fitted.
Note that the coin mechanism can be easily removed for inspection at any time by removing the lid, then the tray slide, and then sliding the mechanism out.
Everyday with Practical Electronics, January 1995
49
MECHANICAL
CHECKS
The electronic part of the fruit machine operation should be fault free, however the mechanical parts do have their limitations.
The first and perhaps most obvious, is that this fruit machine can only be operated in an approximate upright position, purely due to the coin stacking and payout mechanism. It works well if hand held in a slightly tilted position away from the operator.
If the coins inserted in the slot do not pass the coin sensor within a specific time, then a credit will not be accepted, and the credit l.e.d. will not light. This is a software implemented "tamper" fail-safe, so don't try poking lolly sticks into the slot!
There is the possibility of over filling. As the machine has a estimated payout of about 80 per cent, there will be a net gain by the machine over a long period of playing. Eventually the coin stack will fill up (about 65 coins) and then it will overflow. Any more coins inserted will still be registered as credits, but they will fall into the enclosed space around the coin stack within the machine.
This is acceptable, as there are no moving parts to jam in this area. This is considered to be the "money box" area of the machine, as these coins can never be paid out by the mechanism. Eventually, this area will also fill up, and if the coin sensor continually fails to register credits, or is blocked, then remove the back panel of the machine, and clear out any excess coins.
During testing, the payout mechanism was found to be very reliable, but if coin jams occur in the coin mechanism, check the servo operation and try resetting the start and end points of the servo travel with presets VR1 and VR2 (see "Testing").
OPERATION The operation and features of this fruit
machine have been made to mimic commercial gaming machines as much as possible. and those of you that are familiar with the operation of these machines will already know a lot of the following, but read on anyway!
SWITCHING ON When the unit is first switched on, the
7-segment displays will all show the BAR symbol. (Something had to be picked, so why not the jackpot!) The eight yellow l.e.d.s in an arc above the main display are the "Feature" l.e.d.s, and they will flash in a set sequence repeatedly, luring you to put a coin in the slot. When you have done this, these l.e.d.s will go off (with the exception of the left hand l.e.d, showing one credit) and the green start l.e.d. should light.
CREDITS If you decide to be ambitious with your
investment and put in further coins, you can do this! The first eight credits will be registered by lighting up the arc of l.e.d.s above the main display from the left hand side to the right, except during a WIN sequence. Further coins can be inserted up to a total of 255 (£12,75), and the total will be stored in the microcontroller memory. Any further coins inserted will be "lost" credits.
After each "play" the credit count will be reduced by one. When the credit count falls below eight, the l.e.d.s above the main display will go out from the right to the left, warning you of the last few credits available.
OCL QO.
i i i i i i
Finally, after the last "play" has finished, have a hold, the three red l.e.d.s in the
the green start l.e.d will go off. the feature switches underneath the reels will flash. If
l.e.d.s will start sequencing, and pressing you wish to hold any reel (i.e. keep the
the start button with no credits w ill have no current "fruit" on the selected reel), press
effect! You can insert coins at any time, the appropriate hold button, and the l.e.d.
even when the machine is paying out.
will stay on continuously.
If you decide to change your mind, press-
START BUTTON
ing the hold button again will cancel the
Insert a coin and press the start button. hold, and the l.e.d. will flash again. After
Each of the three "reels" will cycle through you have decided on what hold you require,
a sequence of letters and symbols (six in press the start button and only those reels
all), which correspond to the "fruits". This that have not been held will change.
cycle will slow down and stop with each
Remember, you may have a hold after a
reel from the left to the right.
w in! In this case, if it is a w in where only the
WINNING AND
first two reels are the same, these two reels can be held to guarantee a two coin win. and
PAYOUT
possibly a higher win if the third reel is also
A WIN sequence starts with the "Fea- the same after the next "game". Holding all
ture" l.e.d.s flashing through a short pattern three reels is wasteful (unless after a winning
with the piezo sounding, and ends after combination) but this is a valid option.
paying out coins with the green start l.e.d
Another point to remember is that if you
coming on. (If you have remaining credits, have no credits left, you do not know if
that is.) A small win is achieved if the first you have a hold on the next game. Only
two "reels" (left and middle), have the by inserting another coin, will the credit
same "fruit" displayed on them when the l.e.d. will come on and if you have a hold,
"play" has finished. In all six cases, this the hold l.e.d.s will flash. This feature does
win is two coins or
lOp (i.e. double the stake and is similar
Low wins
High wins
to some commercial gaming machines).
- - ANY
£1.00 (Jackpot)
If the third reel has the same "fruit" as
R R ANY
II
II
II
50p
the first two reels, a larger win results. This time, it is dependent on the fruit concerned, and this is listed in the Odds and Wins table in Fig.
I(_ ii_ ANY 10p
n u
n u
ANY
lOp
in i ANY lOp
1 i_
I l_
1 l_
40p
n u
n u
n u
30p
ni in ni 20p
13. The "jackpot" or highest win cor-
ri_ r ANY lOp
20p
responds to the three
dashes or "bars", and this combination pays
Fig. 13. Payout odds and possible win combinations.
out 20 coins (£1).
come up at random, but has been set in
HOLD PEA TURE The hold feature has been included to
the software to happen about every one in three "plays".
make the "play" more interesting, and is incorporated on virtually all fruit
GAMBLE
machines. It shifts the odds of winning in FEATURE
your favour by keeping reels the same as
An added bonus is that after each of the
they were in the previous "play". If you higher wins (three "fruits" the same), the
A "Jackpot" win is indicated by a row of dashes appearing in the reel windows.
B
50
gamble feature is implemented. Here, the green start l.e.d, and the red hold l.e.d. above it will flash. Now the player can gamble by pressing the start button, or he can collect the displayed win by pressing the right hand /ro/r/button which is marked "collect".
If the gamble is taken, the three reels will either "step up" to the next highest win. or they will step down to the next lowest win. Because of this, the gamble feature does not happen on the highest win. the three bar jackpot.
If the gamble is lost, the three reels will step down to the next lowest win and the machine will pay out this amount. If this happens on the lowest value "fruit" i.e. three cherries, then the game is lost.
If the gamble is won, the three reels will step up to the next highest win and then there will be a further opportunity to gamble again, in which case, the entire process is repeated. This may continue right up to the three bar jackpot if you are lucky! The highest number of successful gambles is five, starting at three cherries, and gambling up to the jackpot.
ODDS AND WINS
The format of the winning combinations is shown in Fig. 13, There are six fruits per reel: = BAR; "A" = APPLE; "L" = LEMON; "O" = ORANGE; "P" = PLUM and "C" = CHERRY. This amounts to 216 different combinations that can come up on the three reels (6x6x6 = 216).
Only 36 of these are winning combinations. Of these winning combinations 30 occur when only the first and second "reels" are the same, paying two coins.
PLEASE TAKE NOTE - Part 1
The component designations for the p.c.b connectors listed in the "Components List" were incorrectly given. Although the actual types and quantity required are correct they should be designated as follows:
Plugs: PL1, PL2 and PL5 2-way PL3 S-way. PL4 4-way, Sockets: SKI, SK2 and SK5 2-way. SK3 3-way. SK4 4-way. In the Fruit Machine circuit diagram Fig. 3, the electrolytic capacitors C6, C7 and C8 should, of course, be connected the other way round i.e. the negative side of the capacitors should go to the OV line, the p.c.b. layout is correct. The Futaba servo motor should be type FB. S148. Finally, a change of address should be noted when sending for the ready programmed PIC microcontroller, self-adhesive front panel and a set of three 7-segment displays. The new address to write to can be found by turning to the Shoptalk page.
or twice the slake. This occurs 30/216 times, or once in approximately every seven games.
If all 216 different conditions happen in the same number of "plays" (the theoretical average), then 112 coins will be paid out during these 216 games. This amounts to one of each of the six "high" wins. 20+10 + 8 + 6 + 4 + 4 = 52 coins, and together with the 30 "low" wins. 30 x 2 = 60 coins, give a total of 112 coins.
This means that the payout percentage is 112/216 or about 52 per cent. This value is raised dramatically by the introduction of the hold and gamble features. The precise maths involved using these features is beyond the scope of this article (and the author's brains!), but after extensive tests, the actual payout percentage was found to be around 80 per cent, a similar amount to real gaming machines.
There may appear to be a curious effect where wins and holds do not seem to occur at random, but happen in groups. After playing many fruit machines, this is
acutally quite normal! Quite often a high
win may quickly follow a previous high
win. and then it will hold\
This can be quite disconcerting to a
player who has had a long run of losing,
and the next player captures all the win-
nings, but this is all part of the fun! There is
a small amount of strategy and skill in-
volved to get the maximum possible wins
from the machine, but it was thought best
to leave the constructor or player to find
these out!
The hold feature occurs at random 33 per
cent of the time after a game, (one game in
three) and the gamble feature occurs when
there is a win line of three similar "fruits".
(When a gamble is won, the feature repeats
until either collected).
the
gamble
is
lost,
or
the
win is
Brett and Julyan would like to give special thanks to Mandy Harding for producing the front panel artwork.
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10 m
Everyday with Practical Electronics, January 1995
51
Special Feature
CHECKING
TRANSISTORS
ANDY FUND
Highlighting an unusual problem, and how to easily check for it.
Following publication of the TENS projects {EPE May/June "94). a few readers have experienced problems
with the lead connections of the transistors used in this circuit. Those used in the prototype had the classic "ebc" lead arrangement, but it seems that this is not always the case with transistors obtained from different suppliers and worse,
there is sometimes no indication of the particular arrangement used. Less experienced constructors can easily be caught out by this. Once in circuit, the apparent fault can be difficult to locate even for the experienced, not least because the cause is unsuspected.
This problem first surfaced with a letter from a constructor of the Advanced TENS
project. All apparently went well until a fairly late stage in testing when the unit began consuming large amounts of current and the multiplier's high voltage output failed to appear. Following investigation it was found that the 2N555I transistors had the alternative "ecb" lead arrangement. Strangely, the complementary 2N5401s from the same supplier used the "ebc" arrangement.
Subsequently another reader described similar problems with the BC327 and BC337 transistors and, following some research, discovered at least twelve variants of BC337 and six of BC327. All of this points to the fact that where doubt exists, discrete transistors should be checked carefully before use.
rnri
lati/l;
JI J1 i
n p n TRANSISTOR (al
-H-,
r J j· <
b c pnp TRANSISTOR
lb)
Fig. 1. Elements ofa transistor.
GENERIC TYPES Semiconductors tend to vary according
to manufacturer. Transistors of the same generic type may have different gains and lead connections. Often this will be indicated by a suffix, such as the BC109, where the letter A, B or C indicates the gain group. Epoxy-cased transistors sometimes have a suffix for their lead positions, such as the BCI84L and BC214L. where the "L indicates leads in the "ecb" positions.
Versions of these without this letter usually have their leads arranged as "ebc". The 2N555ls which caused the first reader's difficulties had no such suffix however, and it took some time to determine the exact cause of the problem.
TESTING
TRANSISTORS For a full check of a transistor there is
no substitute for a good transistor tester, either commercially manufactured or home constructed. Many of these have appeared as projects over the years, including at least one by the present author. (The most recent one was the Transistor Checker in the Jan '92 issue - Ed.) A good tester will indicate polarity (npn or pnp), warn of faults such as open or short circuits or excessive leakage, and measure gain.
However, it may be that some readers do not have sufficient use for such an instrument to warrant buying or even constructing one. Where this is the case, simple transistor checking can be carried out with an ordinary multimeter, either analogue or digital, using the "ohms" range. Where doubt exists about a transistor's condition or connections, this can save a lot of trouble and perhaps expense.
The principle of testing with a meter is quite simple. From the point of view of meter measurements, a bipolar transistor consists of two diodes, back-to-back as shown in Fig. 1 a and Fig. lb. It can be seen that the direction of these diodes depends on the polarity of the transistor; in an npn they both point away from the base, in a pnp they both point towards it. It follows that current can flow in one direction only from both emitter and collector to the base, but not between emitter and collector so long as there is no base connection. This allows the use of a meter to determine the transistor's base connection and type.
Before testing a transistor, it is useful to check the response of the meter to a
semiconductor junction and also to determine which probe lead is "positive". The lowest "ohms" range will normally be the most suitable where an analogue meter is used as this usually operates with a 1-5V or 3V battery. Ranges for higher resistance sometimes use a higher voltage which could cause "Zener breakdown" of a reverse-biased emitter-base junction.
A simple check with a small silicon diode, such as a IN4I48 or one Of the "4000" series, such as a IN400I. will demonstrate the meter's response. Usually it will indicate about half-scale, not because the diode has internal resistance, but because it exhibits a forward voltage drop of about 0-6V when conducting. The important thing is that a clear reading is obtained in one direction, with no indication at all in the other.
The position of the probes for the "forward" indication should be noted. Analogue meters often have reversed probe polarity when measuring resistance, so that the black "negative" probe becomes the "positive" source. To avoid confusion it might be worth swapping the probes for transistor testing, so long as it is remembered to swap them back again afterwards.
DIGITAL METERS With digital meters the position is dif-
ferent. Generally, the probe polarity of these is correct, but the voltage used for resistance measurement is often lower than the 0'6V forward voltage drop of a diode, resulting in an open-circuit measurement in both directions. To overcome this, most digital meters have a diode symbol displayed over at least one resistance range to indicate a higher testing voltage, making this particular range
|0 c o (a)
( EE452SG |
ffn lb)
Fig 2. Locating the base.
52
Everyday with Practical Electronics, January 1995
BASE
100k
o
--v _
Fig. 3. Finding the emitter and collector. suitable for diode and transistor testing. Again, simple testing with a small diode will demonstrate the response.
POLARITIES To check a transistor then, the polarity
of the probes and the response of the meter should first be checked. Then a quick sketch of the pins of the transistor can be made as shown in Fig. 2a. A meter probe should be clipped to one lead of the transistor and the other probe used to test each of the other two leads in turn, noting any "diodes" found as in Fig. 2b. This can be done for all three leads in both directions, a maximum of six tests which will take only a few seconds, and should clearly identify the base connection and polarity. In Fig. 2b this is an npn type with the base on the left.
Determining the functions of the other two leads can be slightly more difficult, as many small bipolar transistors actually exhibit some gain when these are swapped! At least, with the base clearly identified, there are just two to choose from. An initial
check should be made to ensure that no current flows between them with the base open-circuit, in either direction. If it does, then the device is either not a bipolar transistor or is highly suspect. Otherwise, the testing can continue with the injection of a small bias current into the base from the supposed "collector" which will be the positive probe for an npn or the negative one for a pnp.
This can sometimes be done with a finger placed across the two leads, but more often a resistor will be needed to apply sufficient current. The amount needed depends on the gain of the transistor, but resistor values between 10k and 100k should usually produce the desired result. Fig, 3 shows the way to do this, the connections producing the highest reading being (probably!) the one in which the probes are correctly connected to the emitter and collector.
CAIN TEST
If a full functional test is required with a value for the gain, the simple circuit shown in Fig. 4 may be used. Here, resistor R1 supplies base current, whilst the meter, on a I OmA current range, measures collector current. Resistor R2 limits current to protect the meter if a short circuit is present, otherwise it has little effect.
With a nine-volt supply, a value of 420k for R1 will give a "gain" scale of 0 to 500 on the meter. Resistor R1 can consist of 150k and 270k in series to give 420k. If the gain of the transistor is lower than 100, an 82k resistor for R1 will alter the scale to approximately 0 to 100. The circuit shown is for testing an npn transistor, for a pnp type the battery and meter polarities should be reversed.
These testing techniques can be applied
to just about any small bipolar transistor
t2740R2k10k+t50kl
\ yI 0 McStorCEA1T0ELmREA 220 TORNANTSEISSTTOR
Fig. 4. Checking the current gain (npn/
and may save a lot of time and trouble where a problem is suspected. They are also useful to some extent with power transistors, though gain readings obtained may be misleading with the small collector currents used. The lower current gain of most power transistors will require the use of a lower value of resistance for the test shown in Fig. 3; a 2N3055 tried by the author required Ik for a positive result. It is not usually possible to test "Darlington" transistors with these methods due to their very high gain and the fact that there are effectively two "diodes" between some leads.
CONFORMITY
In our experience, the occurance of incorrectly marked transistors is unusual. Readers should not feel undue concern when purchasing components from suppliers who can vouch for the source of manufacture and conformity of the product. Ed.
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Everyday with Practical Electronics, January 1995
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53
Electronics from
the Ground Un Mike Tooley, BA
Part 4
ELECTRONICS from the Ground Up is designed to provide you with a comprehensive and up-to-date introduction to the world of electronics. The series
is based on Electronics Workbench, a remarkable new software package that lets you use your PC to build and test a wide range of circuits. Back issues of earlier parts of this series are available - see Back Issues page.
In this fourth part we introduce transistors. We describe
the action of npn and pnp bipolar junction devices and introduce the concept of current gain and amplification. We also introduce the three basic circuit configurations used for transistor amplifiers and the use of characteristic graphs as a means of predicting amplifier performance. We round off this month's instalment with a practical investigation of single and two-stage transistor amplifiers.
TRANSISTORS
Like diodes, transistors are fabricated from semiconductor material. Unlike diodes, a second junction and a third electrode is present. Transistors can be either unipolar or bipolar depending upon the types of charge carrier present. Unipolar transistors use a single type of charge carrier, either electrons (negative charge carriers) or holes (positive charge carriers). Bipolar transistors, on the other hand, employ both types of charge carrier (i.e., both electrons and holes). In Electronics from the Ground Up we shall only consider the operation of bipolar transistors. Readers with the full Electronics Workbench package will be able to experiment with both types of device.
Fig. 4.1 and Fig. 4.2 show the basic construction of npn and pnp bipolar transistors. Each type of device has three connections (emitter, base, and collector) and two junctions (collector-base and baseemitter). The p-type material contains free holes whilst the n-type material has a quantity of free electrons. In normal operation, the collector-base junction is reverse
Kfc, IdH Circuit
Hrlp [ SJi
Part
IB
furictiun Generator
(
. - |f-Tt f-l 1
OJ J
trtnutncv iihh m Ba m OtIIV even cm 3 HHPLITMK I a 3 orrset M M
Dsci)los< <jpe
(JROUHD ·
ii TI WE i."
to. oTTtRIGcGnERijj iS I
X I*OS S tn'- a LEVEL ! .»
. ..r
ECZHlOtWiSHCEi. ZaU i CHAWHt L 8 _;
·fir''V
jShwl
V>
Emitter o(r I > nP
Emitter o-
o9o · ·
-o Collector Emitter o-
p N
p
0n0
00Q
Soo°o0 ··· 0oo0o
-O Collector
6 Base
O Holes · Electrons
6 Base
O Holes · Electrons
-o Collector
Emitter o-
-o Collector
6 Base
Fig. 4.1 Simplified construction and symbol for an npn transistor. 54
6 Base
Fig. 4.2 Simplified construction and symbol for a pnp transistor. Everyday with Practical Electronics, January 1995
" BE
"hr CB
Fig. 4.3 Bias and current flow for an npn transistor.
Fig. 4.6 Common emitter configuration. 'IN %
Fig. 4.7 Common collector configuration.
.+V cc
'OUT 0V
.+v,CC
'
BE
CB
Fig. 4.4 Bias and current flow for a pnp transistor.
'IN 'OUT %
ov
biased whilst the base-emitter junction is forward biased (see Fig. 4.3 and Fig. 4.4).
When the base-emitter junction is forward biased a large number of electrons travel from the emitter into the base region. A small number of electroncs recombine with vacant holes within the narrow base region. However, the vast majority are swept across into the collector region, attracted by the greater positive potential.
Regardless of whether the transistor is npn or pnp, the three electrode currents are related by the expression:
1e = Its + lc where lE is the emitter current, Ib is the base current, and lc is the collector current.
Note that in Electronics from the Ground Up we have adopted the convention that an upper case subscript repre-
I
T018
1092
H
B
T0126
T0220
Fig. 4.5 Some common transistor packages.
Fig. 4.8 Common base configuration.
-+V CC
'IN
'OUT
- - OV
sents a large signal (d.c.) value whilst a lower case subscript denotes a small change, increment or small a.c. value. This is an important point as we shall see later.
Some common transistor packages are shown in Fig. 4.5.
TRANSISTOR CIRCUIT
CONFIGURATIONS Regardless of what type of transistor is
employed, three basic circuit configurations are used. These three circuit configurations depend upon which one of the three transistor connections is made common to both the input and the output. In the case of bipolar transistors, the configurations are known as common emitter, common collector (or emitter follower), and common base. See Fig. 4,6 to Fig. 4.8, respectively.
The three basic circuit configurations exhibit quite different performance characteristics as shown in the Table 4.1 (typical values are given in brackets).
TRANSISTOR
CHARACTERISTICS A number of characteristic graphs (show-
ing the relationship between electrode voltage and current) can be used to predict
the performance of practical transistor cir-
cuits. In order to keep things simple (and to
avoid confusion) we shall confine our study
to the common emitter mode. Similar sets
of characteristics can be obtained for the
other modes.
In common emitter mode the three most
useful characteristic graphs are:
the input characteristic (1B plotted
agathinest
Vbe with transfer
VCE constant, Fig. 4.9). characteristic (lc plotted
agathinest
Ib with VCE constant, Fig. 4.10). output characteristic (lc plotted
against Vce with Is constant, Fig. 4.11).
The input characteristic shown in Fig.
4.9 is similar to that of a forward biased diode. This, of course, should not be too surprising since the base-emitter junction acts just like a p-n junction diode. As with a conventional silicon diode, the junction does not begin to pass current until a forward voltage of approximately 0'7V is reached. The collector-emitter voltage (Vce) has remarkably little effect on the shape of the characteristic and thus only a single curve is drawn for a fixed value of Vce-
In contrast, the transfer characteristic shown in Fig. 4.10 takes the form of an almost straight line. This shows that, as the base current is increased, the collector
Everyday with Practical Electronics, January 1995
55
Parameter
Table 4.1 Transistor circuit configurations
Mode of operation
Common emitter
(Fig. 4.6)
Common collector (Fig. 4.7)
Voltage gain Current gain
medium/high (40)
high (200)
unity (1)
high (200)
Power gain
very high (8000)
high (200)
Input resistance
medium (2k5ft)
high (lOOkO)
Output resistance medium/high (20kn)
low (ioon)
Phase shift
180°
0°
Typical applications
General purpose,
a.f. and r.f. amplifiers
Impedance matching,
input and output stages
Common base
(Fig. 4.8)
high (200)
unity (1)
high (200)
low (20on)
high (tookn)
0°
r.f. and v.h.f. amplifiers
current will increase in direct proportion (i.e., doubling the base current will produce a twofold increase in the collector current, and so on). Once again, the collectoremitter voltage (VCE) has only a minor effect on the shape of the characteristic and again we can make use of a single curve keeping Vce constant.
A set of output characteristics is shown in Fig. 4.11. This set of curves results from the fact that lc will increase both as lB increases and as VCE increases. Note that we must usually construct a family of curves for increasing values of Ib- It is also worth noting that the output characteristics have a pronouced bend (or "knee") for values of Vq below 2V. Above this value, lc will rise only very slowly as Vce increases. We refer to the shape of this part of the graph (above Vce = 2V) as a "constant current" characteristic.
Input resistance The input resistance of an amplifier is
the resistance that is effectively "seen" between its input terminals. As such, it is the ratio of the voltage between the input
100 ,, .. _ .. \ -1-
1 M
c to
1 3
40
S S 20
. - ii .....i...... i
i !i ·
- --
/
/
/ / / >
0 100 200 300 400 500 600 700 Base-emitter voltage, VBE (mV)
lc O-
Input
'BE
o
Fig. 4.12 Current and voltage at the input of a common emitter amplifier stage.
Input
in
Fig. 4.9 Input characteristic (IB plotted against VK with VC£ constant).
Fig. 4 A3 Input resistance of a common emitter amplifier stage.
500
450
400
Ig = 50 mA
350
^ 300 250
l. 200 = 160
100
Ig = 40 pA
- s
Ig = 30 mA
-- ·
lB » 20 MA
lB» 10 MA
15 20 25 30 35 40 Base current, lB (mA)
Fig. 4.10 Transfer characteristic (lc plotted against Ig with Vce constant).
56
4 6 8
12 14 16 II 20
Collector-emitte voltage, VCE (V)
Fig. 4.11 Output characteristic (lc plotted against Vce with lB constant).
Everyday with Practical Electronics, January 1995
terminals to the current flowing into the input. In the case of a transistor operating in common emitter mode, the input voltage is the voltage developed between the base and emitter, VBE, whilst the input current is the current supplied to the base, lB.
Fig. 4.12 shows the current and voltage at the input of a common emitter amplifier stage, whilst Fig. 4.13 shows how the input resistance, R|n, appears between the base and emitter. Note that Rin is not a discrete component · it is inside the transistor.
From the foregoing we can deduce that:
RNn = VI'bbe
The transistor's input characteristic can be used to predict the input resistance of a transistor amplifier stage. Since the input characteristic is non-linear (recall that very little happens until the base-emitter voltage exceeds about 0-7V), the value of input resistance will be very much dependent on the exact point on the graph at which the transistor is being operated.
Furthermore, we might expect quite different values of resistance according to whether we are dealing with larger, d.c. values or smaller incremental changes (a.c. values). Since this can be a rather difficult concept, it is worth expanding on it.
Fig. 4.14 shows a typical input characteristic in which the transistor is operated with a base current, lB, of 50pA. This current produces a base-emitter voltage, VBE, of 07V. The input resistance corresponding to these steady (d.c.) values will be given by:
=
VBL= lB
0T^ = SOpA
14ki2
Now, suppose that we apply a steady bias current of, say, 70|jA and superimpose on this a signal that varies above and below this value, swinging through a total change of lOOpA (i.e., from 20pAto 120pA). Fig. 4.15 shows that this produces a base-emitter voltage change of O05V.
The input resistance seen by this smallsignal input current is given by:
= change in VBE = Vbe change in lB lb
005V lOOpA
soon
It is worth comparing this value with the previous value. The appreciable difference is entirely attributable to the shape of the input characteristic!
1 _CQ
t
C o
3Uoto
AIb= 100MA
CD
AVbe = 0.05V
Base-emitter voltage, VBE (mV)
Fig. 4.15 Using the input characteristic to determine the small signal (a.c.) input resistance of a transistor connected in common emitter mode.
\r -o
It
Input
'BE
--o--
VCE Output _0
Fig. 4.16 Input and output currents and voltages in a common emitter amplifier stage.
CURRENT GAIN The current gain produced by an amplifier
is the ratio of output current to input current. In the case of a transistor operating in common emitter mode, the input current is the base current, lB, whilst the output current is the collector current, t
Fig. 4.16 shows the input and output currents and voltages for a common emitter amplifier stage. The magnitude of the current produced at the output of the transistor is equal to the current gain, A,, multiplied by the applied base current, lB. Since the output current is the current flowing in the collector, lc, we can deduce that:
lc = Ai x 1B
Fig. 4.17 shows how this current source appears between the collector and emitter. Once
'c
]
(S Aj X lB
Output
Fig. 4.17 E.quivalent output current source in a common emitter amplifier stage.
(mA)
1 m c C lB = 50pA oCoO <s
1
I / J
J
VBE = 0.7V Base-emitter voltage, VBE (mV)
Fig. 4.14 Using the input characteristic to determine the larg,e signal (d.c.) input resistance of a transistor connected in common emitter mode.
Everyday with Practical Electronics, January 1995
_p J lc = 2.5mA 0k). 3ok. 0) o o
'b = 50mA Base current lB (Ma)
Fig. 4.18 Using the transistor's transfer characteristic to determine the large signal (d.c.) current gain produced by a transists-w it±1s>s-ft>ri (it .-/\tntttrst-r c>ttiIffor t-ytfi/iO
57
again, the current source is not a discrete component - it appears inside the transistor.
The transistor's transfer characteristic can be used to predict the current gain of a transistor amplifier stage. Since the transfer characteristic is linear, the current gain remains reasonably constant over a range of collector current.
Fig. 4.18 shows a typical transfer characteristic in which the transistor is operated with a base current Ib, of 50)iA. This current produces a collector current, 1c, of 2.5mA. The current gain corresponding to these steady (d.c.) values will be given by:
Jc = 2^mA = ^ lB 50pA Mow, suppose that we apply a steady bias current of, say, 50pA and superimpose on this a signal that varies above and below this value, swinging through a total change of 40|iA (i.e., from 30pA to 70pA). Fig. 4.19 shows that this produces a collector current swing of 2mA. The small-signal a.c. current gain is given by.
_ change in lc _ 'c _ 2mA _ ^ change in lB lb 40pA
Mote that this value is the same as the large-signal (d.c.) value.
Practical assignment 4.1: Transistor characteristics
In this practical assignment, using Electronics Workbench, you will investigate the input and transfer characteristics of a typical silicon transistor.
Objectives: 4.1.1 To plot the input characteristic graph
for a silicon transistor when connected in common emitter configuration. 4.1.2 To plot the transfer characteristic graph for a silicon transistor when connected in common emitter configuration. 4.1.3 To determine the large and small signal input resistance and current gain for a silicon transistor operating in common emitter configuration.
Instructions: 1. Connect the circuit shown in Fig. 4.20
using a 0-6V battery to supply base voltage to the transistor.
Table 4.2 Measured values for Assignment 4.1.1
Vbe OV 0 5V 0 6V 0-65V 0-7V 0.75V 0 8V 0 85V (V)
Ib (mA) 0
2. Switch on the power to your circuit and measure the base current flowing. Record the value of base current in Table 4.2.
3. Repeat steps 1 and 2 using battery voltages of 0-625V, 0-65V, 0-675V, 0-7V, 0'725V and 0'75V. Measure and record the collector current for each value of applied base-emitter voltage.
i d * »1 1 0U
a 2v
Fig. 4.20 Circuit for Assignment 4.1.1 (input characteristic).
i
i d* »1
0U
1 00HA
4. Use the results from Table 4.2 to plot a graph showing base current (1b) plotted against base-emitter voltage (VBE).
5. Use the graph to determine the large signal (d.c.) input resistance of the transistor (Vbe/'b) when VBE is OTV.
6. Use the graph to determine the small signal (a.c.) input resistance of the transistor (AVbe/AIb or VtA) when VBE is OTV.
7. Connect the circuit shown in Fig. 4.21 using a lOOpA d.c. current source to supply base current to the transistor.
8. Switch on the power to your circuit and measure the collector current flowing. Record the value of collector current in Table 4.3.
9. Repeat steps 7 and 8 using source currents of 200pA, 300nA, 400|jA, 500(oA, and 600(iA.' Measure and record the collector current for each value of applied base current.
10. Use the results from Table 4,3 to plot a graph showing collector current (lc) plotted against base current (Ib).
11. Use the graph to determine the large signal (d.c.) current gain of the transistor (1c/Ib) when lc is SOmA.
12. Use the graph to determine the small signal (a.c.) current gain of the transistor (AIc/AIb = IA) when Ids 50mA.
Fig. 4.21 Circuit for Assignment 4.1.2 (transfer characteristic).
Conclusions: To what extent have the objectives for
this assignment been met? Comment on
Table 4.3 Measured values for Assignment 4.1.2
Ib(PA)
0 100 200 300 400 500 600
lc (mA)
0
the shape of the graphs. Are these what
you would have expected? If not, why not?
Comment on the large and small signal
values of input resistance. Are the values
similar? What range of base input current
would be sensible for this device (assuming
<
linear operation)? Comment on the large
E.
and small signal values of current gain. Are
o
the values similar?
c4)
Alc = 2mA
TRANSISTORS AS SWITCHES
3 o
Conventional electromechanical switches and electromagnetic relays will
o4) O
A = 40|JA
O
only operate at relatively slow speeds. In practice most electronic circuits demand switching speeds that are many orders of magnitude faster than can be achieved
with these types of switch. Before going
further, it is worth considering the
properties that we would require an "ideal"
switch to have.
Base current, Ig (pA)
g. 4.19 Using the transistor's transfer characteristic to determine the small signal (a.c.) irrent gain produced by a transistor connected in common emitter mode.
PROPERTIES OF AN
IDEAL SWITCH An ideal switch would operate instan-
taneously, changing from its "off state to its "on" state in zero time. In its "off state,
58
Everyday with Practical Electronics. January 1995
Table 4.4 Typical characteristics of switching devices
Conversely, when no base current is applied (e.g., when the base itself is con-
Characteristic
Ideal
Relay
Transistor
(electromagnetic) (solid state)
nected to ground) the transistor will not pass any collector current. In this condition the transistor is said to be cut off and the
Switching time
zero
{off-on and
on-off)
20ms
10ns
collector-emitter voltage (VCE) will rise to approximately the same as the supply volt-
age (Vcc). Almost no voltage will then be
dropped across resistor R2.
Maximum switching rate (operations
infinite
50Hz
10MHz
The action of this circuit is thus equivalent to that of a switch connected between the collector and emitter. When the switch is "closed", the transistor is saturated and
per second)
all of the supply voltage appears dropped
"On" state
zero
OObii
o sn
across resistor R2. When the switch is "open", the transistor is "cut-off and no
resistance
voltage is dropped across resistor R2. The
transistor switch is operated by a small
"Off" state
infinite
> 10OMfi
> 1 Mil
current (typically less than 1 mA).
resistance
Practical assignment 4.2:
Maximum "off"
infinite
500V
150V
The transistor as a switch In this practical assignment you will in-
state voltage
vestigate the behaviour of a simple transis-
Maximum "on"
infinite
2A
current
tor switching circuit.
5A
Objectives:
4.2.1 To investigate the switch-
ing action of a transistor.
4.2.2 To demonstrate the use
the switch should have an infinite resis
of an l.e.d. (light emitting
tance and be capable of withstanding an
diode) indicator.
infinite voltage applied to the open switch contacts without breakdown, in its "on" state, the switch should have zero resistance and be capable of passing an infinite current.
Whilst these characteristics may sound impossible to achieve, solid-state devices do go a long way towards satisfying even the most demanding of practical requirements (see Table 4.4).
1 kft
UC1 5V =^n
Instructions:
1. Connect the circuit shown in
Al
10V
Fig. 4.23. 2. Switch on the power to your
circuit. Measure and record
the current flowing with the
switch ("1" on your key-
board) in both positions.
3. Connect the circuit shown in
Rg. 4.24. In this circuit, the
SATURATION AND
CUT-OFF Before we take a look at a simple transis-
tor switching circuit it is worth considering two extreme cases of transistor switching operation; saturation and cut-off.
Fig. 4.22 shows a simple transistor switching circuit. The input current is
Fig. 4.23 Circuit for Assignment 4.2.1.
4700
1 kO
/ ideal
ammeter is replaced by a light emitting diode connected in series with a 470fl resistor. 4. Switch on the power to your circuit. Observe the l.e.d. with the switch in both positions (note that the diode symbol will appear darker when illuminated).
applied to the base (via resistor Rl) and the output (i.e., the switched current) flows in the collector (via resistor R2). Provided the current gain is sufficient, the transistor will be driven into saturation when a relatively small base current is applied. In this condition, the collector-emitter voltage
(Vce) will fall to virtually OV (in practice the saturated collector-emitter voltage, VcEsat, for a typical silicon transistor will be of the order of 200mV). Almost the entire supply voltage (Vcc) will then appear dropped across resistor R2.
U1 sw =^n
ideal
Fig. 4.24 Circuit for Assignment 4.2.2 with the ammeter replaced by an l.e.d. indicator and series resistor.
10y
Conclusions: To what extent have the objec-
tives for this assignment been met?
Can you explain the action of the
circuit in your own words (remem-
ber that collector current will only
flow when base current is applied)?
In a practical application, the key-
board operated switch would be
replaced by circuitry that either produces a
small current or does not produce any cur-
rent. With this in mind, can you suggest a
practical application for the circuit?
Fig. 4.22 A simple transistor switch.
+V,cc 'c "
R2
AMPLIFIERS
Many different types of amplifier are found in electronic circuits. Before we1 explain the action of simple transistor amplifiers in detail, it is worth introducing some of the terminology applied to amplifier circuits in general;
TR1
I'b
R1
o--*--WA-
Input
o--
VCE Output -o OV
A.C. coupled amplifiers In a.c. coupled amplifiers, stages are
coupled together in such a way that d.c. levels are isolated and only the a.c. components of a signal are transferred from stage to stage.
D.C. coupled amplifiers In d.c. (or direct) coupled amplifiers,
stages are coupled together in such a way that stages are not isolated from d.c.
Everyday with Practical Electronics. January 1995
59
Voltage gain
A max 0.707Avmax
Bandwidth
*2 Frequency
Fig. 4.25 Amplifier frequency response.
potentials. Both a.c. and d.c. signal components are transferred from stage to stage.
Large-signal amplifiers Large signal amplifiers are designed to
cater for appreciable voltage and/or current levels (typically from IV to 100V, or more).
Small-signal amplifiers Small signal amplifiers are designed to
cater for low level signals (normally less than IV and often much smaller).
Wideband amplifiers Wideband amplifiers are capable of
amplifying a very wide range of frequencies, typically from a few tens of Hz to several MHz.
Low-noise amplifiers Low-noise amplifiers are designed so
that they contribute negligible noise (signal disturbance) to the signal being amplified. These amplifiers are usually designed for use with very small signal levels (usually less than 1 OmV, or so).
current and is measured in ohms. Note that this impedance is internal to the amplifier and should not be confused with the impedance of the load. Frequency response
Frequency response is usually specified in terms of the upper and lower cut off frequencies of the amplifier. These frequencies are those at which the output power has dropped to 50 per cent (otherwise known as the - 3 dB points) or where the voltage gain has dropped to 70-7 per cent of its mid-band value. Fig. 4.25 shows the typical frequency response of an a.c. coupled amplifier. The upper and lower cut-off frequencies are 7z and f, respectively. Bandwidth
The bandwidth of an amplifier is usually taken as the difference between the upper and lower cut off frequencies (see Fig. 4.25). Phase shift
Phase shift is the phase angle between the input and output voltages measured in degrees. The measurement is usually carried out in the mid-band where, for most amplifiers, the phase shift remains relatively constant.
Gain One of the most important parameters
of an amplifier is the amount of amplification or gain that it provides. Gain is simply the ratio of output voltage to input voltage, output current to input current, or output power to input power. These three ratios
give, respectively, the voltage gain, current gain, and power gain. Thus:
BIAS AND LINEARITY
A requirement of most amplifiers is that the the output signal should be a faithful copy of the input signal, albeit somewhat larger in amplitude. Other types of amplifier are "non-linear", in which case
their input and output waveforms will not necessarily be similar. In practice, the de-
gree of linearity provided by an amplifier can be affected by a number of factors including the amount of bias applied and the amplitude of the input signal.
It is also worth noting that a linear amplifier will become non-linear when the applied input signal exceeds a threshold value. Beyond this value the amplifier is said to be "over-driven" and the output will become increasingly distorted if the input signal is further increased.
In general, the optimum value of bias for a linear amplifier is that value which ensures that the active devices are operated at the mid point of their transfer characteristics. In practice, this means that a static value of collector current will flow even when there is no signal present.
Furthermore, the collector current will flow throughout the complete cycle of an input signal (i.e., conduction takes place over an angle of 360°). At no stage will the transistor be saturated nor will it be cut-off (see earlier).
This mode of operation is referred to as "Class-A". Other classes of operation ("B" and "C") offer improved efficiency but at the risk of significantly increased distortion. In Electronics from the Ground Up, we shall restrict our investigation of amplifier circuits to Class-A stages.
TRANSISTOR
AMPLIFIER CIRCUITS
Fig. 4.26 shows a simple Class-A common emitter amplifier circuit. The signal is applied to the base terminal of the transistor via a coupling capacitor, Cl. This capacitor removes the d.c. component of any signal applied to the input terminals and ensures that the base bias current delivered by resistor R1 is unaffected by any device connected to the input. Resistor R2 forms the collector load for the amplifier stage and feeds d.c. current to the collector of the transistor. Capacitor C2 couples the signal out of the stage and also prevents d.c. current flow from appearing at the output terminals. The stage offers a modest voltage gain (80 to 120 typical) with an input impedance of approximately lk5n and an output impedance of around 20kn.
In order to stabilise the operating conditions for the stage and compensate for variations in transistor parameters, base bias current for the transistor can be derived from the voltage at the collector (see Fig. 4.27). This voltage is dependent on the collector current which, in turn, depends upon the base current. A negative feedback loop thus exists in which there is
voltage gam = -Vr'oji--un, current. gam. = -ljo--ut and power gam = -Pp'oi--unt Input impedance Input impedance is the ratio of input voltage to input current and it is expressed in ohms. The input of an amplifier is normally purely resistive (i.e., the reactive component is negligible) in the middle of its working frequency range (i.e., the mid-band) and hence, in such cases, input impedance is synonymous with input resistance. Output impedance Output impedance is the ratio of opencircuit output voltage to short-circuit output
+V-
R1
C1 ·HIP Input
R2 TR1
C2 1]| o
Output
-O 0V
Fig. 4.26 Basic Class-A common emitter amplifier stage.
60
Everyday with Practical Electronics. January 1995
+v cc R2
+V cc
R3
R1
C3
C1
-HO Input
C2
R1
1--Ul--0
Output TR1
O OV
C1
TR1
Input
R2
R4
Output C2
O OV
Fig. 4.27 A practical common emitter transistor amplifier.
Fig. 4.29 An improved common emitter amplifier stage.
a degree of self-regulation. If the collector current increases, the collector voltage will fall and the base current will be reduced.
The reduction in base current will produce a corresponding reduction in collector current to offset the original change. Conversely, if the collector current falls, the collector voltage will rise and the base current will increase. This, in turn, will produce a corresponding increase in collector current to offset the original change.
The negative feedback path in Fig. 4.27 provides feedback that involves an a.c. (signal) component as well as the d.c. bias. As
a result of the a.c. feedback, there is a slight reduction in signal gain. The signal gain can be increased by removing the a.c. signal component from the feedback path so that only the d.c. bias component is present. This can be achieved with the aid of a bypass capacitor as shown in Fig. 4.28.
The value of bypass capacitor, C2, is chosen so that the component exhibits a
very low reactance at the lowest signal frequency when compared with the series base bias resistance, R2. The result of this potential divider arrangement is that the a.c, signal component is effectively bypassed to ground.
Fig. 4.29 shows an improved form of transistor amplifier in which d.c. negative feedback is used to stabilize the stage and compensate for variations in transistor parameters, component values and tem-
lc(mA)
VCC rL
/ / \f 'CQ "
Operating point /
lB = 40 |JA = 30 pA
lR = 10 pA
Pcq
VCC VCE(V.
Fig. 4.30 Operating point and quiescent values shown on the load line for a bipolar transistor operating in common emitter mode.
perature changes. Resistors R1 and R2 form a potential divider that determines the d.c. base potential, Vs. The base-emitter voltage (VBE) is the difference between the potentials present at the base (VB) and emitter (Vg). The potential at the emitter is governed by the emitter current (y. If this current increases, the emitter voltage (Ve)
+v cc
will increase and, as a consequence VBE will fall. This, in turn, produces a reduction in emitter current which largely offsets the original change. Conversely, if the emitter current decreases, the emitter voltage (Vg) will decrease and VBE will increase (remember that Vb remains constant). The increase in bias results in an increase in emitter current compensating for the original change.
PREDICTING
C1
H Input
R1
R2
W^-f--w C2 I
TR1
R3 C3
Output
PERFORMANCE
The a.c. performance of an amplifier stage can be predicted using a load line superimposed on the relevant set of output characteristics. For a bipolar transistor operating in common emitter mode the required characteristics are lc plotted against VCE. One end of the load line corresponds to the supply voltage (Vcc) whilst the other end corresponds to the value of collector or drain current that would flow with the device totally saturated. In this condition;
O0V
Fig. 4.28 Improved version of Fig. 4.27.
where RL is the value of collector or drain load resistance.
Everyday with Practical Electronics, January 1995
61
lc(mA) CC
CO
lB = 40 pA
Operating point
lg = 30 pA
Input (bsaigsneaclurrent) lB = 20 pA
I
lg = 10 pA
l 0 0k 0 Ikrt
ideal
ieu
m
Fig. 4.32 Circuit for Assignment 4.3 with the voltmeter connected to read the value
of V(if;.
Output (collector current) signal
vcc vce(v)
1 00kO 1 kO
i dei1
10W
Fig. 4.31 Input (base current) and output (collector current) waveforms superimposed on Fig. 4.30.
Fig. 4.30 shows a load line superimposed on a set of output characteristics for a bipolar transistor operating in common emitter mode. The quiescent point (or operating point) is the point on the load line that corresponds to the conditions that exist when no-signal is applied to the stage. In Fig. 4.30, the base bias current is set at 20pA so that the quiescent point effectively sits roughly halfway along the load line. This position ensures that the collector voltage can swing both positively (above) and negatively (below) its quiescent value (Vcq).
Fig. 4.31 shows the effect of superimposing an alternating base current (of 20pA peak-peak) to the d.c. bias current (of 20pA). The corresponding collector current signal can be determined by simply moving up and down the load line (as shown). Practical assignment 4.3: Single-stage amplifier
In this assignment you will investigate the behaviour of a single-stage Class-A common emitter amplifier. Objectives: 4.3.1 To investigate the action of a
single-stage Class-A common emitter amplifier. 4.3.2 To determine the d.c. operating conditions for a single-stage Class-A common emitter amplifier. 4.3.3 To use an oscilloscope to obtain waveforms for a single-stage Class-A common emitter amplifier.
Table 4.5 D.C. operating conditions in Assignment 4.3.
4.3.4 To measure the voltage gain and phase shift produced by a single-stage Class-A common emitter amplifier,
4.3.5 To observe the effect of over-driving an amplifier stage.
Instructions: 1. Connect the circuit shown
in Fig. 4.32. The voltmeter is to be connected so that it will indicate the base-emitter voltage (VBE) for the transistor. 2. Measure and record the base-emitter voltage (Vbe) in Table 4.5. 3. Connect the circuit shown in Fig. 4.33. The voltmeter is to be connected so that it will indicate the collector-emitter voltage (Vce) for the transistor. 4. Measure and record the collector-emitter voltage (Vce) in Table 4.5. 5. Use the measured values of Vbe and Vce to calculate the values of base current (la) and collector current (lc). (Remember that Ib and lc flow in the 1 OOkii and Ikfl resistors, respectively. You can apply Ohm's Law to determine the current. The voltage dropped across the 1 OOkil resistor will be 10V minus Vbe whilst that dropped across the Ikfi resistor will be 10V minus Vce (from KirchhofFs Voltage Law). 6. Connect the circuit shown in Fig. 4.34. Set the waveform generator and oscilloscope controls as shown in Fig. 4.35.
Fig. 4.33 Circuit for Assignment 4.3 with the voltmeter connected to read the value ofV(F,
i 00kn lkn IfZLJ
ideal
10V
Fig. 4.34 Single-stage Class-A common emitter amplifier (Assignment 4.3). 7. Display the input and output waveforms
on a common time scale (you might like to sketch these). Determine the phase difference (in degrees) between the input and output signals (remember that a complete cycle is equivalent to a phase shift of 360°).
FREHUEMCV ll
OUTV CVCLE |S0
AMPLITUDE 110
OFFSET
(S
COM (S
HJIIKHZ
h\\ A v 3
(+S
Measured value of base-emitter voltage, VBE (volts)
Measured value of collector-emitter voltage, Vce (volts)
Calculated value of base current, Ib (pA)
GROUND (S
TINE BftSE
TRIGGER
|0 . 50ns/d i v" EDGE EDS ^
0.00 ht LEVEL
IV/Ta B/ft j ft/BI uToJ
CHANNEL A
CHAMNEL 0
I IB nV/Div I 2 V/Div
V POS 11.48 ht V POS -1 2 0
p^iriwi« I AC || B || DC I (m
Calculated value of collector current, lc (mA)
Fig. 4.35 Waveform generator and oscilloscope settings for Assignment 4.3.
62
Everyday with Practical Electronics, January 1995
Fp
BBS
-QJS. a
47kft IkO IMF
4 7k Q
imF ideal
ideal
12V
470^ 47MF
i: 4 7.00 : 47mF
f/g. 4.36 Two-stage Class-A common emitter amplifier (Assignment 4.4).
FREQUEMCV ll DUTV CVCLE [5 0
AMPLITUDE |1 OFFSET
(S
COM (S
haiKHz m
tsl mi ^ m a
for the stage? Can you explain why the output signal becomes distorted when this value of input is exceeded? How could the distortion be reduced?
MULTISTAGE AMPLIFIERS
Multistage amplifiers can be used to provide significantly higher values of voltage gain. Signals can be coupled from
GROUND (S
TIME BMS 50ns /d
TRIGGER EDGE ESJ ^
POS 00 LEVEL ["0 00
V/TIB/A A/B ruimnnran
CHANNEL A 1 nV/Div
CHANNEL B
V P 0 S | 14 0 ai V POS hi .60
I AC | 0 M DC |
IA C || 0 | D C j (mI
Fig. 4.37 Waveform generator and oscilloscope settings for Assignment 4.4.
8. Use the oscilloscope to measure the peak-peak values of the input and output waveforms. Hence determine the voltage gain of the stage.
9. Try increasing the amplitude of the input signal until the output waveform becomes noticeably distorted. You might like to sketch the resulting output waveform.
Conclusions: To what extent have the objectives for this
assignment been met? Can you explain, in your own words, how the circuit works? Comment on the d.c. operating conditions. Are these what you would expect? Comment on the voltage gain produced by the stage. Can you explain why the stage produces a phase shift of 180°? What would you consider should be the maximum input signal
stage to stage (the output of one stage feeding the input of the next) using capacitors or transformers (the former being more common). Stages are effectively connected in tandem (one stage after another) using common supply (Vcc) and ground (OV) connections. Note that in practical circuits it is usually necessary to decouple the supply rail in order to avoid unwanted feedback of signals carried on the supply rail. A suitably large value of capacitor connected from Vcc to ground usually satisifies this requirement.
Practical assignment 4.4: Two-stage amplifier
in this assignment you will investigate the behaviour of a two-stage Class-A common emitter amplifier.
ideal
--H--
ideal
2200
12V --h-
= = 470mF = = 470mF ^a ideal TaT
NT.) 12V
ideal
--H-- ideal
--H--
4 7 0)aF =^= 4 7 0mF -5^ ideal || 2200
Fig. 4.38 Solution to last month's brain teaser.
Objectives: 4.4.1 To investigate the action of a
two-stage Class-A common emitter amplifier. 4.4.2 To determine the d.c. voltages (under driven conditions) for a two-stage Class-A common emitter amplifier. 4.4.3 To use an oscilloscope to obtain waveforms for a two-stage Class-A common emitter amplifier. 4.4.4 To measure the voltage gain and phase shift produced by a two-stage Class-A cbmmon emitter amplifier.
Instructions: 1. Connect the circuit shown in Fig. 4.36.
Set the waveform generator and oscilloscope controls as shown in Fig. 4.37. 2. Use the voltmeter to measure and record the voltages (under driven conditions) at the collector and emitter of each transistor relative to ground. 3. Display the input and output waveforms on a common time scale (you might like to sketch these). Determine the phase difference (in degrees) between the input and output signals (remember that a complete cycle is equivalent to a phase shift of 360°). 4. Use the oscilloscope to measure the peak-peak values of the input and output waveforms. Hence determine the voltage gain of the stage.
Conclusions: To what extent have the objectives for
this assignment been met? Comment on the d.c. voltages. Are these what you would expect? Are they identical for each stage? Comment on the voltage gain produced by the circuit. How does this compare with the voltage gain for a single-stage amplifier? Can you explain why the stage produces a phase shift of 360° (or 0°)?
BRAIN TEASER This month's challenge for those of
you .who are using the full Electronics Workbench package is to design an a.c. coupled Class-A common emitter amplifier with the following specifications:
Voltage gain = 2 Overall phase shift = 18(1 Supply voltage = 10V
Hint: use the circuit shown in Fig. 4.29. In this circuit, if capacitor C2 is omitted, the voltage gain will be approximately given by the ratio of resistors R3 to R4. Operate the transistor TR1 with lc = 2mA and choose values for resistors R1 and R2 that will produce a voltage of between 1-7V and 2V at the base of TR1.
Test your solution using Electronics Workbench.
Answer to last month's Brain Teaser
Last month's Brain Teaser involved the design of a full-wave power supply that provides equal but opposite output voltages with a common earth (0V) connection. The circuit should incorporate smoothing and each output voltage is to be stabilised using a parallel-connected 5V Zener diode. Fig. 4.38 shows one solution arrived at using the full version of Electronics Workbench.
Everyday with Practical Electronics, January 1995
63
Special Review
CAPTOR-VAT ED!
TERRYde VAUX-BALBIRNIE
Don't cough and choke - remove those harmful fumes. Terry extracts the truth about the benefits of using a fume captor when carrying out soldering operations.
Almost anyone constructing electronic circuits will need to solder at times.
Unfortunately, those who do this regularly may breath in excessive amounts of fumes. Both solder and flux produce various chemical substances when heated - either in the form of gases or as suspended solid
particles - and several of these can be harmful to health. Good ventilation will help but will not completely solve the problem.
Those who solder professionally - that is, people employed in commercial premises are protected by the COSHH (Control of Substances Hazardous to Health) regulations (1988). These place a duty on the employer to ensure that any exposure of employees to harmful substances is prevented or at least adequately
controlled. All soldering irons installed in most
commercial premises will therefore be fitted with fume extraction equipment. This normally consists of a rigid tube attached to the side of the soldering iron connected through a flexible tube to a filter and air pump.
BREA THTA KING
I try to hold my breath while making a soldered joint - especially when doing close work. If I don't, the fumes can make me cough and choke for hours afterwards.
I found that with the Captor running, I could work continuously and comfortably. Moreover, the house did not smell of fumes afterwards. The Solder Fume Captor differs from fan-driven domestic devices in actually removing' the fumes rather than simply covering them up with a pleasant smell.
The Captor is effective, runs quietly and consumes only 18W of power. Overseas readers may like to know that it is also
available in a 115V version. I would recommend it to any amateur - especially one who finds soldering fumes irritating or who does a lot of work.
People suffering from asthma, bronchitis and other breathing problems will find it of particular benefit. It would also be useful to schools and colleges - a dozen soldering irons all operating at once can be extremely unpleasant. Possibly two students could share one unit.
At the time of writing, the Solder Fume Captor costs £54.94 plus VAT. This includes three spare filters. Additional filters cost £9.92 for a pack of- five. These are all available direct from the manufacturer on a cheque-with-order basis. Carriage is charged for at cost - it would be wise to telephone for the latest prices before ordering.
For more information contact: Light Soldering Developments Ltd., Dept EPF, Spencer Place. 97-99 Gloucester Road, Croydon, Surrey, CRO 2DN. Tel: 0181-689 0574. Fax: 0181-689 0090.
JUSTA MINUTE
It would be ideal for the amateur to have this type of equipment available at home. It would also prevent the whole house smelling of "electronics". However, it is generally beyond the means of the average amateur - a self-contained fume extraction soldering station would cost several hundred pounds. I was given the oppostunity to try an inexpensive alternative the Solder Fume Captor from Light Soldering Developments in Croydon.
The Solder Fume Captor is a freestanding mains-operated unit containing a fan which draws air through an activatedcarbon filter at the rate of 2-64 cu.m/min. The idea is to place the device close (30cm or less) to the work. The filter traps the solid particles and absorbs the gases so, providing it is replaced regularly, the air emerging from the rear is almost totally free of tarry deposits and odour."
The carbon filter is replaced by first removing the front cover. This is held by two fixings which need to be turned slightly using a coin. The old filter is discarded and a new one placed in position. The cover is then replaced - a one-minute job.
fl · v. orI
Solder Fume Captor from Light Soldering Developments.
64
Everyday with Practical Electronics, January 1995
VIDEOS ON ELECTRONICS
A range of videos designed to provide instruction on electronics theory. Each video gives a sound introduction and ground-
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magazine study. They are proving particularly useful in schools, colleges, training departments and electronics clubs as well
as to general hobbyists and thosefollowing distance learning courses etc.
VT201 to VT206 is a basic electronics course and is designed to be used as a complete series, if required.
VT201 55 minutes. Part One; D.C. Circuits. This video is an absolute must for
the beginner. Series circuits, parallel circuits. Ohms law, how to use the digital
multimeter and much more.
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VT202 62 minutes. Part Two; A.C. Circuits. This is your next step in under-
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VT204 56 minutes. Part Four; Power Supplies. Guides you step by step
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VT205 57 minutes. Part Five; Amplifiers. Shows you how amplifiers work
as you have never seen them before. Class A, class B, class C, op.amps.
etc.
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VT206 54 minutes. Part Six; Oscillators. Oscillators are found in both linear
and digital circuits. Gives a good basic background in oscillator circuits. Order Code VT206
By the time you have completed VT206 you have completed the basic elec-
tronics course and should have a good understanding of the operation of basic
circuit elements.
Now for the digital series of six videos. This series is designed to provide a good grounding in computer technology.
VT301 54 minutes. Digital One; Gates begins with the basics as you learn
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VT303 54 minutes. Digital Three; Registers and Displays is your next step in
obtaining a solid understanding of the basic circuits found in todays digital
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VT304 59 minutes. Digital Four; DAC and ADC shows you how the computer
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analogue and analogue to digital converter circuits. Order Code VT304
VT305 56 minutes. Digital Five: Memory Devices introduces you to the tech-
nology used in many of todays memory devices. You will learn all about ROM
devices and then proceed into PROM, EPROM, EEPROM, SRAM, DRAM, and
MBM devices.
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VT306 56 minutes. Digital Six; The CPU gives you a thorough understanding
in the basics of the central processing unit and the input/output circuits used to
make the system work.
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By now you should have a good understanding of computer technology and what
VCR MAINTENANCE
VT102 84 minutes: Introduction to VCR Repair. Warning, not for the
beginner. Through the use of block diagrams this video will take you
through the various circuits found in the NTSC VHS system. You will
follow the signal from the input to the audio/video heads then from the
heads back to the output.
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VT103 32 minutes; A step-by-step easy to follow procedure for profes-
sionally cleaning the tape path and replacing many of the belts in most
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found in the tape path.
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Each video uses a mixture of animated current flow in circuits plus text, plus cartoon instruction etc., and a very full commentary to get the points across. The tapes are imported by us and originate from
VCR Educational Products Co, an American supplier. (All videos are to the UK PAL standard on VHS tapes)
makes computers work. This series is also invaluable to the computer technician to understand the basics and thus aid troubleshooting.
VT401 61 minutes. A.M. Radio Theory. The most complete video ever produced on
a.m. radio. Begins with the basics of a.m. transmission and proceeds to the five
major stages of a.m. reception. Learn how the signal is detected, converted and
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VT402 58 minutes. F.M, Radio 1. F.M. basics including the functional blocks of a
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VT403 58 minutes. F.M. Radio Part 2. A continuation of f.m. technology from Part
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doubler, stereo demultiplexer and audio amplifier stages. Also covers RDS digital
data encoding and decoding.
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VTSOl 58 minutes. Fibre Optics. From the fundamentals of fibre optic technology
through cable manufacture to connectors, transmitters and receivers.
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ORDERING: Add £1 p&p per order for UK orders. OVERSEAS ORDERS: Add £2 postage for countries in the EEC. Overseas orders outside the EEC countries add £3 per tape airmail postage (or £5 per order surface mail
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1 Publishing Ltd., Publishers of Everyday with Practical Electronics. Tel: 01202 881749. Fax: 01202 841692 _
CICAH uv/
If-HOIOJRANSISIOR
£29 95
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each mc VAT
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WQ Lar« Base Area
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· /y>» Everyday with Practical Electronics, January 1995
D^GlS7dR
| ; i.
Constructional Project
^
VIDEO MODULES zr
DYNAMIC
NOISE LIMITER
ROBERT PENFOLD
Part Three
Your home videos will take on a whole new meaning if you build these low cost modules. Professional presentations couldn't be easier! You can tailor the controller to meet your own special needs and budget.
· Simple and Improved Faderse Horizontal and Vertical Wipers · Video Enhancer · ^-Channel Audio Mixer · Audio Dynamic Noise Limiter · System PSU
WE round-ofe this short series on the design and construction of a
selection of Video Modules for editing home videos with details for building a Dynamic Noise Limiter. We also
include details for a Simple Mains Power Supply for driving the Modules,
The audio quality of camcorders and video recorders varies considerably. Some have monophonic sound with a rather limited bandwidth and modest signal-tonoise ratio, while others have hi-fi stereo sound.
The lower quality sound systems can certainly benefit from the use of a dynamic noise limiter. This improves the apparent
signal-to-noise ratio using dynamic lowpass filtering.
A system of this type relies on the fact that the background "hiss" is masked by the main signal at high volume levels. It is only at low volume levels that the noise
becomes intrusive. At high volumes it will probably not be audible at all.
The basic idea is to have quite strong lowpass filtering at low volume levels. This gives some loss of audio quality, but because the tape "hiss" has a strong high frequency content, it gives a large reduction in the background noise level. At
higher volume levels the lowpass filtering is steadily reduced, and at the highest volume levels it is removed altogether.
A fixed amount of lowpass filtering would tend to give crescendos that were lacking in impact due to the lack of treble content. Dynamic filtering gives what is subjectively an equal amount of noise reduction, but with the full bandwidth provided at high volume levels the reproduced sound has much more "sparkle" and impact.
SYSTEM
OPERATION The block diagram for the Dynamic
Noise Limiter (D.N.L.) is illustrated in Fig. 20. The input signal is applied to a buffer amplifier, and from here the signal is split two ways. The main route is through a voltage controlled lowpass filter (v.c.f.), and then to the output via another buffer amplifier.
The voltage controlled filter has a control which permits the minimum cut-off frequency to be set by the user. This effectively operates as a noise reduction control. The lower the cut-off frequency is positioned, the greater the degree of noise reduction.
AMBUPLFFIFEIRER
1 CUM -Wn
V.C.F.
ABMUPFLFIEFRIER
Of course, using a lot of noise reduction also gives a large loss of audio quality at low volumes. This control therefore has to be set for a frequency that gives the best
compromise between high noise reduction on the one hand, and loss of audio quality on the other.
A side chain is used to generate the control voltage which raises the cut-off frequency of the v.c.f. at high volume levels. The first stage in the side chain is a highpass filter. The high frequency "hiss" is
masked more readily by high frequency signals than by low or middle frequency signals.
It is therefore necessary to make the unit respond much more readily to treble signals than to bass or middle frequency signals. This avoids having strong bass signals raise the cut-off frequency, producing noticeable increases in the background
noise level. If we did not do this, it would produce
some very odd sounds known as "breathing" effects. The highpass filtering makes the unit very insensitive to low frequency input signals, and eliminates the risk of "breathing" effects.
The next stage in the side chain is an amplifier which boosts the signal to an adequate level to drive the subsequent stage correctly. This is a rectifier and
smoothing circuit which produces a positive d.c. output voltage that is roughly proportional to the amplitude of the audio input signal.
This voltage is amplified slightly, and then applied to the control input of the v.c.f. Here it provides the required raising and lowering of the cut-off frequency in sympathy with changes in the input level.
I HttWt I
HIGHPASS * FILTER
AMPLIFIER
SRMEOCOATTNIFHDIIENRG
D.C. AMPLIFIER
Fig. 20. Block diagram for the Dynamic Noise Limiter (DNL).
CIRCUIT
OPERATION The full circuit diagram for the Dynamic
Noise Limiter appears in Fig. 21. IC1 is used as the input buffer stage, and this is a simple operational amplifier voltage follower circuit.
66
Everyday with Practical Electronics, January 1995
A dual transconductance operational amplifier (IC2) is used as the basis of the voltage controlled lowpass filter. The configuration used is actually a form of state variable filter, but in this case it is only the lowpass filtering at the output of IC2b which is utilized. This is a two stage filter giving an attenuation rate of 12dB per octave.
Each section of IC2 has a built-in emitter follower buffer amplifier. Resistors RIO and RI6 are the load resistors for these buffer stages.
Strictly speaking the filter is current rather than voltage controlled. However, simply adding a resistor (R26) in series with the control input gives a current flow that is roughly proportional to the input voltage, and gives normal voltage control of the filter. Rotary control VRI provides a variable bias current to the control input of the filter, and the minimum cut-off frequency can therefore be varied by means of VRI.
HIGHPA SS FtL TER The highpass filter is a simple second or-
der (12dB per octave) active type based on IC3. It has the cut-off frequency at a little over 2kHz. The output signal from IC3 is amplified by an inverting mode amplifier based on IC4.
Preset potentiometer VR2 enables the closed loop voltage gain of IC4 to be varied from just under three (9dB) at minimum resistance, to a little over 10 (20dB) at maximum resistance. This enables the unit to operate properly with a reasonable range of input levels.
The rectifier circuit is a simple half-wave type based on diodes D1 and D2.
«« -
e
·-
<1 A
3 | A.,
Component layout on the completed Dynamic Noise Limiter p.c.b.
Germanium diodes are used here because they have lower forward voltage drops than silicon types. Resistor R24 and capacitor C13 are the smoothing network. The attack time of the circuit is very short, and although the decay time is much longer it is still quite short.
The decay time has to be something of a compromise. It needs to be short enough to ensure that the unit responds rapidly to changes in the input level, so that short bursts of "hiss" are not produced during very brief pauses in the input signal. On the other hand, it must not be so short that the input signal modulates itself and generates significant amounts of distortion. R24 and C13 have a time constant of approximately 5mS, which gives excellent results.
D.C. AMPLIFIER The d.c. amplifier stage is built around
ICS and the closed loop voltage gain of this non-inverting amplifier is only two (6dB); its main purpose is to act as a buffer
amplifier. Note that the CA3140E specified for ICS is an operational amplifier that will work properly as a single supply d.c. amplifier. Most other operational amplifiers need dual balanced supplies for d.c. operation, and will not work properly in the ICS position of this circuit.
For stereo operation the two channels are normally processed separately. Therefore, if a stereo version of the unit is required it is merely necessary to build two noise limiter boards, one for use in each stereo channel. The current consumption of one Dynamic Noise Limiter circuit is approximately 8mA.
CONSTRUCTION Details of the Dynamic Noise Limiter
printed circuit board component layout and full size copper foil master are provided in Fig. 22. This board is available from the EPE PCS Service, code 919.
On the prototype an LM13600N transconductance op.amp i.e. was used.
I00V
3k3
100 k
IuCA 1741
lCO2u
4 C730n
II--(H SKI
R1030k
| INPUT |
3W9 120k
470 -AA/
ILCM12370Q 1R090k
3k9 n 220 yt I
0+12V
.
V10R0Ik
n62iUl
(R.7102
"S ^
C7
R13
iLMc1N3700y^^, +\]|i
R10U0'k fj 150p
II 2C260p
OUTPUT 5K2
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R27IBk IC3 pw-l
^C170 5R^260
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3C3120n 0A91
R1205k
1R52kb
II
H
ICC&3S140
. a 0DAI91
R102k7
I 1£EC6>6G I
R152k4 Q C33130n I
Fig. 21. Complete circuit diagram for the Dynamic Noise Limiter (DNL) module
Everyday with Practical Electronics, January 1995
67
but the LM13700N stocked by some component suppliers is virtually identical and will work just as well. The CA3140E used for ICS has a PMOS input stage, and it therefore requires the usual anti-static handling precautions.
Take care not to overheat diodes Dl and D2 when soldering them to the board. The OA9I is a germanium device which is more vulnerable to heat damage than a silicon diode.
The polyester capacitors should be printed circuit (p.c.b.) mounting types having 7-5mm (0-3 inch) lead spacing. Other types will not fit easily into this component layout.
The hard wiring is also included in Fig. 22, and this is very straightforward. Phono sockets are used for SKI and SK2 on the prototype, but either or both of these can be changed to a different type if it will fit in better with your equipment.
A DJUSTMENT When initially testing the unit it should
be connected between a suitably "hissy" signal source and an amplifier/speaker so that you can monitor the quality of the output signal. Preset VR2 should be set for minimum resistance (fully clockwise) initially. The front panel potentiometer VR1
vR 1
COMPONENTS
guidance only
16
DYNAMIC NOISE LIMITER
Resistors
R1
3k3
R2, R3, R9,
R14
100k (4 off)
R4, R5, RIO,
R16, R17 3k9 (5 off)
R6
120k
R7, R8, R12,
R13
470 (4 off)
R11
82k
R15, R23,
R24, R26 15k (4 off)
R18
27k
R19
33k
R20
5k6
R21, R22,
R25, R27,
R28
10k (5 off)
All 0-25W 5% carbon film
See TALK Page
C3 C4 C5 C6 C8, C9 C10 C12, C13
470n polyester 220p radial elect. 10V 150p ceramic plate 220p ceramic plate lOn polyester (2 off) 47|j radial elect. 63V 330n polyester (2 off)
Semiconductors
D1,D2 OA91 germanium signal
diode (2 off)
IC1, IC3.
IC4
pA741 C op,amp (3 off)
IC2
LM13700N or
LMI3600N
transconducatance
op.amp
IC5
CA3140E op.amp
Potentiometers VR1 100k rotary carbon, log VR2 47k min. preset, horizontal
Capacitors
C1
100g radial elect. 16V
C2, C7, C11 10p radial elect. 25V (3 off)
Miscellaneous SK1,SK2 Phono socket (2 off) Printed circuit board available from the
fPf PCS Service, code 919: 8-pin i.e. holder (4 off); 16-pin i.e. holder; control knob; connecting wire; single-sided solder pins; solder etc.
Fig. 22. Dynamic Noise Limiter printed circuit board component layout, wiring and full size underside copper foil master track pattern.
OO* >-l R13 P«
R'2 p»
»-t ms K
F· L I In4 J. aJ P7 La jS?~*
f
Wz, r{
L--J 0
INPUT |
I OUTPUT |
U jffi
M
O O
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o ICS
bo ."A 1.1
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68
Everyday with Practical Electronics. January 1995
should act rather like a treble tone control, giving considerable control over the background noise level.
The amount of treble cut used is entirely up to the user, but it is probably best to settle for a relatively modest amount if the programme source is mainly music. With other sources a large amount of treble cut might be preferred.
Although one might think that a high degree of treble cut on low level signals would make the action of the dynamic noise limiter fairly obvious, in reality this does not happen. Although human hearing is very good at detecting imperfections in sounds, it seems to be unable to detect the widely varying cut-off frequency of a
dynamic noise limiter. It is therefore quite acceptable to use a large amount of noise reduction provided the loss of treble at low volume levels is deemed acceptable.
With VR2 at minimum resistance it is unlikely that the treble cut will be lifted properly at high volume levels. Adjusting VR2 in a counter-clockwise direction should improve matters, giving a "brighter" sound during the high volume passages.
Using an excessive resistance will result in the treble cut being lifted too readily, giving a lot of "hiss" during quiet passages. The optimum setting for VR2 is the highest resistance that maintains the noise reduction during quiet passages.
IN USE
A Dynamic Noise Limiter is only used during final playback. In a video context
this means that it will normally be connected between the audio output of the video recorder and the audio input of the television set or monitor. It should NOT he used between a camcorder and a video recorder, or at any stage during the editing of a tape.
A dynamic noise limiter is used during final playback since this is where there is the most noise to deal with, and the noise limiter can have the greatest effect. The unit should work with any "hissy" signal source, such as a cassette deck playing old recordings.
MAINS POWER SUPPLY
V V --
Rower the Video Modules with this simple stabilised 12V d.c. output design.
These video and audio processing cir-
cuits can be powered from a 12V battery, such as eight HP7 size cells in a plas-
tic holder. This is not a particularly cheap
ON/OFF Sla
INu4i002
way of powering the circuits though, even if only one or two are constructed. It would be quite an expensive means of powering a Video Controller incorporating several of the modules featured here.
The simple Mains Power Supply circuit of Fig, 23 is a better way of powering the circuits. This provides a well stabilised and smoothed output at currents of up to several hundred milliamps. It
240V oo 15V tMT
M24A0IVNS
o ov
o
0Vo
oo 15V
D2 1N4002
Sib
M
50F0Sm1A IOOCO1JJ
IC1 OUT >JA7812
COM
+12V lCO3On l1OUTPUTSl
tOCO2 n
OV
can, therefore, supply a full set of these video modules, plus stereo versions of the
E O
X
Dynamic Noise Limiter and Audio Mixer, and still have something in reserve for the
IEE469>6 1
possible addition of further circuits at a
later date. The circuit has full-wave rectification of
the push-pull variety, with smoothing sup-
Fig. 23. Suggested Mains Power Supply circuit. It is capable of driving a full set of Video Modules.
plied by capacitor C I. ICI is a monolithic
None of the modules require a par- The electronic smoothing provided by IC1
voltage regulator which provides regula- ticularly well stabilised supply, but in most is therefore of greater importance than the
tion and electronic smoothing.
cases a well smoothed supply is needed. accurate regulation of the output voltage.
C2 and C3 are decoupling capacitors. Their
Power supply board and mains transformer installed in a Video Controller case and main purpose is to prevent 1C1 from
wired to one of the Fader modules.
becoming unstable.
Viz
T
CONSTRUCTION
Full details of the Mains Power Supply printed circuit board and wiring are provided in Fig. 24, This board is available from the EPE PCB Service, code 920.
An anti-surge fuse is used for FS1 and not the more common "quickblow" variety (which would tend to "blow" at switch-on as electrolytic capacitor C1 charged up). FS1 is mounted on the board via a pair of 20 millimetre fuse clips.
The voltage regulator IC1 is bolted to the board using an M3 or 4BA screw and fixing nut. If the supply is only used to power two or three modules it is should not be necessary to fit IC1 with a heatsink. If it
69
is used to power more than three modules it
would be advisable to fit IC1 with a small
finned heatsink.
Be careful to avoid errors when wiring up
the power supply, particularly when deal-
ing with the dangerous mains wiring. Ifyou
are in any doubt about tackling the mains
wiring you must seek the advice of a profes-
sionally qualifiedperson.
A solder tag fitted under one of TPs
mounting bolts provides an Earthing point
on the case, which must be of all-metal
construction. It should also be a case which
has a screw fitting lid, not a clip-on type.
All the normal safety precautions should
be observed when dealing with the power
supply unit.
There are four pairs of output pins, but
there should be no difficulty in connecting
each set of pins to two or more modules if
the supply is used to power more than four
modules. Make sure that each module is
connected to the supply board with the cor-
L
rect polarity.
FINALLY The mechanical aspect of construction
must be varied to suit the particular modules used, and personal preferences. Probably most users will prefer slider controls for the "Wipe" and "Fade" controls, while
\
\ (S)
\
y
\ IC1 y
240V
15V
· · 15V
k Ik . -OTDDi 02
#J
4-12 7 0V
-4-12V 0V
-4-12V 0V 4-12V OV
IEEt69>6 I
LMAINNS E
Fig. 24. Printed circuit board component layout, wiring and full size underside copper foil master for the Mains Power Supply.
COMPONENTS
MAINS POWER SUPPLY
Capacitors
See
01
lOOOp radial
elect. 25V
02,03 lOOn ceramic TALK
(2 off)
Page
Semiconductors D1,D2 1N40021A 100V rectifier diode (2 off) 101 pA7812 1A 12V positive voltage regulator
Miscellaneous
T1
15VA mains transformer:
240V a.c. primary:
15V-0V-15V secondary
SI
rotary double-pole mains
switch
FS1 20mm 500mA anti-surge
fuse
Printed circuit board avaiable from
the EPE PCB Service, code 920; con-
trol knob: pair of 20mm fuse clips;
small finned heatsink: connecting wire:
single-sided solder pins: solder etc.
Approx cost guidance only
70
others (myself included) find these difficult to use and prefer rotary controls.
If slider controls are used the unit must be housed in a large case of the sloping front variety. The slits for the potentiometers can be carefully cut and shaped using needle files. This job needs to be done very carefully if neat results are to be produced.
If rotary potentiometers are preferred it will still be necessary to opt for a fairly large case. A typical Video Controller having something like a Fader, a Wiper, and an Audio Mixer will require a large amount of panel space in order to accommodate the controls and sockets. A low-
profile 19 inch rack-mount case is just
about ideal, if not particularly cheap - see
photographs.
In theory it is possible to wire several
of the video boards in series, and then
operate any required "Fader", "Wiper", or
whatever. In practice this is not a good way
of working.
Feeding the video signal through a chain
of video boards results in the signal passing
through numerous stages, and inevitably
degrades the signal to a significant extent.
It is better if each unit is "patched-in" only
when it is actually going to be used, so that
the video signal board at a time.
is
only
processed
by
one
V *
<t -3
A Video Controller unit made up from some of the modules described. Everyday with Practical Electronics, January 1995
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HART PCB SOLDERING PRACTICE KIT Your chance to learn or try your soldering skills on a real Hart printed circuit board! This kit comes with a range of modern components, a typical Hart quality PCB, a roll of the correct grade of solder and your full learning guide. It enables the enthusiast who is uncertain of his. or indeed her, ability to put together and solder a printed circuit to try their hand first at minimum cost. The instructions explain the right technique and guide even an absolute beginner through the seemingly daunting, but in fact very simple, art of making a good soldered joint. The Hart Printed Circuit Board Soldering Practice Kit repcesents excellent value for money at only £4.99.
with separate chapters on such things as compact
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makes it ideal for the enthusiast of recorded music
wgohiongwoanntisnthoiskCnoDwplmayoerre. about the hidden processes
1992/94 248 Pages. 247 x 190.
0-7506-0614-2
£17.95
INTRODUCING DIGITAL AUDIO CD, DAT AND
SAMPLING 2nd Edition. Ian R. Sinclair.
For enthusiasts, technicians and students.
Covers CD and DAT. Philips DCC and Sony Mini Disc,
the digital techniques involved are explained non-
mathematically.
Digital audio involves methods and circuits that are
totally alien to the technician or keen amateur who
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end product. This second edition has been updated
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taken to add a glossary of technical terms.
1992 168 Pages. 217 x 138. 64 line drawings.
ISBN 1870775 22 8
£7.95
"THE ART OF SOLDERING", R Brewster
Absolutely essential reading for anyone who ever
picks up a soldering iron. Written from knowledge
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to the correct procedures to follow with many illustra-
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"HOW TO USE OSCILLOSCOPES & OTHER TEST
cSuesntdomoOresrregpsdrehevPatrOoirlicyeennOreoaegde.VuseqPfieErrsouasRoaraeyrdoSlaymdldvEsyoeyeeAuprwrn.rSaotJ£ernc-u2lbtco0yscPioptto-sclmywse£hwtae3reoo,asi.fqt5fyebeu0ocuste.ouaote,ErrrPecyrtxFLeioatpaRlEushegrhEeAeTpeEsSoHohsaErroAnLdCncTdsieresoeretDiuniydnnAordoisigfYteuu2cr.trirh,naaIrRenrfnedoseCcqerxeumsAtiaaiwarfntseteyoidmolforeoknuemplilnnwwhoatgownisatnynhdsteotao-pdayIsutNahol£rLimer1sldArti0pse.sNtKlreseD.inwttsthOitse&hrudfyrCrefoiaerouscnmreducplppyroeotnadosneti£,tnd2octse0rafr-5fdEi£cfn1onie.qru5nuAm0ti,irHbrimeeAsraRwifTlr.iollm Overseas
EQUIPMENT", R.A Penfold, 112 pages. 178 x 111.
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Everyday with Practical Electronics. January 1995
71
s
H
H
TROUBLESHOOTING ANALOG CIRCUITS
Author Robert A Pease
Price
£14.95 paperback edition 1993 (see note helow)
Publisher Newnes-Butterworlh ISBN 0 706 1632 6
Most readers of EPE will know just how few electronics books are available between the "100 Best Projects for Beginners" variety and the heavyweight mathematical tomes more suited to university-educated professionals. Any publication which helps to fill this gap is therefore most welcome, especially when it contains the wealth of solid practical information contained in this book.
Author Robert Pease is a senior engineer of vast experience with National Semiconductor Corporation, and has been designing i.c.s and circuits and trouble-shooting customers" problems for many years. With so much of his life spent at the "sharp end" of the business, you name the problem and he's seen it. and here he passes on his wealth of knowledge for the rest of us.
There are chapters covering the various kinds of components, both active and passive, in fascinating detail. The advantages and shortcomings of each are clearly explained. Various causes and cures of real problems encountered through design and
manufacture are discussed in depth, many of these being surprising and far from obvious. Other chapters include working with test equipment and useful design and testing techniques, often with helpful practical circuits.
With so much information, you might think this book would be "heavy" and loaded with difficult maths. Not so, there is hardly a formula to be seen, and the author's humorous style makes this a book you can even enjoy reading at bedtime! Numerous points are illustrated with photographs, often with amusing captions. "Use a big enough heatsink", he advises beneath one showing a power transistor bolted to a motorcycle cylinder head. "Spice printouts are almost always good for something", suggests another in which he is lining the bottom of a birdcage!
His distrust of computers is illustrated with a picture of him hurling a particularly troublesome one from the third floor of a car park. Incidentally, have you heard about the ultimate solar-
powered night-light? Seems it doesn't need a battery, just a 12,000 mile extension lead!
This book is much more than just a guide to trouble-shooting. Fascinating and fun to read, it will prove invaluable to beginners and experts alike and should be in the library of every enthusiast. If you've ever designed or built a circuit that failed to perform as expected and you couldn't see why, the answer is probably here. In the unlikely event that it isn't, you'll still have a most enjoyable read and your understanding of electronics and its problems will undoubtedly be enhanced.
ANDY FLIND
Note: We are advised by the publisher that only the earlier edition at £22.95 (paperback) is now available - ISBN 6 705 6 9499 8 - Ed.
THE CYBERSPACE LEXICON
Author Bob Cotton and Richard Oliver
Price
£19.99
Publisher Phaidon Press ISBN07148 28262
The new Cyberspace Lexicon just brought out by Phaidon Press is a book for all seasons. The word "lexicon" and its sub-title "An illustration of terms from Multimedia to Virtual Reality" could well indicate yet another drab reference book to sit besides the dictionary on the bookshelf, but the reality is very different.
This is an intensely exciting and stimulating book for anyone
remotely interested or involved in today's technology, and a valuable introduction to multimedia for a novice. Excitingly illustrated in striking colours and stylishly written with wit and erudition, it could soon find a place on coffee tables as well as being a valuable addition to the bookshelf of anyone who keeps in touch with the rapid advances in science today.
Just what is Cyberspace? Herbert Marshall McLuhan foresaw it alt in 1964:
72
"Men are suddenly nomadic gatherers of knowledge, nomadic as never before, informed as never before, free from fragmentary specialism as never before - but also involved in the total social process as never before; since with electricity we extend our central nervous system globally, instantly interrelating every human experience." The book takes us through the "information explosion" that has taken place this century and looks ahead to an even more powerful technological and commercial drive to perfect systems that will bring the means of receiving and transmitting information into every home "and even into every pocket". Observing that a large proportion of the planet's business is focused on the development of new cyberspace markets, the two authors set out to provide a guide through the maze of these new and emerging technologies. "As media and telecommunications converge with computing and with consumer electronics to create the cyberspace infrastructure. as concepts collide and catalyse, so the vocabulary needed to deal with this phenomenon becomes polygot, even pidgin." Hence the Lexicon - a key to this new vocabulary and to the new medium of hypermedia and concept of cyberspace. Arranged conveniently in alphabetical sequence, so that it is easy to refer instantly to anything the reader needs to know, the Lexicon lifts its appeal right out of the dictionary class by adding excellent editorial features on the more interesting technological items in each alphabetical section, backed up by outstanding illustrations in wonderful colours. It gives much space to graphic design technology which has in itself contributed much to the production of this handsome book. The range of technology covered is impressive; the contents are likely to have as much appeal to the science professor as to the schoolboy hobbyist fascinated by "Cyberpunk" and Nintendo - (the latter neatly sub-titled "Gameboy of the Western World".) The reader can learn all about such things as Anamorphic Projection and Hyperspatial devices. Fractal Compression, Remote Sensing and Multi-spectral scanners, as well as Augmented Reality and Ray Tracing. Amongst the short features which give the book that "Can'tput-it-down" factor are a description of the Dynabook ("the 25-year-old blueprint of the future") and the Media Lab ("as much a metaphor for the worldwide media situation as it is a particular building in Massachusetts.") We are told this has been called the Bauhaus of the laje 20th century because, just as Bauhaus used the new industrial technologies of plastic, steel and electricity, so the Media Lab fuses the new information technologies of AI, silicon chip microprocessors and fibre-optics. There is a distinctly new slant on Interactive Broadcast TV with its witty sub-heading "Nerd vs Couch Potato", and a fascinating feature on Datagloves and Powergloves - subheaded "Hands on in Cyberspace" with particularly arresting photographs. Surrogate Travel has another engaging subhead "Around the world in 80 nanoseconds." Space is found for a feature on "Virtual Sex", a US Government-funded experiment which is described in some detail, although the piece records the fact that funding was withdrawn when the US Government realised the process could threaten the institution of marriage and encourage "virtual promiscuity" on a large scale. Read all about it in the Lexicon. Photographic enthusiasts will enjoy the striking photographs in "Virtual Reality" and "Music Plus" sections. Keen readers will be interested in Xanadu, an experimental hypermedia/storage management system to provide users with Hypertext links to all the books in the world's libraries and museums "and make you part of a new electronic literature and art, where you can get all your questions answered." The book's authors conclude with an answer to critics who attack the new "smart" media because it threatens accepted standards of literacy and numeracy, destroys our ability to think, and usurps accepted practices of education. The authors reply that there is no real conflict between the older media and the new. "In the world of Cyberspace people will still read books printed on paper, listen to music in concert halls, and look at paintings and sculptures in galleries. But they will have a further choice: to become active participators in a worldwide matrix of media and telecommunications, to become "nomadic gatherers of knowledge", or just enjoy the new experiences of the largest entertainment and education machine yet devised."
HAZEL CAVENDISH
Everyday with Practical Electronics, January 1995
Itancs BACK ISSUES
We can supply back issues of EPEby post, most issues from the past five years are available. An index for each year is also available - see order form. Alternatively, indexes are published in the December issue for that year. Where we are unable to provide a back issue a photostat of any one article (or one part of a series) can be purchased for the same price.
DID YOU MISS THESE?
SEPT. '93 PROJECTS · Sound Activated Camera Trigger · Lightwork (trailer light checker) · Charge - 15 (NiCad charger) · Amstrad PCW-8 Channel ADC, Part 2. FEATURES · Audio Amplifier Design, Engineering or Alchemy, Part 2 · Teach-in '93 Part 11 · Chicago Consumer Show · Special Review Tracktronics · Working it Out.
OCT. '93 PROJECTS · Multi-Purpose Audio System, Part 1 · Magic Socket · Linear Power Supply · Fake Car Alarm · Kettle Alert · L E D. Sandglass. FEATURES · Audio Amplifier Design, Engineering or Alchemy, Part 3 · Teach-in '93, Part 12 · Becoming a Radio Amateur.
tes
BLECTRONfCS
.·· · ·
NOV. '93 NHMhRMM PROJECTS · Portable Miniguard (PIR alarm) · Tracktronics Projects (Thyristor Latched L.E.D. Display, Night Light, Twin Input Status Indicator) · 20 Metre Direct Conversion Receiver · Inside the Electric Guitar · Multi Purpose Audio System, Part 2. FEATURES · Velleman View · Electronics Principles, Special Software Supplement. rU\ctro*. 'Q51Q,5
PROJECTS · Three-Way Christmas Tree Lights Flasher · Auto Alarm · 250W/600W Inverter and Uninterruptable Power Supply, Part 1 · Multi-Purpose Audio System, Part 3 · Waterproof Delay Switch. FEATURES · Safety First, Part 1 · Index for Volume 22.
JAN. '94
PROJECTS · Autolight (automatic
nightlight) · Timer and NiCad Capacity
Checker · 250W/600W Inverter and
Uninterruptable Power Supply, Part 2 ·
Multi-Purpose Audio System, Part 4 · Pond
Heater Thermostat.
FEATURES · Safety First, Part 2 · Calcula-
tion Corner, Part 1 · Electronics Testing and
Fault Diagnosis, tcCcnD. 'OA
Cou rse
Review.
PROJECTS · Whistle Controlled Light Switch · Reviving the Valve Sound (rebuilding the Quad II power amp) · Introduction to Microcontrollers - Timeout · Battery To Mains Inverter and Uninterruptable Power Supply, Part 3 · Multi-Purpose Audio System, Part 5. FEATURES · Calculation Corner, Part 2 · Safety First, Part 3 · European International Audio & Video Fair.
MARCH *94
PROJECTS · Smart-Key Immobiliser · Audio/R.F. Monitor · CCD TV Camera, Part 1 · Visual Doorbell · Three-Phase Generator. FEATURES · Safety First, Part 4 · Calculation Corner, Part 3 · Free Wall Chart - Electronics Formulae 1.
APRIL'94 PROJECTS · MOSFET Variable Bench Power Supply · EPE Soundac (PC sound output board) · CCD TV Camera, Part 2/Frame Grab · Impulse Clock Master Unit · Telephone Ring Detector. FEATURES · Best of British, Part 1 · Calculation Corner, Part 4 · Electronics Workbench Review · Free Wall Chart Electronics Formulae 2. MAY'94 PROJECTS · Simple TENS Unit (transcutaneous pain relief) · Capacitance/Inductance Meter · LED. Matrix Message Display, Part 1 · Stereo Noise Gate · Dual Stepping Motor Driver for PCs. FEATURES · Calculation Corner, Part 5 · Best of British, Part 2. JUNE'94 PROJECTS · Microcontroller P.I. Treasure Hunter · Digital Water Meter · Microprocessor Smart Switch · Advanced TENS Unit (transcutaneous pain relief) · L.E.D. Matrix Message Display, Part 2. FEATURES · Best of British, Part 3 · Calculation Corner, Part 6
, : . PROJECTS · Voxbox Voice Recording Board · Simple NiCad Charger · Watering Wizard (automatic garden watering). Pocket Print Timer · Stereo HiFi Controller, Parti. FEATURES · Best of British, Part 4 · Calculation Corner, Part?. AUG. '94 PROJECTS · Experimental Noise Cancelling Unit · Dancing Fountains, Part 1
· Charged-Up (PC battery tip) · 6802 Development Board a TV Camera Update · Stereo HiFi Controller, Part 2. FEATURES · Calculation Corner, Part 8 a Best of British, Part 5 a I'll Be Seeing You (multimedia communications)
SEPT. '94 PROJECTS a Protector Plus Car Alarm a Greenhouse Watering System a Experimental Seismograph, Part 1 a Three-Channel Lamp Controller, Dancing Fountains, Part2. FEATURES a Calculation Corner, Part 9 a The Invisible Force (magnetic force).
ELECTRONICS
OCT. '94
1
PROJECTS a Digilogue Clock a Visual/Audio Guitar Tuner a Hobby Power Supply a Audio Auxiplexer a Experimental Seismograph, Part 2. FEATURES a Electronics from the Ground Up, Part 1 with Free PC Software a Calculation Corner, Part 10.
NOV.'94 .
a y-M
PROJECTS a 1000V/500V Insulation Tester a Video Modules, Part 1 (Simple Fader, Improved Fader, Video Enhancer) a Active Guitar Tone Control a Power Controller a TV Off-er. FEATURES a Electronics from the Ground Up, Part 2 a Consumer Electronics Show.
DEC. '94 PROJECTS a Spacewriter Wand a EPE Fruit Machine a Universal Digital Code Lock a Video Modules, Part 2 (Horizontal Wiper, Vertical Wiper, Audio Mixer) a Rodent Repeller. FEATURES a Electronics from the Ground Up, Part 2 a Embedded Controllers a Index for Volume 23.
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Everyday with Practical Electronics, January 1995
73
H iCTRONIC
H FT WAR
from E.P.T. Educational Software (Tel; 0376 S14008)
If you are looking for a means of improving your knowledge of
the basics of electronics then this software is for you.
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ELECTRONICS PRINCIPLES II
Insulators, Conductors, Resistance D.C. Circuits
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A.C. Parallel Circuits Reactance and Impedance
A.C. and D.C. Power Frequency and Tuned Circuits
Using Numbers Complex Numbers, Phase Angles
P.N. Junction Diode Transistors Operational Amplifiers
LFloipgiFc lGopastes
Digital Counters
Number Systems and Shift Registers
Microcomputer operation
CoMmebminoartyional
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GCSE ELECTRONICS
Designed to complement our Teach-in No. 7 publication, which contains a complete electronics course aimed at GCSE and A Level students, this software can also be used as a stand alone learning package for everyone interested in electronics. From simple cur-
Electronics Principles II is a major revision of the successful rent flow and Ohm's Law it covers the
original version currently used by electronics hobbyists, schools, whole GCSE sylabus from a.c. to semiconduc-
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and overseas. Some of the modifications are as a result of feed- grounding in microprocessors.
back from teachers, but mostly the changes are due to making An interactive, user friendly medium which
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this makes all those topics available within a module, clearly visible to the user. The layout of the calculations is considerably enhanced, firstly by providing the formulae used and secondly by showing the calculation steps, exactly as in a textbook; the
advantage here being that you can input your own values. Having reviewed a dozen, or more, educational software packages
Only £24.95 inc. VAT Teach-in No 7 152 page A4 book £3.95 including a Special Limited Version of GCSE Electronics software which covers the first two of the 12 parts of the course, thus enabling an assessment of the complete package. Both the book and the software can be used on their own.
designed to "teach" electronics, I was more than a little sceptical when I first heard about Electronics Principles: there seemed to be
DEMONSTRATION DISK
little that could he done that has not been done elsewhere. When I
Special demonstration disk
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pressed with it that I quickly came to the conclusion that Everyday with Practical Electronics readers should have an opportunity to try the package out for themselves! - MIKE TOOLEY B.A. Dean of
Faculty of Technology, Brooklands Technical College Over 200 menu driven screens with interactive graphics enabling a
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GCSE Maths and Mathematics Principles is available for £2 (Overseas orders send £3) includes post and packing.
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ELECTRONICS PC TOOLBOX VERSION 2.0
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Covers D.C. Calculations from Ohm's Law to Loading a Potential Divider; Further D.C. Calculations from Power Ratio Decibels to Kirchhoff's Laws; A.C. Calculations from Average Peak Current to Filters and Admittance; Capacitance Calculations from Values to RC Time Constants; Inductance Calculations from Values to Selectivity; Binary Calculations from Addition to 2's Complement; Numbers and Phase Angles from Addition to Polar to Rectangular; Operational Amplifiers from Inverting Op.Amp to
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Qllly £19.95 inc. VAT
GCSE MATHS A series of programs covering all the major topics required by the school syllabus. Designed to be user friendly enabling you to study or revise in what we believe is an interesting and enjoyable way. There are nearly one hundred and fifty menu driven screens with interactive graphics, enabling a "learning through doing" approach to encourage experimentation. Now being used in many schools throughout the U.K. Overseas customers or those with general interest in maths order Mathematics Principle - covers the same subjects without reference to GCSE.
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These programs require a PC (or fully compatible system) running DOS with an 80286 or better processor and VGA (ideally colour) graphics. In addition you must have 4Mb of hard disk space, a high density (l-44Mb) floppy drive and at least 640K of RAM. We also recommend the use of a mouse. Site licences are available - please enquire.
Distributed by Direct Book Service, 33 Gravel Hill, Merley, Wimhome, Dorset, BH211RW. (Mail Order Only).
Add £1 per order for UK post and packing. Make cheques payable to Direct Book Service.
Direct Book Service is a division of Wimbome Publishing Ltd. publishers of Everyday with Practical Electronics.
Tel: 0202 881749. Fax: 0202 841692. Visa and Mastercard orders accepted (minimum credit card order £5) - please give card number, card expiry date and cardholders address if different
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74
Everyday with Practical Electronics, January 1995
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The books listed have been selected by Everyday with Practical Electronics editorial staff as being of special interest to everyone involved in electronics and computing. They are supplied by mail order direct to your door Full ordering details are given on the last book page. For another selection of books see next month's issue
TESTING, THEORY AND REFERENCE
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Everyday with Practical Electronics, January 1995
75
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138 pages
£4.95
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124 pages
Llitit] £4.95
CIRCUITS AND DESIGN
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76
Everyday with Practical Electronics. January 1995
PROJECT CONSTRUCTION
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TRE. AST. PEeQnUfoIlPdMENT CONSTRUCTION Tamgonnehedtinchstoeib.nnroeSswoxttrkrpiuitephdcnbetwsiosoiciavnrrreiidnabbgneludasdtyiiueanoxsgudetrtreasetmmaaisrleelwhypohurweosrevetfioudalcep,odppnrifoseotpcrrreuaiscallttoesfd,oetpmeslsiuegtsnessiqnm,uoipttpoele-s
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AUDIO AND MUSIC
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cbi9noo6dmopikcmaagitosiennstgofahhuoeltlwspthtahanetdcraewnahdoeecrrecoutvroewrschtoaermnt ebloujouiklsdtinintghgefusoepr ppmrraoonjbeylcetm£osf.2s.t9hb5ye AR.UAD.IPOeAnfMolPdLIFIER CONSTRUCTION dcttrapppTiMliisaaOne.rlnnhcATenehOpsdgge.OtagliohbaelS--gmpeebp.puuFnttuRelpahopphoEesprdglrIefeTpiArop,oefrspepoirrfsacActeartrosrnogtieyrmoieercgvapipcjsavepmeoeebtuetndiyclrfonsiipgdputtffatmgslrieehrairoeevfasdnoiuarmiss,aresdprdrterbcaiistelioanaoraoorsrelrouoncewsie1rsuk[gddloqtma8ianaetuttipWpopasiisssiEvnooclrnetgecerwwioroelinilndeybvuueecpqcheetdErrilruopeenndueoainaaub.,drvmmodsttaeaWeirbr.ytmdpodtu1elaelheleittps2orfroenta.yriiwhreetntveTfosecaroo.mmochdnrnpsleneteeupaoeoascslrcibsptdisiaectfrrgoeetsiuiecienwdrssocarasgmsw,tnesrfetryeuiihucttsalaahsaoarlmmiyotnnna£pwo1yppggchw02lluoisiislo0ffti9mlieetih,indWetate5e---ieerrrt eSsapBPR1ilnrhRde1EodocAe2jGOtewpo.rbIcJofasNPotEnsgeoeNiCtleckhneEsTcsefpRtoSrrclAooodSnjlmesiGcocpstUs,liensIttDochelatuEbhtdTeaaegtOrsiehneeBnrxeoeUagrrmIusLhlhpaDoelrewlIycsNatGfnionecaEtottauhLncrefEekiddlCfeoeTirnntmRhtlemOyoNbapfgurIsaiaC"liczdmStiintpc9hela5eesl
RADIO/TV
cttgS8TwoibmSIhsi.orae6oeEhehTAaDnmnstneiTnpeitohnrse.cixyiaTatnpoefhnrPIpgiieigdItrugmraceoNtehssetcssnshtswaaoudtGpeosisvecplfoeainfteneuoviecvnUtsltvteipttle;hphaso.ePlstilreePrlrsToiboaeaAirsanocrsfdneebtdNnehepasohsdmeenamiamoeendiAdcirkattlnciiakistpdtMnobilgtt;niuegetiyonsonAsgduWvwfttgeoroaTotte:uohhhntrrrlEipaiecigeeTtoccUdthoni'nehhhssvaimeRnt.oeeensemclaeeOdpiegeeRltciistftq.usrebhritAituneuinrtaiadhasniDgcnlkp,rasaeneyItmnugt.hOsitpncu,oenoeegiSefnahedueTntooxaaasdywAnplntnelhe;cteaTtaoretevmhIhitMfOeeebfIoariniseNse,tcsdcegteiettenheuiahcvneorktwi£iaeetsdser3kndhiasnsco.ieidt9noacnadoii5gnhnon-s;f wAdsamwdcTpsbhHE7euanyeheah2o.iXlTAearpvmvtttierpdahehlCrhsPpielksocscbnoattoeeoEerrhs.uhaeognnueWardooRlrsmaasegltisepauaaegtrIoshwmiarrhtdnddMghmdiaityeb,vihdnteegettbfEseeierhncsowhoyiileNaecpotgayrontsnrhxrrwdolnTfoliiisfipyimkmbrricaAaoaenaaiehrgaftcpannrgrLcdhdorireldgillcmriaeelu,neAlaeesmybfdafeid,tinuNinondeoensreitsbiahomdos,uxTltUhgs,alrsptoettEstvycpohiopaen,orZtNoiritlmureoihase-apminirNtlumbcasneriiaOnttorifmsecAlbiine.oef,nccooponcuZvcaaucTiroatnbaalpapemhrmsOktrioanlrpeicsrebutogdiPeaaat,oeilnlidrtpmIwaedinoaiaCseolsagnkiatstoil,unnSoiokwdltmn,stdceutwho.hctaeUtdbhteebiiBthctieiltihsseistfMhaenbircoricmiceeonctotaaataroevahpldruanx-aicnelelssaentortenbmyibdnsfnucdeg.oietias"elis-'erflsok,dleeuala5dtesroepfhsserirtienihr0oeloolcssdyyeas-r.ff,t Jameatstpc2NHPohonmoou2afeEeAPudvert4enpaetawWreNvmmthrcOprrPataeeoDmsaNoanrrssdrigTidtimeBioEoetrseiworacfcuOupSsysfidohsorlseOeisvStaiohbodneeKHcreanrfeltodSmesorOncvacorpdtoG,nRemthmrrsdwrsaeiT1,samicecinUtWattpi"ithiglocssrcQhAosnocasea"iWip,elmfoVenivarnnurdQpseEgecstrucSmareeapaLett"LlreieidiIoovcirstnSinhnifieocrdTgtro,cieestpEdudeceiolosdiNletheftesfesssntIt,tinosNyiihg"nttq,wpasnieGtufteihtshhimsiecroudeaasoapnbet,nutbljsicedogeocsoochuanardhetknnc,aico.ohdngewfbbgiovralesiiieatnest£sorarfgth1setect.eib5rnfooaaeruT.imlnora9nishdlmst5gode--,,
O
ORDERING
Please state the title and order code clearly, print your name and address and add the required postage to the total order.
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DIRECT BOOK SERVICE IS A DIVISION OF WIMBORNE PUBLISHING LTD.
Everyday with Practical Electronics. January 1995
77
BABANIBOOKS
We now supply all the books published by Bernard Babani (Publishing) Ltd. We have always supplied a selected list of Babani books and you will find many of them described on the previous pages or in next month's issue of Everyday with Practical Electronics (all books with a BP prefix to the order code are Babani books).
Many readers have asked us to also supply various other Babani books, which have a reputation for value for money. Our customers tell us they appreciate our speedy service and low postage charge and they
would like to be able to purchase all the books from us and thus keep the postage charge to an absolute minimum (£1.00 for UK p&p no matter how many books you buy). We are pleased to be able to respond: with the aid of Michael Babani (M.D.) we are now able to meet all your requirements for their books, tf it's Babani and in print we can supply it. Babani presently list over 160 different technical titles those oof described in detail on the previous Direct Book Service pages or in next month's issue are listed below:
Code Title
Price
BBBBBPPPPP3344479489 55IEPC00olep5P(cuF5trrlE5oaoTjrnPe)iEcrcotFlsePjieecurcltosdrtijosneEncgiftcfsRePcfeotrlroaTyjBresace.ngtSssiiCnsntRoesrrsaPnrdojTecRtsIACs £££££12222.9999555550
BBBBBPPPPP5777864684 BP90
EEPolleewcctterrroonnSiiuccpSMpeluycsuPircritoPyjreDocjteesvcitcses ADPruiagdciittoaiclPaIlCroCPjeorcmotjspeucttser Experiments
££££££222112...795995550550
BP95 Model Railway Projects
£2 95
BP125 25 Simple Amateur Band Aerials
£1 95
BP126 BASIC & PASCAL in Parallel
£1 50
BBBPPP111334264
2255 SSiimmppllee SInWdoBorroaanddcaWstinBdaonwd AAeerriiaallss F&uFrtohremruPlraaectical Electronics Calculations
££11..9755 £4.95
BP145 BBPP117418
42CE65ao4smSy.ip6Amu6dpt4edl,er-6oTT1nre2orPm8priaiconanjoeldlcaotMnsgdySfoXMErxAWCpmolaBmsintaprneaudddteACrsePrCials
BP176 A TV- DXers Handbook (revised edition)
£1 75 £1.95 ££27 9955
BP182 MIDI Projects
BP190 BBBBBBPPPPPP111122999934236803 BP244
AAMMLBBIBIDPBBOnABBirCooMMsoGCCkSrrIojeenIeOnFCCCBBtAAcrciooftlAAoi&eddsommsdsSSvvreuLppIIaaBCcCIaaOnnntett88cciGtiigo6eebbr6ioOnddllnooeedntEPssnnmuoeolc--ttreAPhhwtscBiBaeeonterorontrAAoaooelnStnkkmmloeiuncl21sspaGtt::SprrETGLaaelyddMcharueanPPPorpgiCCrrhtuoyyssiajceagascnneatddsnd
£2.95 ££££££222222.999999555555 £3 95
£3 95
Code BBBBBBPPPPPP222222544445167950 BBBBPPPP222265561890 BP262 BP264 BP269
Title
DMiugsitiaclaAl AudpipoliPcarotijoencstsof the Atari ST's
ACAMMPLreoCCoooamrrgrooeenrpnnaiAAuccnmtiigddessmvveertaoaiHIInnnnnPgcocttreerrboiooddnbgddyTMrFuuiaeOsccmIstttDRstiiooIiTEHnnnRPqaCttrAunoooidN(pjOUrebmecoN7Svte7osiI/nsX2ketdCeodnistitorunc)tion
AA((rreeCCvvooiissnneeccddiisseeeeddIIiittnniittoorrnnoo))dduuccttiioonn
to to
Lotus 1 -2-3 WordPerfect
Price ££££2532.99955550 £££544 999555 £2.95 £2 95 £3 95 £3 95
AA(rneCvIoinsntecrdoisdeeudAcittidioovnnan-tocceoDdveeUsrkssetvorepsrsPGiuoubnidl6ies.h2toi)ngMS-DOS ££45.9955
BBPP227734 BBBBPPPP222278886403 BP291
AGAAPSPhrreCCCaootctgooorittrnnninacWgcccmaiiiltsssamheeeEveeilIIInennnMSgctttturrroriooopnosdddentQuuuriFhccccuratttioSiiictooomekRnnnnBYestttAocooooeSruVSSisIrvmuCeePpnraCetruCrt'srWCoaHanalsarcterSrduIIcDtiisokn
£££££££3442443.....99999995555555
BP292 Public Address Loudspeaker Systems £3.95
BP293 An Introduction to Radio Wave Propagation £3 95
BP294 BP298
AWA& CCoFriooknnnsdcce(iirrsseeevIIisnnettrrdooeddduuicctittoiioonnn)
to to
Microsoft the Mac System
£4.95 £3 95
BP301 BP303
AUnntdeenrnsatasnfdoirnVgHPFCaSnodftUwHaFre
£4.95 £4.95
Code Title
Price
BP305 BBBPPP333000678 BBBBPPPP333311111234
WAAAAAAAMLnneCCCCCaiaIIncooooonrnidnnnnnnnttrorcccccitoonoiiiiiwdsssssdsgeeeeeuhuscCIIIIIctnnnnntiAiottttlorrrroDnoooondddddtuwtouuuuocccccSitMitttttcoiiiihooooaninnnnncAntrttttooeuoooowrAtsWQQSoamaaSvuuongieaakrPderstderklSrotX5occ.31PahPnrorefnonsoisn3rtg.h0e
£££454.999555 £££££35443..9999955555
BP315 BP320 BBPP332224
An Introduction to the Electromagnetic Wave Electronic Projects for Your PC Circuits Source Book 2 The Art of Soldering
£4 95 £3.95 £4.95 £3.95
BBBBPPPP333322236780 BBBPPP333333146 BP337 BP338
An Introduction to Satellite Communications AAAAfAWDSRMRoaeOerCCCCBaigllnWgSeeooooeediaagnnnncOoiEssicnccceewnExniiiidsnsssp23elsoeeeeeel.wS4ac4rUIUUisttnsnresssoGtepeeerndorrruiassdcistdsGGuGaecPuuTuttriiioiddioodmeenjMeeettctItooooDt(scLLIWLooovoottetuururdssssllfv1o--e22r-r2--s33-i3on 6 2)
£5.95 ££35 9955 £££444..999555 £5 95 £5 95 £5.95
BP339 BP343
AAW5.2CCorfookonnsrccfWiiossreeinWIIdnniottnrrwdoosoddwuuccsttiioonn
to to
WordPerfect Microsoft
£5 95 £5.95
F NO PRICE IS SHOWN THE BOOK IS OUTOF PRINT (0.0.P.) S( EE PREVIOUS PAGE FOR FULLORDERING DETAILS
Printed circuit boards for certain EPE constructional projects are available from the PCB Service, see list. These are fabricated in glass fibre, and are fully drilled and roller tinned. All prices include VAT and postage and packing. Add £1 per board for airmail outside of Europe. Remitances should be sent to The PCB Service. Everyday with Practical Electronics, Allen House, East Borough, Wimborne, Dorset BH21 1PF. Cheques should be crossed and made payable to Everyday with Practical Electronics (Payment in £ sterling only). NOTE: While 95% of our boards are now held in stock and are dispatched within seven days of receipt of order, please allow a maximum of 28 days for delivery - overseas readers allow extra if ordered by surface mail. Back numbers or photostats of articles are available if required - see the Back Numbers page for details. Please check price and availability in the latest issue.
Boards can only be supplied on a payment with order basis.
|
All p.c.b.s on THIS
page reduced to
salEV2 price
(Just send half the price shown, while stocks last.) PCBs ON OPPOSITE PACE: PRICES AS SHOWN
PROJECT TITLE
Order Code Cost
Suntan Timer
AUG 88 610
£3,07
Doorbell Delay
NOV 88 616
£356
Sound-to-Light Interface Midi Pedal Midi Merge Audio Lead Tester
MAR'89 637
£6.24
639
£7.00
640
£3.00
641
£5,77
Light Sentinel: Main Board 4-Channel Auto-Fader Interface
632
£9 20
642 '
£6.80
Electronic Spirit Level
AUG'89 649
£3.85
Music on Hold
OCT'89 646
£3.85
Power Supplies - 25V 700mA
656
£435
Quick Cap Tester
FEB 90 668
£3.92
Stereo Noise Generator
APR 90 681
£4.24
Amstrad Speech Synthesiser
MAY 90 689
£468
Hand Tally: Main Bd and Display Bd
699/700 £10.95
[ PROJECT TITLE
Ghost Walker | Frequency Meter
Spatial Power Display | Amstrad PCW Sound Generator
OCT'90 | JAN'91
Simple Basic Alarm
M AR'91 |
Humidity Tester
APR'91 I
| Model Train Controller (double-sided)
Digital LCD Thermostat
| M AY'91 |
- Control Board
- Power Relay Board
Control and Power Relay Boards together |
1 Modular Disco Lights-Simple Chaser 1 JUN'91 I Sweeper Module
Automatic Light Control - PSU Board Logic Board
Mod, Disco Lights Superchaser (Double-sided) Supersweep (Double-sided)
Bicycle Alarm
NOV'91 I
Knockerbox Mind Machine - Main Board Auto Nightlight
DEC'91 |
Mind Machine - Programmer Board | JAN'92 | Transistor Checker Stepping Motor Driver/Interface Micro-Sense Alarm
Telesound 1 Programmable Timer
Auto Garage Light Versatile BBC Computer Interface Economy Seven Timer
FEB'92 | MAR'92 |
Sonic Continuity Tester 1 Telephone Ringer
APR'92 |
1 Experimental Weighing Scale
MAY'92 |
| 12V Drill Charger/PSU (both boards)
Digital Servo Interface Tie Pulser CCD Reverb Unit Switch-Mode Power Supply
JUNE'92 |
UV Exposure Timer Cricket Game Quick Prom
JULY'92 |
Order Code 703 704 714 715 731 716 736
740 741
745 746 747 748
771 772 773 775 778 779 780 781 782 783 784 785 786 787 788 789 790 792 793 791 794 795 796 797 798 799
Cost £4.32 £5.25 £5.33 £5.03 £4.50 £4.97 £975
£4.05 £3.76 £5.00 £5,00 £517 £4.88 £5,17
£6.91 £8.26 £5.01 £5.35 £7.00 £5.03 £7.39 £4.63 £10.39 £5.42 £4.66 £4.63 £6.10 £11.59 £5.20 £4.79 £5.46 £5.17 £5.31 £473 £5.19 £6.39 £7.01 £533 £677 £5.61
78
Everyday with Practical Electronics, January 1995
PROJECT TITLE
Gas Alarm Dual Metronome
Ultrasonic Tape Measure Quicktest
Extended Range Capacitance Meter Traffic Lights System Mini Lab EPEAItimet (Altimeter) Personal Stereo Amplifier
Universal Infra-Red Remote Control Combination Switch Christmas Lights Colour Spectrum
TV/UHFAerial Amp (double-sided) Continuously Variable Balanced Power Supply Emergency Lighting Unit
Biomet Pulse Monitor
Sensor
Display
Biomet Pulse Monitor
mriTtra
-ADC Interface (double-sided)
Car Electric Window Enhancer
Simplifly Atari STEM Interface
Personal Stereo Amp. Add-On
Electronic Fire Mind Machine Mkll - Signal Generator Ventilation Fan Timer Universal Data Logger Mind Machine Mkll - Magic Lights Superhet Radio Control Receiver Guitar Preampand Distortion Unit Linear Clock-Timing Board
Display Board Universal Alarm Module
Electronic Snooker Scoreboard JUNE 93
Mind Machine Mkll
JULY 93
- Computer Interface
Xenon Strobe
Electronic Gong
Micro Lab - p.c.b., EPROM, PAL and booklet
Bike Odometer (pair of boards) Amstrad PCW A to D Converter (double-sided) Experimental Electronic Pipe Descaler
Sound Activated Camera Trigger SEP'93
L.E.D. Sandglass Main and Display boards
Kettle Alert Linear Power Supply (double-sided) Multi-Purpose Audio System
Six Channel Stereo Mixer
OCT'93
Multi- Purpose Audio System Microphone Pre-Amp module RIAA Pre-Amp module
20 Metre Receiver
Multi-Purpose Audio System
B2
Tone Control and 1W Stereo Amplifier
Tone Control
1W Stereo Amplifier
Three-Way Christmas Tree Lights Flasher
Auto Alarm
250W/600W Battery to Mains Inverter
Multi-Purpose Audio System
10W +10W Stereo Power Amplifier
Amplifier
Power Supply
Pond Heater Thermostat
Timer/NiCad Capacity Checker
Multi-Purpose Audio System
mjgjjjj
Balanced Microphone Preamplifier
Balanced Microphone Power Supply
Whistle Controlled Light Switch
Battery to Mains Inverter - U.P.S. charger board
Three Phase Generator Visual Doorbell
IViAR'94
CCD TV Camera - Control Board (double-sided, plated-through-hole)
Telephone Ring Detector CCD TV Camera
Combined Video, Test & Ext Plug Boards Frame Grab Control
(double-sided plated-through-hole) EPE Sound DAC PC Sound Board MOSFET Variable Bench Power Supply
LE D. Matrix Message Display Unit Display Board CPU Board
Order Code
800 801 802 J303 _ 804 806 MINI LAB 807 808 81 IT/811 R 812 813 814 815 816
Cost £5.47 £6.74 £6.06 £482 £5.63 £5.04 £14.95 £6.30 £6.47 £6,56 £5.68 £597 £7 23 £5.65 £6.77
817
£6.30
818
£630
819
£7.11
821
£5.00
822
£555
823
£3,90
820
£484
824
£5.57
825
£470
826
£588
827
£6 58
828
£5,93
829
£546
830
£800
831
£7 00
9070
£300
832
£9.17
833 834 835 MICRO 836/7 838 839 840
£6,39 £5,84 £7 50 £35.00 £7.00 £9.85 £5.50 £5.34
841/2
£7.30
843
£5.19
844
£977
845
£11 98
846
£488
847
£5.11
848
£6.63
849
£609
850
£5 12
851
£4.88
853
£5.65
854
£5.49
855
£13 92
852a 852b 856 857 858 859 860 862 861 863 865
866a/e 867 868 869 870 871
£565 £5,49 £5.77 £6 30
£5.30 £5.14 £519 £7 38 £5.95 £580
£15.00 £4.72 £11.00 £15.00 £477 £5.80
£18.00 £7 20
PROJECT TITLE
Order Code
Stereo Noise Gate
873
Simple TENS Unit
875
Capacitance/Inductance Meter
876
Advanced TENS Unit
TUtTPITB 877"
Digital Water Meter-Sealer
878
Counter/Display
879
L.E.D, Matrix Message Display Unit
Keypad
872
PC Interface
880
Microprocessor SmartSwitch
881
Microcontroller P.I. Treasure Hunter
882
Print Timer
P1UVif'Tl
Watering Wizard
Simple NiCad Charger
Voxbox
Stereo HiFi Controller - 1 Power Supply
874 " 883 884 885 886
Steren HiFi Controller-2
KTHSBI*
Main Board
887
Expansion/Display Boards (pair)
888
Dancing Fountains -1
Pre.amp
889
Pump Controller
890
Filter
891
6802 Microprocessor Development Board
894
Dancing Fountains-2
Icfd'JifcT-l
PC-Compatible Interface (double-sided)
892
Automatic Greenhouse Watering System
895
Seismograph -1 Sensor/Filter
895
Clock/Mixer
897
3-Channel Lamp Controller
899
Seismograph - 2
PC-Compatible Interface (double-sided)
Visual/Audio Guitar Tuner
Digilogue Clock
Hobby Power Supply
Audio Auxiplexer
Control Board
Receiver Power Cnntrnller
JTiTWHRi
1000V/500V Insulation Tester
Active Guitar Tone Control
TV Off-er (pair)
Video Modules - 1 Simple Fader
Improved Fader
Video Enhancer
898 900 901 902
903 904 905 906 907 908/909 910 911 912
Rndent Reneller
PVlfWPESI ~ 913 "
EPE Fruit Machine
914
Video Modules -2 Horizontal Wiper
916
Vertical Wiper
917
4-Channel Audio Mixer
918
Spacewriter Wand
921
Universal Digital Code Lock
922
Video Modules -
3 Dynamic Noise Limiter
919
System Mains Power Supply
920
Magnetic Field Detector
923
Model Railway Track Cleaner
924
Moving Display Metronome
925
Cost ~£ai4~
£5.84 £6,44 £6.56 £11,19 pair
£5.19 £582 £5.61 £6.60 £5.82 £6,60 £498 £6.90 £5.66
£7.39 £9,80 £5,28 £5.41 £523 £9.15
£10.90 £5.33 £623 £5.87 £8.17
£10.72 £7.55 £12.50 £500
£7.72 £6.24 £4.99 £5.78 £4.50 £7 25 £5.12 £6.37 £5.15 £6.26 £8.14 £6.23 £6.35 £6.20 £4.00 £6.25
£5.92 £498 £5.77 £5.11 £6.24
EPE PRINTED CIRCUIT
BOARD SERVICE
Order Code Project
Quantity Price
Name Address
I enclose payment of £
(cheque/PO in £ sterling only) to:
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Practical Electronics
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Everyday with Practical Electronics, January 1995
79
REPORTING
Tony Smith G4FAL
EPE ON ATV Jim Atherfold, GOFZB, recently asked
if he could read and transmit items from this column, and other parts of EPE. on Amateur Television (ATV) in the Brighton to Chichester area. After consulting the Editor, I gave Jim the go-ahead and at the same time asked him for more information about his activities.
He replied: "Amateur television is an extension of amateur radio so that as well as talking to each other we can also see each other. We can show each other our constructional projects as well as discuss them.
"To do this, we use another radio frequency as a talkback channel. It is usual for one operator to have his camera, with microphone working, showing himself or his video pictures on 1318MHz while the talkback would be on the 2-metres or 70cms bands; i.e., 144 750MHz or432-750MHz in my area.
"The Worthing & District Video Repeater Group have built and successfully run GB3VR, a Television Repeater on the Brighton Race Hill, for many years.
"Some very interesting pictures can be seen of radio amateurs operating club stations, or their own stations: Scouts during Jamboree-on-the-Air: Guides and Brownies during Thinking Day. Computer designed callsigns and graphics to rival the BBC are popular.
"One station has been redirecting pictures from French amateurs. He also transmitted, direct from Bognor Pier last summer, pictures of the Birdmen's annual flying attempts while I did the talkback on 70cms.
"ATV can be watched using a satellite TV receiver costing about £20 to £40 at amateur rallies, providing it will tune to 1318 + 6 MHz for the sound, while an antenna can easily be made from a BBC yagi."
The national organisation for this branch of amateur radio is the British Amateur Television Club. For those interested in taking up ATV, they have a new publication, An Introduction to Amateur TV which can be obtained from Ian Pawson G8IQU, 14 Lilac Avenue, Leicester LE5 1 FN, price £5.00 including postage (cheques payable to BATC). He will send details of the club at the same time. Tell him you read about BATC in EPE\
ISWL NEW PUBLICATIONS The International Short Wave League
has published a useful booklet containing all amateur radio callsign prefixes worldwide, listed alphabetically by country and alpha-numerically by prefix.
It contains two separate listings in this format. The first is the official DXCC list, showing all countries with which contacts qualify for the prestigious DX Century Club Awards administered by the
American Radio Relay League (ARRL). Many awards issued by other organisations are also based on this list.
The second is intended for those who participate in the monthly ISWL contests. This expands on the DXCC list and includes the call areas of countries such as Australia, Canada, and the USA, plus many islands and other locations.
While this publication will be particularly useful for DXers and contest participants, it will also be helpful for other licensed amateurs or short wave listeners, enabling them to identify the country of origin (and sometimes the particular part of that country) where an amateur station worked or heard is located.
The price of the booklet is £2.50 or four IRCs (International Reply Coupons), post paid. Postage stamps are also acceptable. It can be obtained from the International Short Wave League (Ref: EPE), 10 Clyde Crescent, Wharton, Winsford, Cheshire CW7 SLA,
Also available from the same address is the "Guide to English Language Short Wave Broadcasts to Europe (Winter Schedules 1994)". This twice-yearly publication is invaluable in finding a choice of English language short wave transmissions at any time of day and night and costs only £1.50 or three IRCs.
NOVICE ROUTETO SUCCESS The Young Amateur of the Year, 1 994,
is 17-year old Robert Aley G7SRR, from March, Cambridgeshire. The runner-up is 16-year old Stephen Conner GM0TET, from Glasgow, and both started in amateur radio by obtaining Novice licences.
There are now over 1,000 registered Novice Licence Instructors in the UK. Anyone interested in entering amateur radio through the Novice scheme should contact the RSGB, Lambda House, Cranborne Road, Potters Bar, Herts EN6 3JE, for further information, including details of their nearest voluntary instructor.
Unlike the full licence, there is no minimum age for Novices, and the only drawback, until recently, has been that a keen youngster under 14 holding a Novice licence was unable to progress to a full licence until he or she became 14.
The Radiocommunications Agency, however, has just announced a change in the rules. With immediate effect. Novices between the ages of 10 and 14 who have held their licences (Novice A or Novice B) for at least one year may now obtain full amateur licences, Class A or Class B (after passing the appropriate examinations), without having to wait until they are 1 4 to receive their licences.
HAPPY BIRTHDAY G-QRP! The G-QRP Club celebrated its 20th
birthday recently. QRP is defined as low
power operating using not more than five watts input or ten watts output, while many enthusiasts achieve worldwide contacts with considerably less power, sometimes milliwatts!
George Dobbs, G3RJV, Secretary and Founder, says in the Autumn 1994 issue of the club's journal SPRAT, "We began as a small minority group in amateur radio and have grown to be a respected voice for the true nature of the hobby".
If you like constructing radio equipment, the club has a lot to offer. SPRAT is full of projects, and includes many useful tips and ideas for constructors.
The current membership fee (for SWLs as well as licensed amateurs) is £6.00 a year. For more information, including a sample copy of SPRAT, send a first class stamp to The Rev. George Dobbs, G3RJV, St. Aidan's Vicarage, 498 Manchester Road, Rochdale OL1 SHE. Tell him you read about the club in this column. I'm a member myself and like to keep in with the guvnor!
RARE Radio Amateur Relief Expeditions is an
organisation dedicated to using skills learnt through amateur radio for overseas relief work. Their Hon. Sec., Don Sunderland, G6FHM, tells me that in the last year they have provided teams for Summer Camps for children learning English in Romania, giving them an opportunity to learn about amateur radio and to communicate with people in other countries.
Teams have also been in Turnu Severin in the Mehedinti region of Romania, delivering aid to the county hospital which RARE has pledged to support. They also surveyed an Ear, Nose and Throat Hospital which has not yet received any aid, and which they hope to help in some way. Another team went to an orphanage to deal with an infestation of mosquitoes.
Future plans include the installation of radio communications in ambulances in Romania. Don says, "We are still a young organisation and are progressing slowly but steadily. Training, development and fund raising are important issues under discussion for the future. We welcome publicity to make our organisation more widely known to both potential members and User Organisations."
RARE became a registered charity last May and it is looking for more members to enable it to expand its activities. They also need funds to further their aim to provide communications and aid in disaster and emergency situations overseas.
If you are interested in their work, or would like to send a donation, write to Don Sunderland G6FHM, 1 Allfield Cottages, Condover, Shrewsbury, SY5 7AP, mentioning that you read about RARE in EPE
80
Everyday with Practical Electronics, January 1995
PCI3 Ve^mev
For Windows 3.1
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Runs on any PC running Windows in standard or enhanced mode
with 2MB RAM
MS
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On I
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·/ Produce Single or Double sided PCBs. y Print out to any Windows supported printer S Toolbar for rapid access to commonly used
components. S Helpful prompts on screen as you work. ·/ Pads sizes fully customisable.
No charges for technical support. ·S Snap-to grid sizes 0.1", 0.05" 0.025" and
unrestricted. S SMT pads and other pad shapes. S Positive reviews by Robert Penfold and Paul
Stenning, copies available on request.
Phone (0432) 355 414 (Access and Visa welcome)
Niche Software 22 Tavistock Drive, Belmont, Hereford, HR2 7XN. Please Note: Since PCB designer is so easy to use. and to keep costs down, PCB Designer has an On-Line manual, in Windows Help format. A FREE tutorial is also supplied.
TRANSMITTERS
AT LAST. A comprehensive, easy to follow guide to building short range transmitters and surveillance devices. Packed with useOfnullyinCf3or.9m5atiinocnpa&npd. circuits, (inSothmeeUoKf)the circuits included cannot be used legally
KITS
All kits come with pre-drilled PCBs and high spec, components.
MICRO FM TRANSMITTER (a). 1 mile range. 80-100MHz
preset inc. mic.. very small (2*3cm)
C6.95
MICRO FM TRANSMITTER (b). Variable mic. sens , tunable 90-110MHz.
1 mile range
G7.95
FM TRACKER. Transmits an audio tone for direction finding, tracking etc.
so-i iomhz
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FM RECEIVER (a). Tiny high quality FM radio. Will drive headphones
direct (not inc)
C10.90
FM RECEIVER (b). As (a) but with 3 watt audio output and tuning LED G12.60
CARMYRSATADLIOR. ASDinIgOl.eIcnhcilpudraedsitounfoerr,heeaardpphhoonnee, sfe(rnroitteinace.r)ial, etc.
C6.90 C8.90
AUDIO POWER AMPS 3 WATT low cost for intercoms etc 15 WATT General purpose upgrade
CC48..9955
40 WATT High quality. HD 0 003%, switch
on mute ideal for compact disc C15.50
150 WATT Rugged and powerful MOSFET
design. PA/sound systems
C22.95
PREAMPS ETC
GENERAL PURPOSE PREAMP. Variable gain 9-25V 40mV max in G4.00
ULTRA LOW NOISE. For high quality mixers, mics etc 9-25V
C4.50
SMALL SIGNAL. Sensitive FET preamp for piezo transducers £3.90
ACTIVE TONE. 12dB c/b bass and treble with variable gain
£8.95
7 BAND EQ. 150Hz-18KHz for EQ units and tone control.
NOinIScEludGeAsToEn.-Dboyanradmpicrenaomispe arenddupcotitosn. Vsyasritaebmle. Vgaamriable input £12.95
and cut off level. Will accept instruments, tape decks etc
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MUSIC KITS. Full range of on-board units for guitars and other instruments.
Tone boosters, active circuitry, transducers. Send for list.
Prices include P&P Mail Order Only. Make cheques and postal orders payable to:
JCGJUl P0 Box HP79, Woodhouse Street, Leeds LS6 3XN
20 Amstrad Games
£5.00
20 Spectrum Games
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50 BC184; 50£1BCPA54C7KA:S20 BS107;
20 BSS92:10 2N2907A; 20 2N5086:
50 2N5551, 5 2N5657; 20 2N5769:
4 2N6394; 5 2N6400:12 BCY69:
3 BD144; 3 BD145; 10 BD237;
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5 BFW43:10 BFX30; 3 BSU78;
5 BSW68; 3 BSX59: 2 BUF410A:
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polyesters.
5%" to 3!4" floppy converter
leads
r. £1.50 ea'
STC p.s.u. 240V Input; 5V 6A
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£5.95
Temperature probes, with
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£3.95*
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modulator
£2.50 ea*
3AMP mains filters £1.00 ea*
40 Character x 1 -line dot
matrix display
£4.95 ea*
Car Dashboard Display (shows
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4-digit clock display
£2.50*
41 -7d-idgiigtilt.cv.df.. wdiistphla7y211 driver .££23..9550**
Giant 2-digit v.f. display £2.95
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1000 off mixed resistors %W. £4.95*
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50 off mixed terminal blocks. £2.50*
25 off buzzers & sounders £3.50*
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250 off i.e. sockets
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1000 off Ceramic caps £7.50*
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£2.00*
100 off 2200)4F 25V caps £6.00*
100 off 4-7)iF 25V caps £2.50*
31b mixed component pack £4.95
Jumbo component pack £10
Crystal oscillators 10/12MHz. £1 ea
5V DPCO D LL. relay 60p ea*
5V SPCO S.I.L. reed relay 40p ea*
12V Piezoelectric Sounders 50p ea
DIL Switches 3/4/6 and
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35p ea*
3 5mm jack plugs
10 for £1 *
100 off Zener diodes, mixed £2*
21 -piece mini screwdriver set. £3.95*
Universal test lead kit £3.95*
10 crocodile clip leads £3.50*
20 off mixed R F. Filters,
Crystals, etc
£4.95*
100m P.V.C. sleeving £4.50*
WeAaQVlsUAoAILbNuATyBILaTlElYfPoDLrImESAsCSoOEfUeRlNeITNctSGro.nic components, p.s.u's, disk drives etc.
Lists to below address. / TPELSAMPEAALASELYSMFPMEORAEARIRNCDKBTEDUESW£DLI2KIN*T.0CBHW0LUpOHUY&RIDCIpDNEHEGEVARX.LARCTI.ESEOTTPSOTP.
Dept EE, COMPELEC, 14 Constable Road, St. Ives, Huntingdon, Cambs PE17 6EQ Tel/Fax: 0480 300819
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Everyday with Practical Electronics, January 1995
81
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KI.KC TRONIC COMPONENTS TSStERBroMroPaaauntdRntTnieiOcsodrisiesMTe.CrtsoxsDos.ars.misng,RdSpEitxwRoanmsnleic.caesoaChnnidnseyatetdssorr,.msrALs.o,CRliranDeCeorelmemaaaictyrpespos.amIud,cCBetsie.rstuTsor,r.rrgaMslPn.HaIrsrCooIfnAodlRtdruelmOaukcrctsemst,ro.HssrP..TsIRS.CCpaOSmeoeMapnrskitn.IeoeCesrcSsREtiIoalOmCenrcssssd-.,,,
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SUPPLIED READY BUILT AND TESTED. Tmedtrhcoiv.edseWeeclhsimreacnoruecditouasmlvteoapsipalnaroiobwnwlgeerpteoarnijsccouoeyismt.tapNhaeOwtiTnboEerleledthdV-wasutiomad(leelthtmreeerop.pduAreotlallfstemisoinosnicdolefunoldasrelaqatrouneradooliiphtdyeoa,nblbrpaeynolidwmabesairhrlkiosteuryttpcpia.ilnery.cd,uIinipntdetpuerrfsgootrorrayfml..haLeneacitseusiranetk. ,aIngrsleatrasulsimsftieibcnrteaplPria.cCne.dB. .HFaoin-uFdri THOUSANDS OF MODULES PURCHASED BY PROFESSIONAL USERS
OMP/MF 100 Mos-Fet Output power 110 watts R.M.S. into 4 ohms, frequency response 1Hz - lOOKHz -3dB. Damping Factor >300, Slew Rate 45V/uS, T.H.D. typical 0.002%, Input Sensitivity 500mV, S.N.R. -110 dB. Size 300 x 123 x 60mm. PRICE £40.85 - £3.50 P&P
THE RENOWNED MXF SERIES OF POWER AMPLIFIERS FOUR MODELS:- MXF200 (100W + 100W) MXF400 (200W + 200W) LpdFrieEsovtooeAflrtTc*iooUnnLtR*arotEeAlssASltu*LM:MmLIilonlPXusiIO-umnFmFWdienet6csapEate0feRsonde0rdRsoesnAnt(/rto3TeMfsIp0fXNsos0FwwGfW6rieeS0trc0ehRs&p+u.woMMpwpXX.eSl3LiFre.R09sdI00cNe0owWlTfniivatnOhne)erccyt4woMtooOoinrlseHttXodo*MrvwoFSiSiirdttt,9hauaBnlaD0dlOlt.aCy0rTar.dnaHl(nso74fyuC7o55dHrlmsmo0pAaVWeedNraisnk*Npe*E+urHtLaTsingSw4*hdiD5ntOshl0RpLeeIWewr.VEmn.EDraa)alnN.tdpeVrsuo*htemocVrteteitocreyinrr.sclouw*it USED THSEIZWEOS:R-LMMMMDXXXXOFFFFV462900E000000RWWWWIN1111C9999LUxxxxHHHHBSSSSS,1111V4P4a U((((B3332SUUUU,))))CxxxxIDDDDN111E1423M1^"""A4"S, DISCOS ETC.
PRICES:-MXF200 C175.00 MXF400 £233.85 MSPEXCIFA6LI0ST0C£AR3R2IE9R.D0E0L £1M2.5X0 EFA9C0H0 £449.1 5
MP X03 STEREO 3-WAY ACTIVE C
OMP/MF 200 Mos-Fet Output power 200 watts -RS.dMB.,S. Dinatom4pionhgmFs,afcrteoqrue>n3cy00r,esSploenwseR1aHtze - 5100V0K/uHSz, T.H.D. typical 0.001%, Input Sensitivity 500mV. S.N.R. -110 dB. Size 300 x 155 x 100mm. PRICE £64.35 - £4.00 P&P
OMP/MF 300 Mos-Fet Output power 300 watts L -R3.dMB..S. Dinatmo 4pionhgmFs,afcrteoqrue>n3cy00r,esSploenwseR1aHtze - 6100V0K/uHSz,
£ T.H.D. typical 0.001%, Input Sensitivity 500mV. S.N.R.
-110 dB. Size 330 x 175 x 100mm.
PRICE £81.75 £5.00 P&P
OMP/MF 450 Mos-Fet Output power 450 watts R.M.S. into 4 ohms, frequency response 1Hz - lOOKHz -3dB. Damping Factor >300. Slew Rate 75V/uS, T.H.D. typical 0.001%, Input Sensitivity 500mV, S.N.R. -110. dB, Fan Cooled, D.C. Loudspeaker Protection, 2 Second Anti-Thump Delay. Size 385 x 210 x 105mm. PRICE £132.85 - £5.00 P&P
OMP/MF lOOO Mos-Fet Output power 1000 watts
R.M.S. into 2 ohms. 725 watts R.M.S. into 4 ohms,
O o O
o o
frequency response 1Hz - lOOKHz -3dB. Damping Factor >300. Slew Rate 75V/uS, T.H.D. typical
cAbornadosevssaas,c-nomhcveibdedar3s&f-srWetcqoahupyae.nnSTnctheeyelr:.eBNoreaomAsmsco-itMvnivaaielbd7lCe27r55of0mrs/osV5n-0Oti0nv/f8pae0usr0,ct/Hiohazuo.taupMlsuleotidd.w-FTsiunolaplayc1cc1.eo89s/m"3s/xp5taoK1tUiHbthzlcee.aawsplelirt.ohagtEOr2aaM4cmdhRBmcrhapacaebknrlenaoemcOltIpaLhvliaefssi.weBtrihtaacrnsehsdeesimnlevtovoederulatldcsejwosu.nistttcrohthleses
0.002%. Input Sensitivity 500mV. S.N.R. -110 dB, Fan
CAonotil-eTdh.umDp.CD.elLayo.uSdiszpee4a2k2erx 30P0roxte1c2t5iomnm, . 2 Second
L
PRICE £259.00 + £12.00 P&P
Price C117.44 - CS.OO P&P
TEREO DISCO MIXER SDJ3400 SLFsspSfmowpEElToiulDeAu&lciEsotesnTcRwd,cdhVRUr5Ei,unoREOLgcg6sEfoismrfSnanCDeif:epen-ctahthIrfptdeSoioasiurnce.lnCrst,c,.nsCUOlCe:ueD-qDslduseu,MieJ3MfnTauwHlgIaAliXtMispeNutEecEheairYroc,cdRnshmiVptnoahiOwwbdwdboiiwUiieilvnttnteohhTihiaetsdetSh2uiMbtToac(txraAnaml.oerl7NnpkfaoiagegD-tfboodra)Iaa,rtveNt.hpnerGA8hd3esr
ECHO & SOUND EFFECTS*
LOUDSPEAKER
NS7PT7OE5ACTmNE(VD:PA,MRBROOADFSNE--FDSIENSWTPIOUIMDNTTOASHDLEUSNEOLSQKEUSSHOIzPAO.MROmEERVND,ATBEVRACANOSILDTMAAWBPNALIDDETATIIBHRNLDlETOO)WOR-OKIPNHEVPzCE.U.RTSISOENNSS;
LARGE SELECTION OF SPECIALIST LOUDSPEAKERS AVAILABLE, INCLUDING CABINET FITTINGS, SPEAKER GRILLES, CROSS-OVERS AND HIGH POWER, HIGH FREQUENCY BULLETS AND HORNS, LARGE (A4) S.A.E. (60p STAMPED) FOR COMPLETE LIST. McKenzie and Fane Loudspeakers are also available.
Price £144.99 + £5.00 P&P
SIZE: 482 x 240 x 120mm
MINENCE:- INSTRUMENTS. P.A.. DISCO, ET
JttErhoaXeinnsPseLiteAhunnNetiAtrPseTisceOpazRononYbsreeeLvEwaoAdiltduFhetLiadoElnTtoo!SweTAexhrRiedsEtilisonStwogUrtPsdipoPyenLnaaIlkEemevDireclWsmtyhIsTaatnseHsmoE(rsnAdooiCnfHvauropyTicWdteoyEcn1oEa0imT0l)EiwcoRfat.twatsePe(imteezorsor.etAwifsetawetcoerroarspesroopvdueutrcieinss snaeonrtieimsre.pqFruoRivrEeeEdd
TYPE 'A' (KSN1036A) 3" round with protective wire mesh. Ideal for
bookshelf and medium sized Hi-Fi apeakers. Price £4.90 50p P&P.
TYPE 'B' (KSN1005A) 3Va" super horn for general purpose speakers,
i) TYPE B
disco and P.A. systems etc. Price £5.99 - 50pP&P. TYPE 'C (KSN1016A) 2"x5" wide dispersion horn (or quality Hi-Fi sys-
tems and quality discos etc. Price £6.99 50p P&P.
TYPE 'D' (KSN1025A) 2 x6 wide dispersion horn. Upper frequency
TYPE C
TYPE E
response retained extending down to mid-range (2KHz). Suitable (or high quality Hi-Fi systems and quality discos. Price £9.99 + 50p P&P.
TYPE 'E' (KSN1038A) 3V horn tweeter with attractive silver finish trim
Suitable for Hi-Fi monitor systems etc. Price £5.99 * 50pP&P.
LEVEL CONTROL Combines, on a recessed mounting plate, level control
A8RRR11RMRR11111RR1 00EL22EE225EEESEEOLSSSSSSSS1N.....,.02123231FEIFFFFFFFO1T00R00000MRRRRRRR0OO0E00000WEEEEEEEI0RQNQQQQWQQQWWWWWWA.E...WRAAATAAAA4776544N39ETT1TTTT25TTA8769HCSHHHHTTTHHTTHTTRTZ.EzzzzzzzTRR.RRR,RRF,,,.M,,.UFR.....FFF..FFFFMMMMMMMR.RNRRERRRRRSE...Q...EE..EEEI.EESMSSSSSSQTQQQOQMQQ......4S.M....MMMMS2MMERRSRRHRRRR.E8EEEEEEEEEEE1EzEE-O111MS11,S1S1SSSSS2PH202F55OPPPP0PPP-E.--R..-M--,.3-O11T1232T2TTETTTT0OOS2O0OOO000OOQOOG0O-O0000I.6EG14736S3SMLKRNK0.KKGGKGKKHG5PEHE0P.HKUUHHHHEIHEGSLEzPHGNzHINIzzzzz,TPTHU.DT..,,,IE.Z.S,.AGASSSSSSRANP,PEPTREHREEEEESUP(UONNOT,NNN,NNNEOPPRRWWKSCVSlNSSSSSUOSOPPEOE9EI1SE9W9OR191NOKY70CR78.900P9dS0SHBEdAdd33LB9OdBEECBR'BBddzLDEdB,A.SOBB.BAB,BSGES..NKDDAEAU.SEEISNL,GISS)YTSEISCSUNBA,A,WOI9OICRTLDN,8IL.AAEDdVCGUDARRBEOLUDID.D.UCSIEI,RTCADNGXDAEOLIGUCNISR,,ISEGBTPE,VCLAOXDAOOBLRCNISC,EAS,SEPSPPPPPPPAEPNCSKLRRRRRERRRRXGLTOSLEIIII.IIIII,CUCCCCC,CCCCEYGMEEISEEEENEEEPEEBUTXILT.DTACAOC££E£££I£CLAT.33477.R534AH3EE.GAD665203303NILREGR....I.....V7L766D4TS1377H.11OEM774C4942.MNCOPDO------I-TOADINSWCCL££C££££MIC,T333344222EIOO,....D....55R550S5050RE000000T000MTAPPPPPPPPPCIG&&&&&&&&&D.EPPPPPPPPP
and cabinet input jack socket. 85x85mm. Price £4.10 + 50p P&P.
EARBENDERS;- HI-FI, STUDIO. IN-CAR. ET
ibl FLIGHT CASED L Ascba1p2oar"nelenleasfcwcikttaaoteensrrrdtanttneaeadgrlcisusrehe,msnoctcoiaftonilnqvoimduuigtmapayylrliidathmlynoowedulrionntdehtussen,dpdtcsoeelpwapxoektsihratuehuakrrdtseehserewddsfao,eivrtsadhyiloegupfsdmnatiuicgsoittnnyonBieraubydolmltlatfhooictcumktteodadocrksnodpegeveerarleaisdlrklpivueneratsrogi,nltsietwtzaTcaegitnhdiseoedetnusoe.ddfnaiitcsohnpledoqeuslrsausattilreeoieetsnyslt POWEFRRERQAUTEINNGCSYQRUEOSTPEODNISNEWFUALTLTSRRAMNGS EFO45RHEzA-C2H0KCAHBz INET
iibbll FFCC 1122--120O0OWWAATTTTSS((1IO0OOddBB)) PPRRIICCEE CC115795..0000 PPEERR PPAAIIRR SPECIALIST CARRIER DEL. £12.50 PER PAIR
ABRLEALSSS.OSEF,AwRSREaItQNBt.EGE4NLB0DEH8E2-C.5ROF0RNUDENEUQ,IATHLRSIGEI8MSHOPPC.EHTODMOEMSN7PKC(LEHExI.zAceTSNpAtECEPNBEPS8E,-D95R07O4d&L/BE8L.BOE1HD0-M5S0UwBhRAicRShOSa.UrHeNdI-DuFaIl.
impedance IN-PCRAIRC.E
tapped C8.90
a
4 & 8 ohm) G2.00 P&P
R1E0S.SFORWEQA.T4T0HEzB. 1F0R-E5Q0. DRUESAPL.ITMOPSEKDHEzN,CSEE.NTSA.P9P9EdDB 4/8 OHM BASS. HI-FIP,RINIC-CEACR1.3.65 £2.50 P&P
R10ES.1F0ROEWQA. 3T5THzE.BFIROE-QIO. ROESBPA.STSO. H3KI-HFIz..SSTEUNDSIO9.6dB.
PRICE £30.39 £3.50 P&P
BRFSR81RRU12EEEEV&LSSSS6....L0166FFFFW0R00RRRROWWAAEEEEWQQQTQNAAAT....GTT2643TETTE6308THHHHBTEEzEzzzW8BB,...B-FFFFI566N1RRRR--0266EEEETC-00QQQQ1COTT....OCCN(RRRRTOEEEEEW((TT,SSSSBIWWHPPPPNA....IIISCNNGTTTTSOOOOOH.CCNSO32OI2CBT0E0NNKOKKKU)EEHMHHHHD))zIzzzI.PHH-O...FSLIISSS.I--E.IFFEEEHANMIINNNI..NS-IMMSSFSLCI9TUU,8993EI249ELLd-,dddAXTBTRBBBRIIC--O.RAAELALRRLLYRREEAADNDYYITSSDDCDUIIOSSIRSCCECROOTOOCEE.U.TTNCCD..PPPPRRRRIIIICCCCEEEE
£42.12
£9.99 £10.99 £12.99
- £3.50 P&P
£1.50 P&P 1.50 P&P £1.50 P&P
OPTIONAL SDTAelNivDerSy £P6R.0I0CpEePrEpRairPAIR C49.00
R10ES.6F0RWEAQT. 3T5HEzB.1F0R-E6Q0.TRCES(TPW. TINOC1O2KNHEz).HSIE-FNI.SM9U8LdBTI. ARRAY DISCO ETC.PRICE £16.49 £2.00 P&P
PRICES: 41 0S0OI WWPOPORR££ISDC41TE90EAR.9S9L.S99IAF5NCRCCHP2OCLA&5MEU0RPSWSGSS£ICVE2A£HSE.90CO90COPO.E9EEFLPA9RSTCV,EHC.OADOR.TBLD.LYEESRPGAOEL£SSET1,S.,G0Pa124cBBBAhCFO0H5C50oiLArrrmeVg000niiiOSOaLhdddRTMtTttrgggNUWWWePa.uHoS&eeeIrBENOrNAAldddiAeTRseOmoTTTWlITOEEsMMMoMTT,ETD:RwERESSoooSRUbaIERRnnnSEFr.Ml((OaioooUeSAe(1S2d7vm2.i0V,gPXB5Ie50mPNaEoIl.OOSbLtTR+e+i+OlFACnOeBFSposI21m4Tnu7HCA02E-t5EoOosII05NT)GARnf))HCfDioHLSrASS.MtttPeLMeeSrOSrreP&CeepWoooLhe.R..IoEaFikR421cIle505Eee0r00vRWWWoe&Slf
PPRRIONVTEEDNCCOTIMRRAPCLNUEISTTMEBIWTOTIATERHRDCDIARENCSDUIGIHTNIAGSNHIDNQCIUNLASULTDIRTINUYGCCTGIOOLMNAPSSOSNFEIBNRTES 3PWERFOTRRMAANNSCMEI.TRTAERNGE8U0P-P1R0TI8OCME3H£Mz.1IL4E.V8SA5, RSI-IZCEA£P138.0*0C1OP2N3&mTPRmO.LSLUEPDPLYPR12OVFEaSOSI.SOANMAPL FVMERYMSICERNOS FTERTAMNICS,MRIATNTGEPRERI1C100E00-3-£10800.8m8M0,HSIzZ,E£V15A6.R0*I0C4AP6m&P mPT,USNUEPDP.LYCO9MVPBLAETTTEERWYITH
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THOUSANDS OF MODULES PURCHASED BY PROFESSIONAL USERS
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OMP/MF 100 Mos-Fet Output power 110 watts R.M.S. into 4 ohms, frequency response IHz - 100KHz -3dB. Damping Factor >300. Slew Rate 45V/uS T.H.D. typical 0.002%, Input Sensitivity SOOmV, S.N.R. -110 dB. Size 300 x 123 x 60mm. PRICE £40.85 - C3.50 P&P
THE RENOWNED MXF SERIES OF POWER AMPLIFIERS
FOUR MODELS:- MXF200 (100W + 100W) MXF400 (200W + 200W)
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USED THE WORLD OVER IN CLUBS, PUBS, CINEMAS, DISCOS ETC. SIZES:- MMMMXXXXFFFF246900000000 WWWW11119999 xxxxHHHHSSS311'V444 ((((3233UUUU))))xxxxDDDD11114321*"""4"
PRICES:-MXF200 C1 75.00 MXF400 C233.85 MXF600 C329.00 MXF900 C449.1 5 SPECIALIST CARRIER DEL £12.50 EACH
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OMP/MF 200 Mos-Fet Output power 200 watts R.M.S. into 4 ohms, frequency response 1Hz - 100KHz -3dB. Damping Factor >300. Slew Rate 50V/uS, T.H.D. typical 0.001%, Input Sensitivity SOOmV. S.N.R -110 dB. Size 300 x 155 x 100mm. PRICE £64.35 - £4.00 P&P
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OMP/MF 300 Mos-Fet Output power 300 watts R.M.S. into 4 ohms, frequency response 1Hz - 100KHz
U -3dB. Damping Factor >300, Slew Rate 60V/uS.
£ T.H.D. typical 0.001%, Input Sensitivity SOOmV. S.N.R.
-y -110 dB. Size 330 x 175 x 100mm.
PRICE £81.75 - £5.00 P&P
OMP/MF 450 Mos-Fet Output power 450 watts R.M.S. into 4 ohms, frequency response 1Hz - lOOKHz -3dB. Damping Factor >300. Slew Rate 75V/uS, T.H.D. typical 0.001%, Input Sensitivity SOOmV. S.N.R -110 dB. Fan Cooled. D.C. Loudspeaker Protection. 2 Second Anti-Thump Delay. Size 385 x 210 x 105mm. PRICE £132.85 + £5.00 P&P
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cAbornadosvessaas,-ncomhcveibdedar3s&f-srWetcqoahupyaennSTnctheeyelr:eBoNreaomAsmsco-itMnvivaaielbd7lCe27r55of0mrs/osV5n-0Oti0nv/t8pae0usr0c,t/Hiohazuo.taupMlsuleotidd.w-FTsiunolaplayc1cc1.e8o9s/m"3s/xp5taKo1tUHitbhZlcee.aawsplelirt.ohagtEOr2aaM4cmdhPBmcrhapacabeknrlenaoemcDltpIaLhlviaefssiweBrtihtaacrnsehsdeesimnlevtovoederluat dlcsejwosunistttcrohthleses Priced 17.44 - £5.00 P&P
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ECHO & SOUND EFFECTS*
SLLsspSfmFowpElEoTiulDe&ulcAiEsotesncTRwd,cdhVRU5rEi,unoREOLgcg6sEfoismrfSnanCeDif:epen-tcahhtrIfptdeoSioasiunrce.lnCrst,c,nsCUOlCe:ueO-qDslduse,uMieJ3MfnTauwHglIaAliXtMispeuNtEecEehairYroc,cdnRshmiVptnoahiOwbdwwdboiiwUiieilvnttnteohhihTiaetsdteSh2uiMbtToa(ctxraAnaml.oerl7NnpkfaoiaDgeg-tfboodra)Iaa,rvNtet.phnerG&h8d3esr Price C144.99 + C5.00 P&P
SIZE: 482 x 240 s 1 20mm
OMP/MF 1000 Mos-Fet Output power 1000 watts R.M.S. into 2 ohms, 725 watts R.M.S. into 4 ohms frequency response 1Hz - 100KHz -3dB. Damping Factor >300. Slew Rate 75V/uS. T.H.D. typical 0.002%. Input Sensitivity SOOmV, S.N.R. -110 dB. Fan CAonotil-eTdh.umDp.CD.elaLyo.uSdiszpee4a2k2erx 3P00roxte1c2t5iomnm. . 2 Second PRICE £259.00 - £12.00 P&P
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LARGE SELECTION OF SPECIALIST LOUDSPEAKERS AVAILABLE, INCLUDING CABINET FITTINGS. SPEAKER GRILLES, CROSS-OVERS AND HIGH POWER. HIGH FREQUENCY BULLETS AND HORNS, LARGE (A4) S.A.E. (60p STAMPED) FOR COMPLETE LIST. McKenzie and Fane Loudspeakers are also available. MINENCE:- INSTRUMENTS, P.A.. DISCO, ET
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TYPE 'A' (KSN1036A) 3 round with protective wire mesh Ideal to;
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bookshelf TYPE 'B'
and medium sized Hi-Fi apeakers. Price C4.90 50p P&F. (KSN1005A) 3%" super horn tor general purpose speakers,
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disco and P.A. systems etc. Price C5.99 50pP&P.
TYPE 'C (KSN1016A) 2 x5' wide dispersion horn for quality Hi-Fi sys
terns and quality discos etc. Price C6.99 50p P&P.
TYPE 'D' (KSN1025A) 2 x6 wide dispersion horn. Upper frequency
TYPI
response retained extending down to mid-range (2KHz). Suitable tor high quality Hi-Fi systems and quality discos. Price £9.99 + 50d P&P
TYPE 'E' (KSN1038A) 3V horn tweeter with attractive silver finish trim
Suitable for Hi-Fi monitor systems etc. Price C5.99 50p P&P.
LEVEL CONTROL Combines, on a recessed mounting plate, level contro:
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and cabinet input jack socket. 85x85mm. Price £4.10 + 50p P&P.
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SPECIALIST CARRIER DEL. £12.50 PER PAIR OPTIONAL SDTAelNivDerSy £P6R.0I0CEpePrEpRairPAIR £49.00
-
RBENDERS:- HI-FI, STUDIO, IN-CAR, ET
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4 A 8 ohm)
C2.00 PAP C2.50 P&D £3.50 P&B £3.50 P&P
PRICES: 41 0S0OWW ££4190.99.995 2P&50PW£2£.9090.9E9ACH
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PHOTO: 3W FM TRANSMITTER
B.K. ELECTRONICS
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POPORRISDCTEEARSLS IAFNCRCHCOCLAMEURSSGSSICVEAHESCOCOPOEEFLPRSTV,EC.OADOR.TBLD.YLEESRPGAOELS£SET1,S.,G0PO0HCVOOTMNU. IBENNOTIOMEDRURIEFMAS.V,XPI.OSLFACFsICAEINTACDL.
UNITS 1 G. 5 COMESESTEWXA. SYS, SEO6UTTRH. ENO-ON-SEA, Tel.: 070& - 527572 Fax.: 0702 - 4202A3
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Sept 1994-Aug 1995
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Quality Assurance RSI 2750
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OUT OF THIS WORLD
ON SALE NOW
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Over 800 colour packed pages with hundreds of Brand New Products at Super Low Prices.
ONLY
Available from all branches of WH SMITH, John Menzies in Scotland ONiy Eason 6P Son in N. Ireland OND( and Maplin stores nationwide. The Maplin Electronics 1995 Catalogue - OUT OF THIS WORLD!
LuraTech PDF Compressor 6.2.00.04 Lura PDF v2.65