Elementary Electronics 1966 07 08

User Manual: Elementary-Electronics-1966-07-08

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THE

ELEMENTAR

SERfOPNOME SERVER:

IB'LDON
¡HI-FI

WHEELS!

ELECTRON/CS

JULY -AUGUST 75c

By the Editors

BASIC
ELECTRICITY
From the atom to Ohm's law!

of RABIO -T' EXPERIMENTER

Those Fabulous
FUEL CELLS
in reverse!
Electrolysis lin

OT -can
S1Aß1ER!-

Uses SCR's

tdown
countdown

www.americanradiohistory.com

Be creative -and

thrifty too!

Save up to 50% with EICO Kits and Wired.

EICO supports your sense of
achievement with no- compromise

people, ages 8 to 89, have built EICO
kits. If you love to create, EICO is
for you. And if you want the best
buys in ready -to -use factory assembled equipment, again EICO
is for you. Judge critically for
yourself. Send for your free catalog.
See EICO at your local dealer.

engineering, finest parts, dramatic
esthetics, simple step -by -step
instructions and large pictorial
diagrams. You need no technical
background -just pliers, screwdriver, soldering iron. Three million

TEST EQUIPMENT

Model 232 Peak -to -Peak VTVM.
or

must for color

and industrial use. 7-noskip ranges
functions. With Uni-Probe., $29.95 kit,

B &W TV

on all 4

$49.95 wired.

KITS & WIRED

CITIZENS BAND/ HAM RADIO

New Model 779 Sentinel 23 CB Transceiver. 23channel frequency synthesizer provides crystal.
controlled transmit and receive on all 23 channels. No additional crystals to buy ever! Features
include dual conversion, illuminated S RF meter,
adjustable squelch and noise limiter, TVI filter.
117VAC and t2VDC transistorized dual power
supply. Also serves as 3.5 watt P.A. system.

$169.95 wired.

Model 460 Wideband DirecCcopled 5" Oscilloscope. DC.4.5mc for color and B &W TV service
and lab use. Push -pull DC vertical amp., bal. or
unbal. input. Automatic sync limiter and amp.
$89.95 kit, $129.50 wired.

EICOJ

12VDC

117VAC

New Model 3566 All Solid -State Automatic FM
MPX Stereo Tuner 'Amplifier. "Very satisfactory

product, very attractive price" -Audio Magazine.
No tubes, not even nuvistors. Delivers 112 watts
IHF total to 4 ohms, 75 watts to 8 ohms. Completely 'pre -wired and pre.aligned RF, IF and
MPX circuitry, plus plug -in transistor sockets.
$219.95 kit (optional walnut cabinet $14.95t,
$325.00 wired including walnut cabinet. UL
approved.

New Model 712 Sentinel 12 Dual Conversion 5watt CB Transceiver. Permits 12- channel crystal controlled transmit and receive, plus 23-channel
tunable receive. Incorporates adjustable squelch
& noise limiter, & switches for 3.5 watt P.A.
use, spotting, & Part 15 operation. Transistorized

wired only.

STEREO/HI-FI

dual power

supply.

$99.95

Model ST70 70 -Watt Integrated Stereo Amplifier.
Best buy of highest ranked stereo amplifiers
according to independent testing. $99.95 kit,
$149.95 wired. ST40 40 -Watt Integrated Stereo
Amplifier, $79.95 kit, $129.95 wired. ST97 Matching FM MPX Stereo Tuner, $99.95 kit; $139.95
wired,

FREE 1966 CATALOG

e'
New Model 753 The one and only SSB SAM 'CW
Tr -Band Transceiver Kit. "The best ham transceiver buy for 1966" -Radio TV Experimenter
Magazine. 200 watts PEP on 80. 40 and 20

EICO Electronic Instrument Co., Inc.
131 -01 39th Ave., Flushing, N.V. 11352

EE -6

Send me FREE catalog describing the

full EICO

line of 200 best buys, and name of nearest
dealer. I'm interested in:
test equipment
ham radio
stereo /hi -fi
Citizens Band radio

Name

Model 324
range. For
TV,

FM,

modulation.

Signal Generator. 150kc to 435mc

alignment and signal tracing of
CB end mobile. Built -in and ext.

IF -RF

AM.

$32.95 kit, $44.95 wired.

meters. Receiver offset tuning, built-in VOX, high
level dynamic ALC. Unequaled performance, fed.
or^c and appearance. Sensationally priced at

$189.95 kit, $299.95 wired.

Address
City
State

1945 -1965: TWENTY YEARS OF LEADERSHIP IN CREATIVE ELECTRONICS

www.americanradiohistory.com

Zip

EARN -WHILE -YOU -LEARN APPLIANCE REPAIR

AND AIR CONDITIONING

.,,,

,LA.

How You
CAN PREPARE

THESE TWO

AT HOME FOR

BUSINESS

AND JOB

OPPORTUNITIES

FREE BOOKS
CAN START YOU ON YOUR
WAY TO:

new high -pay skill
AID PRAC1

business of your own

us,NONE

STUDY COORS(C

ALL TYPES
OF APPLIANCES
AIR CONDITIONING

AND REPRIGERATEDN
PLUS
SMALL GASOLINE

spare time income

ENGINES

savings on appliance
repairs
THIS NEW, SHORT EASY COURSE

TRAINS YOU AT HOME

THE BEST WAY TO GET AHEAD
is to make yourself better qualified than
the next man. You can prepare quickly
to do professional appliance servicing at
home in your spare time.

NEW EASY COURSE
shows you step -by -step professional
methods for repair of all types of appliances...including air conditioning, even
small gasoline engines, farm and commercial equipment.
AMAZING PROFITS
in your spare time...in improved job opportunities...in a business of your own.
You earn -as- you -learn professional
methods of appliance repairs...are ready
to start servicing appliances after only
a few lessons.
LOW COST TRAINING COVERS
everything...special equipment is included in your course at no extra cost.

SEND FOR FREE BOOKS

MAIL THIS COUPON TODAY!
Appliance Division, Department 506 -076
National Radio Institute
3939 Wisconsin Avenue , Wash.,D.C. 20016
Send me the illustrated free book that tells about opportunities in Electrical Appliance Repair and details
of NRI's new course -plus a sample lesson. understand there is no obligation and no salesman will call.
I

Name

Age

Address
City
APPLIANCE DIVISION, NATIONAL RADIO INSTITUTE

3939 Wisconsin Ave., Washington. D.C. 20016

State

Zip Code

Accredited Member National Home Study Council

TuLY-AucusT, 1966

www.americanradiohistory.com

JULY -AUGUST 1966

ELEMENTARY

NOW THERE ARE OVER 85 RADIO

SHACK STORES COAST TO COAST

ELECTRON/CS

PHOENIX

ARIZONA
3905 East Thomas Rd.

CALIFORNIA

ANAHEIM -507 Eut Natalia Ave.
BAKERSFIELD
1308 19th St.
LA HABRA -1511 West Whittler Blvd.
LONG BEACH
3976 Atlantis Ave.
LOS ANGELES:
Downey -Wormwood Shop. Ctr.

Ladera Shop. Ctr.

5305 Centinela Ave.
10919 Sepulveda Blvd.
19389 Victory at Tampa
Torrance
22519 Hawthorne Blvd.
West Coyly. -2518 Eut Workman Ave.
West L. A.
Pleo Blvd. at Overland
OAKLAND (Ban Leandro)
Bay Fair Shop. Ctr.
SACRAMENTO
600 Fulton Ave.
SAN DIEGO (La Mete)
Grossmont Shop. Car.
SANTA ANA
Bristol Plaza Shop. Ctr.

23
37
41

45
58
63
77
81

Electricity, Magnetism and the Atom
Basics of RTTY
RTTY in the Shack
Using Cross -Coupled Circuits
Block that Leak
Angles on DX
Making Zener Diodes Work for You
Electroplating for the Hobbyist
Those Fabulous Fuel Cells

798 South Santa Fe Dr.

Westland Shopping Center

ILLINOIS

CHICAGO

Plaza at 95th St.

MAINE

Pine Tree Shop. Ctr.

MARYLAND
HampahirsLanIley Ctr.
LANGLEY PARK
MASSACHUSETTS
BOSTON:
167 Washington St.
594 Washington St.

Barrier

110

---730
- - Plus
-N.
- -473

Federal St.

South Shore Plaza
Westgete Mall
Commonwealth Ave.
Fresh Pond Shop. Ctr.
CAMBRIDGE
Shopper.' World
FRAMINGHAM
Central Shop.
LOWELL
E. Shop. Ctr.
SAUGUS
Century Shop. Ctr.
WEST SPRINGFIELD
Lincoln Plaza
WORCESTER

BRAINTREE
BROCKTON
BROOKLINE

MINNESOTA
1121 Nieollet Ave.
MINNEAPOLIS
North Snelling
ST. PAUL
MISSOURI

FEATURES

ST.

Electronics on Wheels

125

18 Traffic A Go Go
49 Build 'em Good
57 Hartman Marine -Auto Converter Report
65 Knight -kit Safari CB Transceiver Report
74 Suitcase Workshop
76 TV on the Go
90 TV Schooling in the Hospital
95 Speedy Readin'
I

Network on the Prowl
Will Travel

DEPARTMENTS

NEW HAMPSHIRE

MANCHESTER-

1247 Elm St.

NEW MEXICO
ALBUQUERQUE -á31S Lomu, N. E.
NEW YORK
BINGHAMTON (Vestal)- Vestal Shop. Plaza
Transitown Shop. Gtr.
BUFFALO (Clarence)
1126 Ave. of the Amer kas
NEW YORK
Shoporema Ctr.
SC ENECTADY (Rotterdam)
SYRACUSE:
3057 Erie Blvd. East.
Fairmount Feb. Shop. Ctr.

CINCINNATI

OHIO

-852

SwItton Ctr.

OKLAHOMA

PHILADELPHIA:

2327G Cottman Ave., Roosevelt Mall
1128 Walnut St.
PITTSBURGH -309 Se. Hill. Village
RHODE ISLAND

- - -

NewScan
E/E Etymology
21 En Passent (Chess Column)
96 FCC Q & A
103 DX Central Reporting
108 Literature Library
8
19

1301 Reservoir Ave.
CRANSTON
Shoppers' Town
EAST PROVIDENCE
TEXAS
ABILENE -2910 North First St.
Collins at Park Row
ARLINGTON

Hancock Shopping Center
AUSTIN
BROWNSVILLE -847 S. E. Elizabeth SL
DALLAS:

Medallion Center

125 Wynnewood Village
Plymouth Park Shop. Ctr.
FORT WORTH:
ISIS So. University Dr.
900 East Berry St.
3520 Denton Highway
2615 West 7611 St.
HOUSTON:

8458 Gulf Freeway
322 Northllne Mall
Bellaire- 4759 Bluonnet

AUTHORS FEATURED IN THIS ISSUE:

Jack Brayton, Len Buckwalter- K1ODH /KBA4480, John W.
Collins, Lester Escargot, James A. Fred, Herb Friedman
W2ZLF/KB19457, Charles Green- W31KH, Carl L. Henry,
Robert E. Kelland, K.C. Kirkbride, John D. Lenk, Marshall
Lincoln- K9KTL, A. A. Mangieri, Martin H. Patrick, C. M.

Art Trauffer

Cover Photo by Leonard Heicklen

Pine St. (Welter Ache Div.)
South County Shopping Center.
Northland Shopping Center

Mayfair Shop. Ctr.
OKLAHOMA CITY
2730 South Harvard
TULSA
OREGON
PORTLAND -1928 N.E. 42nd St.
PENNSYLVANIA

104 Have Brains,

Il,

- -- -

CONNECTICUT
HAMDEN
Hamden Mart. Shop. Ctr.
MANCHESTER
Manchester Shop. Parkode
NEW HAVEN -92 York St.
NEW LONDON
New London Shop. Ctr.
STAMFORD
29 High Ridge Rd.
39 So. Mein St.
WEST HARTFORD
GEORGIA
ATLANTA
Greenbrier Shopping Center

Stereophone Server
87 SCR Touch -Control Switch
92 Calibrated Attenuator

Stanbury

COLORADO

DENVER:

101

- --

PORTLAND

59 Breaking the Crystal
67 SCR Slot -Car Starter

Reseda-

CONSTRUCTION

Hills-

Mission

THEORY

SAN ANTONIO:
150 Wonderland Shop. Ctr.
684 8.W. Military Drive
1820 Highway 75 North
SHERMAN
WACO -1018 Austin Ave.

UTAH
SALT LAKE CITY

ARLINGTON

Cottonwood Mall

VIRGINIA

WeshingtonLee Shop. Cir.
WASHINGTON

SEATTLE:
2028 Third Ave.

Cover Highlights

837 N. E. 110th St.

Burlen Plaza

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

SURPRISE PAKS

With Purchases of $4.95 or Mor

At a fraction of their cost
WHILE THEY LAST! All types,
semiconductors
all kinds
(tested & untested), buy now!

..,s

4 011

ARC/4su
s
M-

60 -pc Transistor
Surprise Pak

t ATE

k"A9
GtHïAR 461Pt1ftff

2 98

NPN's,PNP's
10W, 20W,
50W transistors plus subminiature types.
2.98

27 -034

100 -pc Semiconductor
Grab Pak

298

PNP's, NPN's,

asst. case styles
TO -36 & TO -3
power transistors, top hats, dual germaniums, etc. 27 -037, 2.98

Infra -Red
Transducer Kit
198

Parabolic re-

flector, 3"

filter detec-

tor complete with pictorial di1.98

agram. 27-035

60 -pc Jumbo Rectifier
Surprise Pak
ea.
98 Less than 4¢ top

Includes
hats, epoxies,
zeners, diodes,
27 -033 .. 1.98
buy!
A
great
etc.

10 -pc Power
Transistor Pak
Asst.14

10;20

watt, 50 watt

198

sizes;

nium,

germa-

silicon

types. Asst. TO -3, -5, -8, -13
and TO -36 cases.
Net 1.98
27 -036

svecvEiz+ TWIN -PAKS
Popular PNP Types
98

5 Each

2N107 Types

Wireless Phono Oscillator Module: designed to play your phonograph.
directly through a radio without connecting wires. 27-257
4.95
Amplifier Module: custom -build a modern, convenient interCl Intercom
com system for your home or office. 27 -254
4.95
"Baby- Sitter" Amplifier Module: gives real peace of mind; even lets
you monitor sound of baby's breathing. 27-256
4.95
Phonograph Amplifier Module: designed for use with crystal or
ceramic cartridge. 2 watts peak power. 27 -261
4.95
Telephone Amplifier Module: permits "group- listening" to a phone
conversation; talk with hands free. 27 -260
4.95
Super High-Gain Amplifier Module: for use as a hearing aid, audio
signal tracer, "eavesdropper ", etc. 27 -251
4.95
Power Amplifier Module: the ideal amplifier to use with tuners,
microphones, paging systems, or as signal tracer. 27 -253
4.95
Guitar Amplifier Module: can be used with guitars or any stringed
instrument. 2 watts peak power. 27 -255
4.95
AC Power Supply Module: converts 115 VAC to 6 VAC, 1 amp. Use
with rectifier-electronic filter (below). 27 -258
1.95
Rectifier -Electronic Filter Module: provides dual DC output from AC
power supply. 6 VDC; 24V max., 1 amp. 27 -259
3.95
1-70

10 NPN' & 15 PNP
for

198

For RF applications, switching,
general purpose
.í
audio types. Replace many
numbers without circuit change.
27 -1516

....

Optional Accessories for Modules Above

Cat. No.
Description
27 -1430 Loopstick Antenna
23 -465
"C" Cells (4 required)
27 -1437 Battery Holder (2 required)
23 -006
6V Lantern Battery
27 -258
AC Power Supply
27 -259
Rectifier- Electronic Filter
40 -1203 4" Speakers (2 required)
27 -1384 4PDT Switch
27 -066
50052 Control w /Switch
40 -219
8" Extension Speaker
27 -1264 100 -Ft. Speaker Wire
33 -100
Lapel Microphone
27 -212
500K Control w /Switch
40 -1213 8" Speaker
44 -533
Telephone Pickup
33 -180
Headphone
23 -468
Penlight Batteries (2 required)
27 -1433 Battery Holder
33 -918
Dynamic Microphone
33 -115
Contact Type Microphone

Key Letters

Each

A
A

.59
.14
.25
1.05
1.95
3.95
1.99
.49
.79

A
B, C, D, E,

G, H

B, C, D, E,

B,C,D,2,G,H
H

B
B
B

8.95
2.39
1.89
.79
3.99

D, E,

D, E, G, F

.99
1.98
.10
.22

8.95
1.49

somommimmemieuesmommemolimeximmins

CK722 Types

Exclusive! Ideal
for all audio applications. Base
diagrams incl. 27 -031 ... 1.98

SOLID -STATE MODULES

Please send FREE 1966 Radio Shack

MAIL
TODAY to
NEAREST
RADIO
SHACK
STORE

Please

send

listed below.

Catalog!

EE -7 -66 v
accessories I have
My order totals $4.95 so include my
I
your $2.00 Solid-State Electronic

the

modules

and

copy
I
enclose $
chincludes
postage and handling anywhere in the U.S.A.
book.

50ato

cover

I
I

Name (please print)

Street

City

State

Zip

AminovENMENNUMNntneleMmeemmenl

JULY-AUGUST, 1966

www.americanradiohistory.com

Brand new leader in
value and features!

MAEKSMA11
Pencil
Soldering
Iron
by

ELEMENTARY

ELECTRONICS
JULY -AUGUST 1966

JULIAN M. SIENKIEWICZ
WA2CQL /KMD4313

Editor

WILLIAM HARTFORD

Technical Editor

KKD7432
ELMER C. CARLSON

Construction Editor

KOD1752

WQiKPJI,

Extremely light
in weight.
Highly efficient.
Stainless steel
barrel has long
reach.
Maximum tip

temperature is
750 °F.
1/8" diameter tip
is replaceable
gets into tight
places.
Screwdriver,
chisel and cone
shaped tips
available.
Handle remains
cool, resists
breakage.

Vol. 2 No. 3

Dedicated to America's Electronics Experimenters

RON STAFFIERI

Art Editor

ANTHONY MACCARRONE

Art Director
Corer Art Director

EUGENE F. LANDINO

Associate Art Director

JUDITH ANDERSON

Art Associate

ELLIOT S. KRANE

Advertising Director

JIM CAPPELLO

Advertising Manager

LEONARD F. PINTO

Production Director

CARL BARTEE

Production Manager

HELEN GOODSTEIN

Assistant Production Manager

CLIFF SHEARER

Promotion Director

JOSEPH DAFFRON

Erecutire Editor

President and Publisher
B. G. DAVIS

Erecutire Vice President and Assistant Publisher
JOEL DAVIS
Vire President and Editorial Director
HERB LEAVY, KMD4529

Get a MARKSMAN

Pencil Soldering
Iron or complete
kit at your hobby
or hardware dealer.

IRVING BERNSTEIN

MARKSMAN

117111711

IRON with

HIGH FIDELITY

screwdriver

tip and cord in
vinyl pouch.

Model SP -23.
$2.98 list.

s
r

ELEMENTARY ELECTRONICS, Vol. 2, No. 3 10931 is published bimonthly by SCIENCE& MECHANICS PUBLISHING CO., a subsidiary
of Davis Publications, Inc. Editorial, business and subscription offices:
505 Park Ave., New York, N. Y. 10022. One -year subscription (sin
issuesl -$4.00; two -year subscription 112 issuesl -$7.00; and three year subscription 118 issuesl -$10.00. Add $1.00 per yeor for postage
outside the U.S.A. and Canada. Advertising offices: New York, 505
Pork Ave., 212.PL -2 -6200; Chicago: 520 N. Michigan Ave., 312 -527.
0330; los Angeles: 6253 Hollywood Blvd., 213 -463 -5143; Atlanta: Pirnie
& Brown, 3108 Piedmont Rd., N.E., 404. 233.6729; Long Island: Len Osten,
9 Gorden Street, Great Neck, N. Y., 516- 487 -3305; Southwestern advertising representative; Jim Wright, 4 N. Eight St., St. louis, CH -1965.

MARKSMAN KIT
with iron; screwdriver, cone and
chisel type tips;

soldering aid
and solder.

Model SP -23K.
$4.44 list.

WELLER ELECTRIC CORP., Easton, Pa.
WORLD LEADER IN SOLDERING TECHNOLOGY

EDITORIAL CONTRIBUTIONS must be accompanied by return postage
and will be handled with reasonable care; however, publisher assumes
no responsibility for return or safety of manuscripts, art work, or
photographs. All contributions should be addressed to the Editor,
ELEMENTARY ELECTRCNICS, 505 Park Avenue, New York, N Y. 10022.

Second class postage paid at New York, New York and at additional
mailing office. Copyright 1966.by Science and Mechanics Publishing Co.

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

I
r
I
I
I
I

I
I

ESE

INTERNATIONAL CORRESPONDENCE SCHOOLS

II=

EEI

(In Hawaii: P.O. Box 418, Honolulu.

Dept. 1895 Scranton, Penna. 18515.
In Canada: I.C.S. Canadian, Ltd. In

other countries: I.C.S. World, Ltd.)

Yes! Send me your three -booklet Career Kit, including the new "ElectronlCS" Career
Guide. understand these booklets are absolutely FREE.
I

Age

Name

Address

Working Hours
a

A M.

P.M.

Special training programs for industry

Convenient payment plan.

NMI

I
I

- -- -----I_I

member of U. S. Armed Forces. Send me facts about special low rates.

L -NM

I
I
I
I

Employed by

Occupation

O I'm

Zip Code

State

City

EMI

NEE

IlllllllE

=In

MEN

Cut thus out.
Cut yourself in

on 16 extras:
electronics courses (22) than
1 More
any other school. This lets you choose
one that's just right for you.

2
3
4
5
6
8

Or, to meet special needs, I.C.S. will

tailor -make a course for you, personally.
You may pay for your course month by month,
as your study progresses.
Famous Heathkit® equipment (only I.C.S. has it).
Complete library of texts included
in price of course.
Your money back if you fail to pass test for
1st or 2nd Class Radiotelephone license
after studying the appropriate I.C.S. course.
Experienced home -study counselors
always available to help you.
Broad career guidance facilities.

9
10
11

12
13
14
15
16

I.C.S. mails progress reports to your employer,
if you request.

Programed courses (optional) for quick,

easy study.
I.C.S. constantly reviews all texts
to assure up- to- dateness.

Complete courses in Telephony available
only from I.C.S.
Greater experience in correspondence education
than any other school
(75 years-over 71 million students).
One out of every 14 top executives in America
has at one time studied with I.C.S.
All courses accredited by
National Home Study Council.
New 64 -page "ElectronlCS" fact book,
just off the press, is yours FREE.
It answers the most -often -asked questions
about breaking into electronics.

Any number of schools can teach you electronics.
All of them offer some of these extras.

But only I.C.S. has them all. Why should you settle for less?
Cut yourself in on electronics success.
Mail the coupon that brings you all 16 electronics extras. Do it right now.
JULY -AUGUST, 1966

www.americanradiohistory.com

8 HEATHKIT® Values...See The
New! Deluxe 10 -Band
AM /FM /Shortwave Portable
Tour The Voice Capitals Of The World! 7 bands
cover 2-22.5 mc to bring you the intrigue of
foreign shortwave, amateur and weather stations
a 550 -1600 kc AM band keeps you
posted on the latest news, weather and sports ...
and a 88 -108 mc FM band offers you quiet, relaxed listening of high fidelity music. There's even
a 150 -400 kc longwave band for aircraft and
marine broadcasts, plus a logging scale for
relocating unknown frequencies.
Boasts 16 Transistors, and 44 Prebuilt & Aligned
RF Circuits; separate FM tuner & IF strip (same
as used in deluxe Heathkit hi -fi components); 2
built -in antennas; 4' x 6' speaker; battery -saver
switch. Operates anywhere on 7 flashlight bat -'
teries, or on 117 v. AC with optional charger/
converter, $6.95. Build in only 10 hours. 19 lbs.

...

Deluxe

5 -Band

..._r

..-.:-r-

..r

..
A.: :...,...

^---C-.-:'

Low Cost AM /Shortwave Radio!

Shortwave Radio!

..:-.-..n.
".,.....r-1..,

.--,T.-.4T

d....,_

44444;.=-. -FB.:SL:,.,--.

Built -in 5'
speaker; bandspread tuning; signal
strength indicator; 7' slide -rule dial; log- Kit
4 bands cover 550 kc to 30 mc.

Compare it to $150 sets! Covers 200 -400
kc, AM and 2 -30 mc. Tuned RF stage,
crystal filter for greater selectivity, 2 detec- Kit GR -54
tors for AM and SSB, tuning meter,
bandspread tuning, code practice monitor,
automatic noise limiter, automatic volume
control, antenna trimmer, built -in 4' x 6'
speaker, headphone jack, gray metal cab.,
FREE SWL antenna. 25 lbs.

ging scale; BFO control for code & SSB;
4 -tube circuit plus 2 rectifiers; noise limiter; external antenna connectors; Qmultiplier input; gray metal cabinet; AM
antenna. 15 lbs.

$8495

23- Channel

5 -Watt

GR -64

$31

Solid -State

CB Transceiver!
Kit GW-14

$8995
Assembled GWW -14

$1 2495

transmit & receive channels for
utmost reliability. Low battery drain ... 0.75 A transmit, 0.12 A receive. Only 27/e" H x 7' W x 101/2' D .. .
23 crystal- controlled

ideal for car, boat, any 12 v. neg. gnd. use. "S"
meter, adjustable squelch, ANL, built -in speaker, PTT
mike, aluminum cabinet. 8 lbs. Optional AC power
supply, Kit GWA -14 -1, 5 lbs. $14.95. Optional 6 to
12 v. DC converter, Kit GWA -14 -4, 3 lbs.... $14.95.
Special 23-Channel Crystal Pack (46 crystals), GWA 14-2, reg. $137.50 value, only $79.95. CB crystals
$1.99 each with any Heathkit CB transceiver order.

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

Other 242 In

Catalog!

FREE

New 30 -Watt Transistor FM Stereo Receiver
transistors, 11 diodes for transparent
transistor sound; 20 watts RMS, 30 watts
IHF music power @ ± 1 db, 15- 60,000
cps; wideband FM /FM stereo tuner, two
pre -amplifiers, & two power amplifiers;
compact 3 %" H x 151/4" W x 12" D size.
Assemble in around 20 hours. Mounts in
a wall, or optional Heath cabinets (walnut
$9.95, beige metal $3.95). 16 lbs.
31

Kit AR -14

$V995

(less cabinet)

... New

Best Hi -Fi News of '66

Low Cost Transistor Stereo Twins!

Matching 30 -Watt Stereo Amplifier

New Transistor FM /FM Stereo Tuner
Assembles in only 4 to 6 hours! 14
transistor, 5 diode circuit; 5 uy sensiKit AJ -14
tivity; less than 1% distortion; phase
control for best stereo; 4 -stage IF; filtered outputs; automatic stereo indicator
light; preassembled & aligned "front end". Install in a wall or either Heath
(less cab.)
cabinet (walnut $7.95, beige metal

Assembles in 10 hours! 17 transistor, 6
diode circuit 20 watts RMS, 30 watts
IHF music power @ ±1 db from 1550,000 cps; Handles tuner, phono, auxiliary. No audio transformers ... assures
lower distortion, minimum phase shift.
Install in a wall, or either Heath cabinet
(walnut $7.95, beige metal $3.50). 10 lbs.

$4995

$3.50)

Kit AA-14

$5995

(less cab.)

6 lbs.

Deluxe 6- Transistor AM Portable!
Surpasses miniatures in performance and economy! Boasts large 4" x 6" speaker for a crisp, bold
sound; slide-rule dial; "thumb- touch" controls;
smooth vernier tuning; tuned RF stage & double tuned IF stage for greater sensitivity and selectivity; big 1/4" diameter rod antenna for distant
station pickup; handsome black simulated leather
case. Build in 4 to 6 hours. Uses long-life "D"
size flashlight batteries (not included). 5 lbs.

Kit GR -24

$2825

ITN
HEATHKIT

1966

FREE

1966

Heath Company, Dept 139.7
Benton Harbor, Michigan 49022

Enclosed is

plus shipping. Please send model(s)

Catalog!
Describes these and
over 250 electronic

kits

world's

largest selection.

Mail coupon, or
write Heath Company, Benton Harbor,
Michigan 49022.

Please send FREE 1966 Heathkit Catalog.
Name

Address

State
City
Prices & Specifications subject to change without notice.

Zip
CL-242

JULY- AUGUST, 1966

www.americanradiohistory.com

IN THE JULY ISSUE OF

SCIENCE & MECHANICS
READ THE SECOND FANTASTIC

DOCUMENTED FEATURE ON

THE "MANNED"
SOVIET
SPACE FLIGHTS
THAT WERE
NEVER

Cienct

\EWSCA

Out of the Dark
A newly designed lighting system for the
interior lighting of trailers and truck bodies
permits loading and unloading operations to
be completed quickly, accurately and safely.
The system is the first for van lighting which
can operate fluorescent lamps off either con-

MANNED!
íßf.

Mechanic
NEW
ELECTRIC
CAR!

NOW
ON

WORLDS TOP ASTROLOGERS
IR

PREDICT THE FUTUREI

E-t41 lei Wm SA&

SALE

R- WW1

"My contention is that the Soviet Union uses its
real -and often very crude -achievements in space
research as a springboard for spectacular hoaxes.
Foremost

among these

hoaxes is their

manned

spaceflight program. The status of their technology
cannot support a man -in -space program at this time.
Nor have they ever actually documented one of
their manned spaceflights beyond a question of
doubt. How do I know this? SCIENCE & MECHANICS
assigned me to the job of unearthing this and
many other phony qualities inherent in flights of
the Russian manned space ships." So began space
expert Lloyd Mallan's sensational expose of "The
Russian Spacemen Who Weren't There."
Don't miss the second of 3 provocative AND documented articles in the July issue of SCIENCE &
MECHANICS, now on sale at your newsstand.
SCIENCE & MECHANICS MAGAZINE

505 Park Avenue
New York, N. Y. 10022

Lighting system for truck trailers
provides adequate illumination
for rapid, accurate and safe
loading and unloading of cargo.
General Electric's newly designed
system permits operation of 15watt fluorescent lamps off
either 120 -volt dockside power
or the truck's 12 -volt battery.
ventional 120 -volt dockside power or the
truck's .12 -volt battery power. Trailers normally loaded and unloaded at docks need to
be equipped to utilize only 120 -volt power
from the loading dock. Delivery trucks and
others which operate away from docks

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

Live Better Electronically With

LAFAYETTE
RADIO ELECTRONICS

it .,.
REÜDt BECTRDt1ICAtLI

W11N

LARiRITE

Over 500 Pages

1966

OUR 4s11FYEAR

Catalog 666
lndex-P+te501

RE E
TV

Tibes and Parts
',Electronic Parts

Test Equipment
Citizens Band
Tools
Ham Gear
Stereo Hi -Fi
Tape Recorders
Walkie- Talkies
Auto Accessories

LAF AY ETTE

RADIO ElKS RONKS

1966 Catalog 660

i
:1

Featuring Everything in Electronics for

00ppöQy

HOME

INDUSTRY

LABORATORY

from the

"World's Hi -Fi & Electronics Center"
LAFAYETTE Radio ELECTRONICS
LAFAYETTE'S

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LONG ISLAND
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Cut out and Mail Coupon for FREE Lafayette Catalog

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Dept. DEEG -6

NEWSCAN
should be equipped with a special General Electric- developed inverter -ballast.
This
makes it possible for fluorescent lamps to be
operated off battery power.
Basic components of the system in each
trailer are four 15 -watt fluorescent tubes
housed in especially designed, single -lamp
fixtures, and a male plug inside the door.
The docks they use are equipped with a
switch, cable and female plug. The fixtures,
only about three inches deep, are higher than
the door opening when mounted on the ribs
of the trailer roof. This minimizes the possibility of damage during loading and unloading operations. Lighting levels are about
eight footcandles, three times as high as exist
in the average well -lighted parking lot.
High frequency current from the inverter ballast increases the efficiency of fluorescent
lamps. With this gain, plus the inherent efficiency advantages of fluorescent over incandescent light sources, the new system produces at least four times as much light as
conventional light bulbs of the same wattage
with no increasing battery drain.

does not employ a laser as a light source.
The diode employed as the light source differs
from a laser in that it produces light directly
proportional to the current passed through
it, whereas the laser diode produces more
light at a higher rate than the increase in current. It is predicted that the new data system
will be more popular than laser systems, especially for relatively short range use where
total cost is of great importance.
In addition to transmitting data from the
ground to a missile, the new system has other
potential applications. For example, in send-

Seeing Infrared

Infrared light like that used in many modern cooking ranges may soon carry valuable
data to astronauts on expeditions into deep
space. Beams of the invisible, infrared light
may be used to carry thousands of coded
messages between ground tracking stations
and missiles. The light beams are part of a
new data link system developed by the General Electric Company. The feasibility of
this new method of sending information has
been proven recently by the successful transmission of an extremely clear television picture.
The new system was designed to relieve
the growing congestion of the airwaves at
missile test ranges. Presently, the increased
message load is straining the number of available radio channels. However, the situation
will become even more acute in the future.
For example, larger launch vehicles will require additional monitoring functions. Increased complexity of space missions will demand transmission of even greater quantities
of messages. Interference-free transmission
of messages is also a big advantage of the
new data system. With the light beams there
is no interference with or from radio waves.
Although the new gallium arsenide system is an outgrowth of laser technology, it

Television picture is transmitted
over an invisible light beam,
demonstrating new data link system
developed by the General Electric
Company's Radio Guidance Operation, Syracuse, N. Y. Actual
system consists of compact transmitter shown at far left and
receiver shown on top of the TV
monitor. It may soon be used to
carry valuable data to astronauts,
to transmit other data from one
location at a missile launch
center to another, or to carry
signals from a radio or TV studio
to a transmitter.

ing guidance and instrumentation messages
from missile pad to block house, block house
to launch operation center and from range
safety TV vans to launch operation control.

The advantages of the gallium- arsenide
method over conventional radio systems in
these uses are: it has less equipment, is less
costly, lighter and more compact. The new
system consists, simply, of a transmitter
which is about the size of a loaf of bread. It
ELEMENTARY ELECTRONICS

www.americanradiohistory.com

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You will learn the basic principles of radio. You svill construct. study and work with
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You will receive training for the Novice. Technician and General Classes of F.C.C. Radio
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Oscillator, Signal Tracer and Signal Injector circuits, and learn how to operate them. You
will receive an xcellent background for television, M1 -Fi and Electronics.
Absolutely no r previous knowledge of radio or science s required. The Etlu Kit" is
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You w 11 receive all parts and instructions necessary to build twenty different radio and
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In addition, you receive Printed Circuit materials, including Printed Circuit chassis.
useful set of tools, a
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PRINTED CIRCUITRY

SERVICING LESSONS

You will learn troubleshooting and
You
.
servicing in a progressive m
Will practice repairs on the sets that
will learn symptoms
l homes
and causesu of trouble)
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now

O Send i 'Edu -Kit" postpaid. I enclose full payment of $26.95.
O Send 'Edu -Kit" C.O.D. I will pay $26.95 plus postage.
O Rush me FREE descriptive literature concerning Edu -Kit."

technique of radio construction is now
becoming popular in commercial radio and

new

TV sets.

Name

A Printed Circuit is a special insulated
chassis on which has been deposited a conducting material which takes the place of
wiring. The various parts are merely plugged
in and soldered to terminals.
Printed Circuitry is the basis of modern
Automation Electronics. A knowledge of this
subject Is a necessity today tor anyone in-

terested in

SOLDERING IRON
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"EDU- KITS" INC.

1186 Broadway, Dept. 513DJ, Hewlett, N. Y. 11557

Electronics.

JULY -AUGUST, 1966

www.americanradiohistory.com

ceive and transmit both telephone and teletype messages at the same time. It will also
send and receive fascsimile pictures.
With three Syncoms in orbit, an Army
unit could be flown to any brush-fire war
area, set up its antenna in an hour, point it
at one of the satellites and immediately be
in direct voice contact with Washington.
Such satellite linkage uses microwave frequencies and is not subject to the magnetic
storms which now hinder transoceanic radio
telephone transmission and often knock it out
for days at a time. Besides its use for military communications, the unit could be employed to restore civilian communications in
areas where service is disrupted by disaster
or war. It could be used to communicate
with other ground terminals whether 10
miles away or 10,000 miles away.
The demonstration model built for the
Army consists of three units- antenna, communications hut and power supply- weighing 10,000 pounds combined. It can be
transported in cargo planes or lifted by helicopter into remote areas where no plane runways exist. It uses a transmitter and parametric amplifier, both manufactured by
Hughes. The transmitter is a solid-state,
liquid- cooled unit using a klystron converter
tube with a power output of two to three
kilowatts. Excess noise temperature of the
parametric amplifier is 100 degrees Kelvin,
it is uncooled, and has two stage 40 db gain.
The receiver used with the station is a phaselocked FM tracking receiver with two IF
bandwidths in the 30- and 10-kilocycle bandwidths, and has an IF frequency of 30 megacycles.

NEWSCAN
has an electronic "bulb" which emits the
infrared light. The light is then bounced off
a flashlight -like reflector and beamed to a receiver the size of two loaves of bread end to
end. The system is unique because it has the
widest bandwidth ever reported in this type
of device-the wider the bandwidth the
greater the number of messages which can
be transmitted.

Communications with a Bounce
A small satellite communications ground
station enables an Army commander to go to
isolated trouble spots anywhere on the globe
and remain in contact via satellite with military and government authorities here in the
U. S. or other world -wide communication
centers.
The experimental ground station provides
an answer to a problem which has plagued
military commanders throughout history
the need of far- ranging armies to maintain
communications with their leaders back
home. This system will enable a commander
to literally take his telephone and teletype
with him wherever he goes and `plug in' to a
satellite communications network.
Details of the compact unit, the first ever
designed to be transported by helicopter,
were disclosed as the portable station was
turned over to the Satcom agency for field
demonstration at MacDill Air Force Base,
near Tampa, Fla. The ground terminal, consisting of a collapsible 15-foot antenna and a
6 -by-8 hut, is designed for use with the Syncom communications satellite and will re-

1,,1

,,,,,,1111.1111111111111,,,,,,1,1011111111111111,.,,

11111111111111111111

111111

,,,,,, I,.

IMIM,,,I

This new portable communications
ground station has been developed
as a "space link partner" of
Syncom to enable isolated military
units anywhere in the world to
stay in constant touch, via
satellite relay, with leaders
back home of other units only 10
miles away. This first helicopter transportable system for use in
remote battle areas was developed
by Hughes Aircraft Company for
the U.S. Army's Satcom Agency.
The 15 -foot air -inflated collapsible antenna (at lower left)
is shown in symbolic relation
to the Hughes Syncom communications satellite (top right) which
would relay the ground station's
voice and teletype signals from
its synchronous orbit 22,300
miles above the earth.

Uli

M,,,,,,,10,,,,,,1,,W,M,,,,1111111111M1111111.11111111M1111111111111.111111111110...,,, ,,,111110,1M1M111111,1101111nfflUIM11111111111MHIUMM

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

Electronic Conference Room
A unique conference room that can communicate with its occupants has been set up
at the Federal Aviation Agency Aeronautical
Center in Oklahoma City. It's a room where
the ceilings have ears and the walls have
voices. A flick of a switch can cause the
room to dim its lights, create pictures on its
walls, draw back curtains to reveal magnetic chalk- boards, and talk via audio tapes.
The room can repeat conversations that took
place within its walls only seconds before.
This conference room, with is complete communications system, is a pacesetter that may
be copied widely throughout government
and industry in the next five years. It marks
the first time that audio equipment has been
used to its full capabilities in helping people
communicate.
The difficult task of designing the facility,
complete with audio-visual capabilities, was
undertaken by engineers of the Aeronautical
Center's Plant Engineering Division. They
have created a communications system that is
actually two complete sound systems within
the conference room.
The first is a stereophonic speaker system
linked to the AM- FM- Multiplex tuner, tape
recorder, phono turntable, projection TV
tuner and 16 -mm projector. Comprised of
three University Medallion speaker systems,
the stereo sound units are mounted flush with
the wall below the rear -projection screen.
The 18 -foot wide rear projection screen
may have a 16- millimeter moving picture and
two 35-millimeter slides projected simultaneously. The projector lenses and light
sources provide images balanced as to size
and brightness.

UNUSUAL BARGAINS
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BARGAIN! 3" ASTRONOMICAL TELESCOPE
Phases of Venus, planets
60 to 180 power-famous Mt. Palomar
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Equatorial mount; finder telescope; hardwood tri272 pod.
Included FREE: "STAR CHART
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rselnating new see -through model computer
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r
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$5.98 Postpaid
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Fantastic Visual Effects!
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"Balls of Fun" for Kids
SURPLUS GIANT WEATHER BALLOONS

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Panoramic view of conference
room at Oklahoma City's FAA
Aeronautical Center shows placement of ceiling sound system.
Microphones are behind audio
grilles along inside edge of
lights; speakers are mounted along
outside rim of light fixtures.
Air conditioning ducts form center of ceiling pattern.

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NEWSCAN
The second and more complicated sound
system is designed to pick up and amplify
voices within the room and to tape record
conversations taking place at its conference
table. This second system has given the most
headaches to FAA engineers who designed
the communications network. It has been
largely a matter of experimentation, and the
approach to the acoustics problem had to be
altered several times.
This sound system includes nine University
Model 1150 microphones and seven speakers
in the ceiling, arranged so that the speakers
do not interfere with the microphones. The
microphones are special professional "cardioid pattern" like those used by many radio
and 'television networks.
The ceiling sound system is arranged to
cover every portion of the specially-built oval
conference table which sits in the center of
the room. Words spoken at the table are
picked up by the overhead microphones, fed
into amplifiers and back into the dual cone
speakers in the ceiling. These microphones
and speakers are engineered so that words
picked up by mikes in the front of the room
are amplified more in the speakers at the
back of the room, and vice versa. Feedback
from speakers to microphone is practically
non -existent at optimum usable loudness.
Nerve center of the sound system is a control panel on the lectern at one end of the
room and a duplicate control panel which is
recessed into the end of the conference table
opposite the removable portion.
The lectern itself has a built -in drinking
water spigot for the speaker, a motorized
height adjustment mechanism, an ash tray,
clock timer, reading light and light to illuminate the speaker's face. Standing at the
lectern or table control panel, the speaker
can control the room merely by pushing buttons. A buzzer into the projection room signals the operator to start or change the view graph image. A dual setup for projectuals
allows one to be switched while the other is
being shown. The room's fluorescent lighting can be dimmed or turned off in sections
front, center and rear. Another button will
automatically open and close drapes along
one wall which conceal magnetized chalkboards. As the drapes open, lights come on
to illuminate the chalkboard image. Fingertip control allows the speaker to record conversation in the room, stop the recorder, re-

Pushbutton lectern - -at the FAA
electronic conference room - -as
well as control board at center

table - -puts all sound and visual

systems at the speaker's fingertips. Lectern raises and lowers
automatically, has built -in
lights, water spigot and ashtray.
wind it, play back what it has recorded, or
move it forward. The 16- millimeter projector can be turned on and off by push- button
control. The lectern and table panels also
control the two speaker systems (stereo and
overhead) and two 35- millimeter slide projectors. A digital selector allows random access to each 100 -slide magazine, and both 35millimeter projectors can be used at once.
Perhaps the most amazing thing about the
room is that it has been put together with
fully developed, manufactured sound equipment -yet its capabilities are almost un-

matched anywhere.

Electronic Lung Power
The New York Jets of the American Football League may have solved the problem of
crowd noise that often drowns out the audible signals which quarterbacks frequently
call at the line of scrimmage to change plays
at the last minute. A specially designed helmet seems to be the answer. The helmet contains a transistorized public address system
which boosts the quarterback's voice to about
three times louder than a TV set turned on
full blast. The Jets now have four of these
helmets ready for use.
Six transistorized radio loudspeakers,
modified by the Jensen Manufacturing Division /The Muter Company to blare out 50
times more power than those which charm
the rock 'n' roll set, will carry the quarterback's normal speaking voice to the farthest
split end or flanker. The tiny loudspeakers
solved the problem raised by an American
Football League ruling which prohibited the

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

Jets from using an earlier design which
used autoradio type speakers mounted in outboard pods on the helmet.
Jensen Manufacturing, developer of the
first pocket -radio loudspeaker, was contracted by Technical Materials Inc., (developers
of the helmet amplifier) to design a speaker
system which would fit inside the helmet,
and thus conform to AFL rules. Complaints

Star player of New York Jets,
Joe Namath, points to speakers'
grill. By limiting frequency
response, speakers' (3 on each
side of helmet) rating is
boosted to about 50 times output
of average transistor radio.

YOUR NEW
COPY IS
WAITING

from parents of teenagers aside, the tiny 2inch speakers used in popular transistor radios aren't very loud, because they must try
to reproduce a wide range of musical tones.
Jensen engineers restricted the range of the
speakers to voice frequencies (900 -3000
cycles per second), and thus boosted their
power to about 50 times normal ratings.
The six speakers are mounted inside the helmet, three over each of the quarterback's
ears. Small vents permit the sound of his
amplified voice to issue freely from the helmet. Padded enclosures far from the helmet
webbing protect the quarterback's head from
bumping against the speakers or amplifier.
All parts of the system, including the speakers, are completely waterproofed.
When he chooses to call an audible at the
line of scrimmage, the quarterback speaks
into a small microphone fastened firmly to
the inside of his face guard. A switch cuts off
the loudspeakers while signals are called in
the huddle. More than the lungs of professional football quarterbacks will be saved by
the new helmet-countless yards lost each
year when confused linemen jump off sides
will be added to the offensive might of the
Jets and other teams.

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JULY -AUGUST, 1966

www.americanradiohistory.com

ELECTRONICS ON WHEELS

Make a better mouse trap and sooner or later
someone is going to add electronic circuitry to
it. The automobile is no exception -electronics
is not falling behind as Detroit runs its horsepower race. Three new products worth knowing
about can add more oomph to the family car,
increase night visibility, and bring a "toot- toot"
to those factory installed horns.
Quartz Iodine Hi- Beams. The typical sealed
beam bulb used in automobile "brights" give
23,000 cp (candle power) of light at 100 feet
now you can get up to 65,000 cp from new replacement headlamps with quartz iodine elements without drilling any holes, rewiring, or
any other modifications to your car. The new
lamps are universal replacements for cars and
trucks using 53/a -inch sealed beam bulbs. Truly
a breakthrough, the iodine quartz bulbs give
three times the light of conventional units without taking any extra current from the battery
with an added plus of longer bulb life. Since the

is the ignition

system (the method of igniting
the gasoline by an electric spark). The Kettering
ignition system was invented in 1911 and is still
used in almost all vehicles today. Its great virtues

Quartz Iodine Hi -Beams look very much like
ordinary auto seal-beam lamps until you peek of
the back-Iodine quartz light element is removable.

quartz iodine element is a separate part of the
unit, the lamp will continue to "burn" even
when the glass lens is broken -safe driving is
possible as you wheel your way home or to a
local garage. A pair of 53/4 -inch High -Beam
Headlights with Quartz Iodine Elements (No.
89 -1716) is available from J. C. Whitney & Co.
for only $19.95. A replacement element (No.
89 -1718) is ony $4.95. Send order to J. C.
Whitney & Co., 1917 Archer Avenue, Chicago,
Illinois 60616. While you are at it, ask them to
send you their latest catalog.
Fall -Safe Ignition Converter. The one thing
that has not changed on vehicles over the years

xrelwMMSMeeMwswYSSlWtee.
"tIKFdFT1/M9APF,f4,ANFNi IttNG Ve

Real cool transparent packaging shows the Fail -Safe
Ignition Converter to the buyer. Nothing is left
to waste. Complete installation instructions are
on back of box -comes complete with hardware.

are its reliability and simplicity. Its greatest
weakness is the fact the points will burn and
pit after just a few thousand miles of operation,
which can throw a car's entire tune -up and timing completely off. This, of course, wastes gas,
causes mis -firing and slower starting- that's if
you start at all.
Norman Industries have changed all this with
their "Fail- Safe" solid -state ignition converter.
The device converts your car's ordinary ignition
into a solid -state system
allows the points
to make and break contact without passing the
damaging high -voltage from the coil's inductive

-it

Long cable and terminal strip in Fail -Safe unit
permits rapid installation without special tools.

ELEMENTARY ELECTRONICS
-x,

www.americanradiohistory.com

kick that causes the points to arc and pit. The
heart of the Fail -Safe system is a heat resistant
SCR, which is an improvement over conventional transistors and capable of handling higher
currents and voltage. The payoff comes back to
the driver in better gas mileage performance,
faster cold weather starts, 50,000 miles plus on
points and an all important feature -the unit
fails safe. In the event the unit fails the ignition
system reverts back to its original design -no
getting stuck on back roads on dark nights.
Designed for 12 -volt, negative -ground systems Fail -Safe can be installed in 10 minutes.
Sells for about $29.95 at most auto accessory
stores. For more information write to Norman
Industries Incorporated, Dept. NK, 814 Diversey
Parkway, Chicago, Ill. 60614.
Electronic Two -Tooter -New Call of the Road.
The first application of electronics to produce a
distinctive new sound in auto horns has been
introduced by Kinematix, Inc. The device, called
the "Two- Tooter", is a tiny transistorized unit
that converts the ordinary simultaneous sound
of paired auto horns to a rhythmic alternation
of the individual high and low notes. The "Two Tooter" is establishing a brand -new trend in
auto horns. The bright continental Paris -RomeVienna flair has already captured the enthusiastic support of drivers everywhere, especially
among the younger set, and your car can be
equipped, too!
Measuring only 61 inches long, the converter
mounts under the hood in minutes, requiring
only four simple connections. The compact, all solid state circuit contains several of the latest
type of semi -conductor devices yet retails for
under $25. The complete unit, suitable for Ilse
in both 6 -volt and 12 -volt electrical systems, also
incorporates a variable repeat -speed control in-

now there are

time & tool-saving
double duty sets
New PS88 all- screwdriver

set

rounds out Xcelite's popular,
compact convertible tool set line.
Handy midgets do double duty
when slipped into remarkable
hollow "piggyback" torque amplifier handle which provides the
grip, reach and power of standard
drivers. Each set in a slim,
trim, see -thru plastic pocket case,
also usable as bench stand.

PS88
5
3

slot tip,

Phillips

screwdrivers

PS7
2 slot tip.
2 Phillips

screwdrivers,
2 nutdrivers

The "Two- Tooter" is

all solid state and mounts
under the hood -anyone can do it.
side the car that enables the driver to use his
horns as a distinctive, easily recognizable salute
or an urgent warning as needed. With no moving parts and nothing to wear out, the converter
carries a full year's guarantee. Complete information and prices on the new Kinematix "TwoTooter" can be obtained by writing to: Kinematix, Inc., 2040 Washington Boulevard, Chicago, Illinois, 60612, attention of Martin J.
Santa, Director of Sales Development.

XCELITE INC.

80 BANK ST., ORCHARD PARK, N. Y. 14127

Please send free literature N563.
name
address

city

state & zone

L
17

JULY -AUGUST, 1966

www.americanradiohistory.com

TAF'E THIS AD TO THE BACK OF YOUR TV SET

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UNIVERSAL TUBE CO.
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?ItANCHISE OPPORTUNITY: Un venal Tube Co. can set
you up in your own highly.pro$ table business as an Electron
Tube Distributor, with an exclusive territory, selling to appliance dealen and /or servicemen. For full details write Immediately to Franchise Manager, address above.

TEST ALL RADIO and TV TUBES!
The revolutionary new home tube tester that's
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YOU PREFER the twang of guitar music
with bongos á la stereo when motoring-it's
yours. A stereo tape cartridge player will "surround" you with music of your choice within the
confines of your car. There are no dead reception spots, as in radio, no static, no need to take
your eyes off the road to fuss with the dial, and
even a child can start and turn off the music. So
great is the cry for travel entertainment by tape
cartridge players, three major automobile manufacturers will include stereo cartridge players as
original equipment in 1967 cars. Reaction to car
stereo systems has been so spontaneous that the
one millionth unit will be sold early in 1967
and this was made possible with the development
of the tape cartridge.
How It Works. What is a tape cartridge? And
how does it work? A cartridge is a flat, small
(about 4" x 5 ") plastic container housing, on a
single reel, an endless loop of 1/4 -inch recorded
and specially lubricated audio tape -no threading or rewinding to trouble the operator. On
insertion, the tape is automatically moved by the
player's drive mechanism from the hub or inside
of the reel past the playing head and back onto
the outside of the same reel. Use of a lubricated
tape and a loose wind on the reel eliminates
friction as tape layers must constantly pass over
each other as the tape works its way toward the
hub of the reel.

Hughie Enterprises, 363 Dieppe Street, Dept.EE -1
London, Ontario, Canada

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Over 90,000 graduates now employed. Resident classes at our
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11396 West Fullerton Parkway
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IN YOUR SPARE TIME
In the July /August Issue of INCOME OPPORTUNITIES, at
your newsstand, there's a feature on "22 Ways To Make
Money With Your Car." This is one of a number of fascinating articles detailing the many opportunities available
to enterprising and energetic people Interested in going

into business for themselves. Don't miss it!
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Use the coupon below.
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EE793

Begin my special 6 months subscription to INCOME OPPORTUNITIES at the special $1.25 offer. Enclosed is my
check or money- order.
Name
(please print)

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TAPE WINDS
BACK ON REEL

PREESRAGAINSST
DRIVE CAPSTAN IN PLAYER

Redrawn from drawing made by Audio Devices, Inc.

Four -track recordings, consisting of two pairs
of stereo tracks, were the earliest type and are
still going strong-the playing time of a fourtrack stereo tape is equivalent to both sides of
an LP disc. But 8 -track stereo, which has required major development in the art, doubles
playing time on the same length of tape, and is
well on the way to becoming the accepted cartridge. As in all stereo production, one pair of
tracks is played at a time for the full length of
the tape. The player then automatically transfers
to each succeeding pair of tracks until the recording ends, and will continue to cycle (returning to the first pair of tracks) until the player is
(Continued on page 107)

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

ELEMENTARY
ELE

MODEL
RACING
FANS!

ELECTRONICS

ETYMOLOGY
By Webb Garrison

00 ©l91

logo

Broadcast

Do you know which national contest you can enter to

A Perfection of instruments and methods

by which to transmit messages without use
of wires led to a sharp break in the stream

of western speech. For though Americans
called the new medium of communication
the "radio," English technicians in the field
stubbornly insisted on referring to it as the
"wireless telegraph."
Yet even the most conservative Britishers
recognized radical distinctions in the two
media. A telegraph message (at least in those
days) went to only one receiving station. A
message transmitted by wireless radiated over
a huge area and could be received by any
number of instruments simultaneously. What
to call so public an act of communication?
Centuries earlier, farmers of Britain had
used two techniques in planting. Sometimes
they carefully dropped seeds into precise
rows, drills, or holes. But when sowing grain,
turnips, and other crops they walked through
their fields casting handfuls on both sides.
Influence of the latter practice led to wide
use of the farm -born term. Orators and writers who urged political reforms took pride in
their ability to broad cast their ideas. Fused
into a single word, the hoary tern for the act
of scattering seeds or ideas at random became broadcast.

$5000 scholarship?
A Plymouth Barracuda?
A trip abroad?

Find out all about this exciting
contest, and more, in "Contests
You Can Enter in '66.'r It's all in
the

NEW 1966
Mid -Year
Edition
at your

newsstand

$1.00
New kit builts Ready -to -run cars
all featured and imparnew sets
tially rated in test reports compiled
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Space Is A Problem;" "Ready -ToRun, Kit Or Scratch -Built;" "Know
Your Motors;" "Painting & Decorating " A great magazine for youths of
all ages. At your newsstand or use the
coupon.

Ohm
A By the mid -point of the 19th century,
research workers realized that they needed
some unit by which to measure electrical
resistance, and a name by which to speak of
it. At the 1861 meeting of the British Association for the Advancement of Science
Sir Charles Bright suggested that the term
"ohmad" be adopted. This action, he urged,
would perpetuate the name of a pioneer.

ML_ALA7-.\MODEL RACING BUYERS' GUIDE
EE -793
505 Park Avenue /New York, N.Y. 10022
Enclosed is $1.25 (includes postage & handling). Rush
me my copy of MODEL RACING BUYERS' GUIDE.
Name

(please print)
Addres

City

State

yip

JULY -AUGUST, 1966

www.americanradiohistory.com

E/E ETYMOLOGY
Georg Simon Ohm, one of the earliest
theoretical physicists to work with electricity,
produced a great volume of published work.
Only one of his reports, issued in 1827 when
FOR INBOARD, OUTBOARD OR OUTDRIVE
he was 40, is today regarded as marking a
milestone in the progress of science. This
BOATING JOURNAL CRAFT PRINT #360. Save
$1,000 or more while building this outstanding brief paper presents findings that throw much
new performer. Here is the new look in hull delight on processes that produce electricity.
sign, a boat that adapts the principle of a soft
"Ohmad" proved too cumbersome a verbal
riding planing bottom into a boat for building at
memorial to the German experimenter. But
home. SEA ANGLER can cut through waves
from any quarter without pounding, porpoising,
clipped to the form of his surname, it soon
or losing steering control. Runners along the' entered
the international vocabulary of scibottom raise the craft up onto high -speed plane
without any sacrifice of outstanding sea -kindly ence. By edict of Queen Victoria, the ohm
was legally defined as "the resistance to an
qualities.
invariable electric current by a column of
EE793
BOATING JOURNAL
mercury at the temperature of melting ice,
Craft Print Div., 505 Park Avenue, New York, N. Y. 10022
Please send me Craft Print No. 360, DEEP -V SEA ANGLER.
14.4521 grammes in mass, of a constant
I enclose $5.
cross-sectional area, and a length of 106.3
Allow 3 -4 weeks for 4th class delivery. 1st class delivery may
centimetres."
Methods of measurement have
be requested for an additional 50(. (Outside U.S.A. & Canada
add $1 for 1st class delivery.)
been greatly refined, but the name of Georg
Ohm remains basic to the vocabulary of
NAME
electronics.
ADDRESS

SEA ANGLER

Feedback

CITY
STATE

ZIP CODE
N.Y.C. residents add 5%.

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818 - 18th St., NW, Washington, D.C. 20006

(Phone: 298 -7460)

A No one knows exactly when or how radio
operators discovered that circuits can be
coupled in such fashion that part of the
energy in one is transferred to the other. Instead of being the fruit of costly professional
research, this was probably the result of random experiments by amateurs.
At first it was considered interesting but
not especially important that one can feed
back current in this fashion. Important practical applications were soon discovered, however, and deliberate use of feed -back techniques was coming into vogue before the end
of World War I.
Already, operators of public address systems and radios had observed that under
some conditions part of a system's output is
returned to it. It was logical to extend the
use of "feedback" to name such processes
as well as those operating by linked circuits.
Refinement of electronic amplifying systems led to recognition that feedback can increase volume, decrease it, or reduce quality
of control.
Jumping from electronics into general
speech, the term came to name any return to
input of part of the output of a system,
machine, or process. Now used in such
diverse fields as biology and economics, feedback is a basic concept in cybernetics.

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

JOHN W. COLLINS

Chess columns are beginning to appear in the
literary magazines,
most unexpected places
medical magazines, religious newspapers. And
now in this electronics magazine. All to the
good, chess being, among other things, an art, an
anodyne, a way of life and a discipline. Always
eager to spread the gospel of the Royal Game,
I was delighted to accept Editor Julian Sienkiewicz's offer of a column in ELEMENTARY ELECTRONICS. We both believe that many of those
interested in electronics are also interested in
chess. His vision and imagination are admirable.
I hope the readers who play the game will derive
enjoyment and instruction from the columns and
1 hope the ones who are unfamiliar with it will
be enticed into learning.
En Passant will appear in every issue of ELEMENTARY ELECTRONICS. It will present book reviews, games, endgame studies, instruction, news
and two move problems. It will look at the
game, in its various forms, here at home and
abroad, and at its past and present.
News and Views. Grandmaster Robert (Bobby) J. Fischer of Brooklyn, a former prodigy
now 23, won the U. S. Championship (for the
seventh time!) last December in New York. He
scored 8t/2 -21/2, losing to R. Byrne and S. Reshevsky and drawing with W. Addison. In 1964,
in a somewhat weaker field, he swept the boards
11 -0.

World Champion Tigran Petrosian and challenger Boris Spassky, both of the U.S.S.R., will
meet in a twenty -four game match for the world
title beginning sometime in April in Russia.
The second Piatigorsky Cup Tournament will
be played in Santa Monica, California, during
July- August. Eight leading grandmasters (probably including Fischer and Petrosian) will compete for the $3,000 first prize. Gregor Piatigorsky is a world famous cellist and his wife Jacqueline, a former Rothchild, is a top woman chess player and a patron of the arts.
Lombardy Wins. Grandmaster William Lombardy of New York, a siminarian at St. Joseph's,
won the Western Open in St. Louis last July with

The June /July issue of Radio -TV Experimenter,
now at your newsstand, has a number of construction projects that most anyone can build from our
instructions.
One such project is an Audio Compressor that will
be of special interest to amateurs and CB'ers; the
other is a neon -bulb calculator that does simple
multiplication and is an excellent Science Fair project.
These are just a few of the editorial features that
can be found in this issue -but typical of the fascinating reading of interest to everyone, that can
always be found in each issue of RADIO -TV
EXPERIMENTER. Subscribe today.
EE793
RADIO -TV EXPERIMENTER
505 Park Avenue, New York, N.Y. 10022
Begin my subscription to RADIO -TV EXPERIMENTER
$4.00 for
with the August September issue. Enclosed is
Bill me. (Foreign: add 75g a yr.)
1 yr;
$7.00 for 2 yrs;
Name

.... ............................... (please

print)

City ..

ELEMENTARY
ELECTRONICS
Tells You Why And How
If you have only a passing interest in electronics, or
on the other hand, if you have a sincere desire to
make electronics your career, either way ELEMENTARY ELECTRONICS has to be "must" reading.
For ELEMENTARY ELECTRONICS is instructional in
teaches in easy -to- understand language
nature
the basics of electronics -no matter what the subject.
And as electronics and its many by- products becomes
more and more a way -of -life, the need to acquire an
understanding of this fascinating subject becomes
even more important.
And the best way to begin to understand electronics
is through the exciting and stimulating pages of

-it

ELEMENTARY ELECTRONICS.
EE 793
ELEMENTARY ELECTRONICS
505 Park Avenue / New York. New York / 10022
Begin my subscription to ELEMENTARY ELECTRONICS with the next
$7.00 for 2 yrs.;
$4.00 for 1 yr.;
issue. I am enclosing
$10.00 for 3 yrs. (foreign; add 7n a year).

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JULY -AUGUST, 1966

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EN PASSANT

I shall give

a two mover in every column, sometimes an old classic and sometimes a new original. This first one dates to 1938, has a crosscheck theme and earned First Prize for a great
American Composer.

a score of 8 -1
by a woman,

(7 wins and 2 draws). Directed
Pearl Mann, the event had 143
entries. One of Lombardy's cleverest wins was
from Bill Bills of Houston, Texas. The opening
was a Caro -Kann Defense, Two Knights' Variation and was a 14 move miniature which went

Problem 1.
By F. Gainage
Black

this-

P-0B3

P-K4

2.
3.
4.
5.
6.
7.

N-0B3

P-Q4

N-B3
NxP

PxP

P-KN3?
B-N2
B-B4
N-B3

P-04
P-KR3

N-N3

8. NxB

9.
10.
11.
12.
13.
14.

QxN
O-O?

P-B3

0-N3
QxP!
B-K2

ON-02
0-K5

0-R6
N-N5!

P-B4
Resigns

Position after 14 N -N5!

ELL)

White
White to move and mate in two.
Solution in next issue.

Why did Black resign? Because he is already
a Pawn behind, he must lose either his Queen,a piece, the exchange (Rook for Bishop) and
because he knows he is playing a Grandmaster!
Here is the analysis

...
...

A. If 14
Q -B7 15 B -Q3, N -N1 16 Q-B4
and the Black Queen is lost.
B. If 14
Q -B4 15 P -KN4, Q -Q4 16
B-B3, Q -Q3 17 QxQ, PxQ 18 BxR and White
has won the exchange.
C. If 14
QxNP 15 B -B3, N -N1 16 Q -N7
and the Black Queen is lost.
D. If 14
Q -Q4 15 B -B3 wins the exchange.
E. 14
Q -R5 15 P -KN3, Q -R3 16 NxBP
and White wins the Queen for Bishop and

...
...
...

Knight.

...

Learn by Reading. A number of excellent
books are available to those who want to learn
to play chess. I recommend "An Inviation to
Chess" by Irving Chernev and Kenneth Harkness. It is specifically designed for persons who
do not know one chess piece from another and
its approach is visual, pictorial, with photographs and diagrams. It has 221 pages, is published by Simon and Schuster and costs about
$3.50.
About Our Columnist. Who is John W. Collins?
Well, he is a former U. S. Correspondence Champion,

New York State Champion, Marshall Chess Club Champion, Hawthorne Chess Club Champion and Brooklyn
Chess Club Champion. He has been secretary of the
Brooklyn Chess League and the Metropolitan Chess
League. He teaches the game privately and by correspondence and he has been the early teacher- mentor
of U. S. Champion Bobby Fischer, Grandmasters W.
Lombardy, R. Byrne and D. Byrne, Senior Master R.
Weinstein and is now teaching a fourteen year old
rising star, Sal Matera. He was co- reviser of Modern
Chess Openings, 9th Edition, the so- called "chess player's bible." And currently he has land has had
for several years) columns in Chess Review (Postal
Games and Book of the Month) and Chess Life, official publication of the United States Chess Federation
(GAMES By USCF Members) and is a member of the
Manhattan Chess Club, oldest and foremost in the
country. The Editors of ELEMENTARY ELECTRONICS
welcome John to the staff and we are privileged to
have him work with us.

F. 14
N -NI 15 NxQ, NxQ 16 NxN#
BxN 17 BxN, PxP 18 PxP, BxP 19 0 -0 and
White is a whole piece ahead.
There is an old saw among chessplayers which
warns "never take the Queen Knight Pawn!" (it
loses too much time). Lombardy exploded that
myth in this one!

Problem. Many are the ways to enjoy chess.
One is solving problems-the poesy of the game.
22

Cartoon by Cork
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To have a firm foundation, build

your knowledge of electronics theory
with a basic building block -the atom

Electricity,
Magnetism
and the

Atom

Prepared by the

Editors of
Elementary Electronics

One of the most thought provoking discoveries of modern physics is the fact that
matter and energy are interchangeable. Centuries of scientific head -scratching about the
nature of matter, the mystery of fire, and the
once-terrifying crack of lightning have all
come to focus on the smallest particle that is
the building block of any given substance:
the atom. An atom is necessarily matter and
yet this atom of matter can undergo nuclear
fission and release quantities of energy that
are beyond the imagination. In the atom lies
the secret of all phenomena. One theory of
the universe, hypothesized by Georges Lemaitre, even regards the present universe as
resulting from the radioactive disintegration
of one primeval atom!
A Monumental Discovery. By the beginning of the 19th century, the atomic theory
of matter-which actually originated in 5th
century Greece when the atom was named
-was firmly established. It was due primarily to the efforts of 17th century scientists
who -actually working in the tradition of
medieval alchemy-sought the prime constituent of all matter. Mainly through the
work of John Dalton, whose investigations
as to how various elements combine to form
chemical compounds, it came to be regarded
that an atom was the indivisible and indestructible unit of matter.
This viable and working view of the indestructible atom served science until 1897

when the atom itself was found to be destructible! To anyone concerned with electricity or electronics, the year 1897 is a
memorable one: it was the year J. J. Thomson, the English physicist, identified and experimentally revealed the existence of the
first subatomic particle-the electron!
The First "Electronic" Experiment. We
blithely speak of electricity as the flow of
electrons yet, often, we are little aware of the
great body of research that went into elucidating this fundamental of basic electricity.
In fact, before the discovery of the electron,
convention held that the flow of electric current was in the direction that a positive
charge moved. This convention of positive
current, being the flow of positive charges
and opposite to the direction of electron flow,
is still found to be useful in circuit analysis
and is used even today.
Thomson's experiment established that a
particle much lighter than the lightest atom
did indeed exist. The electron, as it was
named, was the first subatomic particle to
be defined.
The experiment was conducted utilizing a
rudimentary version of a cathode ray tube
the modern version of which is in almost
every home today in the form of the television picture tube. Before Thomson's experiment, it was discovered that when electric
current was passed through a gas in a discharge tube, a beam of unknown nature

JULY -AUGUST, 1966

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ELECTRICITY, MAGNETISM
AND THE ATOM

traveled through the tube from the negative
to positive terminal (opposite to the direction conventionally held as the direction of
the flow of current) .
This "cathode ray" beam also traveled in
a straight line and was deflected by electric
Fig. 2. Charge of each electron balor magnetic forces applied perpendicular to
ances that of a proton. Other particles affect atomic mass but can
the beam. What Thompson did was to use
be ignored in study of electronics.
these facts to determine for one of the mysterious particles comprising the beam of stick at: neutrons, positrons, neutrinos, mecathode rays the relationship of its mass, m, sons, and more. The number continues to
to its electric charge, e. By deflecting the grow and yet the ultimate nature of- matter
beam with a known electric force (Fig. 1) remains a riddle. But, in a discussion of basic
electricity, only the electron and proton need
( +1
concern us.
MAGNETIC FIELD
DEFLECTION
Electrons in Orbit. An atom of matter has
a
number
of electrons orbiting around its
UNDEFLECTED
POSITION
nucleus. A hydrogen atom, for example, has
a single electron; carbon on the other hand
ELECTRIC FIELD
DEFLECTION
has 6. These electrons are arranged in rings
or shells around the central nucleus-each
ring having a definite maximum capacity of
that
picture
tube
in a TV
Fig. 1. Electron beam, like
electrons which it can retain. For example,
(CRT), can be deflected magnetically or by an electric Held. Force needed "measured" the electron.
in the copper atom shown in Fig. 3 the maxiand then measuring what magnetic force mum number of electrons that can exist in
applied in the opposite direction would bring
the beam back to its original undeflected position, he could determine the relationship
of e to m. He established a definite value for
elm and thereby "discovered" the electron
which, as we now know, is 1,837 times
smaller in mass than the lightest atom, the
hydrogen atom. It also carries the smallest
charge that occurs in nature; every electric
charge is actually an integral multiple of the
charge of the electron.
From Minus to Plus. With the discovery
of the electron, it was still over a dozen years
into the 20th century before a graphic conFig. 3. The number of electrons to
each ring are limited-2 in first; 8
ception of the atom evolved. Since the atom
in second; 18 for the third and a
is electrically neutral and electrons are negatotal of 32 in fourth orbital ring.
tively charged, the existence of positively
charged particles was a necessity, and the the first ring (the ring nearest the nucleus)
existence of a proton was postulated. Eventu- is two. The next ring can have a maximum of
ally the nuclear model of the attain was eight, the third ring a maximum of 18, and
evolved. Each atom was conceived to re- the fourth ring a maximum of 32. However,
semble a solar system in miniature. The the outer ring or shell of electrons for any
nucleus -positively charged
surrounded atom cannot exceed eight electrons. Howby a number of electrons revolving around it; ever, heavier atoms may have more than four
the charges balance and the atom is electri- rings.
The Outer Orbit. The ring of electrons
cally neutral (Fig. 2). Further research in
the 20th century has gone on to reveal more furthest from the atom's nucleus is known as
elementary particles than you can shake a the valence ring and the electrons orbiting in

-is

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this ring are known as valence electrons.
These valence electrons, being further from
the nucleus, are not held as tightly in their
orbits as electrons in the inner rings and can
therefore be fairly easily dislodged by an
external force such as heat, light, friction,
and electrical potential. The fewer electrons
in the valence ring of an atom, the less these
electrons are bound to the central nucleus.
As an example, the copper atom has only
one electron in its valence ring. Consequently, it can be easily removed by the application of only the slightest amount of external
energy. Ordinary room temperature is sufficient to dislodge large numbers of electrons
from copper atoms; these electrons circulate
about as free electrons. It is because of these
large numbers of free electrons that copper is
such a good electrical conductor. There
could be no electrical or electronics industry
as we know it today if it were not for the
fact that electrons can fairly easily escape,
or be stripped from the valence ring of certain elements.
METAL ROD
INSULATOR

Fig. 4. Electroscope is a
simple device to indicate
electrical charges that
are too weak to be measured with standard meters.

Electronic Charges. If an electron is
stripped from an atom, the atom will assume
a positive charge because the number of positively charged protons in its nucleus now
exceed the number of negatively charged
orbiting electrons. If, on the other hand, the
atom should gain an electron, it will become
negatively charged as the number of electrons now exceeds the protons in its nucleus.
The atom with the deficiency of electrons is
known as a positive ion, while an atom with
a surplus of electrons is known as a negative

ion.

Presence of an electrical charge on a body
can be illustrated by use of an electroscope
(Fig. 4). Two leaves of aluminum or gold
foil hang from a metal rod inside a glass
case so they're free from air disturbances.
When the meal rod is touched by a charged
body, the leaves acquire static electricity of
the same polarity and, since like charges
repel, they stand apart. The greater the
charge, the further apart the leaves spread.
Electron Flow. When an electrical conductor is placed between these two oppositely

charged bodies, free electrons are attracted
by the positive body -free electrons will
move through the wire. This movement of
free electrons will continue only until the
excess of electrons is equally divided between the two bodies. Under these conditions, the charges on both bodies will be
equal and the electron flow will end.
Fig. 5. Electron flow in
any circuit is from negative to positive
this
is opposite to current,
which flows from positive
toward negative terminal.

In Fig. 5 are a battery, lamp and connecting leads between the battery and lamp. In
this instance, the battery serves as an electric
charge pump -free electrons continually developed at its negative terminal by chemical
action flow through the connecting leads and
lamp back to the positive terminal of the
battery by the attraction of oppositely
charged bodies. The battery, connecting
leads, and lamp form an electrical circuit
which must be complete before the free electrons can flow from the battery's negative
terminal to its positive terminal via the lamp.
Thus, the battery serves as a source of potential difference or voltage by continually
supplying a surplus of electrons at its negative terminal. Summing up, we can say a flow
of electric current consists of the movement
of electrons between two oppositely charged
bodies.
We cannot progress very far into the study
of electricity without first becoming familiar
with the basic properties of electrical circuits.
Just as we define distance in feet and inches,
so do we define electrical properties in specific terms and units.
Potential. Earlier, we saw that an electric charge difference has to exist between the
ends of an electrical conductor in order to
cause a flow of free electrons through the
conductor. This flow of electrons constitutes
the electric current. The electric charge difference, or potential difference exerts a force
on the flow of free electrons, forcing them
through the conductor. This electric force or
pressure is referred to as electromotive force,
abbreviated EMF.
The greater the charge or potential difference, the greater will be the movement of
free electrons (current) through the conductor as there will be more "push and pull" on
the free electrons. The symbol used to designate electrical potential is the letter E which

JULY-AUGUST, 1966

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ELECTRICITY, MAGNETISM
AND THE ATOM

stands for electromotive force. The quantity
of EMF is measured by a unit called the volt.
Hence, the common name most often used
in place of EMF is voltage.
Current Intensity. We have learned that
an electric current consists of a flow of
charge carrriers (generally free electrons)
between two points of different electrical
potential. The rate of flow of these charges
determines the intensity or strength of this
current flow. Current strength is expressed
in units known as amperes. One ampere of
current flows in a circuit when 6,240,000,000
electrons flow out of a negative terminal,
through a conductor, and back into a positive terminal in one second. The symbol
for the ampere is the letter I which stands
for intensity.
Resistance. The flow of electric current
through a conductor is caused by the movement of free electrons present in the atoms
of the conductor. A bit of thought then indicates that the greater the number of free electrons present in the atoms of a particular
conductor, the greater will be its electrical
cqnductivity. Gold, silver, and copper rank
as excellent electrical conductors as their
atoms readily release free electrons. On the
other hand, the atoms of such elements as
sulphur have almost no free electrons available and they are thus very poor electrical
conductors. Such materials are known as
electrical insulators. Between these extremes,
lie elements such as carbon whose atoms
have a moderate number of free electrons
available and thus are moderately good
electrical conductors.
Even the best electrical conductors offer
some opposition to the passage of free electrons. This opposition is called resistance.
You might consider electrical resistance similar to mechanical friction. As in the case of
mechanical friction, electrical resistance generates heat. When current flows through a
resistance, heat is generated; the greater the
current flow, the greater the heat. Also, for
a given current flow, the greater the resistance, the greater the heat produced.
Electrical resistance can be both beneficial
and undesirable. Toasters, electric irons, etc.
all make use of the heat generated by current
flowing through wire coils. Resistance is also
often intentionally added to an electrical cir-

cult to limit the flow of current. This type of
resistance is generally lumped together in a
single unit known as a resistor.
There are also instances where resistance
is undesirable. Excessive resistance in the
connecting leads of an electrical circuit can
cause both heating and electrical loss. The
heating, if sufficient can cause a fire hazard,
particularly in house wiring, and the circuit
losses are a waste of electrical power.
Electrical resistance is expressed by a unit
known as the ohm, indicated by the letter R.
An electrical conductor has a resistance of
one ohm when an applied EMF of one volt
causes a current of one ampere to flow
through it.
Resistance Factors. There are other
factors beside the composition of the material that determine its resistance. For example,
temperature has an effect on the resistance of
a conductor. As the temperature of copper
increases, for example, its resistance increases. The increase in temperature causes
the electrons in the outer ring of the atom to
resist release to the free electron state. This
increase in resistance with an increase in
temperature is known as a positive temperature coefficient. Not all conductors show
this increase in resistance with an increase
in temperature; their resistance decreases
with an increase in temperature. Such materials are said to have a negative temperature coefficient. Certain metallic alloys have
been developed which exhibit a zero temperature coefficient: their resistance does not
change with changes in temperature.
As you might suspect, the length of a conductor has an effect upon its resistance. Doubling the length of a conductor will double
its resistance. By the same token, halving the
length of a conductor will cut its resistance
in half. Just remember that the resistance of
a conductor is directly proportional to its
length.
The cross -sectional area of a conductor
also determines its resistance. As you double
the cross -section of a conductor, you halve
its resistance; halving its cross -section doubles
its resistance. Here again, the "why" of this
is pretty easy to see: there are more current
carrying electrons available in a large crosssection conductor than in a small cross-section conductor of the same length. Therefore, the resistance of a conductor is inversely
proportional to its cross-sectional area.
Circuit Relationship. Now that we have a
basic understanding of voltage, current, and
resistance, let's take a look at just how they
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AMMETER

BATTERY
4VDC

.BATTERY
RESISTOR
1n

AMMETER

=
=

BATTERY
8VDC

In.

C:.

RESISTOR

AMMETER

4VDC

In.

AMMETER

BATTERY
4VDC

RESISTOR

1/2n

RESISTOR

AMMETER

BATTERY
2VDC

RESISTOR

Fig. 6. In A, B and C,
(above left) the value
of the resistor remains
constant while the supply voltage is raised and
then lowered with a resulting current change.

BATTERY
4VDC

RESISTOR

Fig. 7. Battery voltage
in A, B and C (above) is
held constant while resistor is halved and doubled in value. Resulting
current increase, decrease
are basis for Ohm's law.

interact under circuit conditions.
Fig. 6A shows a battery, ammeter (a device to indicate current strength), and resistor connected in series. Notice that the
ammeter indicates that 4 amperes are flowing
in the circuit.
Fig. 6B shows the identical setup with the
exception that the battery voltage has now
been doubled. The ammeter now shows that
twice the original current, or 8 amperes, are
now flowing in the circuit. Therefore, we
can see that doubling the voltage applied to
the circuit will double the current flowing in

the circuit.
In Fig. 6C the same circuit appears again;
this time, however, the battery voltage is one half its original value. The ammeter shows
that one -half of the original current or 2
amperes, are now flowing in the circuit. This
shows us that halving the voltage applied to
the circuit will halve the current flowing
through the circuit.
All this boils down to the fact that assuming the same circuit resistance in all cases,
the current flowing in a circuit will be directly proportional to the applied voltage -increasing as the voltage is increased, and decreasing as the applied voltage is decreased.
In Fig. 7A we again see the circuit consisting of the battery, ammeter, and resistance. Notice that the ammeter indicates that
4 amperes are flowing through the circuit.

In Fig. 7B we see that the value of resistance has been cut in half and as a result,
the ammeter indicates that twice the original
current, or 8 amperes, is now flowing in the
circuit. This leads us to the correct assumption that for a given supply voltage, halving
the circuit resistance will double the current
flowing in the circuit.
Fig. 7C again shows our basic circuit, but
with the resistance now doubled from its
original value. The ammeter indicates that
the current in the circuit is now one -half of
its original value.
Summing things up: for a given supply
voltage, the current flowing in a circuit will
be inversely proportional to the resistance in
the circuit.
Ohm's Law. From what you have seen so
far, you are probably getting the idea that
you can determine the current flowing in a
circuit if you know the voltage and resistance
present in the circuit, and the voltage if you
know the current and resistance, or the resistance if the voltage and current are known.
All this is quite correct, and is formally
stated by Ohm's Law as follows:

E
R

Where: E = voltage
I

= current

R = resistance
Now, let's take a look at how this formula is
used:
To find voltage:
E (voltage) = I (current) x R (resistance)

To find

current...

I (current)

E (voltage)
R (resistance)

To find resistance:

R (resistance)

E (voltage)
I (current)

A handy way to remember Ohm's Law is
by means of the triangle shown in Fig. 8.
Simply cover the quantity (voltage, current,
or resistance) that you want to determine,
and read the correct relationship of the remaining two quantities. For example, if you
27

JULY- AUGUST, 1966

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ELECTRICITY, MAGNETISM
AND THE ATOM

E=IR

Fig. 8. Shaded portion of triangle
indicates unknown quantity in the
formula. Visible factors appear in
their proper mathematical relation.
Just fill in the known values and go
on with multiplication or division

want to know the correct current (I), put
E
your finger over I and read
Covering
R
E
E or R will yield I x R or
respectively.
I

200

VOLTAGE UNKNOWN

0.5 AMPERE

20VDC

ing known factors (ohms
and amperes) in a simple
multiplication process
the voltage is calculated.

JUNKNOWN

E=IxR

r400
I

}

U."

OHMS

^I
4.1-

UNKNOWN
VOLTAGE

0.3 AMPERE

Fig. 10. Although problem looks different the
basic circuit is same as
that for Fig. 9. Putting
triangles in Fig. 8 to
use is simplest, easiest
way to determine formula.

of light bulbs, the total resistance of which
is 400 ohms. You find that the bulbs draw
0.3 amperes when lighted. Let's say you
would like to operate this string of bulbs
from the standard 120 -volt house current, but
you don't know the voltage rating of the individual bulbs. By using Ohm's law for voltage,
you can easily determine the voltage to light

CURRENT

to determine the value of unknown current
in a circuit in which both the voltage and
resistance are known.
Fig. 11 shows a series circuit with a battery and resistor. The battery voltage is 20
volts DC and the value of resistance is 5
ohms. How much current is flowing through
the circuit?
E
Ohm's law for current I

E (unknown voltage) = 0.5 (current in amperes) x 200 (resistance in ohms) = 100 V.
Let's go through this again, this time using
a practical illustration. Fig. 10 shows a string

Fig. 11. Formula needed
here is different since
current is unknown. Just
look for triangle in Fig.
8 that has I shaded and
substitute values for E
and R
simple division.

5 OHMS

applying Ohm's law. Us-

Ohm's Law to Determine Voltage. Let's
delve a bit more deeply into Ohm's law by
applying it to a few cases where we want to
determine the unknown voltage in an electrical circuit. Take a look at Fig. 9, which
shows a simple series circuit consisting of a
battery and resistor. The value of this resistor
is given as 200 ohms, and 0.5 ampere of
current is flowing through the circuit. We
want to find the value of battery voltage.
This is easily done by applying Ohm's law
for voltage as follows:

the bulbs as follows: E (unknown voltage)
= 0.3 (amperes) x 400 (bulb resistance) _
120 volts.
Ohm's Law to Determine Current. Now,
let's take a look at a few examples of how

Fig. 9. Unknown quantity,
voltage, found easily by

OHMS

(unknown current)

20 (battery voltage)

5 (resistance in ohms)

4 amperes

Again to get a bit more practical, let's take
15

AMP FUSE

ELECTRIC
HEATER

(20
120

-h

OHMS)

L__J

Fig. 12. Basic circuit is
same as that in Fig. 11.
Although three factors
are given, current is unknown quantity because
the problem is to decide

proper rating for fuse.

a look at Fig. 12. Here we see an electric
heater element connected to the 120 -volt
house line. We know that this particular
heater element has a resistance of 20 ohms.
The house current line is fused with a 15ampere fuse. We want to know whether the
heater will draw sufficient current to blow
the fuse. Here's how to find this out by use
of Ohm's law for current.
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I (unknown current)

(line voltage)
- 120
20 (Heater resist-

use in conjunction with Ohm's law for resistance as follows:

ance in ohms)

114 (voltage
dropped by

I = 6 amperes
We find from the above use of Ohm's law
for current that the heater draws 6 amperes,
so it can be safely used on the line fused with
the 15 ampere fuse. In fact, a 10 ampere
fused line can also do the job.
Ohm's Law to Determine Resistance.
Ohm's law for resistance enables us to determine the unknown value of resistance in a
circuit. Fig. 13 again shows a simple series
Fig. 13. Most Ohm's law
problems are simple series circuits or can be reduced fo simple series
circuits and then solved
using the formula with
known values substituted.

UNKNOWN RESISTANCE

20VDC
0.5 AMPERE

R (unknown resistance)

E
I

resistor)
0.2 (bulb
current in
amperes)

R = 570 ohms
Resistance in Series. Many practical
electrical and electronic circuits use two or
more resistances connected in series. The
point to remember in this case is that the
total resistance is the sum of the individual
resistances. This is expressed by the formula:

R (total resistance) = RI + R2 + R3 + etc.
where R1, R2, R3, etc. are the individual
40A

circuit with the battery voltage given as 20
volts and the current flowing through the
circuit as 0.5 ampere. The unknown resistance value in this circuit is found as follows:
Ohm's law for resistance R =

10n

Fig. 15. Resistances in series are
added. As far as voltage applied
and current flow is concerned the
individual resistors are only one.

20 (battery

R (unknown resistance)

- 0.5voltage)
(current
in amperes)

R =40 ohms
Fig. 14 is a practical example of how to
determine unknown resistance. Here, we
DROPPING
RESISTANCE
UNKNOWN

120
VOLTS

6 -VOLT
BULB
0.2 AMPERE

Fig. 14. This Ohm's law
problem is somewhat
more complex since dropping resistance must take
care of voltage, from
source, not needed by 6volt bulb in circuit.

want to operate a 6 -volt light bulb from the
120 -volt house line. What value of series
dropping resistor do we need to drop the
120 -volt house current down to 6 volts? The
bulb draws 0.2 ampere.
We must first determine the voltage which
must be dropped across the series dropping
resistor. This is done by subtracting the line
voltage (120) from the bulb's voltage (6).
This gives us a value of 114 volts which we

Fig. 16. Resistors in parallel are
added algebraically
the result
will always be a value less than
that of the lowest in the circuit.

resistances. Thus, in Fig. 15 the total of the
individual resistances is R (total) = 40 + 6
+ 10 + 5 = 61 ohms.
Resistances may also be connected in parallel in a circuit as in Fig. 16. In this case the
current flowing in the circuit will divide between the resistances, the greater current
flowing through the lowest resistance. Also,
the total resistance in the circuit will always
be less than the smallest resistance since the
total current is greater than the current in any
of the individual resistors. The formula for
determining the combined resistance of the
two resistors is:

R (total)

JULY- AUGUST, 1966

- R1R1 X+ R2
R2
29

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ELECTRICITY, MAGNETISM
AND THE ATOM

Thus, in Fig. 16 the effective resistance of
R1 and R2 is:
R (total) =

2X4
=
2 +4

--+-+-+...1

Quite often an electronic circuit will con tain a combination of series and parallel re-

or 1.33 ohms.

In a circuit containing more than two
parallel resistors as in Fig. 17 the easiest
way to determine the total circuit resistance
is as follows: first, assume that a 6 -volt
battery is connected across the resistor network. Pick a value that will make your
computations simple. Then determine the
current flowing through each of the resistors
using Ohm's law.

Fig. 18. Series- parallel circuit is
not really difficult. Add R2 and R3
algebraically. Add effective resistance to R1 for total resistance.

sistances as in Fig. 18. To solve this type
of problem, first determine the combined
resistance of R2 and R3:
6 X 12

R (total)

= 4 ohms

This total value of R2 and R3 may be considered a single resistance which is in series
with R1, and forms a simple series circuit.
This simple series circuit is solved as follows:
6 OHMS

Fig. 17. Ohm's law can be used to
determine the equivalent resistance
of two or more resistors in parallel.
Total current-then solve for ohms.

E
-=
-=
6

I =

- - E

= 2 amperes

R
As an example, assume that a toaster draws
5 amperes at an applied voltage of 115 volts.

and P = 12R

P =

amperes

Power. The amount of work done by electricity is termed the watt and one watt is
equal to one volt multipled by one ampere.
This may be expressed as: P = E x I where
E = voltage in volts, 1 = the current in
amperes. Also:

I =

R (total) = 6 + 4 or a total of 10 ohms.

ampere

Its wattage would then be:

Next, add the individual currents flowing
through the circuit:

+ 3 ampci-es +
I = 6 amperes

2 amperes

ampere

Inserting this 6 amperes in Ohm's law, the
total circuit resistance is found to be:
6

R=-=1ohm
6

The combined equation for determining
the total resistance of n number of resistances
would be:

115 x 5 or 575 watts.

Magnetism and the Electron. The atom,
and a concept of its structure were a necessary preface to our discussion of basic
electricity. By the same token, both are necessary to understanding basic magnetism.
As we've mentioned, electrons are in continual motion about the nucleus. The orbit is,
in fact, a small loop of current and has a magnetic field that's associated with a current
loop. In addition, experimental and theoretical investigation seems to indicate that
the electron itself has a spin. Each electron,
having its own axis, is a spinning sphere of
ELEMENTARY ELECTRONICS

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electric charge. Electron spin, like the quantum and wave theories of light, is not so
much a literal jnterpretation of a phenomenon, but a useful concept that holds water
when applied to the phenomenon of magnetism.
When the electron spins, the charge that is
in motion produces a magnetic field. And, to
briefly state the electronic explanation of
magnetism, it seems that the magnetic properties of matter can be attributed to the
orbital and spinning motion of the electrons
comprising the atoms of the matter.
Millennia of Magnetism. Some of the
basic principles and effects of magnetism
have been known for centuries. The Greeks
are credited as the ones who first discovered
magnetism. They noted that a certain type of
rock had the ability of attracting iron. Later,
the Chinese noted that an elongated piece of
this rock had the useful property of always
pointing in a North -South direction when
suspended by a string. This was the beginning
of our compass.
This strange stone which intrigued people
over the centuries is actually a form of iron
ore known as magnetite. Not all magnetite
shows magnetic properties. Another name
for the magnetic variety of magnetite is lodestone -the term lodestone being derived from
two separate words, lode and stone. The term
lode stands for guide, hence lodestone mean
"guide stone."
All magnets, whether natural or man
made, possess magnetic poles, which are commonly known as the magnet's north and
south poles. As is the case of the electrical
charges (which we studied earlier) between
unlike magnetic poles and repulsion between
like poles, it has been found that this magnetic attraction and repulsion force varies inversely as the square of the distance from the
magnetic poles.
The Magnetic Field. We all know how
a magnet exerts a force of attraction on a
piece of magnetic material such as iron or

Fig. 19. Lines of force around bar
magnet can be made visible by

sprinkling iron filings onto white paper over magnet. Tap paper gently.

steel. Also, when the north poles of two
magnets are brought close together, they will
try to repel each other, while there will be
attraction between the north and south poles
of two magnets. Although it is not clearly
understood just what this force of magnetic
attraction and repulsion is, it is convenient
to visualize magnetic lines of force which
extend outward from one magnetic pole to
the other as illustrated in Fig. 19.
Permeability. Magnetic lines of force can
pass through various materials with varying
ease. Iron and steel, for example, offer little
resistance to magnetic lines of force. It is
because of this that these materials are so
readily attracted by magnets. On the other
hand, materials such as wood, aluminum and
brass do not concentrate or encourage the
passage of magnetic lines of force, and as a
consequence are not attracted by magnets.
The amount of attraction a material offers
to magnetic lines of force is known as its
permeability. Iron and steel, for example,
possess high permeability since they offer
CURRENT
DIRECTION

DIRECT ON

MAGNETIC FLUX

CURRENT
DIRECTION

Fig. 20. Direction of flux lines is
changed by direction of the current.
Heavy current is needed to make flux
lines visible with sprinkled filings.

little resistance to magnetic lines of force.
Nonmagnetic materials have low permeability. For practical purposes, we can say that
reluctance is to magnetic lines of force what
resistance is to an electrical current.
Electromagnetism. Any electrical conductor through which flows an electrical current will generate a magnetic field about it
which is perpendicular to its axis as shown in
Fig. 20. The direction of this field is dependent upon the direction of current flow, and
the magnetic field strength proportional to
the current strength. If this current -carrying
conductor is wound into a coil, forming a
solenoid, the magnetic field will be increased
by each individual turn that is added. If
an iron core is inserted in this current carrying coil, the generated field will be increased
still further. This is because the lines of
force are concentrated within the iron core
which has considerably less reluctance than
the surrounding air.

JULY- AUGUST, 1966

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@/@

netic field to be built up around it. In the
brief instant that the field is building up to
maximum, it will "cut" the turns of coil B,
inducing a current in it, as indicated by a
momentary flick of the indicating meter.
When the switch is opened, breaking the
current flow through coil A, the field around
coil A will collapse, and in so doing will
again induce a current in coil B. This time,
however, the flow of current will be in the
opposite direction. The meter will now flick
in an opposite direction than it did when
the switch was closed. The important thing to
remember is that the conductor must be in
motion with respect to the magnetic field or
vice versa in order to induce a current flow.
You can perform this simple experiment
using two coils made of bell wire wrapped
around large nails, a few dry cells in series,
and a DC zero -center scale meter.
Self Induction. As mentioned a short
while ago, a magnetic field is built up around
a coil at the application of current through
the coil. As this field is building up, its moving lines of flux will cut the turns of the
coil inducing a counterelectromotive force

ELECTRICITY, MAGNETISM
AND THE ATOM

The magnetizing power of a multi -turn
current- carrying coil through which a core
is inserted is proportional to the current
flowing through the coil as well as the number of turns in the coil. The current through
the coil is termed ampere turns. As an example, if a coil consisting of 200 turns is
carrying 2 amperes, its ampere turns equal:
Ampere turns = 200 turns x 2 amperes or
400 ampere turns
Similarly a coil of 100 turns through which
a current of four amperes flows also has 400

ampere turns.
Electromagnetic Induction. We saw earlier how a current carrying conductor will
generate a magnetic field which is perpendicular to the conductor's axis. Conversely, a
current will be induced in a conductor when

CIRCUIT 2

SECONDARY

A
PRIMARY
CIRCUIT

Slew

+111111-

Fig. 21. Two -core transformer is inefficient since an

air gap at either end does not have permeability of o
ferrous metal and some flux lines do not go through
core of secondary winding (8) -their effect is lost.

the conductor is passed through a magnetic
field. The strength of this induced current
is proportional to both the speed at which
it passes through the field and the strength
of the field. One of the basic laws pertaining
to electromagnetic induction is Lenz's law
which states: "The magnetic action of an induced current is of such a direction as to
resist the motion by which it is produced."
Fig. 21 illustrates two coils, A and B,
which are placed in close proximity to each
other. Coil A is connected in series with a
switch and battery so that a current may be
sent through it when the switch is closed, and
coil B is connected with a current -indicating
DC meter. When the switch is closed, current will flow through coil A, causing a mag-

Fig. 22. Toroidal core is highly efficient but is very
difficult to manufacture. Familiar C- and E -shape core
has less waste and windings are slipped over the core.
Efficiency is good-about 90 percent for most designs.

or counter EMF which opposes the current
flowing into the coil.
The amount of counter EMF generated
depends upon the rate of change in amplitude
of the applied current as well as the inductance of the coil. This value of inductance
is dependent upon the number of turns in the
coil; a coil with many turns will have greater
inductance than a coil with few turns. Also,
if an iron core is inserted into the coil, the
inductance of the coil will increase sharply.
The unit of inductance is known as the henry.
The Transformer. One of the most important and widely used applications of magELEMENTARY ELECTRONICS

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netic induction is the transformer. Transformers find the major application in stepping
up or down voltage and current in countless
applications.
Fig. 22 shows the basic construction of a
typical transformer. While two separate
windings are shown here, some transformers
can have as many as five or six windings.
A transformer consists of two or more separate windings, electrically insulated from
each other. One winding, which is known as
the primary winding, is fed from a source of
alternating current.
The alternating currents flowing through
the primary induce a current in the secondary
winding by virtue of magnetic induction. The
transformer core is constructed from a relatively high permeability material such as iron
which readily conducts magnetic flux between the primary winding and secondary
winding.
The alternating current flowing in the primary of the transformer produces a variation
in the magnetic flux circulation in the transformer core which tends to oppose the current flowing in the primary winding by virtue
of self- induction. The counter EMF is just
about equal to the voltage applied to the
primary winding when no load is connected
to the transformer's secondary winding. This
accounts for the fact that very little current
flows through the primary winding when no
load is connected to the secondary. The negligible current that does flow under this no -load
condition is known as the transformer magnetizing current. As the current drawn from
the secondary winding increases, the primary
current will increase proportionately due to
the reduction in the counter EMF developed
in the primary winding of the transformer.
In any transformer the ratio of the primary to secondary voltage is equal to the
ratio of the number of turns in the primary
and secondary windings. This is expressed
mathematically as follows:
Ep

where Ep = primary supply voltage
Es = voltage developed across
secondary
Np = number of primary turns
Ns = number of secondary turns

The above formula assumes that there are
no losses in the transformer. Actually, all

transformers possess some losses which must
be taken into account.
Transformer Losses. No transformer can
be 100 per cent efficient due to losses in the
magnetic flux coupling the primary and
secondary windings, eddy current losses in
the transformer core, and copper losses due
to the resistance of the windings.
Loss of magnetic flux leakage occurs when
not all the flux generated by current flowing
in the primary reaches the secondary winding. The proper choice of core material and
physical core design can reduce flux leakage
to a negligible value.
Practical transformers have a certain
amount of power loss which is due to power
being absorbed in the resistance of the primary and secondary windings. This power
loss, known as the copper loss, appears as
heating of the primary and secondary
windings.
There are several forms of core loss
hysteresis and eddy current losses. Hysteresis
losses are the result of the energy required- to
continually realign the magnetic domain of
the core material. Eddy current loss results
from circulating currents induced in the
transformer core by current flowing in the
primary winding. These eddy currents cause
heating of the core.
Eddy current loss can be greatly reduced
by forming the core from a stack of individual sheets, known as laminations, rather
than from a single solid piece of steel. Since
eddy current losses are proportional to the
square of core thickness, it is easy to see that
the individual thin laminations will have
much less eddy current loss as compared
with a single thick core.
Another factor which effects eddy current
loss is the operating frequency for which the
transformer is designed to operate. As the
operating frequency is increased, the eddy
current losses increase. It is for this reason
that transformers designed to operate at radio
frequencies often have air cores and are void
of ferrous metals.
Theory and Practice. We've come a long
way from our initial discussion of the atom
and its importance for an understanding of
electricity and magnetism. And there's still
a long way to travel to understand all about
the subatomic nucleus and its satellites and
how they are being harnessed in an everexpanding electronics technology. But, we
move ahead by mixing theory with practice
so, put your new knowledge to work in a
project or two!

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Basics

RTTY
Speeds of

60 wpm

are attainable, with
characters typed
as fast as sent out.
"I read you five by five" is a familiar
phrase in Ham radio. But the only crowd
who can use it literally is the one on RTTY
-Ham radioteletype. These communications are by printed page, with typed -out
messages you can really read. Instead of
speaking into a mike or hitting a key, the
RTTYer sits at a machine (Fig. 1) that
looks like an overgrown electric typewriter.
There's the usual back -and -forth rag chewing, but it's neither voice nor Morse code.
In the words of the RTTYer stations "print"
each other.
These are the guys responsible for funny sounding pulses you've probably heard on
CW-the ones that sound like a chirpy CW
signal running at high speed. And you might
have wondered how anyone could copy such
fast code. No one can, of course, since the
pulses are too fast for the human brain to
follow. But the Ham's Teletype machine
thrives on speed, and tools along at 60 words
a minute.
Is high speed the reason for hams on
RTTY? In most cases it is not. The main
appeal of RTTY is that the field is wide open

for the experimenter. It's something entirely
fresh for the natural -born tinkerer. It takes
a while to get used to the idea of putting oil
on a piece of radio gear, but once a ham gets
accustomed to this marriage of mechanics
and electronics, he seldom gives it up. For
the fellow who likes to turn thumb screws
as well as tuning capacitors, RTTY offers a
never -ending challenge. Many Hams rise to
this challenge like a rocket leaving the
launching pad, and devise original circuits
for receiving and decoding the RTTY signal
that makes the wheels go 'round.
Pulses. A Teletype machine feeds on a
special diet of electrical pulses. These pulses
trigger a mass of levers and gears inside the
machine into motion which print letters and
figures on a paper roll. As in Morse code,
there is a different combination of pulses
for each printed character, plus a few extras
for spacing and functions such as carriage
return, line feed, shifting from figures to
letters, even ringing an attention -getting bell.
For each letter, figure, or machine function, there is a set of seven pulses. First is
a start pulse which tells the machine in ef-

by Marshall Lincoln
K9KTL
JULY-AUGUST, 1966

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@AD

BASICS OF RTTY

fect: "There's a signal starting to come in.
Hitch up gears and get ready." The last pulse
is a stop pulse, which instructs the machine:
"You're done with that letter, relax for a
few milliseconds before the next one comes
along."
Those five pulses between start and stop
are the ones which determine which letter
or figure the machine will print, as shown
in Fig. 2. This is why the Teletype code used
by Hams is called a five -level code. The
intelligence- carrying job is primarily done
by various combinations of five pulses. Consider it this way. Think of five zeros:
0 0 0 0 O. Each zero represents a fraction
of a second, or interval of time. Let's say
the signal for the letter R comes into the
machine. Letter R consists of a pulse in
the second and fourth intervals (with no
pulse in the first, third and fifth intervals).
You could represent the R in code like this:
O X O X O. The letter Y, on the other hand,
is just the opposite: X O X O X. So we see
that different pulse and space combinations
determine the character. Incidentally, letters
R and Y frequently are used to test Teletype
machines. They're electrical opposites, and
make the machine reverse gears, so to speak,
after each interval. This provides a good
test of all vital parts in the machine.
In RTTY parlance, the presence of a pulse
at the machine is a mark and the absence of
one is a space. The terms are carryovers
from the old days of the printing telegraph,
when dots and dashes were actually printed
by the receiving machines. Both mark and
space are referred to as pulses, but at the
machine itself a mark means pulse of cur-

rent, while a space is the absence of current
for a definite interval.
There are 32 possible combinations (Fig.
3) of these five mark and space pulses.
They cover 26 letters of the alphabet and
the mechanical machine functions already
mentioned. There are no lower case letters
on the machines -all letters are capitals. By
pressing a Figures key the machine is set up
to print figures (numerals) and punctuation
marks. Pressing a Letters key gets the machine back to letters again. Many machines
also have levers which shift them to printing
letters when the space bar is pressed.
When Hams first started using Teletype,
they simply keyed the transmitter carrier;
on for mark, off for a space. This was done

Fig.

1. Copy is actually read at this Ham shack.
There are some differences in Teletype keyboard but
if you can type you can transmit RTTY messages.

'
f IGs
L

TPS

-? :S3!4 8'

ABCOEFGH

(

) .

,9pSi 4°57;

2/6"

JKLMNOPQRS TUVWXYZ[-:C1

Fig. 2. Punched tape indicates all characters available on keyboard
of RTTY printer. No small (lower case) characters are used with this five level code. Depressing Figures key allows you to send numerals,
punctuation marks and ring attention- getting bell used by news services.

dLuw

Q?á
UJJ
Lt.

ELEMENTARY ELECTRONICS

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;'Z'E

;

4)?.,

41),

4110

ANT.

RTTY
HAM RECEIVER

RF SIGNAL

Fig. 3. Keyboard
only needs three rows
of keys since the
twenty -six lower -case
letters of the
alphabet are not used.
Letters are in some
positions on typewriter.
Fig. 4. (below) Block diagram
for RTTY receiver.

SIGNAL

AUDIO

SPKR

CONVERTER (TU)

FILTERS

RELAY

TELETYPE
PRINTER

LINE
CURRENT

MSM

111

rapidly by the switching mechanism inside
the machine.
The Problems. Interfering signals or
noise pulses could fill in the brief interval
of "dead air" when the transmitter was off
during a space. This would make the receiving machine print garbled copy (wrong
letters).
So, they tried transmitting a signal on one
frequency for mark and on a sightly different
frequency for space. It worked well, and
that's the way it's done today. It's called
frequency-shift keying (FSK). The transmitted carrier remains on continuously, but
it is flipped rapidly back and forth between
two adjacent frequencies. That's the reason
an RTTY signal sounds chirpy.
The FCC allows Hams up to 900 cycles
of shift for RTTY work. Hams have pretty
much standardized on 850 cps. This provides wide enough shift to make it fairly
easy to adjust equipment, and leaves a margin for error and still stay within the legal
limit. Some operatofs are experimenting
with narrow shift, down around 170 cps or
so. This requires better equipment to distinguish between the two frequencies so close
together, but has the advantage of being less
susceptible to interference.
Incoming. To receive an RTTY signal, a
ham generally uses an ordinary communications receiver with the BFO turned on so

Fig. 5. Teletype tape does not usually have
any printing but experienced operators often read
tape perforations across width of paper tape.

the frequency shifts of the incoming signal
produce a varying audio beat note in the
receiver. (The overall system is in Fig. 4.)
These audio notes are fed to a device variously known as a terminal unit (TU), receiving converter, or demodulator. Basically it contains a pair of filters tuned to two
audio frequencies which are 850 cycles
apart. Conventionally, these are 2975 and
2125 cps. One filter accepts the mark frequency (2125 cps), the other accepts the
space frequency (2975 cps) and passes them
through a stage of amplification then to a
keyer tube on relay. This controls current
to the Teletype machine. Current flows for
mark and is turned off for space. This operates an electromagnet in the machine
which, in turn, triggers a series of levers
which operate type bars.
On six meters and above, Hams use a
slightly different method for sending RTTY

JULY-AUGUST, 1966

www.americanradiohistory.com

BASICS OF RTTY

Fig. 6. Tapes can be

prepared in advance and
then zipped ouf at 60 wpm
by tape distributor
(to left of keyboard).
Fig. 7. Received copy
rolls right out of printer
that resembles typewriter.
Generally special long
lengths of paper are used
unfolding directly from
packing box into printer.

signals. Instead of shifting the carrier frequency to correspond to mark and space
pulses, the steady carrier is modulated with
two audio tones -one for mark, the other
for space. This is known as audio frequency
shift keying (AFSK). Converting the received tones to electrical pulses is done much
the same as with FSK, except the receiver
BFO does not need to be turned on. AFSK
is not permitted below 50 mc, so hams on
the lower frequencies must use FSK.
Outgoing. Transmitting Teletype signals
is relatively simple. The keyboard of a Teletype machine operates a set of electrical contacts that open and close in sequence to form
the mark and space pulses of the Teletype
code. These contacts are connected to the
transmitter VFO (in the case of FSK) or
to an audio -tone generator (in the case of
AFSK) which feeds its output to the transmitter. Many people are surprised to learn
that a Teletype actually is two separate machines in one cabinet. Although both are
driven' by the same motor, the receiving and
sending units are otherwise completely separate. They may be connected together electrically so the receiving unit prints what the

sending unit is sending, or they may be operated independently. An operator may bang
away at the keyboard, sending a message,
while at the same time monitor his sending
on the same machine. Or, he can receive a
message on one frequency while sending a
message on a different frequency -with the
same machine!
A more versatile arrangement is to use
a machine which punches holes in a paper
tape (Fig. 5.) corresponding to mark and
space pulses. This tape may then be fed
through a device called a tape distributor
which operates the transmitter the same way
as a keyboard. A tape distributor (Fig. 6.)
contains its own motor and a set of electrical
contacts like those operated by a Teletype
keyboard. As the tape is pulled across a set
of sensing pins by a cog wheel, the pins
(feeling holes in the tape) operate electrical
contacts. They create electrical pulses identical to those produced by a Teletype keyboard. The result is shown in Fig. 7.
With this set-up, a Ham can prepare a
long transmission or series of messages in
advance of going on the air. Then the tape
distributor can do the actual sending at a
smooth, constant speed. Or, he may receive
an incoming transmission on his printer
while at the same time preparing his answer
by punching a tape. When his turn comes
to transmit, he feeds the punched tape into
the tape distributor, which obediently bangs
away at an impressive 60 wpm.
If the prospect of humming machinery
wedded to electronic circuits looks inviting,
why not look further into RTTY? Part 2 of
this article tells you what you need to know
for getting a rig on the air.

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

0000

00000

000

Communicate
with instant messages. A
typed sheet of
copy straight
from the receiver
gets those cans
off your ears and
the pencil out
of your "fist" but
RTTY's hard work.

000.0.0

..
..

Putting
RTTY
in the
Shack

0.0
00.00

000.0

by Len Buckwalter
K10DH

000.0
0.

You won't have to hock the family jewels
or get an engineering degree to get on radioteletype. If you're a ham with a reasonably
good rig, you may already own about 75%
of an RTTY station. How about the other
25% -and the myriad items you need to
know about before you can hit those 32
green keys? Before considering them, here's
the most important question of all.
Is It Your Cup of Tea? If the ink is barely
dry on your Ham ticket, better get your kicks
first on phone and CW. They provide solid
operating experience needed for more sophisticated RTTY. Later, when the thrill goes
out of brass pounding, and your voice grows
hoarse from calling CQ, you're a candidate
for QSO'ing on a teleprinter machine. As
scores of once -jaded Hams will attest, it can
put the sizzle back in ham radio.
Hams who won't touch a screwdriver,
maybe cringe at the sight of an oil can, or
can't wire an AC plug, probably won't enjoy the game. Though you need no great
skill or know -how, it's an asset to enjoy

fiddling and experimenting with equipment
-even if you have to go by the book. Your
RTTY machine will have a mass of mechanical parts going ta- pocketa ta-pocketa, and
they need a roll -up-your -sleeves lube job at
regular intervals. RTTY is for the nuts -'nbolts man.
Take Stock. Some Ham RTTY rigs resemble the inside of the blockhouse at Cape
Kennedy. But in the beginning there's no
need for that level of complexity. Let's begin with the basic rig; a receiver and transmitter combination you might already have.
There is no special circuit needed inside the
receiver. Any reasonably good model fills
the requirement. About the only type that
won't give satisfactory results is the AC -DC
gutless wonder that quivers as you walk
across the room. The receiver must be fairly
stable or you'll have to do a lot of retuning to
keep the RTTY signal on the nose. But
given plenty of warm -up time, a moderately
priced set will stop drifting and provide the
required stability. Other worthwhile receiver
41

.JULY- AUGUST, 1966

www.americanradiohistory.com

RTTY IN THE SHACK

A typical Ham RTTY CCU can be punched into
tape. Spliced end -to -end it can be run
continuously through tape keyer for calling.

Teletype machine, in front of operator (below)
is used with units on shelves at rear. All
}hat's needed is a TU converter. The Twin City
converter
3 -tube job
shown at right.

-a

-is

Some of the Ham RTTY publications (right)
help point up the state-of-the-art of
Ham equipment and RTTY experimental units.

features: an easily adjusted BFO and band spread tuning. Exceptional selectivity in the
receiver is nice to have, but not imperative
for the beginning RTTY'er. Chances are
you'll start with standard (as opposed to narrow) shift operation where the signal is relatively wide. The only modification to the
receiver in a simple system is tapping the
incoming audio signal from the speaker terminals.
The frequency bands used for radioteletype correspond to those of regular phone
and CW work. RTTY stations commonly use
80, 40 and 20 meters. Within each band
there are RTTY frequencies where stations
tend to cluster (like 3620, 7140, and 14,090
kc.). Some operators prefer VHF bands
6 and 2 meters. These are valuable for
QRM -free, local contacts. Thus the regular
ham rig provides the necessary frequency
coverage on HF, with receiving converters
added for VHF, if desired.

Transmitter requirements. No complex
circuits are needed inside the transmitter, but
it should have variable -frequency oscillator
(VFO). (Crystal- controlled oscillators don't
lend themselves to frequency -shift keying.)
You'll have to make up a simple adapter to
enable the Teletype machine to vary transmitter frequency. It helps to have a stable
transmitter that won't drift and cause tuning
problems for the Ham trying to copy you at
the other end of the QSO.
On the matter of transmitter power, most
old- timers say pour on the coal. Good advice, but you can still do plenty of operating
at moderate power, especially for local rag
chewing and short skip. Try to get at least
100 watts into a good antenna. At higher
power there's more chance to work crosscountry and occasional DX. Lower power
has increased garbling, strike -overs and
missed words.
Total Tab. If you own a suitable rig, con-

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

,1;

high, but cost is piddling if you build the
popular home-brew job known as the Twin
City converter. As shown in the photos it's
a 3 -tube chassis. All new parts cost about
$35, but a generous junkbox can slash that
figure. We built ours for some $10 in new
components.
Thus the grand total for getting on the air
with a functioning RTTY rig might dip as
low as $70. Sure you can get ritzy accessories, like a scope for visual tuning of the
RTTY signal but it's not a beginner's necessity. (Later on you'll give up candy bars
to buy one.) There's one other item -the
keyer unit which enables the Teletype mar
chine to drive your transmitter as you type.
In some Ham rigs, it is done simply with the
addition of a potentiometer (with instructions provided by the manufacturer) or an
uncomplicated 1 -tube or 1 -diode circuit.
Get The Dope. Before buying any hardware consider these sources of information.
They contain much valuable data on Ham

RTTY:

sider next the cost of adding RTTY. The
price of a brand new Teletype machine is
about the same as a fully equipped Volkswagen. But incredible as it may sound, fine
Teletype printers -which function for both
send and receive-can run under $100! The
machine shown in the photos (a Model 26)
cost $60. It spews out signals as well as the
best of them. The secret is simply that Teletype machines are retired in sizeable numbers to make way for newer, faster machines
demanded by commercial and military services. If it weren't for this cost-busting factor,
RTTY and Hamming simply couldn't mix.
How you can get these machines -and they
are not freely available except to hams
detailed in a moment.
After the machine, next item is the terminal unit (TU). This is the device which converts audio signals from your receiver into
a form that can drive the Teletype printer.
.Again, the price of a commercial unit is sky

-is

The New RTTY Handbook by Byron H.
Kretzman. Cowan Publishing Corp., 14
Vanderventer Ave., Port Washington, L.I.,
N. Y. 11050. $3.95. This 191 -page book
covers theory and practice. It contains the
Twin City converter circuit and construction
data. Listed are Hams in each of the call
areas who might supply you with leads on
where to purchase equipment locally.
Ham -RTTY by W2NSD /1, W4RWM. 73
Inc., Petersborough, N. H. This is another
source book; 113 pages, $2.
RTTY Bulletin. This is a monthly bulletin
published by the RTTY Society of Southern
California, 372 West Warren Way, Arcadia,
Calif. Rate is $3 per year. This publication,
by the leading ham RTTY organization, is
newsy journal of what's happening in RTTY;
from circuits to contests, and anything else
that touches the hobby. A useful feature is
the Horse Trades column. Each month it
lists a raft of RTTY equipment for sale and
trade. Ads are free to members.
Copying Commercials. It might be apparent that it's possible to set up one -half
of an RTTY system-the receiving end
and be able to copy commercial stations
transmitting press, telegrams and other traffic. Several factors work against it. For one,
these stations exist out of the regular Ham
bands, although occasionally they can be
pulled in when they're close to the band
edges. But even if you tuned with a generalcoverage receiver, where such stations

JULY- AUGUST, 1966

www.americanradiohistory.com

RTTY IN THE SHACK

Scope (above) helps to tune RTTY signals for
best, error -free copy at advanced installations.
For trouble-free operation you'll have more
than the usual amount of maintenance work. Regular
use of the oil can, and cleaning, will be a must.
Dust and lint must be removed and oil gets gummy.

abound, your machine would copy few signals. Most commercial stations have switched to newer equipment and higher speeds.
The Ham system is synchronized to 60 words
per minute and prints gibberish on most
signals other than Ham.
Tickling The Keys. While it helps to know
how to touch -type when operating a teleprinter, there's no deterrent to the hunt-'npeck typist. Operating speed is not comparable to CW, for example, where the fast
operator must slow down for the beginner.
The reason is that the printer makes a typed
record of an incoming transmission. If a
particularly slow typist is sending, you don't
even have to sit at your machine. Fill in the
log, touch up a tuning knob or even leave
the shack for a few minutes. The machine
will clack away unattended. Thén you can
walk over to the machine and read the whole
transmission in a minute or so.
Sometimes another operator comes tearing back at top speed like a typing champ.
Don't be fooled. He may be a two -finger
typist who has punched a tape during your
transmission. Played back through tape
equipment, it transmits at maximum speed.
Although this kind of snappy operation
typifies the advanced RTTY'er, manual
typing skill is an advantage and it makes operating more pleasurable.
Before You Plunge. Getting a basic
RTTY rig on the air is neither complex nor
time -consuming. But there's an important
qualification: It is definitely not like build-

ing a kit, or even a construction project like
the ones in this magazine. There is no single
publication in RTTY literature that takes
you by the hand and tells you to hook wire A
to terminal B. And even if you are well-

stocked with diagrams, this is no guarantee
that you'll wire equipment correctly.
But there's an answer. By checking
through the publications listed earlier, and
the Call Book, you should be able to locate
an active RTTY'er in your area. If he's
typical of most hams, he'll heap you with
advice and helpful suggestions. When we
got our machine, we puzzled for hours over
some dangling leads. A phone call to an active RTTY'er in the area solved the problem
in about three minutes. Of course, once you
get on the air, the rig becomes a direct radio
link to hundreds of fellow hams who'll lavish you with sound RTTY advice.
Meet You On The Green Keys. That's
one expression you'll be seeing -and printing
you go RTTY. Is it worth the effort and
cost? Yes, if you want to get in on one of
Hamdom's remaining outposts for the experimenter seeking an exciting and different
mode of communication. As a bonus, you'll
be able to copy news bulletins each evening
from the ARRL's station W1AW. They cover everything from reports on OSCAR, the
orbiting Ham satellite, to propagation reports on band conditions. And when you
work other RTTY'ers around the country,
you, too, can sign off with; "see you further
down the page. OM."

-if

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

Cross coupling

two single -stage

Using

Cross - Coupled Circuits

amplifiers
produces a
simple multivibr ator that
can be used to
demonstrate
circuits used
in all digital
computers

by Jack Brayton

Cross -coupled circuits can add, subtract,
gate, read information in or out, count, generate square waves, eliminate unwanted
pulses, shift numbers left or right, store information indefinitely, and accomplish many
other tasks far too numerous to list.
In addition to their wide use in computers,
they're also used for timing, triggering, pulse
shaping, etc. In spite of the many functions
cross-coupled computer circuits can perform,
they're not complicated, difficult to understand, nor expensive to build. In fact, we'll
outline 3 experiments, all of which can be
breadbroaded (using the same parts for each
experiment and clip leads for switches) for
about $4.00. Even this low figure can be
cut in half if you have a 6-volt DC source
and a few scrap parts.
Also, for those who want something more,
plans for a complete cross -coupling demonstrator (Fig. 1) are included. This unit,
which costs about $8.50, makes a good Science Fair project and includes the three
basic types of cross-coupling. That is, DC
(direct- current), AC (alternating- current)
coupling, and a combination of AC and DC
cross-coupling can be selected simply by
flipping a switch. All three circuits are
broadly classified under the multivibrator
heading. And, although the circuits look
similar, they're very different in the jobs they

perform.

Fig. 1. Demonstration unit has
three types of multivibrator
circuits easily selected by a
front panel 3- position swifch.

.ÌIIi.YAIIOIIST, 1966

www.americanradiohistory.com

CROSS- COUPLED
CIRCUITS

Now, let's run through each of the experiments and discover exactly how they work
and why they work that way.
DC Cross -Coupling. Fig. 2 shows the
schematic used for the first experiment; a
flip flop or bi- stable multivibrator. It consists of two DC- coupled, common- emitter
amplifiers. Q1, R3, R5, and Il form the
first amplifier while Q2, R4, R6, and I2
form the second. You'll notice that the Fig. 2. DC or direct coupled bi- stable multivibrator
first amplifier's output is directly coupled circuit will let but one lamp light at a time.
pushbutton (SI or 52) grounds base and
(through Rl ) to the input of the second Pressing
transistor jumps to cutoff and other transistor
amplifier. Further, the second amplifier's jumps into saturation and is held there by the
output is directly coupled (through R2) to high -negative bias applied to base connection.
the first amplifier's input. This causes the Fig. 3. Charge and discharge of Cl and C2 cause
circuit to have two stable states. That is, Q1 lamps II, 12 to blink, alternately, on and off.
can be conducting with I1 lighted or Q2 can
be conducting with I2 lighted. Thus the
transistors act like simple switches for the
lamps and have either a high resistance
(open) or low resistance (closed) across
their emitter /collector leads. The crosscoupling, as we'll show, prevents both transistors from conducting at the same time.
To explain, let's trace the circuit's action.
When power is first applied to the circuit,
one of the transistors will turn on faster
than the other, which causes this transistor
to conduct while the opposite transistor cuts off. We'll assume Q1 conducts while Q2 cuts For example, if I1 is lit and Q1 is conducting
off.
we would close S1. This switch momentarily
When Q2 is cutoff its collector rises to shorts the current flowing through R2, 125
-6 volts. This results from the fact that the and the emitter /base junction of Q1 to
resistance of Q2's emitter /collector junction ground. Thus, the base current of Q1 is
is then much higher than the series circuit removed and Q1 is cutoff causing its colcomposed of R4 and the lamp. Thus, al- lector to go to -6 volts. Now, current can
most the full battery voltage appears across flow through R1, R6, and the base /emitter
Q2. However, some current flows through
junction of Q2. Q2 saturates and its collector
R2, R5, and the emitter /base junction of
voltage goes toward ground potential, reQ1. This current, although not large enough moving the forward base bias from Q1. Havto light I2, is large enough to cause Q2 to ing switched states, the circuit will hold or
saturate. Thus, Q l's emitter/collector re- "remember" its new state until the opposite
sistance becomes much lower than that of switch (S2) is closed momentarily. This
R3 and Il. This being the case, most of action, of course, closely resembles that of
the battery voltage is dropped across Il and a latching relay except the circuit switches
R3. This, in turn, causes I1 to light. Q2
much faster, has no moving parts to wear
cannot conduct, under these conditions, be- out, and usually costs less than electrocause Q1's collector potential is at, or near, mechanical relays.
ground and hardly any current flows through
AC Cross-Coupling. Fig. 3 shows the
Rl, R6, and the emitter /base junction of Q2.
second experiment; an astable or free -runThe circuit can be switched from one ning multivibrator. This circuit is similar
state to the other merely by closing the input to the first circuit except there are no input
switch to the transistor which is conducting. switches and the resistors (Rl and R2, of
46

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

the first circuit) have been replaced by capacitors Cl and C2. This causes the circuit
to oscillate and the lamps to blink on and of
alternately. It also causes a square wave to
be produced at both collectors. To find out
how this is accomplished let's take a closer
look. Again, we'll assume Ql conducts and
Q2 is cutoff when the power is first applied.
Also, we'll assume C2 was previously discharged.
When Q2 is cut off its collector rises to
-6 volts and, since C2 has already been discharged, it offers almost no resistance to current flow during the first instant. Thus C2
starts to charge through I2, R4, R5, and the
emitter /base junction of Ql. This causes
Ql to saturate; its collector goes toward
ground potential; and Il lights. At the same
time, Cl starts to discharge through the
emitter /collector resistance of Q1 in saturation; R4, and the back resistance of Q2's
emitter /base junction. It's important to note
that C2 is charging and holding Q1 in saturation while Cl is discharging and holding
Q2 cutoff. Thus, the circuit is at a standstill
for a length of time determined by the
charge and discharge times of Cl and C2.
(This time can be altered simply by increasing
or decreasing the size of these capacitors.)
When C2 has finished charging, current
flow through the capacitor stops, which
means Q1 is no longer forward biased. Thus,
Ql is cutoff causing Il to go out and its
collector potential to go to -6 volts. Cl
having discharged -either partly or fully
starts to charge to this higher collector potential. It does this through Il, R3, R6, and
the emitter /base junction of Q2. Q2, in turn,
saturates causing I2 to light and its collector
to go toward ground potential. Now C2
starts to discharge through Q2's emitter -collector resistance in saturation, R5 and the
back resistance of Ql's base -emitter junction.
Again the circuit is at a standstill until Cl
and C2 have charged and discharged. Then
the entire cycle repeats itself, endlessly.
Because the collector potentials are constantly changing from ground to -6, staying at -6 for a length of time, then returning
to ground, a square -wave is produced at each
collector.
Before we go on to the next experiment,
it should be noted that Cl and C2 do not
have to be the same value. Making them
different will cause one lamp to stay on
longer than the other. With the values shown
the lamps blink on and of about twice a
second.

Fig. 4. Pressing SI sends Q1 to cutoff. 12 will
remain lighted until Cl charges. Both lamps
will remain dark until SI is released-then 11
will light and remain lit while S1 is open.

AC /DC Cross-Coupling. The third circuit
(Fig. 4) is really a combination of the first
two. That is, one AC and one DC coupled
amplifier is used to form a one-shot or monostable multivibrator. The one -shot -as its
name implies-provides one cycle for each
input pulse.
When power is first applied to this circuit,
I2 will always light for an instant because
Cl allows a heavier base current to flow
through Q2 than resistor R2 allows in Q1.
However, 12 will not stay lit very long because as soon as Cl has charged Q2's base
current drops to zero and that transistor is
cutoff. This, of course, causes a heavy base
current to flow through R2, R4, and the
emitter-base junction of Ql. Ql saturates;
Il lights and stays lit, indefinitely.
Of course, momentarily closing S1 will
cause Q1 to cutoff; Cl to charge; Q2 to
saturate; I2 to light and stay lit for as long
as it takes Cl to charge. After that Q2 will
cutoff and the circuit will return to its orig12

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Fig. 5. Double -pole, 3- position switch changes
the connections to the different circuits. For
some demonstration purposes a neatly breadboarded
circuit can use clip leads in place of S4.
47

JULY -AUGUST, 1966

www.americanradiohistory.com

CROSS- COUPLED

CIRCUITS

1e"

az DIA.(2 REO)

sá1DIA.(4RE))
2.DIA
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16'

DIA
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state. Thus, as we've already mentioned,
one input pulse generates one output pulse.
About The Demonstrator. Looking at the
demonstrator's circuit shown in Fig. 5 we
can see that it's exactly like the experiments
except we've included all three types of cross
coupling and provided a means of switching
from one to the other. Thus, the demonstrator works similar to the experiments and
its theory is identical.
Construction. Laying out the chassis is, of
course, the first step and this is done according to Fig. 6. The layout should be drawn
on graph paper then taped to the front panel
and the hole- centers punched.
The slot for the lever switch can be easily
made in the following manner. First, drill
the 1/4 -inch hole at the slot's center as shown.
Then, using a keyhole hacksaw, cut the slot
and file the edges smooth. Since the slot
only has to be about Ms -inch wide, very little
(Continued on page 110)
final

.-,r -.--.

,
. ; -:---

Fig. 6. Front and sloping panel layout for the
cabinet calls for 4 -inch width since rounded edges
of some cabinets do not leave more usable width.
Rubber cement or tape full -size template to panel.

..-.

BOARD

I1
S3

NOTE

SPACERS

Z -4 or equiv I
6 -volt electrolytic capacitor
TE -1106 or equiv.)

C2- 300 -mf.,

(Sprague,

12 -Pilot
lamp, 2.0 -volt, 0.06 amp.,
bayonet base. (type 49 or equiv.)
01, Q2 -pnp transistor, 2N322, 2N188A,
2N241 A, 2N270, 2N404A or equiv.
R1, R2- 1800 -ohm, 1/2 -watt resistor
R3, R4
-ohm, 1/2-watt resistor
R5, R6-470 -ohm, 1/2-watt resistor
Si, S2- S.p.s.t., momentary contact pushbutton switch (Leecraft, 7 -1 or equiv.)

I1,

-68

Fig. 7. With the sloping panel down,
all major components are visible
none hidden. Transistor circuitry
is on phenolic board with leads
going to switches and lamps on panel.

53-S.p.s.t.

PARTS LIST

-6 -volt battery (Burgess,

Cl,

Fig. 8. Perforated phenolic board
is ideal for assembling this small
circuit. Wiring is not critical
since feedback from stray capacitance
is not likely in this low- impedance,
low -frequency multivibrator circuit.

R6
R3

PHENOLIC

étRt

toggle switch (Cutler- Hammer,
8280K14 or equiv.)
S4
-pole, 3- position, positive index, lever
switch (Centralab, 1454 or equiv.)
Battery holder (Keystone, 175 or equiv.)
2 -Pilot lamp sockets ILeescraft, 7 -11 or equiv.)
Sloping -panel utility box (41/2 "H x 41/4 "D x
4- 3/16 "WI (Premier, ACPC -1200, or equiv.)
Misc.-Perforated-phenolic board (2- 7/16" x
33/e "); machine screws; spacers; flea clips;
wire; solder, etc.

-2
11-

Estimated construction cost: $8.50
Estimated construction time: 2 hours

ELEMENTARY ELECTRONICS

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Buîld'em
Good
by John D. Lenk

Tips on soldering and
tools for good-looking
electronics projects
Any electronics kit, built in the home
workshop, can look just as professional as
those factory-wired jobs. Those squared -off
wiring turns and neatly positioned resistors
and capacitors don't just happen by accident,
though. It does take a little more effort and
some know -how to keep that chassis from
looking like a "ball of snakes" from which
all wiring emanates.
Of course we're referring to that other
fellow's projects, not the ones you've built.
Your kits never have panels that were
scorched by hot soldering irons or scratched
by a slipped screwdriver-they never look as
if they were built using a blowtorch, pipe
wrench and a sledge hammer. Do they?
Well, here are some tips you can pass on
to those less adept constructors when they
ask you for your secrets of producing finished
gear (kits or home brew) that not only
works well but looks good-inside.

The Facts. We contacted the service representatives of various kit manufacturers to
find out where most home workshop kit
builders go astray. The consistent repair
problems are those caused by improper work
habits, incorrect use of tools, poor wiring and
soldering practices and the inability to follow
instructions exactly.
Introduction To Soldering. Before going
into the practical side of electronics wiring
and construction, let's go over the fundamentals of soldering.
Soft solder, which is used in all electronic
construction except for a few specialized applications, is a fusible alloy, consisting essentially of tin and lead. (We could tell you in
technical jargon that its purpose is to join
two or more metals at temperatures below
their melting point. Soft solders secure attachment by virtue of a metal solvent or intermetallic solution action that takes place
49

JULY-AUGUST, 1966

www.americanradiohistory.com

BUILD 'EM GOOD

Lead is wrapped around
tie-point lug (above)
before applying heat to
lug (right) -close to
wrapped lead end.

Pencil -type soldering irons are popular with numerous
technicians as well as hobbyists. Temperature selection iron is Heathkit GH -52 -has 8 ranges.

at relatively low temperatures. But that won't
help you make a better-soldered joint.) Soft
solders are not to be confused with hard
solders or brazing alloys whose action involves the formulation of a fusion alloy with
the metal that is joined; nor are they to be
confused with welding alloys, whose action
again involves actual fusion with the respective metals. Soft solder secures attachment
by dissolving a small amount of the two
metals.
A soldered joint is chemical in character
rather than purely physical. Therefore, the
properties of a soldered joint are different
from those of the original solder alone because of the soldering process. The solder
is partly converted to a new and different alloy. Thus, a soldered connection is continuous in intermetal continuity while an unsoldered one is discontinuous. When two
metals are soldered together, they behave like
one solid metal, but when bolted, wired, or
otherwise physically attached, they are still
two pieces of metal, and often they are not
even in direct physical contact with each
other due to the extremely thin insulating
film of oxide on the surfaces of one or both
of the metals.
When tin is added to lead, which melts at
621 °F, it lowers the melting point of lead.
Also, when lead is added to tin, which melts
at 450 °F, it lowers the melting point of tin.
The alloy of tin and lead with the lowest
melting point of the combined metals is
known as the eutectic composition. It consists of 63% tin and 37% lead, and has a
sharp and distinct melting point of 361°F.

Solder is applied to
lug -not to soldering
iron tip. Only when
lug is hot enough to
melt solder can you
be sure of good joint.

Except for this eutectic alloy, all tin -lead
solders are mixtures which do not melt sharply at any one temperature, but will pass
through an intermediate range of plasticity in
cooling from the liquid to the solid state.
Any solder containing less than 63% tin is
said to be eutectic plus lead while a solder
containing more than 63% would be eutectic
plus tin. Both melt at a higher temperature
than the eutectic composition.
Commercial solders cover the entire range
of tin -lead ratios from pure tin to pure lead.
A 50/50 (50% tin, 50% lead) or a 40/60
alloy is typical for electronic solders. Most
commercial solders in common use also contain impurities. In special cases, other elements are added to the solder to change its
characteristics. Such elements include silver,
antimony, bismuth and cadmium.
The Flux of the Matter. All common
metals are covered with a non -metallic film
known as an oxide, which forms an effective
insulating barrier that prevents metals from
touching each other. As long as this non-

ELEMENTARY ELECTRONIC$

www.americanradiohistory.com

Properly soldered connection

(top left)

uses

little

solder. Poorly soldered
connections (below) are not
smooth, have excessive
solder and may not even be
good electrical connections.

With printed- circuits, soldering technique is about
the same. Pigtail lead is inserted and bent
fo a slight angle. Foil and lead are heated
together. Foil, being thin, heats rapidly.
Excessive heating can loosen

foil from board.

fact, the kit manufacturers will void your
guarantee if there is evidence of soldering
with anything but rosin type solder.
The chloride or chemical acid fluxes contain a strong acid that cuts the oxides quite
nicely, but the remaining acids will continue
to corrode the metals after the soldering
surthe
on
is
present
barrier
oxide
metallic
face of metals, the metals themselves can- process is completed.
Organic fluxes contain mild acids that do
not make actual metal -to -metal contact, and
metals. However,
as a result intermetallic solvent action (sol- not tend to corrode the
in the presence of
unstable
are
fluxes
organic
dering) cannot take place.
of them leave
some
and
The soldering fluxes remove the metallic - high temperatures,
residue.
greasy,
sticky,
a
metals
of
the
oxide film from the surfaces
The rosin fluxes are ideally suited to elecand keep it from re- forming during the soltronic
work for two reasons. First, the rosin
free
dering operation, in order that the clean
act
as an acid, to cut the oxides, only
will
contact.
metallic
mutual
make
may
metals
The rosin returns to its norheated.
when
Soldering flux has the same effect as scraping
does
flux
The
soldering.
a metal just before
not constitute a part of the soldered joint.
After soldering, the flux residue (still retaining its quota of captured oxides) lies
inert on the surface of the soldered joint.
Soldering fluxes are available as a paste
which is applied to the metals just prior to
soldering, or can be contained within the
solder as a core. Wire solder with a flux core
is the most common form of solder for electronic wiring. The paste is used primarily
to tin or prepare the surface of a soldering iron tip, or where a large surface must be
soldered.
Fluxes can be divided into three general
groups: (1) the chloride or acid type, (2)
the organic type, and (3) the rosin or resin
Solder is applied to junction of soldering -iron
type.
tip, foil and lead. Since junction of this foil
are
solder
of
types
organic
or
The acid
and fine wire heats rapidly, solder is applied
used mostly in sheet metal and plumbing only a fraction of a second after heat. Very-thin
work and should not be used in wiring. In solder (20 gauge) is preferred by professionals.
51

www.americanradiohistory.com

(gAg

BUILD 'EM GOOD

mal, non -acid, state when cool. This prevents
corrosion of the metals. The other reason
for the use of rosin flux is that it has a very
high electrical resistance (3300 trillion ohms
per cubic inch!) .
Putting the Heat on. No matter what type
of solder and flux is used, much of the success in soldering is dependent on heating the
metals and solder. Part of the application of
heat is dependent upon the soldering technique (which will be discussed later). The
other part of the heat problem is selection of
the soldering tool. While many tools, meth-

Poorly soldered boards are not a lost cause
they can be repaired if you work carefully. Heat,
reapplied to the joint on bottom board, will
flow solder properly if lead is clean. At top,
excess solder can be removed with stiff brush.

Soldering Guns. These are generally used
as repair tools rather than for initial con-

is soldered, clip it off close to board.
to insert a group of components, solder,
then clip them. Doing individual components
will slow down assembly considerably-but the best
advice is to follow the manufacturer's instructions.

After lead

is best

ods, and processes are used in industrial and

commercial work, either the soldering iron
or soldering gun are used almost exclusively
in electronics work. Actually, the term iron
is a hold -over from sheet metal soldering
methods. The soldering tools usually have
copper tips -some are plated on top of the
copper to prolong the life of the tip.
The ideal soldering tool should produce
enough heat for "high- heat" soldering (like
chassis solder lugs) but should not be too
hot for "low- heat" soldering (like circuit
board connections). A small efficient soldering iron (also called a soldering pencil) with
a Vs - to 1/4-inch diameter tip is ideal for
most circuit connections. Soldering irons are
inexpensive and have the advantage of being
hot (if they're plugged in) whenever you
need them.

struction. This is because they develop high
heat quite rapidly and cool off just as fast.
This high heat will quickly melt previously
soldered connections for removal of parts
or wires.
Most soldering iron tips are pretinned.
That is, the tip has been "wetted" with a thin
film of solder. When the iron heats, the
solder melts and transfers heat to the surfaces that are to be soldered. Unless you are
using a plated tip, it may be necessary to retin the tip from time to time. The tinning
process is similar to that of soldering. The
tip (or surface that is going to make contact
with the metals to be soldered) is cleaned
of oxides by scraping, filing or with fluxes
then solder is applied to the cleaned tip.
Once a thin film of solder is formed over the
tip, excess solder is wiped off.
A popular misconception is that the wattage of a soldering tool is the most important
characteristic to look for when considering
a new purchase -it's not.
Tip Temperature. Far more important is
the heat available at the working end of the
soldering iron. This is directly related to
the shape and size of the tip and how the
heat is applied to the working end.
Different designs of the heating elements
have great effect, too. Some of the 60 -watt
economy -type soldering irons are no hotter
than the 231/2 -watt combination element -tip
units that thread into their special handles.
Probably the best example of the relation of

ELEMENTARY ELECTRONICS

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tv-

Most electronics kits can be built with these few
hand tools and a soldering iron. Ruler, at fop,
is used to measure lead lengths. Small screwdriver
is used mostly for tightening knob setscrews.

design to tip temperature is the catalog data
for one brand element.
When the tip and element are made in one
permanent unit, the 231 watt tip (depending
upon shape) teaches a temperature of 650°
to 700 °F while the same wattage element
with a thread -on tip is rated between 600°
and 650 °F. This 50 °F difference can be
quite important when working in an area
that is cool or drafty.
Heat Transfer. Getting heat to the joint
to be soldered is the most important part of
the process. A clean hot iron will transfer
heat the fastest. Clean does not mean dry
clean means free from oxidization and
charred flux. For maximum heat transfer in
the shortest possible time the tip must be
wet with solder -this makes better contact
between the tip and the joint.
To some extent a low -heat soldering iron
can damage more components than a moderate -heat iron. The faster a joint heats the
less time the heat has to be applied. With a
sufficient heat (and soldering experience)
you can solder a joint and get the soldering
iron away before the heat has a chance to
creep up the lead. Take a good look at that
production-wired printed- circuit board
there just isn't any space to get a heat sink
on the component leads. Besides, most heat
damage to transistors and diodes occurs only
when current is flowing through them -just
make real sure that they have cooled off completely before you apply power to the circuit.
Wiring And Soldering. The service
centers of kit manufacturers spend much of
their time unscrambling home kit builder's
butchered wiring and soldering. Except for
not following instructions precisely, poor
soldering is the major cause of kit failure.
And it has proven by actual record that a

Soft -plastic tool (lower left) is used to start nuts
in difficult places. Nutdrivers (socket wrenches) do
an expert job of tightening. Wire strippers are
adjustable. Slip -joint pliers are often handy, too.

sloppy kit- wiring job goes hand in hand
with intermittent or poor performance. In
any case, the poorly wired kits seem to find
their way into the service shops more often.
The following steps may seem quite basic,
but they can't be over- emphasized:
Wiring must be mechanically secure on
the terminal before applying heat or solder.
Pass the wire around and through the terminal, then crimp it with needle nose or long
nose pliers. Clip off any excess lead length.
Make certain not to drop the wire bits back
into the chassis. Small lengths of wire make
excellent shorts between power leads and
ground.
Apply heat to the terminal, not just to the
wire. The soldering-iron tip should be placed
on the joint so that heat will be transferred
through the terminal to the wire. Use the
correct amount of heat. Too little heat can
cause a cold -solder joint (poor electrical contact), and will cause the solder to appear dull
or crumbly after it has cooled. The correct
amount of heat produces a bright solder
connection. Naturally, too much heat, applied too long, will damage surrounding
parts.
Some solder must be applied to the iron
too much can run into the terminal before
it's properly heated. This can cause 'either
poor electrical connection, or a cold-solder
joint, or both. It goes without saying that you
must use a good grade of rosin core. (To remove excess flux clean the connection with a
small stiff -bristle brush dipped in a non -inflammable solvent, immediately after the
connection has cooled.)
Once you have mastered the basic solder-

,TIILY-AIIGIIST, 1966

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®/@

BUILD 'EM GOOD

Resistors and capacitors above are neatly positioned.
Often this is not practical in high- frequency work
where leads must be kept as short as possible or cut
to an exact, specified length to prevent trouble.

Jumble of parts (below) looks like someone dropped
a handful out of a bog. Excessive lead lengths
help create short circuits and often break easily
from vibration. There is no excuse for sloppiness.

Carefully checked and placed kit components are easy
to find and less likely to be lost or damaged.
Cabinet, dial parts and knobs are left wrapped until
all other work is finished-this prevents scratches.

ing theory and technique, you are well on
the way to becoming a good craftsman in
the art of electronic construction. Here are
some additional tips that should make life
a.lot easier on your next construction job.
Follow Instructions. This is one rule that
those experienced in electronics (engineers,
technicians and old -time Hams) often break.
They often start at Step 15 or so, instead of
Step 1. The kit manufacturers go to great
lengths to - prepare the instruction manuals
so that all parts would be mounted and wired

of the many types, shapes and styles of commonly used capacitors. Individual units are described
or illustrated by kit manufacturers to prevent the
mistakes possible by selecting wrong unit.
Some

in a specific order.

(The same is true of
many construction articles found in magazines.) By not following this order, you find
that some particular part will not quite fit as
indicated in the instructions. So you stick it
in at the next best spot. The kit may work
that way, but the net result is a jumble of
parts that mark the unit as home-made.
Have A Place For Tools. Select all of the
tools you will need before you start. Lay
them out in a readily accessible spot on the
work bench (unless you have a peg board or
rack for. them). Do not mix tools in with
the kit parts. Once you have used a particular tool, lay it back down (or hang it
up) in the same place. This will not only
make life easier, but it will prevent a kit part
from being scraped by a screwdriver blade.
Protecting Parts. Don't dump all of the
parts into one big box. After you have
checked parts against the packing list, set
aside those that will not be used right away
remove them from the work area. Group all

ELEMENTARY ELECTRONICS

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WRONG! Sloppy work (below) will give a /ot of heartache. Shorts and intermittent
operation will give poor
results that are often blamed
on kit manufacturer since
constructor will seldom admit
to faults being in work.

Side view of printed-circuit
board (above) shows IF
transformer, resistor and

capacitors properly
inserted. Leads are bent
slightly to prevent
components from falling
out before soldering.
Solder-then trim leads.

of the remaining parts by type (resistor, capacitor, etc.) Note the recommended method
of using the edges of a corrugated carton
(shown in photo) for parts storage during
assembly.
Make certain that you know the electrical
values of all parts. This is necessary even
with kit parts, but is especially important
with home -brew construction.
Resistor Values. Resistors are identified
as to value and tolerance by color-code
bands. Kit instructions usually explain the
color -code system. Sometimes, however, the
bands are not clear, or have been rubbed off
(or you might even be color blind without
knowing it). To better learn the color -code
check all resistors with an ohmmeter. If you
plan on much electronics building in the future, you will find that an ohmmeter (combined with a volt and milliammeter
multitester or VOM) is a handy instrument to
have, and well worth the small investment.
Fixed capacitors may be identified as to
value by a color code similar to that used
for resistors although most capacitors are
stamped as to value and tolerance. If these
markings are not clear, it will be necessary
to check the capacitor on a capacitance
bridge. Once identified, the capacitors should
be marked -with a pen, grease pencil or on a
tab of adhesive-backed tape.
Check for Polarity. Electrolytic capacitor
leads are marked as to polarity (+ or
.
Unlike most other types of capacitors, the
leads of an electrolytic must be connected
as indicated in the instructions. If not, the
equipment will not operate properly, and the

-a

Pigtail leads are cut at short arrows. Long arrows
indicate distance between terminal lugs. Allow
some lead length for dressing components for neater
layout. Use sleeving or spaghetti where needed.

capacitor will most likely be damaged.
Batteries are clearly marked as to polarity,
too. However, instructions sometimes require that you connect leads to battery terminals and then route the leads to other connections. This can cause confusion if the
leads are not tagged (at the open end) when
first connected to the battery. A small strip
of masking tape makes a good tag since it
can be removed easily once the lead is soldered in place.
The Outside. Since a finished project is
going to become part of your home decorations, its outward appearance is just as important as proper operation. That quality
look can be achieved, or preserved by using
a little extra care during assembly.
The outside parts (panels, cases, etc.) of
kits are usually given extra protection when
packed for shipment. Since these parts are
not required until the last steps of assembly,
they should not be unwrapped and left ex-

JULY- AUGUST, 1966

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BUILD 'EM GOOD

posed to hot soldering irons and sharp tools.
Leave such parts in their wrappings, and
store them away from the working area.
Use the correct mounting hardware, and
in the correct assembly order! Although this
may seem obvious it's often overlooked and
it is usually not spelled out in magazine construction articles (they assume that you will
know the right way to do it!). Properly prepared kit instructions call for a flat washer
under the attaching nut of panel-mounted
controls. Lockwashers, if any, are placed
on the control -shaft bushing behind the panel. If a lockwasher is used outside, its prongs
can crack, gouge or otherwise scar finished
surfaces.
Sleeving or spaghetti is used on one lead to prevent
its touching other tie -strip lug. Where practical,
dress leads to prevent soldering -iron damage that
can occur if it's ever necessary to replace part.

Leads are bent slightly to keep component body

perpendicular to tie strip. Lead to tie -strip lug
is wrapped -lead to smaller tube -socket lug
is not. Close spacing makes shorts more likely.

Never use pliers to tighten control mounting nuts against the panel! This is a very
common fault, and even the old timers are
guilty. It's quite human to get used to a
particular tool, and use this tool for everything. Unfortunately, pliers were not designed to tighten nuts. One slip, and you'll
have a gouge or scratch that can't be covered
up easily. And if it happens to be the front
panel you'll have a permanent record right
out where everyone can see it.
A socket wrench of the correct size should
be used to tighten nuts, both inside and out.
But it is of particular importance for nuts
which tighten against the outside panels. Do
not over -tighten nuts, and do not press on
the socket wrench, scraping against the panel
while turning.
Although few people are ever going to
look inside your kit or other construction
project, the mark of a good craftsman is neat
work -both where it does and does not show.
.

Signal-carrying leads should be as short and direct
possible. Power leads, both AC and DC, can be
squared off and kept away from low -level signal points.
as

Besides, proper placement of parts and wire
routing can improve performance. Improperly routed wires can cause hum pickup and
signal loss.
Kit instructions are usually quite specific
on the method of mounting components.
They usually caution you to make sure the
(Continued on page 112)

ELEMENTARY ELECTRONICS

s-t7se
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B/B

COMMUNICATIONS

so,, ro
sure

HARTMAN MODEL MC -62

Y1tvAY4Mli
6N

YNN.'

il@

2000

SW /Solid -State

71I
IS7U

t00

1883
1182C0

I830

Ship -to -Auto Converter

rARfNf OPERATOR

MARINE FREQUENCIES

For no other reason -other than it's logical-one would assume that what takes place
on the marine frequencies is of interest only
to someone on a boat. However, this is not
always the case. Just as SWL's (short -wave
listeners) like to hear what's going on in the
world, boat enthusiasts like to know what's
going on even when they're not cutting a
wake through King Neptune's domain.
Many times a lot of aimless preparation
and sailing is saved by hearing the marineband chit -chat -about good fishing grounds,
choppy seas, or a bunch of juvenile delinquents with a 100 -hp. motor on the back of
a rowboat-while driving to the boat yard.
For just this purpose (eavesdropping on
the marine band), Hartman, a manufacturer
of marine radiotelephones, makes available
a Ship -to-Auto Converter Model MC-62.
The MC -62, priced at $19.95, is a solid state device which converts a standard AM
auto radio into a marine -band receiver. It
is powered by a built -in 9 -volt battery, so it
can be used with any auto radio (tube or
solid-state) and with any auto battery voltage
or polarity. Other than the antenna connection, the MC -62 requires no direct connection
to the radio or the auto's electrical system.
Stow It. The Hartman MC -62 mounts
under the dash with a single screw which
is factory attached to the cabinet. To use it,
you simply unplug the antenna cable from
the radio and insert it into the matching antenna jack on the rear of the MC -62. Then
you connect a supplied cable between the
MC-62's output jack and the auto radio's
antenna jack. Finally, you adjust the radio's
antenna trimmer (an accessible user adjustment) for maximum sensitivity. The power

Men

Mc-62

switch determines whether the converter or
the antenna is connected to the radio. (The
converter does not interfere with normal
radio reception.)
Unlike many converters, the Hartman
MC -62 is not tunable: the AM radio is used
to tune the marine band. The MC -62 is a
broadband device with its oscillator frequency fixed at 3.5 mc. Marine-band frequencies beating against the 3.5 -mc. local
oscillator produce a difference frequency
which falls in the AM broadcast band. For
example, WWV at 2.5 mc. beating 3.5 mc.
has a difference of 1,000 kc. Therefore, if
the user tunes the auto radio to 1,000 kc.
he will hear WWV (which originally started
out at 2.5 mc.). Similarly, any signal on the
marine band between 2 mc. and 3 mc. will,
by beating against the 3.5 mc. oscillator,

appear at a standard broadcast frequency.

Mounted under the dashboard with a single wingnut
the Hartman MC -62 can be installed by anyone. Only
wire connections it requires are for the antenna.

Jut.Y-Auevsx, 1966

www.americanradiohistory.com

SHIP -TO -AUTO
CONVERTER

The MC-62 has a front panel chart (made
to look like a slide -rule dial) which lists the
common marine frequencies -including the
marine operator
their broadcast -band
dial settings. For example, if you were interested in hearing 2830 kc., you would check
the chart and determine that it falls between
60 (600 kc.) and 70 (700 kc.) on the AM
radio dial. Tuning the radio to this setting
would bring in 2830 kc.
Performance. The Hartman MC -62 did
exactly what it's supposed to do. We picked
up the marine band with average sensitivity
(comparable to inexpensive SW receivers).
There was no noticeable leakthrough of
broadcast signals. Though atmospheric interstation noise was somewhat high, this is
true of any receiver not equipped with a
noise limiter (a limiter can always be added
to the auto radio).
Our unit pulled exactly 0.4 ma. from its
battery, indicating that the battery should

-at

Readily available transistor -radio battery powers the
solid -state circuitry of the Hartman MC-62 converter.
Jacks are for auto -radio antenna and jumper to radio.

last its normal shelf life of 6 to 12 months
even with frequent use.
The MC-62 cannot be used to convert a
table radio (or any loop antenna equipped
radio) to the marine band, as just the shortest
exposed antenna lead will result in severe
broadcast signal leakthrough. The STAC
requires the complete antenna system shielding common to auto radios.
For additional information write to Hart-.
man Marine Electronics Corp., 30 -30 Northern Blvd., Long Island City, New York
11101. While you are at it, ask them to send
information and specifications on their complete line of converters.

BLOCK THAT LEAK
Checking the DC resistance of a capacitor
using the high -ohms range of a .VTVM is
often unrevealing due to the low voltages
used in the meter circuit. The DC resistance
may be unacceptably low when tested at high
voltages.
Coupling and bypass capacitors are easily
checked for leakage using a DC voltage
range.
In the diagram, the DC voltage appearing
across Rg is due to leakage through coupling
(or blocking) capacitor C and any grid current that may flow through the grid resistor.
Remove V2 to prevent grid current and
measure the voltage across Rg using a low
DC range of the VTVM.
For a more stringent leakage test disconnect C from Rg and connect the VTVM to
the free end of C. You can calculate the
equivalent DC resistance (Rc) of C at test
voltage Va, by formula:

Rc = Rm

Reject capacitors giving erratic readings,
as these introduce noise and instability into

the next stage.
Coupling or blocking capacitors in TV
horizontal and vertical oscillator and output
stages, video output, DC restorer and sync
stages produce a host of troubles when leakage is erratic or high.
Consider its function in the circuit before
you reject a capacitor. For example, paper
and ceramic bypass capacitors shunted across
relatively low-value cathode resistors need
not meet the very -low leakage needed for a
blocking use.

Where Rm equals the input resistance of
the VTVM and Va and Vb are the measured
DC voltages at points A and B.

Vacuum -tub,, voltmeter connec ed at point B to measure DC voltage due to leakage through capacitor C.

ELEMENTARY ELECTRONICS

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Breaking
the
Crysta

Barrier

Simple

1- transistor

amplifier boosts the
weak audio output.

by Robert E. Reiland

Heathkits' popular crystal
radio, the CR1, has probably
been a major contributing
factor in getting many people
initiated into the field of
electronics. The radio has
excellent selectivity, but its
sensitivity, like most all crystal
sets, leaves much to be desired.
The addition of a single stage
transistor amplifier to the
radio will increase the volume of weak stations and
will enable you to "operate"
with a shorter antenna. Full
details for making the modification are given in this
article.
Only a few inexpensive
electronics parts
59

JULY -AUGUST, 1961

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if')o
60

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

Soldering gun is
heating coil lug.
Emitter lead has a
heat sink to prevent
overheating junction
inside transistor
even though lead is
special low-heatconductance alloy.
ANTENNA
HIGH

RF
TRANSFORMER

PHONES
CRYSTAL DIODE
DI

iii

- IMPEDANCE

.01MF

365MMF
AMPLIFIER
INPUT

Complete circuit of
modified Heath CR -1 kit.
Crystal -type phones
can be used across points
A and 8 but phones of
2000 to 5000 -ohms resistance are required for
collector circuit.

GE2

(see parts list) are all that's needed to
make the modification. No chassis drilling
or cutting is required, so it shouldn't take
the most wary experimenter any more than
a couple of hours to complete the job. The
exterior appearance of the radio is not
changed in any way as all new parts mount
neatly inside the case.
The modified schematic is shown above;
pictorial diagram shows arrangement of
parts. As you can see from the photos and
pictorial a few of the existing components
must be shifted around to make room for
connecting the new ones.
First move the grounded end of capacitor
C4 from the grounded phones jack over to
the ground lug of the Gnd jack. The
grounded end of. L2 is shifted at the same
time to the same lug. Crystal diode D l is
unsoldered from the Phones jack lug and left
free until the terminal strip is mounted.
The grounded Phones jack and its associated soldering lug must be insulated from
ground. This is the most important step.
However, this is an easy task, as you follow

PARTS LIST

-1.5 -volt dry cell (AA -size penlight cell)
C5- .01 -mf. disc capacitor
Q1- Transistor, p -n -p audio (General Electric
B1

GE2, 2N107, 2N241A, 2N404, 2N525A or

equiv.)

R1-330,000 -ohm,

1/2-watt resistor
Misc. -Terminal strip; #6 flat fiber washer,
wire, solder, etc.
Estimated construction cost: $2.00
Estimated construction time: 1 hour

the same procedure used to insulate the other
jack when you first constructed the Heath
CRI, that is, you mount a flat insulating
washer between the chassis and the lug and
secure the assembly with the nut. An insu sting washer is already provided on the top
side of the chassis. Make sure the jack and
lug are insulated from the chassis. (You can
test with an ohmmeter -meter prods placed
between the lug and ground should give an
infinite -resistance reading on the meter.)
The three -tier upright terminal strip is
mounted next. Remove the retaining nut
61

JULY-AUGUST, 1966

www.americanradiohistory.com

BREAKING THE
CRYSTAL BARRIER

Original Heathkit CR-1
Crystal Receiver will
not look any different
after the paris in
front of it are wired
into the existing
All parts
are shown except
insulated washer and

circuitry.

the few short
lengths of wire needed.

I.SV

TERM. STRIP

from the second phones job (which is already insulated from ground) and mount the
terminal strip between the soldering lug and
the fiber washer. The lower lug on the terminal strip may be removed as it is not used
in this modification.

The AA penlight cell is soldered into the
circuit and is supported by a piece of heavy
copper wire. There's plenty of room to mount
a battery holder, but this will mean drilling
mounting holes. Besides, when the battery
is expended it is only necessary to unsolder
it and solder in a fresh one. When soldering
in the battery you will find it easier if you
first clean the ends of the battery with sandpaper or steel wool.
You can now start soldering in the other
parts. The main thing to be careful with here
is the transistor and diode; use a heat sink to
prevent any damage to them. Follow the
pictorial and photos and the job should be
finished in short time.
Put the radio back in the case, attach the
antenna and phones. You'll be receiving stations with much more volume-you may
even hear some new ones. To turn the radio
o)i remove one of the headphone pin tips;

Power switch is not needed. Transistor draws
little current and disconnecting headphones opens
the circuit preventing all current drain from
single penlight cell that is sole source of power.

a separate switch thus won't be needed.
Of course this amplifier can be added to
any crystal -radio circuit, like that sold by
Allied Radio as catalog number 85U024
AMW or to your favorite home -brew set. Just
connect the amplifier input (points A and B)
to the earphone connections and tune the set
the way you always have. Good listening!

ELEMENTARY ELECTRONICS

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There's a lot of
bounce in those DX
signals-here's why!

The
Angles On

DX
by

C. M.

Stanbury II

Originally DX simply meant distance and even today,
when DX now means rare or unusual reception, distance is
still an important factor. "Of course!" you say. But it's not
quite that simple. For example, below 7 mc. a radio station
2500 miles away can be easier to log than one which is
1900 miles away. No, to cope with distance, a straight line
approach won't do. You must play the angles.
But let's start at the beginning and that beginning is the
ionosphere, the four layers of ionized gasses which surround
the earth. As many of our readers already know, it is these
layers which reflect radio waves back to, and around the
curvature of, the earth. If it were not for the ionosphere,
there would be no radio reception beyond the horizon. A
more detailed picture of the ionosphere layers above the
earth appears in the illustrations.
It should be noted that every time a radio wave tangles
with the ionosphere, it's not only reflected (at least we hope
it's reflected) but also weakened. (Technically, the signal
(Continued Overleaf)
63

JULY- AUGUST, 1966

www.americanradiohistory.com

(Di@

ANGLES ON DX

DAY
F2 LAYER
F

Roughly these are the
positions of the layers
during the day and at
night-they are not to
scale. F layer is low
during the day and
rises at night. E layer
does not always exist
in a given area. Bends
or ripples in the layer
act like curved mirrors
fo concentrate or spread
reflected signals.

LAYER

res- 222

spoRAO(G

Angles of Arrival Via the

5°
6°
7°

1900
1772
1650

(deg.)
8°
9°
10°

LAYER

(55 -65 MI)

the received signal is weakened when it tangles with the ionosphere.)
Therefore, when transmitting from one point
on the earth to another, the signal should
strike the ionosphere as few times as possible.
Or, putting it another way, there should be a
minimum of hops or reflections.
For geometric reasons, due to the height
of the reflective layers and the earth's curvature, the maximum single -hop distance is
about 1900 miles. On the basis of this (ignoring the antenna height and averaging the
layer height), radio stations of the same effective radiated power (e.r.p.) that are located between 1500 and 1800 miles away
should be received with about the same signal
strength but a transmitter of the same e.r.p.
2000 miles away (beyond the 1 -hop limit)
will be noticeably weaker as are stations less
than the 1500-mile distance that cannot be
received by a direct or ground-wave signal.
Therefore a station outside the 1 -hop area is

Angle

LAYER

035 -145 H1)

layer-anyhow

Angle Hop Length
(deg.)
(miles)

N!,

an even betterDX plum; for this station will
be a rare one in your area.
All Hopped Up. This 1500 to 1800 -mile
distance figure is for reception via the F layer at night. This is the only layer which regularly affects reception during the hours of
darkness. During the daytime there are actually two F layers (F1 and F2) and, even
more important, an E layér.
If radio wave reflection takes place via the
E layer, maximum hop distance is only 900
miles. Under certain abnormal conditions
the E layer does not dissolve with the coming
of night. Such a sporadic E layer is even
capable of reflecting VHF signals. Thus, 900
miles can also be considered a step on the
DX ladder -for VHF.
The Angle. Both our barriers of 900 and
1800 miles are based on an angle of arrival
of 5 degrees above the horizon. The longer
the hop the smaller the angle of signal ar(Continued on page 114)

layer

Hop Length
(miles)
1575
1500
1400

IONOSPHERE

F LAYER

RADIO WAVES

This drawing is nearer to scale.
At too sharp an angle the radio
waves pass through layer

-too

shallow angle and reflections
do not return to earth.

Although it's not to scale this
will give you an idea how
waves can bounce from either side
of ionized layers for DX.
61

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

0/8

COMMUNICATIONS

KNIGHT -KIT SAFARI I.

23- Channel, 5 -Watt
CB

Transceiver

While Knight-Kit's Safari I (Allied Radio)
CB Transceiver is another of the so- called
high -performance rigs, for a change, high performance really refers to performance in
measurable terms, rather than a slew of gen-

erally unneeded features and fancy chrome
plating, for the Safari I includes not a single
useless feature; every single feature contributes directly towards better communications.
What's in the Box. The Safari I is frequency synthesized to cover all 23 channels
on á single selector switch. While frequency
synthesis does not mean one iota of better
performance, it does, because fewer crystal
are needed for complete coverage, result in
considerably reduced cost. Naturally, the
receiver uses double conversion with two
stages of 455 kc. IF amplification. A front
panel ANL (automatic noise limiter) on -off
switch is provided as well as a PA (public
address) on -off switch which allows the
transceiver to be used as a PA amplifier. A
terminal strip is provided on the rear apron
for the external speaker. The S -meter doubles
as a relative RF output meter when the transceiver is switched to the transmit mode.
To insure reception of received stations
which may be off the center channel frequency, a front panel control allows the re1 kc. off-channel.
ceiver to be tuned
Wired In Quality. Most of the extras
have gone into the transmitter, in fact, into
the modulation. The mike is a rather good
quality noise -cancelling type. A front panel
microphone gain control is provided which
adjusts the microphone sensitivity from full
oll to at least twice as sensitive as the average transceiver.
In short, whether you roar like a lion or
squeek like a mouse you can tailor the mike
gain to your specific need.
Two modulation indicators are provided,

and unlike other modulation indicators which
simply flicker to indicate you're talking, the
Safari I's indicators are calibrated. The Normal modulation indicator goes on only when
the percent modulation reaches 50 %. A red
Overmodulation lamp flickers only when the
percent modulation exceeds 85 %. (For all
practical purposes 85% modulation equals
100 %.) Maximum undistorted modulation
is obtained if the mike gain control is adjusted so the 50% lamp is on most of the
time while the 85% lamp flickers occasionally.
To avoid sideband- splatter and its interference, caused by overmodulation (in excess of 100 %), the modulator limits the percent modulation to slightly less than 100%
regardless of the sound level into the mike or
the setting of the microphone gain control.
Performance. While anyone can build -in
the features required for high -performance,
it's another thing to actually get it. But the
Safari I actually delivers all the performance
built into it.
Transistors on back panel are for the DC power
supply -no vibrator is used. TVI trap will
make operator popular with local TV sef owners.
CRYSTAL BANKS

VOC

POWER SUPPLY

TRANSISTORS
65

JULY-AuCUSx, 1966

www.americanradiohistory.com

(DM

KNIGHT -KIT SAFARI

ANL SWITCH

PA SWITCH

Finger points to calibrated
overmodu/ation lamp which
indicates when modulation
peaks exceed 85 per cent.
Control to the right of
the microphone connector
adjusts mike gain from full
on to full off.
MIC GAIN
CONTROL

FUSE

S -METER

NORMAL
MODULATION LAMP

OVER
MODULATION

LAMP

ZERO ADJ.

Terminal strip al extreme left is the remote
speaker output. Transmitter is tuned
by adjusting two pi- network capacitors through
holes at right. Power plug permits rapid
conversion from 12 -volt DC fo 115 -volt AC.
EXTERNAL
SPEAKER
TERMINALS

TRANSMITTER
TUNE

Measured input sensitivity for a 10 db
+ noise to noise ratio (a much
tougher test than just signal to noise or usable
sensitivity) was 0.65 microvolts at the antenna terminals (anything lower will pick up
Mars' probes). Adjacent channel rejection
through the front end was -42 db on both
sides of center channel -better than the
Knight specs and indicating a good, balanced
IF amplifier design. Image rejection, again
better than Knight's specs, was -53 db. AGC
action, indicating the difference in output
level, for a change in input signal of 54 dbrepresenting an increase of signal strength
from 2 to 10,000 microvolts -was 11 db. (In
practical terms meaning that if you have the
gain cranked open to hear a weak signal you
won't be blasted out of your seat if a very
strong signal comes on the monitored
channel.)
RF output into 50 ohms was 2.4 watts; the
transmitter's pi -net tuning controls are on the
rear apron. Modulation was exceptionally
clean with no trace of distortion (on an oscilloscope) up to the test value of .85%
modulation.
Summing up Performance. As you can
see, not only is the Safari I's performance
good (if not outstanding, but in almost all insignal

stances Knight's claims are pessimistic, and
our test unit actually outperformed the specs.
The only negative aspect we could find was a
slight residual loudspeaker hum (but no
modulation hum); though not unusually high,
it can be somewhat distracting in a very quiet
room. However, once a signal breaks the
squelch the hum is "buried" under the received signal.
Construction. Instead of commenting on
the construction we'll report on an unusual
"test." The unit was severely damaged in
transit from workbench to test lab, and the
entire panel was stove in. Even with a hammer we could not straighten the panel or the
speaker mounting to original form without
leaving a few scars and scratches. Yet this is
the same unit that delivered the performance
given above. (We can't think of a better
testimonial.)
What you get. The Safari I is supplied
with 23 channel coverage and both the AC
and DC cables. (The 12 VDC supply is
solid- state, no vibrator.) Also a gimbal
bracket for mobile mounting or tilted base
mounting. It is priced at $129.95 in kit
form. For additional information, write to
Allied Radio, Dept. 20EE, Chicago, Illinois,
60680.

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

SCR

Slot Car

Starter
by Herbert Friedman

This electronic

referee will
settle your
Slot -Car race
starting disputes
as quick as a
wink

to create an argument is to
call out Ready, Set, Go when starting a
race. First thing you know someone yells
"You fudged "; another claims you didn't
start the stopwatch in time, or someone
be polite -will say, "I didn't hear you say
go." And if you do any serious slot-car racing, where a split second makes the difference between winning and losing, you know
that every race leads to an argument. But all
the arguments are really unnecessary if you
steal a trick from the commercial drag strips
this instance RAnto -TV
and use a starter
EXPERIMENTER'S SCR Slot-Car Starter
start your slot races.
The SCR Slot -Car Starter is an automatic
device that signals when the race begins. If
anyone "jumps the gun" a penalty light goes
on to indicate that someone has cheated. The
exact penalty should be settled before the
racing begins. Either the culprit can be
banned from the track (rather severe penalty), can be fined one lap, or can be penalized one or more car lengths for the next
race. To avoid disagreements over whether
the Start signal is early or late the entire
control -from Start signal to penalty light
is automatic. When S2 is set to the Time position the Mark light goes on. After about 2
seconds the Ready light goes on; and finally,
after another 3 seconds or so the Go light
illuminates. If any car attempts to roll before the Go light a Penalty light goes on indicating which track jumped the gun. At the
ASURE WAY

-to

-in

-to

JULY-AUGUST, 1966

www.americanradiohistory.com

SLOT -CAR STARTER
I

instant the Go light flashes on the penalty
circuits are locked out. In short, there is no
more room for human error. If you get a
Penalty light you cheated -it's that positive.
To avoid having the slot racers anticipate
the timing of the Start light the time sequence
between Mark and Ready is shorter than
between Ready and Go. The slight hesitation
before the Go light goes on is deliberate, so
don't attempt to change the timing circuits
so Ready and Go have the same delay. Many
is the racer who is going to mentally time
the Go signal only to find he's earned a
penalty.
The unit shown will accommodate any
slot track using a 10- to 18 -volt power supply. If your track uses a track voltage lower
than 10 volts simply change K2 and K3 to
their 6 volt equivalents and substitute 6 volt
lamps for I4 and I5.
Construction. Note that there is no common connection to the metal cabinet. For
maximum safety, since the circuit is connected directly to the AC main, be absolutely
certain no wire or component touches the
metal cabinet.
The unit shown is built in a Bud SC -2132
Cowl Type Minibox, which, like all other
components used in this project, is standard
stock from Allied Radio. Since parts layout
is not critical any other type of housing can
be substituted.
D.p.d.t. relay K1 may be rated either 115
VAC or 115 VDC, whatever you have or
can get. If you use the DC relay, diode D8
must be used; if you use a 115 -VAC relay,
eliminate D8. Diode D8, like diodes DI to
D7, can be the cheapest diodes you can get
-as long as they are rated a minimum of
200 PIV at 400 milliamperes.
Relays K2 and K3 are the 12-volt DC
models for slot tracks having a 10- to 18 -volt
DC power supply; use their 6 volt equivalents if the track uses 10 volts or less. Either
way, a Potter & Brumfield (P & B) type
RS5D relay is used, and since their wiper
contact is common to the mounting frame
they must be insu'ated from the cabinet.
Mount the relays on a piece of perforated
wiring board, as shown, then mount the
board in the cabinet with '/4 -inch insulating
spacers between the board and the cabinet
at each mounting screw.
Neon pilot assemblies I1, I2 and I3 are

T81

SCR2
D6
D?

SCRI

04
Only K2 and K3 are mounted on the perforated
phenolic. Other components are wired to
terminal strips attached to base of metal
cabinet with machine screws. Additional
perforated -phenolic board can be used to hold
the resistors, capacitors, diodes and SCRs
wired to terminals inserted in the perforations.
Other -end view of the completely wired Starter
(above, right) shows rest of components.
Both /4 and IS should be positioned so that
filament of lamp is centered on pilot jewel.
PARTS LIST

-2 mf., 450-WVDC electrolytic capacitor

C2-4 mf., 150 -WVDC electrolytic capacitor
D1- D8-400 ma., 200 PRV (PIV) or higher
rating rectifier diode
I1, 12, 13 -Neon pilot lamp (see text)
(Snaplight, Allied Radio 7U758 or equiv.)
14, 15
-volt pilot lamp (type 1487, 18151
K1-D.p.d.t., 115 -vac relay (Knight, Allied
Radio 74U657 or equiv., see text)
K2, K3- S.p.d.t., 12 -vdc relays (Potter 8
Brumfield RS5D, Allied Radio 75U504 or
equiv., see text)
R1 -100 -ohm, 1/2 -watt resistor
R2-330,000 -ohm, 1/2 -watt resistor
R3-220,000 -ohm, 1/z -watt resistor
R4, R5- 1,000,000-ohm, 1/2-watt resistor
S1- S.p.s.t. toggle switch
52-4 p.d.t. rotary switch (Mallory 3242J or
equiv.)
SCR /, SCR2- Silicon controlled rectifier C68
(General Electric)
TS1-4 or 5 terminal (screw type) barrier strip
1
x 8 x 6 -inch cowl -type chassis box (Bud
SC -2132 or equiv.)
Misc.-Pilot lamp assemblies; perforated
phenolic board; terminal strips; assembly
hardware; wire; solder; etc.
Estimated Construction Cost: $18.00
Estimated Construction Time: 6 hours

-12

-3

ELEMENTARY ELECTRONICS

www.americanradiohistory.com
cttikst'

position. For clarification, to avoid wiring
errors: S2A turns on the Mark light while
S2B and S2C activates the Ready and Go
timing circuits (do not attempt to save on a
switch by connecting the S2B and S2C circuits together; it won't work). S2D closes
the penalty circuit and then clears the Penalty
lights when S2 is reset to Standby.
The penalty lights, I4 and IS, are 12-volt
types for tracks using 10- to 18 -volts and the
6 -volt type for tracks using under 10 volts.
Whether they are screw or bayonet base
doesn't matter as long as they match the
lampholder. However, in the 12 -volt type
it is easier to obtain a bayonet base, so figure this in when ordering the parts.
The connections shown to terminal strip
TS1 are only for clarification. The exact
layout of the TS1 connections will be determined by what is most convenient for
your track layout.
To avoid soldering -heat damage make certain you use a heat sink when soldering to
the diodes and SCRs.
Connecting to the Track. First, note that
at TS1 the two main leads from the slot car
power supply are labeled A and B; this is
for wiring reference only and has no relationship to the actual polarity of the power
supply. The B connection is that power
supply terminal connected to the common
track connection -whether it is actually positive or negative doesn't matter; you are only

1{f

SCR2

TSf

shown in a box in the schematic diagram because they come with built -in current limiting resistors. If you attempt to cut costs by
using standard NE -2 lamps, make certain you
connect a 100,000 -ohm series resistor.
Switch S2 is a 4.p.d.t. rotary -do not
substitute two separate D.p.d.t. switches as
all circuits must be activated simultaneously.
Note the connections carefully; all circuits
shown in the schematic are in the Standby

+e
1

00r

I+

I21

330K
+

SCRI

S2B
D

R4
k

117

VAC

SLOT -CAR
POWER
SUPPLY

CONTROLLERS
TO TRACK

a
(GROUNDED TO CASE)

Lead connected to

TRACKs2

TRACK.

* RES STORS PART OF LAMP
ASSEMBLY - SEE TEXT

S2D

4
TSI

COMMON

on TSI is A lead

-B

lead connects to 4. Relays isolate track from SCR circuitry.
69

JULY-AUGUST, 1966

www.americanradiohistory.com

SLOT -CAR STARTER

`K3

TSI

Relays K2 and K3 are mounted on perforated
phenolic because frame is electrically connected
to the movable contact on the armature.
Rear view (top, right) shows location of
power on -off switch and terminal strip TS1.
SI could be installed on front panel.

Front -panel layout (right) is uncluttered.
S1 could be mounted to the right of S2.

concerned with that it goes directly to the
tracks (one leg of track #1 and one leg of
track #2). The A connection is whatever
power supply terminal is connected to the
controllers. The controller connection, TS I
terminals 1 and 2, are connected after the
controllers where they are attached to the
track (generally at the track connecting
block); do not cut into the controller wiring.
The connections from TS1 terminals 3 and
4 go directly to the slot -car power supply.
Checkout. Set power switch Si to Off,
S2 to Standby (the position where S2A is
on the unused terminal) and plug PLI into
the AC outlet; then turn Si On. After a few
seconds turn S2 to Time. The instant S2 is
closed D. should light; after a couple of seconds I2 should light; and after another three
seconds or so, 13. If all three lights go on at
once check for a wiring error, particularly
reversed polarity on diodes D4 and D6. If
I3 lights before 12 either Cl and C2 are
interchanged or R4 and R5 are interchanged;
or, you have reversed the 12 and 13 mounting
positions.
If 12 and 13 don't light, in addition to the
usual problems of wiring errors or defective SCRs, check that Cl and C2 are installed
with the correct polarity -the positive capacitor terminals to the common buss. If
the three neon lamps operate correctly connect the slot starter to the tracks and perform the following tests.

I3
iii

Hi.

S2
1,1111111,11111111111,,,,111,,,,11111,,,,,,,111,1,,,,,,111111111111,11,,,111,,,,,,,,,,,,=

Set S2 to Standby for a few seconds then
flip it to Time. After I2, the Ready light,
goes on, but before 13, operate both track
controllers; if the unit is wired correctly both
penalty lights should go on and then stay on

even after I3 lights and the controllers are
released. If the Penalty lights fail to latch,
that is, if they go out after 13 lights or after
the controllers are released, check the connections to K2 and K3's wiper contacts. If
the Penalty lights fail to go on under any
condition check that K1's contacts are
normally closed until I3 lights.
If both Penalty lights operate properly
reset S2 to Standby for a few seconds then
set S2 to Time. After the Go light, 13, goes
on, operate the controllers. If the unit is
wired correctly neither Penalty light should
go on. If the Penalty lights go on when the
controllers are triggered after the Go light,
13, goes on, check that Kl is operating in
step with I3 -the contacts should open when
I3 lights.
The Race Is On. Turn power switch Si
On and set S2 to Standby- thereby clearing all lights. When you're ready to race
flip S2 to Time. When Go light I3 goes on
it's down on the controllers. If anyone jumps
the gun
they start before the go signal
their respective Penalty light will flash on;
and regardless how loud they shout the slot
starter doesn't lie
they get a penalty light
they cheated.
U

-if

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

Go mobile

with

your hi -fi. Once this
unit is on wheels you
can listen to your
favorite discs in
comfort, anywhere,
anytime, without
disturbing anyone:

The

Stereophone
Server
You'd like to relax and enjoy your favorite
stereo and mono discs, but it's getting late

roll
and your neighbors have retired? Just
or
chair
easy
your
to
over
Server
the Stereo
it's
at
stereo
some
bed, and serve yourself
This
best, and without disturbing anybody!
hospitals,
in
use
feature makes it ideal for
in
libraries, record shops, radio stations, and
similar situations.
It's nice to have everything in one package
and ready to use where and when you want
hi -fi
it. No need to rig up your stationary
a
sound system for headphone use, and use
the
phones.
drive
to
lot of power just
As shown in the illustrations, the Server is
simply a wheeled cart with a push-handle.
The turntable and stereo pickup go on top;
the stereo headphone amplifier goes on the
in
shelf; and the records and headphones go
bottom.
the
in
the large partitioned space
The back of the record space is closed to help
keep out dust, but the back of the amplifier
space is left open to make it easier to make
the rear -panel connections.
Construction. The Server in the photograph is 181/2 inches high, 15 inches wide, and
12' inches deep. The amplifier shelf is 4

the
inches below the top, and the balance of
their
in
LP's
inch
space below easily takes 12
record jackets. But you may want to alter
own
some of these measurements to fit your
equipment.
Lumber used for the server is 5 -ply plywood 1/2 -inch thick. Cut to size and sanded,
nails
it was put together with small finishing
heads
nail
The
glue.
hide
and good quality
holes
were sunk below the surface and the
overall,
sanded
was
filled. The assembly
dusted thoroughly, and sprayed with several
coats of thinned light-brown lacquer.
Partitions for the record cabinet are four
14
3/16 -inch diameter metal rods about
the
Space
shown.
as
mounted
inches long,
rods two in front, and two in back, as shown.
The push -handle is a 33 -inch length of 3/8inch OD aluminum tubing bent and screw
make
If
you
cart.
the
of
side
fastened to the
large, round bends in the aluminum tubing
if
it will not flatten at the bends as it will you
try to make sharp, square bends. The aluminum tubing can be polished and given a
coat of clear lacquer so it doesn't blacken
your hands when handled.
Four ballbearing swivel casters are at71

JULY-AUGUST, 1966

www.americanradiohistory.com

,1,,,,,1/,,,,,,0,11,,,,,,,,w0m111111uo

a,umnmulmwn..ampanniimm,,.

OH HANDLE.
TOP

OB BACK

i
STEREO SERVER
don't have to be an
expert cabinetmaker to
put this simple unit
together -it's little
more than a crate
with a shelf and a few
rods for supporting
You

ACORN OR

the records.

CAP NUTS

If the

cabinetry is beyond
your shop facilities
some lumber dealers

will cut stock to sire

for a small fee. You
might also find an
unpainted nighttable
or telephone stand of
suitable dimensions.

Plan shows simplicity of the

construction. Casters should be
21/2 to 3 -inch tea-wagon type
if
you have to roll Server over
carpeting, or use outdoors on a
patio. Largest wheels roll best
and are less likely to bind or
jam against small objects.

15.

i5
PARTS LIST
1/2 -inch 5 -ply veneer
x 14 x % -inch pressed
hardboard
SHELF-121/2 x 14 x 1/2 -inch 5 -ply
veneer
SIDE-171/2 x 121/2 x 1/2 -inch
5 -ply veneer (2

-15 x
BACK -15
TOP

121/2 x

DRILL

required)

-15
-14

BOTTOM
x 127/2 x 1/2 -inch 5 -ply veneer
DIVIDERS
x 3/16 -inch rod (4 required)
HARDWARE -Acorn or cap nut,

-inch flathead
machine screw, 6 -32 thread
(4 required)
aluminum tubing
1

-33

HANDLE
x % -inch OD
(to be bent as shown)

-2 -inch wheel surface mount
STRIP -6 x
x % -inch hardboard
CASTERS

quired)

(4 re-

Misc. -Glue, finishing nails, wood
screws, sand-

paper, wood filler and finish
varnish, enamel or lacquer).

coat (stain,

^)
WOOD SCREWS

GLUE

STRIP

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

111111110

1111

,,,,

1/III

TURNTABLE
POWER

PHONO

CHANNEL

CORD

PHONO

CHANNEL2

SWITCHED
AC

OUTLET

( v
117

STEREO RECORD PLAYER

VAC,

60,v

STEREO HEADPHONE

(2)

JACKS

JENSEN MODEL
HS-2 STEREO

.-PM SPEAKER

HEADPHONES

3-CIRCUIT
PLUGS

Connections for the author's hi -fi
equipment consist of inserting
plugs into the appropriate jacks.
Other hi -fi equipment will have
similar connections that are
generally outlined in the manual
supplied with the instrument.

iii

Connecting speaker to 3 -contact plug is simple. An
additional speaker can be
used in place of the 10 -ohm
resistor if you want to hear
both stereo channels-use
separate cabinets for stereo.
11100111.1111111.1111111111111111111111,161,111,1111111111111

vacuum -tube amplifier
is used make sure there
is enough ventilation
-leave back of shelf
open or drill holes.

10-OHM, 1-WATT
RESISTOR
I

11711666611410.1

121

3- CIRCUIT
PHONE

STEREO)
PLUG

SMALL PM SPEAKER

011111111111111111110

tached to the bottom, using four 3/s -inch
long round-head wood screws for each caster. For heavy duty, use flat-head machine
screws-heads flush; nuts on bottom.
The back of the record cabinet is covered
with a 15 by 14 by 1/2-inch sheet of pressed
wood. This can be screw -fastened, or glued
and tacked.
The connection diagram shows how the
author's hi -fi system is hooked up in the
Server cart.
Speakers. While the 20 milliwatts per
channel isn't going to break any leases you
can use it to drive speakers just as easily as
you drive the earphones. A pair of good
quality, high- efficiency speakers will give
you good listening in a quiet room.
One 3- circuit (stereo) phone plug can be
used for the stereo speakers. One lead from
each of the speakers is connected to terminal
1 of the plug. The other lead of one speaker
goes to terminal 2 and the second lead of the
second speaker goes to terminal 3 of the
stereo plug.

Completed Stereophone
Server is ready for the
hi -fi equipment. If a

Even if you don't want to go in for a
stereo speaker set up, a small monitor speaker
comes in handy at times. Just mount a 3 -inch
PM speaker in a small plastic, wood, or
metal box, and wire the speaker to a 3 -circuit (stereo) phone plug. Since this is a
single speaker plugged into a 2-channel
stereo output jack, it might be well to use
a load resistor in the unused channel, as
shown. The 10 -ohm, l -watt resistor can be
wired into the circuit inside the speaker box.
Use light-weight flexible 3-conductor cable
to wire the speaker and resistor to the phone
plug, as shown. If the shell of the plug is
large, the resistor can go inside.
Well, there's the idea. Now some of you
expert woodworkers, with small children in
the house, might want to add hinged doors
to the front and a hinged cover on top-to
keep out dust and the little tots' inquisitive
fingers. Or you can simply cover the turntable and pickup arm with thin plastic sheeting when the Server is not in use. Good
listening!
'13

JuLY-Aucusx, 1966

www.americanradiohistory.com

By Charles Green W3IKH
A shop you can set

up anywhere-in a motel
room, while traveling, or
a small apartment.

Nowadays most people seem to be on the
go. Traveling is part of many jobs and those
of you who relax by building some electronic

project leave this form of recreation at home.
Since everything else has become compact,
why not a compact workshop, too? Just pack
everything into an inexpensive suitcase.
How can a complete electronics workshop
fit into a suitcase with space for storing the
construction project? The trick is in the selection of tools for the project construction.
Since the project can be broken down into
three stages of construction -chassis fabrication, the wiring, the testing -tools and materials can be separated into three packages.
Here, three metal boxes, sold as cash boxes,
fit neatly into a large suitcase. A cardboard
box is used to fill in the remainder of the
space. Use this space for a small folding
high- intensity lamp, the construction project
and a short electrical extension cord.
A section of hardboard is cut to fit in the
lid of the suitcase. The hardboard is a work
area and a divider for the suitcase to provide
additional storage space in the lid. Here you
can store your manuals, a few scraps of perforated phenolic board and some sheet aluminum.
Don't just rush out and buy the first things

you see. Check what you have, and leave
room for the things you plan to get. Check
what is available in the stores and make a few
measurements of the tool, file card and tackle
boxes you see. Planning will get more into
the space you have.

Cash boxes are used instead of adding compartments
to suitcase. Labe" boxes or buy different colored boxes.

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

High -speed hand grinder drills (above),
routs as well as grinds metal, plastic
and wood. Delicate bits and burrs can
be protected in plastic box. Many of
the tools (left) are unnecessary for
"breadboarding" experimental circuits.

Supply of hardware (left) is a
must. Rubberbands around boxes
will prevent accidents. A thin
sheet of sponge -like foam in the
cover will keep washers and lugs
from adjoining compartments when
you are traveling. Typewriterribbon spools and boxes can be
used for wire, tape and solder.
Sponge -like foam pads box (below) to protect compact multi meter and grid -dip oscillator during travel. GDO is useful os a
wide -range signal generator (left) and, with adaptors, can be
used to measure inductance and capacitance. If VOM doesn't
have an off or transit position set selector to lowest current range
and put a shorting jumper across input jacks to protect meter.

JULY- AUGUST, 1966

www.americanradiohistory.com

Tv
on the
-

by Harold E. Holland
Jack up the
truck? Gee,
boss,

Fy-EAS

Rnoo

thought

you said, "back
up the truck! !"

"Seriously, boss,
isn't it time
you considered
a truck for this
sort of thing ?"

\C l
RADIO AND TV

SERVICING

Now don't get all upset, boss,
this is my own set."
76

ELEMENTARY ELECTRONIC$

www.americanradiohistory.com

Zener diodes do
their job at the
low voltages
where gaseous
reference diodes
are useless.

The Zener diode -solid state's answer to
the voltage regulator tube-can work miracles in experimenter circuits. It'll pin down
a swaying supply voltage that's causing drift
in an oscillator, or neatly string out voltages
in a power supply. These are just a few applications of the versatile Zener, whose circuit simplicity and wide range of voltage
ratings put the old tube regulator to shame.
Like any simple component that performs
a sophisticated job, the Zener must be fitted
carefully into the circuit. There are several
calculations to be sure, but you won't need
a slide rule to do them. Before considering
the steps, here's a fast refresher on what
the Zener does.
The Beneficial Breakdown. Zeners are
similar to conventional diodes; they pass
current in only one direction. When the
diode's polarity is matched to that of the
circuit, current flows pretty much as though
the diode weren't there. But reverse the diode
in the circuit and it Iooks like a high resistance. Little circuit current squeezes
through.
Let's leave the diode connected in that reverse, or high- resistance direction -and raise
circuit voltage. At some point during voltage
increase, the diode breaks down-not in a
puff of smoke-but electrically. Current
shoots up fast as resistance drops to nearly
nil. This effect, created by a process of electron multiplication in the semiconductor
material, is called the breakdown, avalanche
77

JULY -AUGUST, 1968

www.americanradiohistory.com

@/@

ZENER DIODES WORK

or Zener voltage. And it happens to all
diodes, regardless of type, at a particular
value of reverse voltage. But the Zener is
no ordinary diode. Due to careful manufacturing techniques, it goes through the breakdown phase far more sharply than run -ofthe -mill diodes. It functions more nearly like
a switch. Now to put the Zener in a circuit
that not only prevents excessive reverse current -and possible burn-out -but one that
provides voltage -regulator action.
Shown in Fig. 1 is one of the most imSERIES
RESISTOR
CATHODE

6 -VOLT
SOURCE

4.7 VOLTS
4.7 VOLTE)
ZENER

TO LOAD

Fig. 1. Current drawn by Zener diode drops
voltage from 6 -volt source to rated value of diode.
Improper design can ruin diode if load is
disconnected when power remains on at source.

portant Zener circuits you'll use. It's the
shunt regulator, a nifty way to tame or drop
voltage to some value required by a transistor radio, a test instrument or some other
project that misbehaves with varying voltage.
Here we're assuming that the supply is the
6 -volt source, and the device (load) to be
powered operates on steady 4 volts.
The first choice of components is simple;
it's the 4.7 -volt rating for the Zener diode.
This is chosen to agree with the voltage you
wish to apply to the device. Since Zeners
are not available in every possible voltage
rating, you'll have to pick one that most
closely approximates the desired load voltage. You'll find, however, that most electronic devices can function at voltages within 20% of their specified value. Thus the
load in Fig. 1 may actually require 4 volts,
but can function at 4.7. It's usually voltage
variation that causes trouble. Let's examine
how the Zener operates in the shunt regulator
of Fig. 1.
A Shunt Regulator. For one, we see that
the diode is wired into the circuit in a reverse direction; if you look at the Zener
symbol, you'll note that the bar, representing
the cathode (
, is connected to the positive leg of the circuit. (Some Zener diodes
are marked with this symbol, others identify

the cathode by a rim, or hex nut.) Also apparent is that the diode is wired in shunt, or
parallel, across the + and
legs of the
power source.
If the circuit of Fig. 1 is considered to
be in operation, the Zener is now in its
breakdown condition. This is because the
6 -volt power supply voltage is higher than
4.7 volts. But for the system to operate, another component is brought into play. It's
the series resistor. As the Zener conducts
reverse current, it is pulling that current
through the resistor. And as Ohm's Law
dictates, current through a resistor means a
voltage drop occurs across that resistor. This

is how the 6 -volt supply is cut down to size.

What's more, if any up or down shifts occur
in the supply voltage, the Zener automatically applies a correction. It happens this
way: If the supply suddenly rises to 7 volts,
additional current flows through the Zener.
This, in turn, raises the voltage drop across
the series resistor. That extra volt is dropped
by the resistor and never reaches the load.
Conversely, a dropping of supply voltage also
tends to be equalized by the Zener. The diode
pulls less current through the resistor, thereby lowering its voltage drop. Thus the system provides regulation. Large fluctuations,
as might occur in the electrical system of a
car, are neatly smoothed before application
to the load. Hi -fi manufacturers of solid -state
tuners use a similar Zener arrangement to
keep transistors from drifting with line voltage chañges.
We've seen that the series resistor plays
an important role in smoothing out voltage.
But it supplies another important function.
It limits the maximum current that may
flow through the Zener. As with resistors,
transformers and other components, a Zener
has a maximum wattage rating that is not to
be exceeded. Otherwise its silicon material
will heat excessively. This calls for some
calculation.
Figuring Circuit Values. Let's determine
the rating of the series resistor. Before its
value in ohms can be selected, you'll have
to get out the multimeter and run some
measurements on both the power source and
the load, or device, you wish to power. Let's
say you have a small transistor transmitter
or handie -talkie that works on a 9 -volt battery. You want to operate it in your 12 -volt
automobile using the car's battery. This is a
fine application for the Zener. For not only
will it help reduce car's battery voltage to
the right value, but will iron it out.

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

safety margin and avoid burnout.
The final figure we'll need is IZ-or Zener
current. It is recommended that a Zener be
operated at no more than about 20% of its
maximum rated current. If we consult the
spec sheets and select a 9.1 -volt Zener diode
rated at 1 watt, the maximum current rating
might be stated as 90 ma. This figure is
divided by five to determine Zener current
in the practical circuit. This gives an Iz of
18 ma.
Figuring the Formula. Once you've determined each of these circuit values it's possible to plug the numbers into a formula and
come up with the required series resistance.
Let's continue with our example, whose
values are shown in Fig. 2.
The formula:
R. = VIN VZ

Inserting the values:
Rs
Larger-wattage Zener diode can be mounted on
chassis or proper heat sink. This oversized view
shows Zener fo be identical fo conventional
diodes. Low -wattage units have pigtail leads.

First measure the power source. Since it's
the car's electrical system, run a voltage
check on any 12 -volt lead. You'll find that
if you race the engine, voltage can soar up
to 15 volts. This figure, the highest possible
supply voltage, we'll call VIN-for input
voltage. It is the unregulated source.
Next value is V.-the Zener voltage. As
mentioned earlier, the diode's voltage rating
is selected to match that of the load. Since
we need 9 volts, in this case, we could select
the closest standard Zener value of 9.1 (actual examples would be a Motorola 1M9.Z
or IR 1N3019). The power rating of the
Zener, in watts, is shown in a moment.
Now to find out the amount of current
consumed by the load- another job for the
multimeter. In the transistor radio, this is
simply done by operating the set on its regular battery and disconnecting one battery
clip. Insert the meter probes (with meter
set to read ma.) at the break. The radio will
play and you'll see current consumption. Try
all operating conditions-like changing the
volume control setting-and observe the least
amount of current drawn by the radio. We'll
assume that it is 20 ma. That number, written as amperes (.02 A) is IL, or load current.
What this whole procedure is leading to
is a set of operating conditions for the regulator that produces the greatest stress for
the Zener. Once they are known, it's an easy
matter to design into the circuit an ample

-9.1 =5.9 =150

.018 + .02 .038
The answer, 150, is the series resistance Rs
in ohms. By coincidence, this is a standard
resistance value. In other cases, use the nearest value.
Rs

150n

Fig. 2. Calculations for Zener -regulated 9 -volt
battery substitute operated from 12 -to -1S volt DC
automotive electrical system. Current drawn
by Zener will vary with input voltage and load.

From the same formula, resistor wattage
is also calculated. Just multiply top and bot-

tom figures of the formula, which are resistor voltage and current: 5.9 X .038 = .22
watt. Double the wattage to .44 for safety
and use a .5
standard half-watt resistor
of 150 ohms.
Circuit Features. This, then, is the basic
shunt regulator. It will automatically keep
voltage to the radio at a constant, correct
value regardless of car speed. By using this
approach you can design the Zener into
other applications for the control and regulation of other DC- supply voltages. There
are, however, certain features of the shunt
design which should be considered.
In general, the shunt circuit is used where
a fairly large voltage drop is needed between
source and load. Also, the shunt arrangement regulates not only during shifting supply voltages, but changing load current, such
as occurs in the transistor radio.

JULY-AUGUST, 1966

-a

www.americanradiohistory.com

ZENER DIODES WORK
In Series. Another Zener circuit is the
series type, shown in Fig. 3. This system,
however, is limited. Since the Zener must
handle both resistor and load currents, the
diode's wattage rating can run to high, impractical values. Also, the series circuit regulates only the effects of changing load current, and can't smooth out power supply
fluctuations. It may be found useful, however, where voltage difference between supply and load are small (as illustrated in Fig.
3) and the supply voltage is constant.
;,,,,,1111111111111,111,11111111,,,,11111,,1111,,

,,,,,,,,1,,,,,,,,,11,,,,,,,1,

,,,,1,,,,11,

111111,1111111111,,,111111111111,.1,

PARTS LIST
C1- 30 -mf., 150 -volt electrolytic capacitor
C1- 50 -mf., 150 -volt electrolytic capacitor
D1- 100 -ma., 300 -pry (pivl silicon diode
L1-9-henry, 50 -ma filter choke

R1-47 -ohms,

1/2

-watt resistor

Rs-see text

51- S.p.s.t. on -off switch
T1 -117 -volt primary, 125 -volt,
t

50 -ma secondary power transformer
-volt Zener diode, 1N1781 or equiv.
Z1
-volt Zener diode, 1N1779 or equiv.
Z2
Z3
-volt Zener diode, 1N1777 or equiv.
-volt Zener diode, 1N1773 or equiv.
Z4
Z5 -9.1 -volt Zener diode, 1N1770 or equiv.
Z6 -6.8 -volt Zener diode, 1N1767 or equiv.

-27
-22
-18
-12

28V

4V ZENER

INPUT

24V
OUTPUT

Fig. 3. Series -connected Zener diode will
provide a constant voltage drop. If voltage goes
fo 29 volts, voltage across output will rise
to 25. Circuit has many limitations- seldom used.

Handy Power Supply. Here is a versatile
source of power for the experimenter. Based
on Zener diodes it provides a number of useful functions around the workbench. Not
only will it act as a voltage reference for
checking calibration of a meter, but can
supply a large number of regulated -DC voltages for powering small transistor projects.
We'll give a basic circuit here, but you can
easily vary it to suit a particular need.
The complete supply appears in Fig. 4.
The section on the left is a conventional
half -wave transformer supply operated from
AC line voltage. Suitable values are shown
next to each component. Ratings for the
silicon diode are minimum and you can use
a larger (and more common) unit. The capacitors may be one dual -section electrolytic,
the kind usually sold for replacement.
The output of the supply utilizes a group
of six Zener diodes connected in series across
the DC output of the supply. Although output voltage from supply is over 100 volts
DC, each diode will display its own Zener
voltage across its terminals. Not only can you
obtain six different output voltages, but
various combinations.
By connecting across the terminals of any
single diode you'll obtain its specified Zener
voltage. Hook across two or more Zeners
and you'll get the additive voltage among
them. For example, hook to the top of Z2
and the bottom of Z3 and you'll obtain 40
volts. Thus there is a remarkable number of
voltage possibilities-plus the full output of
the supply. Note that in hooking across any
Zener or combination, the positive side of
the circuit is the upper connection; the negative is the lower terminal.
We've shown a typical assortment of Zen (Continued on page 110)
TO

Zio
SPST
-OFF SWITCH DI

Fig. 4. Diodes can be wired
in any order that gives
the greatest number of usable
voltages for your use.
Additional diodes can be added
as long as DC across
circuit is increased in like amount.

-4

Rs
(SEE TEXT)

47f1
+

30MF

27V

Z20

Z30

22V

to
18V,

50MF

240
POWER

TRANSFORMER
117VAC

12V

#o
9.1V

250
Z6

$0
s.8V

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

Expensive chemicals and elaborate equipment
are not always needed for many electroplating jobs
Most of the articles dealing with electroplating will tell you to go to the drugstore,
or some chemical supply house, to purchase
chemicals to use in the electro -bath; not so
with this type. You need only tap water,
sugar, and a pinch of salt, and the results are
comparatively good, especially for small
articles found around the house or workshop. This type of plating will probably intrigue the do-it- yourselfer, if for no other
reason than its sheer simplicity.
Almost any type of plating, within reason,
can be done this way: copper on iron or
brass; silver on brass or copper; gold on copper or brass; and yes, even stainless steel on
brass or copper. The nicest part of it is that
you can steal the metal to be deposited from
discarded objects around the home or workshop. For example, if the distaff side of the
family should become tired of the color of
her earrings, why not plate them with a coating of stainless steel which is not unlike that
of silver? Or, if you should have some gold
plated objects no longer useful, why not give
the earrings a plating of gold?
To start, select a small drinking glass or
any similar vessel and heat it to a point
where it becomes uncomfortable to hold.
Fill the glass half full with warm water.
Pour in a teaspoonful of sugar and stir. Insert into the liquid the metal you wish to
plate. For example, say you want to do

copper plating. Then, the positive electrode
will be some form of discarded copper, and
the negative electrode will be the object you
wish to plate.
Connect these to one of the circuits given.
Be sure to observe the proper diode polarity.
After all connections have been made, drop
a pinch of table salt into the warm water.
Wait for about ten seconds and observe the
light bulb. If after ten seconds there is no
glow, drop another pinch of salt into the solution. Continue until you observe even the
faintest glow. Cover the solution with a
cardboard to prevent the bursting bubbles
from splashing. Let the plating continue for
a while, checking it periodically. Always disconnect the power when you do your checking. In less than an hour you should observe a deposit building up along with a
discoloration of the electrolyte-in this case,
a light blue.
Using the same circuit and a new solution, you can plate with almost any discarded metal. The object to be plated will always
be the negative connection. The author used
gold from an old watch case to plate a set
of earrings, stainless steel from an old knife
to plate some Fahnestock clips, and silver
from a discarded spoon to plate some electrical- contact points.
The obvious advantage of this type of
plating is that special chemicals are not re-

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11
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11,18

for the Hobbyist
by Martin H. Patrick
JULY- AUGUST, 1966

www.americanradiohistory.com

((

PARTS LIST

B1, 82

ELECTROPLATING

-1.5 -volt dry cell (Number

D1- 750 -ma,

300 PRV (PIV) or higher rating
silicon diode (1N539, 1N1489, 1N1763 or
equiv.)
D2- 750 -ma, 50 PRV (PIV) or higher rating
silicon diode (1N536 or equiv.)
I1 -15 to 50 -watt, 110 to 125 -volt light bulb
12- 250 -ma, 6 to 8 -volt pilot lamp (type 44,
46 or equiv.)
M1
to -amp DC panel meter
R1
-ohm, 25 -watt rheostat
T1 -117 -VAC to 117 -VAC isolation transformer
(Lafayette 33R7502 or equiv.)
T2- 6.3 -V, 1 -amp centertapped filament transformer, any inexpensive unit will do
Misc.-Socket, clips, wire, scraps of precious
and semiprecious metals, water, salt, etc.

quired and that the same basic procedure is
followed with all metals.
The quality of the electroplating depends
directly on the preparation of the object to
be plated. The object must be thoroughly
cleaned of grease and oil, and if a shining
result is desired, it is necessary that the object be buffed and polished before plating.
If objects made of iron fail to take a plating,
try copper plating it first. Then follow by
plating with first selected plating metal.

-0

-15

12mm
1N539

PLATING
METAL
(ANODE)

3.15V
CT

--1

3.15V

SMALL DRINKING GLASS
ISOLATION
TRANSFORMER

OBJECT TO BE PLATED
(CATHODE)

FILAMENT
TRANSFORMER

Even using a 1:1 isolation transformer does not make the circuit
above safe -117 volts is quite a
jolt even when current is limited
by 11. Without T1 it is really a

death trap -don't eliminate TI.
Setup with T2 is quite safe. The
lamp (12) limits current to protect the transformer, and whether
the full 6.3 volts or the centertap value of 3.15 volts is used,
touching the bared wires produces

little

CATHODE

more than a strong tingle.

DRINKING
GLASS

ANODE

ITEM TO BE PLATED
PLASTIC

ROD OR

WOOD DOWEL

STRONG THREAD

ANODE
SATURATED
COTTON WICKING

FROM BRUSH

BATTERY CLIP

SURFACE
TO BE PLATED

Dry cells are safe, too. For ex- 3
tensive electroplating use large I
cells (or filament transformer
circuit at top). For one small job
you can even use the penlight
types of cells. Electroplating re-1
quires current-the larger the
surface the greater the current
needed. Too little current increases the time required while
too much current causes excessive
bubbling at immersed electrodes.

(CATHODE)
11111117111M

MHZ

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

Those
Fabulous
duel Cells

Reverse electrolysis
generates the power
instantaneously
as long as fuel
and oxidizer are
supplied to cells.

No moving

parts to

wear out-silent
operation that
provides pure water
as a waste byproduct. And it's
80% efficient.

by Len Buckwalter

Any high school science student can
probably tick off a half-dozen ways for producing electricity. There's the spinning coil
inside a magnetic field (generator), chemicals
reacting in a container (battery), heating
metals (thermoelectricity), friction (static
electricity), squeezing a crystal (piezoelectric) or light waves on semiconductors
(photoelectric)
Now There's A New Way. It's the fuel
cell; a compact package that surrenders more
electricity per pound than any other source
except nuclear energy. So promising is this
neat electrical device that researchers have
already racked up some remarkable successes. Chrysler Motors can point to a
model automobile that's buzzed around a
test track with an engine that neither growls
nor spits exhaust. Power is by fuel cell and
electric motor.
Allis- Chalmers won a place in history
.

JULY- AUGUST, 1966

www.americanradiohistory.com

FABULOUS FUEL CELLS

Cutaway view of General Electric fuel cell shows
ribbed current carrier, hydrogen inlet and purge tubes.
Cell is about 7 x 8 inches-96 cells are in a battery.

when its full -size tractor, power by fuel cells,
wound up in the Smithsonian Institution.
Even now, the military services use them to
power small field -type radar sets. Gone is the
gas- engine generator whose noise might warn
a nearby enemy.
But the most dramatic use of the new power source is in space. Those weeks-long
Gemini flights just couldn't have been made
without the light weight and efficiency made
possible by fuel cells.
Reversed. If you've ever seen the classic
experiment in chemistry -the electrolysis of
water-you witnessed the operation of a fuel
cell, but exactly in reverse. This is the
demonstration that proves water is actually
made of the gasses hydrogen and oxygen. To
conduct the experiment, a current of electricity is passed through water. As water
molecules (H20) absorb energy, they split
apart into component parts. The wet stuff
disappears and two gasses are created.
Reverse That Process. Begin with the
gasses hydrogen and oxygen, cause them to
combine, and they'll not only form water,
but release electrical energy as well. That's
the heart of the fuel cell and, in fact, many
practical fuel cells do just that. There are,
to be sure, some exotic chemical techniques
to aid the process. Catalysts (platinum for
example) must coax the gases into combining. And special membranes keep the
reacting agents free of contamination.
The excellence of the fuel cell lies in its
ability to convert energy- chemical to electrical-in a surprisingly direct manner. Far
cry from the traditional method of power
generation; say, burning coal to produce
steam, to spin a turbine, to turn a generator,

and so on. Although we get much electrical
power this way, efficiency is a meager 40 %.
Fuel cells, on the other hand, reach up in the
80% efficiency region. But before you call
your utility company and have the house current turned off, look at costs. Fuel cells produce a huge number of watts-per -pound, but
cost is still prohibitive for residential or commercial use. If your monthly electric bill is
now $10, it would skyrocket to about $100
if fuel cells ran lights, TV and other household appliances. But in military and space
applications, performance, not cost, is the
boss. In one case, a 55 -pound fuel cell
eliminated 1000 pounds of ordinary storage
batteries (like the one in your car). This is a
bonanza for rocket-powered vehicles where
weight is reckoned by the ounce.
It might seem the fuel cell bears some resemblance to any ordinary battery. It does up

ANODE

CATHODE

GAS CHAMBERS

CATALYTIC
ELECTRODES

SOLID POLYMER
ELECTROLYTE

FUEL
(HYDROGEN)

OXIDIZER
(OXYGEN)

H2O

Fig. 1. Simplifed diagram of fuel cell indicates fuel
and oxidizer inlets, gas chambers, electrolyte and the
catalytic electrodes. Inset circles diagram action
that produces electricity, a pure -water by- product.

to a point. Both fuel cell and battery are
fundamentally devices which depend on
chemical reactions to obtain electrical power.
But here the similarity ends. A conventional
battery is considered a storage medium of
energy. It is limited by the extent of its
primary charge or by frequent recharging.
But fuel cells continue to operate so long
as fuel and oxidizer (hydrogen and oxygen,
for example) are fed in from an external
source. Another big difference is that materials which make up the fuel cell do not
change as they process fuel into electricity.
What's more, a by- product of fuel -cell operaELEMENTARY ELECTRONICS

www.americanradiohistory.com

Clean -room assembly
of fuel -cell batteries
rivals cleanliness
of hospital operating
room at General
Electric's Direct
Energy Conversion
Operation at Lynn, Mass.

Cutaway mockup of
Gemini fuel -cell battery is displayed
by Roy Mushrush, Man-

ager of General
Electric's Direct
Energy Conversion
Operation. One fuel cell stack is held
in his right hand.
Photos courtesy of General Electric

Toughness of solid polymer electrolyte is demon strafed by Dr. Russell Hodgdon of General Electric's
Fuel Cell Laboratory. New electrolyte, developed by
GE, has increased cell life expectancy four times.

tion is water, suitable for drinking or cooling.
Here's How. Fuel cell operation is illustrated in Fig. 1. The cell consists of a number of basic elements: anode and cathode, an
electrolyte to act as a transportation medium
between electrodes and the fuel oxidizer.
Note that the two gasses are seen entering
the center portion of the cell. Near the lower
left of the drawing is a blow-up of what
happens when hydrogen gas (2H2) reaches
the anode. The reaction causes the gas mole clue to surrender electrons. These negative
travel upward and constitute
charges (
the electric current flow to the load (which
might be a lamp, radio, etc.) As hydrogen
supplies electrons to the load, it becomes
ionized (4H+) and travels into the electrolyte solution between the electrodes. Hydrogen ions reach the cathode where they combine with electrons returning from the load,
and ogygen entering the fuel cell. The inset at

lower right illustrates the chemicals combining, which produces water. Note that
H50 (water) drains from the bottom right.
A valuable feature of the cell, in addition
to high efficiency or watts-per -pound, is that
it's "self- throttling." It consumes fuel only
as required. Power can be switched off instantly by opening the load circuit. This
stops the chemical reaction.
As in conventional battery systems, the
fuel-cell type consists of a cell which is
usually combined in series or parallel to obtain voltage or current (or both). An operational cell made by GE, for example, typically produces rather low voltage, somewhat
less than one volt. Wattage depends on the
surface area of the cell and may be up to 75
watts per square foot. Several of these cells
are connected in series to form a module
or battery of approximately 30 volts output.
Three such modules can then be placed in

JULY- AUGUST, 1966

www.americanradiohistory.com

FABULOUS FUEL CELLS

parallel for high- current output. The final
package is then termed a fuel-cell battery.
Performance ratings of a one -thousand watt
unit, used in spacecraft, is shown in Fig. 2.
It may be seen that as the current drain
(amps) rises, the output voltage of the battery drops slightly, but remains in the 30 -volt
region.
More complete specifications for this fuel cell battery, and a smaller version, rated at
353025-

w 201_115-

105

o
10

Ì5

CURRENT (AMPS)

Fig. 2. Voltage -current curve of typical fuel -ce11
battery. A few calculations will show that
battery's internal resistance is less than 0.2 ohm.

350 watts, are given in the table. You can
see, for example, that to produce one thou-

sand watts for one hour, the 1 -KW unit requires about .1 pounds of hydrogen; and .8
pounds of oxygen.

The Future. Today's techniques of fuelcell operation are by no means final. There
are plenty of other experimental approaches.
One is the hydrocarbon concept. Instead of
gases, tanks are filled with common hydrocarbons, like gasoline, or kerosene. Then,
acting like a miniature chemical plant, the
hydrocarbon fuel is split into gases which
enter the cell and generate electricity. Only

problem here is that plenty of heat is needed
to convert the hydrocarbon fuel into gas
form. Yet there is hope; primitive models
using this principle needed some 1000 degrees F, but recent versions can do it at 150
degrees F. If the scientists ever do it at room
temperature, it could rock our concept of
how to propel the family car.
Experts in the field wort name the day
they'll start production, but they've already
stroked in outline designs of a fuel -cell powered car. For one, the efficiency of such a
vehicle would be about three times higher
than that of the present automobile power
plant. They envision small electric motors
mounted in each of the car's wheels, with
electrical power generated by fuel cells. This
does away with bulky transmission, radiator
and big engine compartment. Air pollution
problems simply don't exist -the exhaust is
water! Even the car's braking system is
radically changed -to a type now used on
both trains and tape recorders. It's called
electrodynamic; the spinning car wheels ro(Continued on page 111)

TYPICAL FUEL CELL CHARACTERISTICS
1

350 W FUEL CELL

KW FUEL CELL BATTERY

Contains 3 modules of 32 fuel cells, pressure
regulators and sensors, product water separator.
Fuel: Hydrogen, approx.

0.1 lbs /kwhr

BATTERY

Contains one 32 -cell module with pressure regulators and sensors, product water separator.
Fuel: Hydrogen, approx.

0.1

lbs. /kwhr.

Oxidant: Oxygen, approx, 0.8 lbs/kwhr

Oxidant: Oxygen, approx. 0.3 lbs. /kwhr.

Output:

Output: 350w peak.

kw peak

By- product: Water, approx.

Weight:

70 lbs.

pint /kwhr

By- product: Water, approx.

Weight:

approx.

35 lbs.

pint/kwhr.

approx.

Size: 12.5" dia., 25" long

Size: 14" die., 16.5" long.

Cooling need: Liquid coolant. Temperature at
inlet: 400-100 °, 75° avg. Higher
temperatures tolerated for brief
periods.

Cooling need: Liquid coolant. Temperature at
inlet 40° -100 °, 75° avg. Higher
temperatures tolerated for brief
periods.

Efficiency: 50 % -60%

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

You don't need any

special powers to
operate this switch.
Touch it with your
finger, elbow or
even with the back
of your hand.

SCR
Touch-Control Switch
by Lester Escargot
Most science-fiction super heroes have the
power of the universe at their fingertips; they
simply point and buildings collapse, the sun
darkens, and the vilest of enemies are banished to the sixth dimension. You've got power in your fingertips, too; not enough to destroy buildings, or get scantily-clad girls to
throw themselves at your feet, but enough
to forever eliminate turning knobs, throwing
switches, and even fumbling in the dark for
the light switch.
Yes, the power is there -it's the residual
AC voltage picked up by your body from
the power lines in the immediate vicinity;
just concentrate the power to your index
finger, say the magic word "Zotz," and voila,
you can turn anything on or off by just pointing your finger. Got a ham rig? Just touch
the mike stand and the transmit relays snap
to attention. Fumble for the keyhole after
a few slurps of the sauce? Just put some tinfoil alongside the door and your index finger
will turn on the porch lights until you enter.
Use CB? Just point your finger when you're
ready to talk and you're on- the -air. In fact,
you can control anything that goes on and oft

by just pointing your finger.
Of course, some of us haven't yet mastered
the art of concentrating power to the finger,
so you'll have to use a finger-power concentrating amplifier, otherwise known as a Touch
To- Operate SCR Load Control, (which we
will naturally refer to henceforth as the SCR

Control.)
What Is It? The basic SCR Control
courtesy of General Electric-is shown in
Fig. 1. C2 is a fixed capacitor of approxi-

mately 25 mmf. and Cl supposedly represents the capacitance of the body to ground.
When a finger is touched to point X the body
completes the capacitive voltage divider
across the AC power line, C2 starts to charge,
and when C2's charge reaches the ionization
voltage of neon lamp NL1, the lamp conducts, C2 discharges into the SCR gate, the
SCR is triggered (conducts) and power is
applied to the load. The SCR will conduct as
long as the finger (or hand, or any part of
the body) contacts point X.
If the load is a 117-VAC relay the relay
will operate in step with bodily contact to
point X. If the load is a lamp it will go on
87

.JULY -AUGUST, 1966

www.americanradiohistory.com

POLARIZED

@Ag SCR

AMP

TOUCH- CONTROL

SCR

117

VAC

POLARIZED

TINFOIL
PLATE
R2

Fig. 2. With aluminum or tinfoil plate attached fo
the inside of a showcase this circuit is quite safe,
for use without transformer 71. Linecord plug
polarity is still important for the operation of
the circuit. Showcase glass acts as dielectric
of capacitor
is one electrode and body
capacitance (C1 in Fig. 1) completes circuit fo
ground. Circuit 28 (below) is mors -or -less
identical to 2A (above) except That the lamp is
replaced by the relay coil in the circuit.

-foil

ANODE GROUNDED TO CASE

Fig. 1. Cl is capacitance between human body and
earth ground. If direct contact fo point "X" is
possible T1 (below) must be used in circuit.

Fig. 3. Components used here are identical to those
used in the other circuits except for TI.
TO LOAD

POLARIZED
PLUG

CIRCUIT
CONTROL

117

VAC

TO
POWER

INDICATOR

and off with point X. If an impulse relay is
used as the load a touch to point X will
turn the relay on, and it will stay on until
a second pulse is applied through contact to
point X.
Where to Use It. Fig. 2 suggests possible
applications of the touch control. Fig. 2A
is an SCR substitute for the old capacitance- operated relay (which used an RF
oscillator and cost at least 5 times the price
of SCR control). The load in this instance is
a porch light, and point X, as shown in the
photographs, is connected to a large strip of
aluminum foil tacked to the doorframe opposite the doorlock. As you reach for the
keyhole at night your hand will brush the
foil, tripping the SCR and turning on the
porch light until you enter.
Fig. 2B is a touch -to -talk circuit. It could
be used by Hams and CB'ers. Relay K1 controls the transmitter or transceiver's push -totalk (PTT) circuits-either relay or electronic switching. A little metal foil can be
cemented to the mike base or a length of
bare wire can be stapled to the edge of the

operating desk and connected to point X.
Whenever the foil or wire is touched the rig
switches to transmit; when the hand is removed the rig switches back to receiving.
For latching control, simply use the circuit shown in Fig. 2B but substitute an impulse relay for K1. An impulse relay "trips"
and stays tripped until a second pulse is applied. To trip the impulse control you'd
simply touch the wire or foil connected to
point X and then remove your hand. The
single pulse will cause the impulse to close.
To open the relay you'd touch point X again.
While the SCR results in DC flowing
through the load, you can use an AC relay
of the same voltage rating. If the input voltage is 117 VAC the relay can be rated 117
VAC or 117 VDC. If there is severe chatter
when using an AC relay connect a 400 PIV,
500 ma. silicon rectifier across the load with
the anode connected to the SCR side of the
load.
Carefull As you probably have noticed
the G.E. circuit can be a death trap as you
must be absolutely certain the ground side
ELEMENTARY ELECTRONICS

www.americanradiohistory.com

ninnianitisnntnnitin

Inmum,,,n,,u,,,,,,,,,,ni,,unnn

1111111111

Transformer TI is the largest item in
the SCR Touch-Control Switch. The
completed unit (left) shows the layout
of components, which is not critical.
While perforated- phenolic board is

used here the layout could be on plain
stock and holes drilled to suit the
components. Flea clips are inserted
in the perforations -only holes that
need be drilled are for the transformer.
When connecting the SCR be sure to
locate the proper leads in relation
to the dot on the molded case.

SCR1

R2
R1

PARTS LIST FOR SCR TOUCH-CONTROL SWITCH

C1-25-mmf., 500-VDC disc capacitor
I1-Neon Lamp, NE-83 or NE-211 (see text)
R1-100,000-ohm, 1/2-watt resistor
R2-5600-ohm, 1/2-watt resistor
SCR1-Silicon controlled rectifier, C6B or

;

ninnonnnamannn nounninnunnninnonninnion

C601

(G.E.)

Tl-Transformer (see text)
Misc.-Perforated board, flea clips,

etc.

Estimated construction cost: $5.00
Estimated construction time: 1 hour

tan

of the AC line is connected to the grounded
side of the SCR control. If you put a nonpolarized plug on the SCR control you may
go before the fuse. For maximum safety,
use an isolation transformer as shown in Fig.
3. And it is not necessary to ground the line
at the load. The voltage picked up by the
body is sufficient to trip the SCR without
the ground connection. A typical SCR control is shown assembled on a section of perforated board in the photo above.
The SCR control shown is a light-duty
model. Transformer T1 is a standard power
transformer with 6.3 volt at .6 amp and 125
volt at 15 ma. secondaries. While 15 ma.
will certainly not light a lamp it is sufficient
to trip a sensitive AC relay-the 6.3 -volt output is used to power a pilot lamp. Naturally,
T1 must be able to handle the load, and since
isolation transformers of any substantial rating can be expensive, you could use a pair
of heavy- current surplus filament transformers back to back. (In a sense the SCR control is experimental, so do as you please.)
If you want to control a heavy load such
as a 500-watt bulb it's best to have a light
duty SCR control with a sensitive relay for
the load -then have the relay turn the lamp
on and ofj.
A sensitive SCR is needed, otherwise the

"power in your body" is not going to trip
the gate. The SCR to use is the General Electric type C6B or C601B. Both models handle up to 0.6 amperes without a heat sink,
the difference being the C6B has leads while
the C601B has tabs (for perf-board and
printed circuit mounting). Do not substitute
the G.E. experimenter SCR, the X5-its
voltage rating is only 50 volts.
Neon Lamp I1 should be the NE -83, a
special neon made for use in the dark (no
light). If you cannot obtain the NE -83 the
more or less standard NE -2H can be substituted though there may be a slight loss in
sensitivity if the SCR control is placed in a
cabinet (dark).
If you experiment with the circuit, and
you should as that's what it's for, you'll discover you can get astounding sensitivity if
your finger is placed at the junction of R1
and C2 instead of at point X. Don't do it as
a matter of course. R1 is a protection device
that isolates you from the AC line should
C2 or I1 fail; it also keeps you isolated
from the SCR gate.
We've shown just a few uses for SCR
Touch Control; we'd like to see what ideas
you readers out there in magazine land can
develop. If it works well and is safe, how
about scratching it out and passing it along?
89

JULY-AUGUST, 1966

www.americanradiohistory.com

TV Schooling

for
Hospitalized

Students

Television can be
more than cowboys,
comedy and
commercials.
As the shut -in's
window -on- the -world
it can prevent
boredom or help

continue education.

Young school-age patients at the Massachusetts Hospital school, Canton, Mass.,
don't fall behind in their school work. They
attend classes without leaving their beds
thanks to a closed-circuit television (CCTV)
system.
The hospital school is world famous for
the treatment and education of handicapped
children. It now accommodates about 150
children but capacity will be 230-after the
completion of the building addition.
If they're able, young patients attend classroom sessions. However, many are confined
to the hospital beds for lengths of time varying from a few days to months. Prior to installation of CCTV, bed students averaged
20 minutes of individual tutoring each day.
These youngsters still receive tutoring, but
they also share the educational climate of
the classroom with their fellow hospitalized
students.
A standard curriculum, in grades 1 to 12,
is offered at the school. Any student, whether
he's in bed or in the hospital classroom, may
take advantage of any course taught. CCTV
cameras scan classroom sessions and relay
them to bedside TV receivers. A two -way
communications system between teacher and
the bed -student and the bed -student and the
classroom lets anyone ask or answer questions, at any point in the lesson, just as
though the patient was present in the classroom.
Recorded Material. Much of the material

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

Classroom (above) does not have hospital
atmosphere. Teacher Eleanor Woods prepares
to playback previously recorded material for
bedridden and classroom students alike.
Science teacher, Donald Gay (top left) points
out parts of the human anatomy to classroom
students-those in bed view scene with help
of CCTV camera on wall, at top center, which
scans classroom activity.
Key elements in this 16- channel system are two
90 -pound Ampex Videotape recorders.
Equipment used to transmit motion -picture film

and slides, as well as monitoring equipment
are packed into control room shown at left.
Recording tape is on wide reels.

has been previously recorded on Ampex
Videotape television recorders for showing
at class time. As the teacher wishes, she may
show students a lecture (recorded months
ago and many miles away) by an expert on
a particular subject, an experiment performed in the laboratory class hours before, or any other presentation.
According to Dr. Margaret Brayton, the
Director of Education at Massachusetts
Hospital School, "The Videotape recorders
are expected to play an important part in
the school's new educational system. For
instance, cost might prohibit bringing an outstanding lecturer here from the West Coast.
By recording the lecture on video tape and
having that shipped to the school, our students will have the benefit of an educational
experience otherwise unavailable."
Ampex Corporation's Videotape recorders
are key elements in many CCTV systems-

preserving moving pictures on magnetic tape
much as sound is recorded. A 90 -pound
portable recorder, used at the Massachusetts
Hospital School is a direct descendent of
larger models used to record network TV.
Dr. Brayton added. "You don't mind
spending time and energy on a project if
you know it won't be lost as soon as it's presented. With our television tape recorders
we can play back a recorded presentation as
many times as we desire. The original value
of the presentation is expanded many times."
Massachusetts Hospital School's $170,000
CCTV system was engineered and installed
by Lake Systems Corporation, Watertown,
Mass. The system permits 16 channels to be
telecast to individual bedside receivers
throughout the hospital area. Also, as soon
as the day's schooling is completed, commercial off-the -air TV programs are available on the same receivers.
91

JULY-AUGUST, 1966

www.americanradiohistory.com

Calibrated
Attenuator
by
James A. Fired
When we turn the knob on the volume
control of a radio, TV set or hi -fi amplifier
little do we realize the care that has gone into
the selection and design of this component.
When choosing the value and taper of the
control the design engineer must decide what
volume of sound he wants for each degree of
control rotation. The process of making the
sound softer is called attenuation.
A modern American dictionary defines
attenuation as, "1. to make or become thin,
2. to weaken." So in technical language we
attenuate a signal when we make it weaker.
We hope to fill a twofold purpose: 1, to
show the relationship between the resistance
taper of a variable resistor and its attenuation
curve, and 2, to show how to design a control for any desired amount of attenuation
and to build a 60 -db attenuator using the
principles discussed.
Before we go into the actual design of an
attenuator let us first find out something
about variable resistors. If you consult cata-

A fortune is not
needed to have a

calibrated control
instead of a plain
volume control on
your amplifiers,
recorders and hifi equipment units.
Circuit changes
are slight - only
a small resistance

has to be added to
the layout to make
calibration easy.

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

R1
I

J4
1

J3
1

.:1111111111111111/2111
,,
,

111111111/M11111111111
111111211111111111111111

11/1111111111111111=ó,o

MIR11111111111111111111
90
70
80
60
40
50
10

PERCENT OF ROTATION

"sue

Front panel (above) shows all components except R2
which is mounted on R1's terminals inside case.

Characteristic curve (above) will vary from one
control to another depending on quality.

(below), measured from CW
mirror image of curve of normal
control- measured from CCW lug, curve
is pivoted top -to- bottom.
Reverse resistance

terminal

logues of such variable- resistor manufacturers as Centralab, Clarostat, and Mallory you
will find two terms used to describe variable resistor characteristics. One term is overall
resistance and the other is taper. Overall resistance means just what it says, while the
taper indicates how the resistance varies with
rotation. For example, some variable resistors
may have only half the resistance in the
circuit when turned 80% of the way on
(clockwise), and compress the other half of
the resistance into the last 20% of rotation.
If the resistance varies directly with rotation
(25% of the rotation equals 25% resistance,
50% rotation equals 50% resistance, etc.)
the manufacturer calls it a linear taper or
simply linear.
Volume control characteristic curves are
usually drawn showing percent of resistance
versus percent of rotation. This allows for
quickly comparing one control against another without regard for resistance. The taper
is usually specified as being a certain percentage of resistance at 50% of rotation,
so 5 percent of resistance at 50% of rotation
is usually referred to as a 5% taper. Of
course each manufacturer has his own
identifying symbols for his own tapers. A
cross reference of tapers and designations for
three companies are listed in the table titled
"Resistance Tapers."
Two variations of the term that you will
find in catalogs are left -hand and right-hand
tapers. If you hold a variable resistor with the
end of the shaft facing you and the terminals
down, the left -hand terminal will be the counter-clockwise (CCW) terminal and the righthand terminal will be the clockwise (CW) ter-

100

100
9

-°

\oo

PQhIPp.I,ÌI

/.R'

`,°'o

Ariii,

.,,///.33

MINN

a
1

I,L'V®'
,%1 AL,
;,,1,

/%í'
/_',
_

?
e

PERCENT OF ROTATION

minal. Normally when the contact arm (in
the variable control) is at the CCW terminal
you think of the control as being off, and
when the contact arm is at the CW terminal
you think of the control as being full on.
Left -hand tapers are most commonly used
in electronic equipment.
Design An Attenuator. Now that we
have learned about controls in general let us
use this knowledge to design and build a simple attenuator. This attenuator is basically
a potentiometer connected to the grid circuit
of a tube. Actually a potentiometer or variable resistor can be used in many circuits. To
be most effective the resistance of the varable control should be nearly the same as the
impedance of circuit to which it is connected.
In other words if you were building a gridcircuit attenuator the resistance would be
93

JULY-AUGUST, 1966

www.americanradiohistory.com

".1
J31

CCW

AUDIO
GENERATOR OR
0-I011/60 CYCLE AC

_J
ATTENUATOR

AC
OR DB

VTVM
METER

Internal wiring of attenuator
(above) is contained within the
dotted lines. Connections to
equipment shows calibration
setup. Some of the controls
tested are shown at left with
screwdriver -adjusted resistor
connected to potentiometer lugs.
Typical volume -control circuit,
used in most inexpensive radios,
is shown

J1, J3-Red
99G6233)

42, J4 -Black

PARTS LIST FOR 6 0 -DB ATTENUATOR
-way binding post (Lafayette
Plastic box (Harry Davis Molding Co., type

5 -way

binding post ILafayette

99G6233)

-1 -meg

potentiometer (Centralab C2; Mallory M201; Clarostat Y)
R2-Trimmer resistor (Mallory MTC -see text)
R1

RESISTANCE TAPERS
General

Description

C-1

S
Y

Audio
Audio
Audio
Audio
30% Audio
40% Audio
Right hand
30% Audio
Right hand
20% Audio
Right hand
10% Audio

C-2

C-4

C-6

Reverse

Reverse
M -206

C -3

Reverse

M -204

PZjEN/

..
I
%

Q,4,`'

MIMI
20

0
6.02
9.54
12.04
13.97
15.56
16.90

Resistance

Ratio

Voltage
Ratio

8.0
9.0
10

100
1000
10000

18.06
19.08
20.00
40.00
60.00
80.00

M -208

C -5

E ii/I

solder, etc.
Estimated construction cost: $4.00
Estimated construction time: 1 hour

1.0
2.0
3.0
4.0
5.0
6.0
7.0

M-204
M-205
M-206
M-207
M-208

..,,
d .

FA
o

-Knob (Mallory

Resistance
db
Ratio
Voltage
Ratio

M-101
M-201

220; Newark Electronics Corp., 26F1451
368 -1)
1 -Dial plate (Mallory
390)
Misc. -Sheet aluminum for box cover, wire,
1

ABBREVIATED TABLE OF RATIOS

Centra -Claro- Mallory
Mallory
lab
stat Dist. Co. Conts. Co.

Linear
5% Audio
10%
15%
20%
25%

at upper left.

11,11111111111111111111111111111111111111111111.

F,()

100

Q1A-,

w
50 LL

33w
16

100

PERCENT OF ROTATION

Curves of resistance and attenuation do not coincide
except at minimum and maximum points on graph.

very high, while if the attenuator were used
in a speaker circuit its resistance would be
very low.
A Ratio. The total attenuation of a variable resistor is determined by the ratio of the
residual resistance at the CCW end (which is
the Minimum resistance of the control) and
its total overall resistance. In other words a
one -megohm variable control with a minimum resistance of 1000 ohms would have a
ratio of 1000 to 1. By consulting the voltage -ratio column of a standard db chart you
would find that a ratio of 1000 is equal to 60
db.
(You may have some objections to the
above statement because we are converting a

ELEMENTARY F.I.&CTRONICS

www.americanradiohistory.com

resistance ratio to decibels. This method is
perfectly logical and has been confirmed experimentally.)
Due to manufacturing processes all variable resistors have wide variations in actual
resistance values. The most common resistance tolerance is ±30 %, while ±20% is
often used, but ±10% is available only on
special order. The only way to design an attenuator for an exact amount of attenuation
is to look up the voltage ratio for the db attenuation you want. Then carefully measure
the resistance of the control you intend to
use and divide by the voltage ratio previously
used. This answer will tell you the CCW end
resistance needed. If the measured end (residual) resistance is less than that needed you
can add a trimmer resistor to make up the
difference. Adjust the trimmer until the CCW
end resistance is cgrrect. The circuit diagram
will help you here. Refer to it on the page
opposite.
Any technician or experimenter can use
the methods outlined in this article to make
attenuators of any desired resistance or
range. By using the following example you
can get a better idea of what we mean. The
photograph shows a plug -in 60 -db attenuator
built and used by the author in experimental
audio work. A dial plate allows the control
to be set for each 10% of rotation and a
calibration chart supplies the amount of attenuation. A 0-10 -volt AC voltage source is

needed for calibration as shown in the circuit diagram.
This supply can consist of a 12 -volt filament transformer in series with a variable voltage transformer or, in a pinch, a tube
tester could be used to supply the necessary
voltages for the setup.
The control used measures 1,113,000
ohms overall, so a trimmer resistor was
added, in series, to adjust the CCW -end residual resistance to 1,113 ohms. The control has
a 5% audio taper and by looking at the graph
titled "1 megohm, 5% Audio Taper Carbon
Control" you can see both the resistance and
attenuation curves. The attenuation curve is
far from linear. By measuring all the controls shown in the photograph we were able
to determine that a control with a 21/2 % audio taper would give a nearly linear attenuation curve.
The parts needed to make the attenuator
shown are in the parts list. The suggested
variable resistors specified will give nearly
linear attenuation curves. This small device
can be used in the circuit shown for the grid
potentiometer attenuator. It can be used between the output of an audio signal and an
audio amplifier when plotting a response
curve.
Note! Potentiometer, variable resistor, and
variable control all mean the same thing and
are used interchangeably. So don't do any
betting about which is right!

SPEEDY READIN'
The National Cash Register Co., a major producer of computer systems, makes a high -speed
unit that prints 1,000 lines (of 120 characters each),
in a minute -starting and stopping the paper at
least 1,000 times a minute. Otherwise the lines of
characters being printed would be blurred, unreadable smudges.
Special silicon -alloy steels from Allegheny Ludlum Steel Corp., Pittsburgh, Pa., are used in parts
of the drive units that bring paper tape to a halt
for the fraction of a moment needed to read the
tape or print the answer.
Computers can deposit worker's pay directly to
their bank accounts, eliminating payday lineups
and individual distribution of checks at the plant.
Think what would happen if the computer information were not legibly printed so it could be understood. Chaos would occur if the tapes and papers
that whirl through printer and reader systems were
not accurately controlled-and NCR engineers say
still higher speed is needed to record and recall information to reduce computer- services costs.

The tape in the NCR computer unit is read
at a rate of 1,000 lines per minute.
High -speed is made possible by special
silicon -alloy steels made for the electrical
and electronics industries. These special
"electrical" steels are used in clutch plates
and brake shoes requiring high performance
and exceptional wear resistance.

JULY-AUGUST, 1966

www.americanradiohistory.com

FCC

Using questions
typical of the type
asked for all FCC
exams (commercial or
amateur) you can
prepare yourself for
that big day.

by
Carl L. Henry
96

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

A. Study Fig. 1 carefully. Generally on
questions such as this a diagram will be given
that is incorrect, and you must correct it.
This circuit may be redrawn several ways,
but basically the plate (and screen if it is a
pentode) must be connected to the B +, the
cathode to the B- or ground; and the crystal
either as shown, grid to ground, or for a
Pierce circuit, grid to plate. There must be a
plate load, either a resistor, a choke, or a
tuned circuit. An important point to rememthe
portant part of the transmitter, the oscillator. ber about crystal oscillators is that this is
a
Novice.
for
of
oscillator
type
only
determining
It is evident that the frequency
element of a transmitter is its most important
section, since without accurate frequency Q. A crystal for the 80 -meter band is specfrecontrol communications would be at best in- ified to be within 0.05% of its stated
you
frequency
lowest
is
the
What
termittent and at worst impossible. Most quency.
limit
lower
the
within
stay
to
order
about
should
exams,
FCC
the
on
questions asked
kc
oscillators, are concerned with testing: 1. of the band, allowing an additional 1.0
parameand
circuit
for
temperature
2.
(KHz)
And:
is?
do you know what an oscillator
operate
do you know how to keep it on frequency? ter variations; assuming you wish to
limit.
lower
this
at
band
the
inside
just
KiloHertz
The new terms Hertz (Hz),
problem is:
(KHz), and MegaHertz (MHz) are given A. A simple formula to solve this
after the long-used terms cycle -per- second
frequency (lower band limit)
(cps), kilocycle -per- second (kc), and megacrystal tolerance + 1.0 kc (KHz)
1
cycle -per- second (mc) to familiarize you
Using this formula:
with them.
3500 kc (KHz)l
Q. What is the relationship between fre0.0005, + 1.0 kc
1
quency and wavelength?
=
3501.6 + 1 or 3502.6 kc (KHz)
A. Frequency, in cps (Hertz) = 300,000,the nearest kc
000 /wavelength (in meters), or frequency, If the question is specified to 3503 kc. If
be
would
answer
the
(KHz),
in mc (MHz) = 300 /wavelength (in meters).
kc to the nearest
This is a simple relationship that you should the answer had been 3502.4
be
3503 kc. Since
still
would
the
answer
kc,
memorize. The second formula is the one to
to err toward
operator
any
FCC
expects
the
the
and
most,
this
use
will
remember. You
safety.
maximum
of
other can be developed from it. As a further the direction
aid to memory, recall 30 mc (MHz) equals
Q. A 3800 kc (KHz) low -drift crystal hav10 meters, or 300 mc equals 1 meter.
ing a negative temperature coefficient of
5 cps (Hz) per mc (MHz) per degree Centitypical
a
in
an
oscillator,
Q. Why should
40- degrees
transmitter, have a separate plate -supply? grade is started in operation at
is linear,
relationship
If
the
Centigrade.
supply
in
-voltage
plate
common
A. Using a
be at
the
crystal
of
frequency
will
the
a transmitter can cause frequency modula- what
degrees?
65
plate
in
the
Variations
tion of the oscillator.
means
voltage, due to variable loading (current A. Negative temperature coefficient
frequency
in
shift
down
will
crystal
the
that
final
by
the
drawn) on the power supply
amplifier. This does not mean that an enRF
tirely separate power supply must be used,
OUTPUT
just that the section supplying the oscillator
TANK
should be isolated from the balance of the
CIRCUIT
be
tube,
a
This
can
regulator.
by
a
supply
XTAL
such as an OD3. In this manner the voltage
variations (due to the loading on the supply)
will not be reflected to the oscillator.
B+

Here we are going to discuss questions you
will encounter on tests for all classes of FCC
operator's licenses, whether amateur or commercial. The questions will be of the type
asked by the FCC on its exams; the answers
will be in depth. Rather than the conventional type of question and answer, we intend
to cover each subject with answers that will
help you to learn the subject fully.
For a beginning we are going to discuss
FCC questions covering the single most im-

Q. Draw

diagram of

oscillator.

crystal -controlled

SCREEN BYPASS°
CAPACITOR

Fig.

`SCREEN

DROPPING
RESISTOR

Diagram of a crystal- controlled oscillator.

JULY-AUGUST, 1966

www.americanradiohistory.com

FCC Q &A
SIGNAL INPUT

Fig.

Bask diagram of ECO and

AM defector Frequency Meter.

vl
R

Q. Draw a schematic of a simple heterodyne
frequency meter with provision for monitoring

transmitter output.

A. The circuit in Fig. 2 is of an electroncoupled oscillator. /The frequency of the oscillator is determined by the parallel LC network in its grid circuit. (These components
must be selected for high stability for use in
a frequency meter.) The output of V1 (the
ECO) is coupled to the input of V2, the second stage, which is an AM detector. The
signal to be measured is also coupled to V2's

input, and the beat between the ECO and
the frequency being measured is heard in the
earphone. The ECO is adjusted for zero beat
with the transmitter's frequency, and the accurately measured frequency is read off the
ECO dial. Transmitter output (modulation)
can also be monitored by V2, which is then
acting only as an AM detector.
Q. What device is used to derive a
a I00 -kc oscillator?

signal from

SCREEN
DROPPING
RESISTOR

SCREEN
BYPASS
CAPACITOR

with increasing temperature. Here it is specified as 5 cps /mc /degree. The temperature
change is 25 degrees, so the frequency shift
is:
X 25 X 3.8 mc, or
475 cps (Hz).
So if the relationship is linear, the new frequency will be 3799.525 kc (KHz).

-5

HEAL,-

PLATE

%L1

10 -kc

PHONE

LOAD
RESISTOR

CATHODE

B+

BIAS RESISTOR

A. The device is called a frequency divider.
(See Fig. 3.) This is a type of multivibrator
(RC oscillator) that will lock -in on a submultiple of an input signal supplied to it.
The values of resistance and capacitance are
calculated to cause oscillation at the desired
frequency. A known- accurate signal is then
applied to one of the grids at some multiple
of the desired output, in this case 100 kc (or
KHz). If the input signal amplitude is great
enough the output signal will lock -in with
the input at some submultiple, and this output signal will have the same percentage of
accuracy as the input signal.
Q. Draw a schematic of a basic multivibrator.
A. See Fig. 3. The test will have a diagram
such as either of these, with something missing or drawn incorrectly. Study the sche-

matics carefully. Both circuits are identical
and both methods of drawing are correct
either may be used.
Q. For maximum stability, how should the
tuned circuit of a crystal be tuned?
A. At the exact plate -current dip point, or
resonance, the oscillator will be critical, and
slight circuit changes may cause it to stop
oscillating. If the tuned circuit is adjusted

Fig. 3. Basic multivibrator circuit can be drawn in more than
one way. In amplifier-like layout (below) Cl handles
feedback. Cross -coupled layout (left) is correct too.

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

to slightly above the resonant frequency, this
instability will be reduced or prevented.
Q. What advantage has a mercury thermostat (used for temperature -controlled crystals) compared to a bimetallic thermostat?
A. Mercury contacts are not subject to pitting or corrosion.
RFC

BIAS RESISTOR
V1

Q. At what frequency will an X -cut, 600 -kc
(KHz) crystal oscillate when it has been calibrated at 50- degrees Centigrade, has a
temperature coefficient of -20 parts per
million per degree, and its temperature has
been raised to 60- degrees Centigrade?
A. It will oscillate at 599.88 kc (KHz). The
temperature coefficient is -20 cps (Hz) per
mc (MHz) per degree. It will shift -200
cps per mc, or -200 X 0.6 = -120 cps.
Subtract this from the original frequency.
Q. What are the operating characteristics
of the electron -coupled oscillator?
A. The electron-coupled oscillator has its

PLATE
COUPLING

OUTPUT ;

Fig. 4. Hartley oscillator has tapped coil for
feedback voltage divider. Remember H for Hartley,
and H for Henry (unit of inductance in a coil).

Q. Draw a diagram of a Hartley and a Col pitts oscillator.
A. The Hartley oscillator is given in Fig.
the Colpitts in Fig. 5. These are shunt fed
oscillators. The diagrams on the test may be
either shunt or series fed. The tube may be
a triode or a pentode ECO.

input (or grid) circuitry buffered from the
variations in load which occur in the output
tube with a screen and
(plate) circuitry
suppressor grid is used. Interaction from output to input circuitry occurs through the
grid-to -plate capacitance of the tube. The
addition of the other grids substantially reduces this capacitance. Hence the stability
of the ECO is better than other types of LC
oscillators, but it still has less stability than
a crystal oscillator.

-a

a frequency meter known to have
a possible error of 0.1%, what is the highest
frequency on the 3500 -4000 kc band to
which an amateur transmitter can be safely
set?

Q. Using

A. The same simple formula that we used on
the crystal band -edge problem can be used
here:

frequency (indicated by meter)
= 4000/1 + 0.001
or for the low end of the band:
Fig. 5. Colpitts oscillator has series capacitors in
feedback voltage divider. Remember C for Colpitts,
and C for Capacitor and you can't go wrong.

Q. What precautions should be taken to
prevent a crystal from oscillating at a frequency other than its fundamental?
A. 1. Use a buffer amplifier between the oscillator and its load.
2. Regulate the plate voltage supplied to

the oscillator.
Keep the temperature of the crystal
constant.
4. Keep feedback in the oscillator to the
minimum needed to maintain oscilla3.

tions.
5. Keep all parts of the oscillator me-

chanically rigid.

frequency (indicated by meter)
= 3500/1 0.001
Do not add an error factor of 1.0 this time

since it was not specified.
Q. Why are quartz crystals sometimes operated in temperature controlled ovens?
A. Since the frequency of crystals vary with
temperature, the crystal temperature is kept
constant by enclosing the crystal in an insulated box (called an oven) which contains
a heater and a preset thermostat. Ovens are
usually purchased with the controlled temperature specified. Usual practice is to keep
the crystal temperature above the highest
possible ambient temperature that the unit
will encounter, in order to give the oven
thermostat a good control margin.
99

JULY- AUGUST, 1966

www.americanradiohistory.com

GAD FCC

Q &A

Q. What procedure should be followed if
it becomes necessary to replace the tube in

heterodyne frequency meter?
A. Changing any of the oscillator components will affect the calibration. It should be
a

checked and recalibrated if necessary.

Q. Explain, in detail, how oscillator frequency is measured, using a secondary

frequency standard.
A. The first step is to verify the accuracy of
the secondary standard. Tune in one of the
standard- frequency station on a receiver,
and loosely couple the secondary standard
to the receiver antenna. When the transmitted modulation goes off the carrier zerobeat the secondary standard against the carrier. When the modulation returns, you will

hear a flutter as the secondary standard beats
with the modulated carrier. Slightly adjust
the secondary standard until the flutter is as
slow as possible. (In some cases, an oscilloscope can be used to see the beat directly.)
Now zero beat the secondary standard with
the oscillator's frequency, following the man ufacturer's instruction for using the second ary standard. Use an oscilloscope to obtain
an exact zero -beat at the output of the mixer
in the secondary standard. If interpolation is

necessary, such as when the secondary stand and is crystal controlled and not variable,
feed the output of the mixer into the vertical
input of an oscilloscope. Connect an accurate audio oscillator to the other horizontal
input of the oscilloscope, and adjust the oscillator to get a known ratio Lissajous pat tern on the screen. Add this interpolated
frequency to the known frequency of the
crystal. Using this method it is necessary to
have a rough idea of the oscillator frequency
before making the measurement.

lt's a

"
. and where
did you get

that kit ?"

Woman's
World?
by

Jack Schmidt

"OK, you can get the antenna

rotor...

100

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

Civilian plans

for this

SATCOM

network are
still up in the
air but easily
set up units do
promise better
education for
underdeveloped
areas around
the world.

Was a day when you could build a radio
network and it would stay put. But that day,
alas, is now part of a dim and mildewed
past. For the new mode in networks is the
portable look. A network with transmitting
and receiving terminals that can be folded
up like a tinker toy, loaded on a plane, flown
half way round the world, unloaded, reassembled, and put back in business within 48
hours.
Come Fall of this year, a fleet of communication satellites will be launched into space
by the United States Army. These-the first
world-wide satellite communications -will
relay radio, teletype messages, and facsimile
photographs to portable terminals spotted
round the world. And each portable rigged
to transmit and receive over four voice
channels, four teletype channels at the same
time.
Designed and built by Hughes Aircraft
Corporation, the new type network is in
the Army now, but when it changes to civvies, it might well do its bit to aid the world.
For its principles converted to telecasting
might prove the missing lint in finishing the
needed world -television network.
For when SYNCOM became operational,
international television was feasible technically. But there was an important handicap.
One of the major motives in creating such a
network would be the intention to telecast

education to peoples in hungry areas of the
world, to help people help themselves.
For the screen could teach people to read,
write, and use simple tools in areas where
illiteracy breeds poverty. It could show the
people how to increase the yield from the
land, multiply their food supply to help meet
multiplying population needs.
But one thing lacking was the means to
place receivers in the backward areas, areas
handicapped by insufficient power supply,
and limited or non -existent transportation
facilities. Once this portable "network" design could be transferred to transmitting the
television picture, portable receiving stations,
transported by plane, could reach these remote areas.
Until we can see a portable television network, the new restless network will have to
win its stripes as the first world satellite communications network, limited now to military
use but promising all sorts of implications in
the future.
How the idea was conceived. It happened like this: With today's constantly
changing political, economic and military
climates, communications can no longer stay
static.
One day a transmitting- receiving "station"
may be needed in Alaska. A few weeks later,
one may be necessary in a remote spot in
Africa, or in the Far East. A few months
101

JULY-AUGUST, 1966

www.americanradiohistory.com

NETWORK ON PROWL

Cocoon -like radome, with one section peeled
open, houses ground -link terminal of SATCOM net.

AA111
later, none of these terminals may have any
use at all in their areas. But the Army cannot
travel around the world, building and then
abandoning transmitting- receiving stations.
The only practical solution: a portable
broadcasting network.
Hughes built a terminal station consisting
of a 40 -foot diameter parabolic antenna, the
largest of its kind in the world. Each antenna
is protected from hostile weather conditions
by a dual -wall inflatable radome 58 feet in
height. In operation, each antenna can withstand winds of 60 mph; when not in operation, it can withstand winds of 120 mph.
Three thirty -foot mobile vans service each
terminal, and three 100 kva Diesel generators supply power. An operations van carries control console and electronic equipment. A cargo van, the radome and reflector;
the maintenance van, spare parts and test
equipment.
One terminal is ready, built at Helemano,
Hawaii, 20 miles north of Honolulu. This
one will broadcast between Hawaii, and the
United States, serve as relay to and from
terminals spotted through the Western Pacific.

Another portable-also in the Army, and
also a brainchild of Hughes Aircraft
doesn't need a plane to get around. It travels
on the back of a soldier, has 10,000 voice
channels, and can strut its stuff in the densest jungle.

Technicians, dangling in bosun chairs (left),
are dwarfed by 40 -foot diameter parabolic antenna.
Air-transportable terminal is set up in 48 hours.

Called "Manpack," it is transistorized,
weighs a neat 29 pounds with wet cells, is
18 inches high, 12 inches wide, and 334
inches thick. The solid state pack has a 2
to 12 megacycle range, its channels offering
a frequency flexibility meant to confuse any

jamming enemy.
The portable's high frequency signals reflect from the ionosphere, to give longer
range than line -of- sight, so that its HF signals are effective in the most difficult mountain or jungle country where very high or
ultra-high signals would fail. Reason for its
plus portability is it can run on ordinary
flashlight type dry cell batteries or on wetcell batteries.
According to field tests, its influence
reaches far. Not around the world as the
portable network will, but one test broadcast succeeded between points 500 miles
apart. And Senior Vice -President of Hughes
Aircraft, C. Harper Brubaker, says, "We
even have received clear transmission at our
Fullerton (California) facility from a 'Manpack' broadcasting from more than 7500
miles away."
When this distance "Manpack" and the
traveling network turn civilian, will we see
a world -wide satellite network that will relegate our presentday stay -at -homes to an
antiquated past? A network that will broadcast from the most remote areas, hop around
the world at will.

102

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

CENTRAI,
REPORTING

Here we are again with a report on the
most interesting aspect of short wave listening, the "utility" stations. This includes all
radio transmitters with the exception of
broadcast stations and Hams.
Just for kicks this month, let's look at
some of the more interesting stations operated by U.S. and Canadian federal and state
governments.
For instance, there's a "mystery" net of
government stations which we keep hearing
on 5422.5 kc. Calls are KAE310 (in New
York), KAE311 (Boston), KAE312 (Miami), and others in San Juan, San Francisco, Honolulu, Seattle, San Diego, Chicago,
New Orleans. See if you can figure out who
operates this net. We know that it's the government, but which agency?
NBS. Do your friends have QSL cards
from the National Bureau of Standards station WWV? You can send them into tailspin by betting that you know NBS (National Bureau of Standards) stations which they
can't name. First they'll say WWVH (Hawaii), then WWVB and WWVL (Colorado). You'll still be two up on them. It's
never before appeared in print, and it isn't
generally known, but the NBS operates stations KGD28 (7975 kc) and KGD29
(10687.5 kc) in Sterling, Va. These aren't
WWV -type stations, but regular 2-way
'phone stations used to communicate with
the NBS office in Boulder, Colorado. Another little-known NBS station is KQ2XAU
(6080 kc) in Cincinnati, Ohio. Lord knows
why the station exists, but they can often
be heard with a "dead carrier" on the fre-

quency when it isn't being used by the Voice
of America station in Bethany, Ohio. The
callsign, KQ2XAU, is sent each half hour in
CW. They run 1,000 watts into a vertical
antenna. A QSL can be obtained by sending
a detailed reception report to the National
Bureau of Standards in Cincinnati.
The Canadian Government has a well
known "time" station which sends out a
nifty QSL. Station is CHU which operates
on a 24 -hour basis as follows 3330 kc (300
watts), 7335 kc (3 kw.), and 14670 (300
watts). Their time signals consist of a series
of CW dots, with voice announcements each
5 minutes. Send your reports to: Station
CHU, Dominion Observatory, Department
of Mines and Technical Surveys, Ottawa,
Ontario.
Weather. Stations of the United States
Weather Bureau offer interesting listening,
especially during the hurricane season. The
hurricane net operates on 2776 and 6977.5
kc and is really in full swing when the bigblow is at its height. Listen for these stations:
Athens, Ga.
KAE46
Nantucket, Mass.
KAE51
Cape Hatteras, N. C.
KEB86
Cape Hatteras, N. C.
KEB87
KGD64 Athens, Ga.
KGD68 New Orleans, La.
KGD72 Washington, D. C.
Nantucket, Mass.
KID75
New Orleans, La.
KOE26
KC6222 Mobile Station #2
There are plenty of other Weather Bureau stations besides this particular net, but
they aren't reported as frequently.
Right after a hurricane or any other major
emergency, you can dig the sounds of the
massive Civil Air Patrol radio network. The
CAP stations may be heard on 2374, 4467.5,
4507.5, 4585, and 26620 kc. Most of the
time the stations use "tactical" (name) calls
such as "Yellow Jacket 205," "Beaver Bird
(Continued on page 107)

CHU
THANK YOU

DOMINION OBJERVATORY
OTTAWA CANADA

FOR YOUR

REPORT OF THE DOMINION

OBSERVATORY'S VOICE

TIME SIGNAL OW-

3330 kc.
7335
14670 ke.

ke.

Nifty QSL from Canadian "time" station isn't hard
to get

if you're

set up in o good reception area.
103

JIILY-AIICIIBT, 1966

www.americanradiohistory.com

104

ELEMENTARY ELECTRONICS

www.americanradiohistory.com

Electronic "brains"
make the split -second
decisions for these
high -speed
passenger trains
for Canada.

For the first time in the long history of
transportation, we will apply "brains" to
running our railroads. For a new pushbutton
train, the first of its kind, a train that will
first a series of new -era models, will soon
make its debut.
When the World Exhibition in Montreal,
Canada, opens next year, a sleek, new six car automated passenger train, named Expo
Express, will pick up visitors at the Mackay
Pier in Montreal Harbor, speed them by
"brainpower" to the Fair site on an island
in the St. Lawrence River.
A streamlined job that will carry as many
as 30,000 passengers an hour, it will run on
electronic judgment and power 99- 44/100's
of its time, relying on the more fallible human variety for the remaining fraction.
The Thinking Man's Train. To get lowdown details on this exciting new train trend,
we went to VIPs in the Union Switch and
Signal Division of the Westinghouse Air
Brake Company, pappa- creator of the new
train. And we were told the master key to
the eight -car Montreal model will combine
electronic with human brain at the main control center.
A key dispatcher, or supervisor, will pushbutton the system of eight trains at the Fair
from a computer console. A huge illuminated
map hanging high on the center wall will
show where each train is at each second,
show its direction, destination and speed.
When the dispatcher sees Train A should
head for location B, he will press a button
that will light a sign standing on the platform next to the train signalled. The attendant in the train's cabin will watch for this
go- ahead, let passengers board, close the
elevator -type doors automatically, then push
still another button.
In response to this signal, wayside transmitters will send low- voltage, audio -frequency impulses down the uninsulated steel
rails. Impulses will be picked up inductively
from the rails by electronic hardware inside
the train, automatically controlling start,
speed and stop when preset destination is
reached.
The on -train mechanism that controls
propulsion power and brakes the train is a
servo -mechanism, a velocity control programmer answering commands from cab,
speed and wayside control. The attendant
inside his cab can watch speed on an indicator panel, check with the main console center
through a voice -communication set-up.
At the end of each system at the Fair, there

JULY-AUGUST, I966

105

www.americanradiohistory.com

HAVE BRAINS
Carryphone, a
2 -way radio unit
to be used for
communications between dispatcher,
station areas
and train personnel.

An artist's overall view of the WABCO
transit control center. A small control
console (lower right) faces the large
map display of the transit system. New
information is indicated automatically.
Position and speed of all trains can be
seen and changes made by pushbutton.

will be track stub -end terminals with diamond cross -over, switch -over set-ups. Interlocking will also be automatically controlled
so that trains will have their chosen station
berths as they move into terminal, the
switches positioned automatically for in -and-

out moving. This speedy system, WABCO
experts believe, will accommodate the most
passengers in the shortest period of time,
dispatching a train every 150 seconds.
The Weak Link-Man! Though Westinghouse Air Brake engineers claim they can
fully automate their wonder train now, they
have, in this generation stage, resorted in a
moment of temporary weakness, to limited
human assistance. For each attendant is
trained to take over manually in case of
what WABCO calls "abnormal" electronic
behavior assuring a "fail- safe" system for
passengers.
But while Expo will be faster, safer and
miles ahead of the chugging furnace that
first panted across the continent in the
eighties, its sophisticated ways will only forerunner "brainy" jobs we'll see in the future.
Things to Come. Next on the passenger
list, according to U. S. Department of Commerce sources, will be a fully- automated
whippet, absorbing many Expo tricks, that
will race across the country at speeds of 200
miles an hour and up. To travel such fantastic speeds, railroaders feel automatic
switch -over is a "must." The human brain
just can't think fast enough to guide a train
that determined. Only the electronic quiz kid can catch hep when serious problems
arise such as passenger jam -ups during storm time, or after a major sports event, or measuring distances between the speed demons,

or stopping the racers without lurch when
destination is reached.
Too, with multiplied populations in offing
within the next few years, creating megalopolitan areas where cities will blend into
cities from Boston to Washington, automatic
rendezvous will be needed. An express may
rendezvous often with spur trains moving in
on the main trunk line, or link with other
expresses, or switch to a separate track to
avoid a local.
To achieve such high-paced juggling, train
technicians say they intend to borrow from
space technology, adopt techniques learned
in the Gemini rendezvous program. Then
smaller-branch train -sections can link up
with mainliners regardless of pace. Though
train experts expect linking trains may well
prove more difficult than space maneuvers.
For a Gemini rendezvous is but a single
maneuver while an automated high -speed
train system will need make flawless rendezvous many times in 24 hours, regardless of
atmospheric conditions.
But when space technology does rendezvous with automated Expo systems, we will
see fantastic speed -up in service that will
make today's train as past -tense as the horse and- buggy. And while no one reálly expects
a future train to travel the speed of sound,
we can happily promise models that will attend the funeral of the old black monster we
know today.
And we predict it won't be two -three decades before today's archaic beast will only be
seen under the shed of a museum. While a
new robot -run fellow will race across the
country, run by pushbutton, one that will always keep its electronic head.
ELEMENTARY ELECTRONICS

106

www.americanradiohistory.com

MAD ABOUT MOD
A tiny solid-state device that virtually eliminates heat problems in microwave communications systems has been developed by
Sylvania Electric Products Inc. The device,
a MOD (Microwave Oscillating Diode),
smaller than a shirt button, will give engineers considerable latitude in designing and
packaging short -range, low -power microwave radar systems that can be used by astronauts during "docking" of space ships at
satellite stations. The MOD also could be
applied in automobile and boat collisioncontrol units; missile radar systems and for
transmitting television signals between orbiting spacecraft.
The experimental system's low -power microwave beam is generated by a tiny solid state device which is powered by a standard
30 -volt battery. Together, they represent apothullt11,1111111111n111111111111111111111111111,111,,,111,1111.,n1,

proximately 1 /50th the weight of comparable
equipment presently used to produce a microwave signal in commercially available
systems. The laboratory model was designed
by General Telephone & Electronics Laboratories Incorporated.

lM1 t

1$1111111111111,li,liiili,licilollloili11111111.11,1111,,,,,,,,iiiiiii.ttI.tiiii.iiiiiii,i,;,,,.,.ninim,

DX Central Reporting
Continued from page 103

23," "Star Fish 57," etc. There are probably
thousands of stations in operation on these
frequencies and you can make an entire DX
career out of listening to the CAP alone.
To the Rescue. The Royal Canadian
Mounted Police do quite a bit more than
chase Snideley Whiplash, you can even listen
to Dudley Doright (ta- tahhhh!!!) and his
friends conducting "Mountie" communications on a number of frequencies. Most frequently heard "Mountie" stations seem to be
reported on 4785 and 4895 kc. Most stations
heard are in the western provinces.
Getting Out. Getting away from the continental United States, the U. S. Navy operates station NGD at McMurdo Sound,
Antarctica. They were recently reported on

13874 kc around 0610 GMT working New
Zealand.
Another military station at a distant
"rare" location would be ABK in the Marshall Islands. Operated by the U.S. Army,
they are being reported on 9910 kc (0730
GMT), 13570 kc (0538 GMT), 16370 kc
(0420 GMT), and 17690 kc (0055 GMT).
You can take a whack at getting a QSL,
but there aren't any guarantees about getting one. Try: Chief Operator, Station
ABK, United States Army, Eniwetok, Marshall Islands.

We are looking forward to receiving reports from our readers concerning reception
of "utility" stations on either 'phone, SSB,
or CW. Please include the callsign, frequency (or approximate frequency), time (in
GMT), etc. You might even send along a
photo of your SWL shack. Who knows, you
might even become immortalized in our
pages.

I111111111111111111111111111111111111111,

Traffic

a Go Go

Continued from page 18

turned off or the cartridge is removed.
What's Available? There are already over 20
makes on the market today with new units popping up like dandelions. They vary from the
simple, early non-stereo 4-track hang -on models,
which cost approximately $60 installed, to recent
8 -track hang -on types offered at prices up to

$155 installed. Factory-installed cartridge tape
players are available in certain cars for about
$130-get the exact price from your new -car
dealer.
Tape cartridges have a bright future. Public
acceptance with its mass purchasing has lowered
the unit cost for cartridges to a level which is
competitive with LP's. The demand for home
units is on the increase -more and more tape
cartridges will be made, lowering the price to
where the LP will give ground and eventually
yield to the magnetic ,audio tape.

JULY -AUGUST, 1966

107

www.americanradiohistory.com

HEAiHi
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