Snap Circuits K 24 Users Manual REV D 7 23 02
2015-02-02
: Snap-Circuits Snap-Circuits-K-24-Users-Manual-492059 snap-circuits-k-24-users-manual-492059 snap-circuits pdf
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WHOOPER ALARM KIT MODEL K-24 Assembly and Instruction Manual Elenco Electronics, Inc. Copyright © 1989 Elenco Electronics, Inc. Revised 2002 REV-D 753224 PARTS LIST If you are a student, and any parts are missing or damaged, please see instructor or bookstore. If you purchased this whooper alarm kit from a distributor, catalog, etc., please contact Elenco Electronics (address/phone/e-mail is at the back of this manual) for additional assistance, if needed. RESISTORS Qty. 1 2 1 1 2 1 1 Symbol R8 R3, R6 R2 R5 R1, R9 R4 R7 Description 100W 5% 1/4W 1kW 5% 1/4W 2.2kW 5% 1/4W 6.8kW 5% 1/4W 15kW 5% 1/4W 22kW 5% 1/4W 27kW 5% 1/4W Color Code brown-black-brown-gold brown-black-red-gold red-red-red-gold blue-gray-red-gold brown-green-orange-gold red-red-orange-gold red-violet-orange-gold Part # 131000 141000 142200 146800 151500 152200 152700 CAPACITORS Qty. 2 2 Symbol C2, C3 C1, C4 Value .047mF (473) 100mF Description Discap Electrolytic Part # 244780 281044 SEMICONDUCTORS Qty. 3 1 1 Symbol Q1, Q3, Q4 Q2 Q5 Value 2N3904 2N3906 MPS6531 Description Transistor Transistor Transistor Qty. 1 1 1 1 1 2 Symbol Description PC Board Switch Slide SPDT Solder Roll 24” Battery Snap 9V Speaker 8W Wire 4” Blue Part # 323904 323906 326531 MISCELLANEOUS S1 B1 SPK1 Part # 518024 541102 551124 590098 590102 814620 PARTS IDENTIFICATION Resistor Transistor Capacitors Battery Snap Discap Electrolytic -1- Speaker Switch IDENTIFYING RESISTOR VALUES Use the following information as a guide in properly identifying the value of resistors. BAND 1 1st Digit Color Black Brown Red Orange Yellow Green Blue Violet Gray White Multiplier BAND 2 2nd Digit Digit 0 1 2 3 4 5 6 7 8 9 Color Black Brown Red Orange Yellow Green Blue Violet Gray White Resistance Tolerance Color Multiplier Black 1 Brown 10 Red 100 Orange 1,000 Yellow 10,000 Green 100,000 Blue 1,000,000 Silver 0.01 Gold 0.1 Digit 0 1 2 3 4 5 6 7 8 9 Color Silver Gold Brown Red Orange Green Blue Violet Tolerance +10% +5% +1% +2% +3% +.5% +.25% +.1% BANDS 1 2 Multiplier Tolerance IDENTIFYING CAPACITOR VALUES Capacitors will be identified by their capacitance value in pF (picofarads), nF (nanofarads), or mF (microfarads). Most capacitors will have their actual value printed on them. Some capacitors may have their value printed in the following manner. The maximum operating voltage may also be printed on the capacitor. Multiplier For the No. 0 1 2 3 Multiply By 1 10 100 1k 4 5 8 10k 100k .01 10mF 16V First Digit 9 0.1 Note: The letter “R” may be used at times to signify a decimal point; as in 3R3 = 3.3 Second Digit Multiplier 103K Tolerance 100V The letter M indicates a tolerance of +20% The letter K indicates a tolerance of +10% The letter J indicates a tolerance of +5% Maximum Working Voltage The value is 10 x 1,000 = 10,000pF or .01mF 100V METRIC UNITS AND CONVERSIONS Abbreviation p n m m – k M Means Pico nano micro milli unit kilo mega Multiply Unit By .000000000001 .000000001 .000001 .001 1 1,000 1,000,000 Or 10-12 10-9 10-6 10-3 100 103 106 1. 1,000 pico units = 1 nano unit 2. 1,000 nano units = 1 micro unit 3. 1,000 micro units= 1 milli unit 4. 1,000 milli units = 1 unit 5. 1,000 units = 1 kilo unit 6. 1,000 kilo units = 1 mega unit -2- MINIATURE RADIO TRANSMITTER The Whooper Alarm puts out a wavering sound that is sure to startle an intruder. It can be used independently or as an accessory to the Burglar Alarm Kit K-23. The Whooper Alarm circuit consists of two oscillators, a low frequency oscillator which drives a higher frequency unit at a predetermined rate. The high frequency oscillator drives an output transistor which powers the speaker. CIRCUIT OPERATION Figure 1 shows the circuits of the low frequency oscillator. When the power is first applied to this circuit, transistors Q1 and Q2 will not conduct. This is because the base of transistor Q2 is about 5.4V while the emitter is at zero volts. A current is flowing in resistor R2 charging capacitor C1. When the voltage across C1 reaches 6V, transistor Q2 starts sending a current in the collector of Q1. The current in the collector of Q1 is mulitplied by the gain of transistor Q1 and this rapidly turns on transistor Q2. Capacitor C1 quickly discharges through resistor R8 as shown in Figure 2. Note that C1 charges through a 2200W resistor R2, but discharges through a 100W resistor R8. Thus, the charge to discharge ratio is 22:1. When C1 is discharged, Q1 and Q2 turn off and the whole cycle repeats itself. Figure 1 HIGH FREQUENCY OSCILLATOR The circuit of the high frequency oscillator is shown in Figure 3. Transistors Q3 and Q4 are wired as amplifier stages. The bias for these amplifiers are controlled by the sawtooth of Figure 2. These amplifiers normally would amplify the low frequency pulses, except for the addition of capacitor C3. This capacitor takes the output of Q4 and feeds it in phase to the input of Q3. This causes the circuit to oscillate. The frequency of oscillation is controlled by the RC time constants of C3 and R6. The frequency of oscillation is about 1,000 cycles per second. This frequency is modulated with the low frequency oscillations to produce the Whooper Alarm sounds. Transistor Q5 further amplifies the signals and drives the speaker. Figure 3 -3- Volts Time Figure 2 CONSTRUCTION Introduction The most important factor in assembling your K-24 Whooper Alarm Kit is good soldering techniques. Using the proper soldering iron is of prime importance. A small pencil type soldering iron of 25 - 40 watts is recommended. The tip of the iron must be kept clean at all times and well tinned. Safety Procedures • Wear eye protection when soldering. • Locate soldering iron in an area where you do not have to go around it or reach over it. • Do not hold solder in your mouth. Solder contains lead and is a toxic substance. Wash your hands thoroughly after handling solder. • Be sure that there is adequate ventilation present. Assemble Components In all of the following assembly steps, the components must be installed on the top side of the PC board unless otherwise indicated. The top legend shows where each component goes. The leads pass through the corresponding holes in the board and are soldered on the foil side. Use only rosin core solder of 63/37 alloy. DO NOT USE ACID CORE SOLDER! What Good Soldering Looks Like Types of Poor Soldering Connections A good solder connection should be bright, shiny, smooth, and uniformly flowed over all surfaces. 1. Solder all components from the copper foil side only. Push the soldering iron tip against both the lead and the circuit board foil. 1. Insufficient heat - the solder will not flow onto the lead as shown. Soldering Iron Component Lead Foil Soldering iron positioned incorrectly. Circuit Board 2. 3. 4. Apply a small amount of solder to the iron tip. This allows the heat to leave the iron and onto the foil. Immediately apply solder to the opposite side of the connection, away from the iron. Allow the heated component and the circuit foil to melt the solder. Allow the solder to flow around the connection. Then, remove the solder and the iron and let the connection cool. The solder should have flowed smoothly and not lump around the wire lead. Rosin 2. Insufficient solder - let the solder flow over the connection until it is covered. Use just enough solder to cover the connection. Soldering Iron Solder Foil Solder Gap Component Lead Solder 3. Excessive solder - could make connections that you did not intend to between adjacent foil areas or terminals. Soldering Iron Solder Foil 4. Solder bridges - occur when solder runs between circuit paths and creates a short circuit. This is usually caused by using too much solder. To correct this, simply drag your soldering iron across the solder bridge as shown. Here is what a good solder connection looks like. -4- Soldering Iron Foil Drag ASSEMBLE COMPONENTS TO THE PC BOARD SPK - Speaker: Cut two 4” wires and strip 1/8” of insulation off of both wires. Solder a wire to each lug of the speaker and then insert the other end of the wires to the PC board in the place shown on the top legend. Black Jumper Wire (see Figure C) Red Q3 - 2N3904 Transistor (see Figure A) B1 - Battery Snap: Insert the red wire into the positive (+) hole and the black wire into the negative hole. Solder and cut off the excess leads. C4 - 100mF Electrolytic Cap. R3 - 1kW 5% 1/4W Resistor (brown-black-red-gold) S1 - Slide Switch R6 - 1kW 5% 1/4W Resistor (brown-black-red-gold) Q1 - 2N3904 Transistor (see Figure A) C3 - .047mF (473) Discap R1 - 15kW 5% 1/4W Resistor (brown-green-orange-gold) Q4 - 2N3904 Transistor (see Figure A) Q2 - 2N3906 Transistor (see Figure A) Q5 - MPS 6531 Transistor (see Figure A) R5 - 6.8kW 5% 1/4W Resistor (blue-gray-red-gold) R9 - 15kW 5% 1/4W Resistor (brown-green-orange-gold) R4 - 22kW 5% 1/4W Resistor (red-red-orange-gold) R8 - 100W 5% 1/4W Resistor (brown-black-brown-gold) C2 - .047mF (473) Discap R2 - 2.2kW 5% 1/4W Resistor (red-red-red-gold) C1 - 100mF Electrolytic Cap. (see Figure B) R7 - 27kW 5% 1/4W Resistor (red-violet-orange-gold) Figure A Figure B Figure C Mount the transistor with the flat side in the same direction as shown on the PC board. Solder and cut off the excess leads. Electrolytic capacitors have polarity. Be sure to mount them with the negative (–) lead (marked on side) in the correct hole. Use a discarded resistor lead to form a jumper wire. Flat Polarity Marking Foil Side of PC Board -5- TROUBLESHOOTING Consult your instructor or contact Elenco Electronics if you have any problems. DO NOT contact your place of purchase as they will not be able to help you. 1. One of the most frequently occurring problems is poor solder connections. a) Tug slightly on all parts to make sure that they are indeed soldered. b) All solder connections should be shiny. Resolder any that are not. c) Solder should flow into a smooth puddle rather than a round ball. Resolder any connection that has formed into a ball. d) Have any solder bridges formed? A solder bridge may occur if you accidentally touch an adjacent foil by using too much solder or by dragging the soldering iron across adjacent foils. Break the bridge with your soldering iron. COMPONENT CHECK 1. Be sure that all of the components have been mounted in their correct places. 2. Be sure that the electrolytic capacitors C1 and C4 have been installed correctly. These capacitors have polarity, the negative and positive leads must be in the correct holes, as shown on the top legend of the PC board. 3. Be sure that transistors Q1 - Q5 have been installed correctly. The flat side should be in the same direction as shown on the top legend. 4. Use a fresh 9 volt battery. 5. Read the circuit operation lesson manual to familiarize yourself with the workings of the circuit. SCHEMATIC DIAGRAM -6- QUIZ 1. The Whooper Alarm has ___________ oscillators. 2. The low frequency oscillations are generated by transistors __________ and __________. 3. The high frequency oscillations are generated by transistors __________ and __________. 4. When the power is first turned on, the voltage at the base of Q2 is ___________. 5. When the power is first turned on, the voltage across C1 is ___________. 6. Capacitor C1 charges through resistor _______ and discharges through resistor __________. 7. The charge to discharged ratio on C1 is ___________. 8. Capacitor C3 causes transistor Q3 and Q4 to _____________. 9. The frequency of oscillation of Q3 and Q4 is about ____________ cycles per second. 10. The speaker is driven by transistors ________ and ________. Answers: 1) two; 2) Q1, Q2; 3) Q3, Q4; 4) 5.4V; 5) zero; 6) R2, R8; 7) 22:1; 8) oscillate; 9) 1,000; 10) Q4, Q5 Elenco Electronics, Inc. 150 W. Carpenter Avenue Wheeling, IL 60090 (847) 541-3800 http://www.elenco.com e-mail: elenco@elenco.com
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