Snap Circuits K-24 User's Manual
Contents
1. 1 micro unit 1 000 micro units 1 milli unit 001 1 000 milli units 1 unit 1 1 000 1 000 000 1 000 units 1 kilo unit 1 000 kilo units 1 mega unit 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 22000 resistor R2 but discharges through a 1000 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 HIGH FREQUENCY OSCILLATOR T2. 42200 146800 151500 152200 152700 Part 244780 281044 Part 323904 323906 326531 Part 518024 541102 551124 590098 590102 814620 IDENTIFYING RESISTOR VALUES Use the following information as a guide in properly identifying the value of resistors BAND 2 2nd Digit Resistance Tolerance Color igi Color Multiplier Tolerance Black 10 Brown 1 15 Rea 2 Red 100 195 Orang 1 000 _ 2 Yellow 10 000 Green Blue Blue 6 Viole Gray Gray 8 White Wie o BANDS 1 2 Multiplier Tolerance IDENTIFYING CAPACITOR VALUES Capacitors will be identified by their capacitance value pF picofarads nF nanofarads or uF 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 ame Fomor 4 Note The letter R may be used at times First Digit oe to signify a decimal point as 3R3 3 3 Second Digit Multiplier Talatang The letter M indicates a tolerance of 20 The letter K indicates a tolerance of 10 The letter J indicates a tolerance of 5 b Maximum Working Voltage The value is 10 x 1 000 10 000pF or 01uF 100V METRIC UNITS AND CONVERSIONS Multiply Unit By 000000000001 000000001 000001 67 Abbreviation 1 000 pico units 1 nano unit 1 000 nano units
3. WHOOPER ALARM KIT 7 Assembly and Instruction Manual Elenco Electronics Inc Copyright 1989 Elenco Electronics Inc 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 Qty lt a Qty e e e Symbol R8 R3 R6 R2 R5 R1 R9 R4 R7 Symbol C2 C3 C1 C4 Symbol Q1 Q3 Q4 Q2 Q5 Symbol S1 B1 SPK1 RESISTORS 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 Description 1000 5 1 4W 1kQ 5 1 4W 2 2kKQ 5 1 4W 6 8kQ 5 1 4W 15 5 1 4W 22kQ 5 1 4W 27 5 1 4W CAPACITORS Value Description 047uF 473 Discap 100uF Electrolytic SEMICONDUCTORS Value Description 2N3904 Transistor 2N3906 Transistor MPS6531 Transistor MISCELLANEOUS Description PC Board Switch Slide SPDT Solder Roll 24 Battery Snap 9V Speaker 80 Wire 4 Blue PARTS IDENTIFICATION Speaker Switch Discap Electrolytic Part 131000 141000 1
4. dentally 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 2N3904 56551 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 __ __ 4 When the power is first turned 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 Elenco Electron
5. he 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 Figure 1 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 e Wear eye protection when soldering e Locate soldering iron in an area where you do not have to go around it or reach over it e 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
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7. iron and let the connection cool The solder should have flowed smoothly and not lump around the wire lead 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 4 Here is what a good solder connection looks like LL 222222222 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 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 Jumper Wire see Figure C Q3 2N3904 Transistor see Figure A SPK kag JUMPER o R3 1kQ 5 1 4W Resistor brown black red gold R6 1kQ 5 1 4W Resistor brown black red gold 047uF 473 Discap O Q4 2N3904 Transistor see Figure A Q5 MPS 6531 Transistor see Figure A R9 15 5 1 4W Resistor brown green orange gold R8 1009 5 1 4W Resistor brown black brown gold C2 047uF 473 Discap O C1 100uF Electrolytic Cap see Figure B Figure A Figure B Figure C Mount the transistor with the Electrol
8. 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 Soldering Iron 1 Insufficient heat the the copper foil side only Push the soldering iron tip against both the lead and the circuit board foil LILI 2222224 solder will not flow onto the Component Lead lead as shown Soldering iron positioned incorrectly Circuit Board 2 Insufficient solder let the Soldering Iron solder flow over the connection until it is covered Use just enough solder to cover the connection 2 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 3 Excessive solder could make connections that you Solder did not intend to between adjacent foil areas or 3 Allow the solder to flow terminals around the connection Then remove the solder and the
9. ytic capacitors have Lice aiiecarded resistor lead flat side in the same direction polarity Be sure to mount to form a jumper wire as shown on the PC board them with the negative Solder and cut off the excess lead marked on side in the SS ss leads correct hole 51 Slide Switch Q1 2N3904 Transistor see Figure A O R1 15kQ 5 1 4W Resistor brown green orange gold Q2 2N3906 Transistor see Figure A R5 6 8kQ 5 1 4W Resistor blue gray red gold R4 22kQ 5 1 4W Resistor red red orange gold R2 2 2kQ 5 1 4W Resistor red red red gold R7 27kQ 5 1 4W Resistor red violet orange gold Flat i Marking Foil Side of PC Board 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 acci
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