Elenco Electronics Electronic Snap Circuits Pro SC-500 User manual

Copyright © 2012, 2010 by Elenco®Electronics, Inc. All rights reserved. No part of this book shall be reproduced by 753104
any means; electronic, photocopying, or otherwise without written permission from the publisher. REV-D Revised 2012
Project 317

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Table of Contents
Basic Troubleshooting 1
Parts List 2
MORE AboutYour Snap Circuits®Parts 3, 4
MORE Advanced Troubleshooting 4
MORE DO’s and DON’Ts of Building Circuits 5
Project Listings 6, 7
Projects 306-511 8 - 61
Other Snap Circuits®Products 62
1. Most circuit problems are due to incorrect assembly.
Always double-check that your circuit exactly
matches the drawing for it.
2. Be sure that parts with positive/negative markings are
positioned as per the drawing.
3. Be sure that all connections are securely snapped.
4. Try replacing the batteries.
5. If the motor spins but does not balance the fan, check
the black plastic piece with three prongs on the motor
shaft. Be sure that it is at the top of the shaft.
Elenco®is not responsible for parts damaged due to
incorrect wiring.
Basic Troubleshooting
Note: If you suspect you have damaged parts, you can
follow the Advanced Troubleshooting procedure on page 4
to determine which ones need replacing.
Review of HowTo Use It (See page 3 of the Projects 1-101 manual for more details.)
The Snap Circuits®kit uses building blocks with snaps
to build the different electrical and electronic circuits in
the projects. These blocks are in different colors and
have numbers on them so that you can easily identify
them. The circuit you will build is shown in color and
with numbers, identifying the blocks that you will use
and snap together to form a circuit.
Next to each part in every circuit drawing is a small
number in black. This tells you which level the
component is placed at. Place all parts on level 1 first,
then all of the parts on level 2, then all of the parts on
level 3, etc.
A large clear plastic base grid is included with this kit
to help keep the circuit block together. The base has
rows labeled A-G and columns labeled 1-10.
Install two (2) “AA” batteries (not included) in the
battery holder (B1). The 2.5V and 6V bulbs come
packaged separate from their sockets. Install the 2.5V
bulb in the L1 lamp socket, and the 6V bulb in the L2
lamp socket.
Place the fan on the motor (M1) whenever that part is
used, unless the project you are building says not to
use it.
Some circuits use the red and black jumper wires to
make unusual connections.Just clip them to the metal
snaps or as indicated.
Note: While building the projects, be careful not to
accidentally make a direct connection across the
battery holder (a “short circuit”), as this may damage
and/or quickly drain the batteries.
WARNING: SHOCK HAZARD -
Never connect Snap Circuits®to
the electrical outlets in your home
in any way!
WARNING FOR ALL PROJECTS WITH A SYMBOL
Moving parts.Do not touch the motor or fan during operation.Do not lean
over the motor. Do not launch the fan at people, animals, or objects. Eye
protection is recommended.
!!
WARNING: CHOKING HAZARD -
Small parts.
Not for children under 3 years.
!
Batteries:
• Use only 1.5V AA type, alkaline batteries
(not included).
• Insert batteries with correct polarity.
• Non-rechargeable batteries should not
be recharged. Rechargeable batteries
should only be charged under adult
supervision, and should not be
recharged while in the product.
• Do not mix alkaline, standard (carbon-
zinc), or rechargeable (nickel-cadmium)
batteries.
• Do not mix old and new batteries.
• Remove batteries when they are used up.
• Do not short circuit the battery terminals.
• Never throw batteries in a fire or attempt
to open its outer casing.
• Batteries are harmful if swallowed, so
keep away from small children.
• Do not connect batteries or battery
holders in parallel.
!WARNING: Always check your wiring before
turning on a circuit. Never leave a circuit
unattended while the batteries are installed. Never
connect additional batteries or any other power
sources to your circuits. Discard any cracked or
broken parts.
Adult Supervision: Because children’s abilities
vary so much, even with age groups, adults should
exercise discretion as to which experiments are
suitable and safe (the instructions should enable
supervising adults to establish the experiment’s
suitability for the child). Make sure your child reads
and follows all of the relevant instructions and
safety procedures, and keeps them at hand for
reference.
This product is intended for use by adults and
children who have attained sufficient maturity to
read and follow directions and warnings.
Never modify your parts, as doing so may disable
important safety features in them, and could put
your child at risk of injury.
!

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Qty. ID Name Symbol Part # Qty. ID Name Symbol Part #
r32-Snap Wire 6SC02 r1Analog Meter 6SCM2
r15-Snap Wire 6SC05 r1SCR 6SCQ3
r1Diode
1N4001 6SCD3 r1Relay 6SCS3
r17-Segment
LED
Display 6SCD7 r1Transformer 6SCT1
r1FM Module 6SCFM r1Recording
Integrated
Circuit 6SCU6
You may order additional / replacement parts at our website: www.snapcircuits.net
Q3
M2
FM
D3
5
2
S3
T1
U6
D7
Note: There are additional part lists in your other project manuals. Part designs are subject to change without notice.
Important: If any parts are missing or damaged, DO NOT RETURN TO RETAILER. Call toll-free [phone] or e-mail us at:
[e-mail]. Customer Service • 150 Carpenter Ave. • Wheeling, IL 60090 U.S.A.
Parts List (Colors and styles may vary) Symbols and Numbers

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(Part designs are subject to change without notice).
The FM module (FM) contains an integrated FM radio circuit.
Refer to the figure below for the pinout description:
The meter (M2) is a very important indicating and measuring
device. You’ll use it to measure the amount of current or voltage
depending on the circuit configuration. Notice the meter has a “+”
sign, indicating the positive terminal (+ power from the batteries).
The other snap is the negative terminal (– power return to
batteries). The meter has a switch to change between scales,
indicated as LOW and HIGH (or 10mA and 1A).
The recording IC module (U6) contains an integrated recording
circuit. You can record a message up to five seconds long. There
are also three pre-recorded songs. Refer to the figure below for the
pinout descriptions:
The relay (S3) is an electronic switch with contacts that can be
closed or opened. It contains a coil that generates a magnetic field
when current flows through it. The magnetic field attracts an iron
armature, which switches the contacts (see figure).
The transformer (T1) consists of two coil windings on one core.
One coil is called the Primary (input) and the other the Secondary
(output). The purpose of the transformer is to increase the amount
of AC voltage applied to the primary. This transformer is a step-up
transformer.
Diode (D3) - Think of a diode as a one-way valve that permits
current flow in the direction of the arrow. The anode (arrow) is the
positive side, and the cathode (bar) is the negative. The diode
conducts or turns on when the voltage at the anode is 0.7V or
greater.
MORE AboutYour New Snap Circuits®Parts (Note: There is additional information in your other project manuals).
(+)
OUT(–)
FM Module:
(+) - power from batteries
(–) - power return to batteries
T - tune up
R - reset
OUT - output connection
See project #307 for example of
proper connections.
(+)
OUT
(–)
Recording IC Module:
(+) - power from batteries
(–) - power return to batteries
RC - record
Play - play
OUT - output connection
Mic + - microphone input
Mic – - microphone input
See project #308 for example of
proper connections.
RCPlay
Mic –
Mic +
COM Relay:
Coil - connection to coil
Coil - connection to coil
NC - normally closed contact
NO - normally open contact
COM - Common
See project #341 for example of
proper connections.
Coil
Coil NO
NC
B
CTB
Transformer:
A - less windings side
A - less windings side
B - more windings side
B - more windings side
CT - center tap
See project #347 for example of
proper connections.
A
A
Anode
Diode:
Anode - (+)
Cathode - (–)
Cathode
(+)
(–)
Meter:
(+) - power from batteries
(–) - power return to batteries
Less Windings
More Windings
Our Student Guides give much more information about your parts, along with a complete lesson in basic electronics. See www.snapcircuits.net/learn.htm or page 62 for more information.

Elenco®is not responsible for parts damaged due to incorrect wiring.
If you suspect you have damaged parts, you can follow this procedure to systematically
determine which ones need replacing:
1 - 20. Refer to project manuals 1 & 2 (projects #1-101, #102-305) for testing steps 1-20, then
continue below.
21. FM Module (FM): Build project #307, you should hear FM radio stations.
22. Meter (M2): Build the mini-circuit shown here and set the meter switch
to LOW (or 10mA), the meter (M2) should deflect full scale. Then, replace
the 10kΩresistor (R4) with the 2.5V lamp (L1), and set the meter switch
to HIGH (or 1A). The meter should deflect to 1 or higher.
23. Recording IC (U6): Build project #308. Make an 8 second recording, then listen to the three
prerecorded songs.
24. Relay (S3): Build project #341. The red LED (D1) should be on when the slide switch (S1) is
on, and the green LED (D2) should be on when the switch is off.
25. Transformer (T1): Build the mini-circuit shown here.
Pressing the press switch (S2) flashes the green LED
(D2). Connect the jumper wire to the CT point. Pressing
the press switch flashes the green LED.
26. Diode (D3): Build the mini-circuit shown here, the red LED (D1) should
light. Reverse the direction of the diode, the LED should not light now.
27. SCR (Q3): Build the mini-circuit shown here. Turn on the slide
switch (S1) and the motor (M1) should not spin. Press the press
switch (S2), the motor should start spinning. Now turn the slide
switch off and on, the motor should not spin.
28. 7-Segment Display (D7): Build project #337. All segments light, displaying the number 8.
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SCR (Q3) - An SCR is a three-pin (anode, cathode
and gate) silicon-controlled rectifier diode. Like a
standard diode, it permits current flow in only one
direction. It will only conduct in the forward direction
when triggered by a short pulse (or steady voltage
applied) between the gate and cathode terminals.
A
high current may damage this part, so the current
must be limited by other components in the
circuit.
The 7-segment display (D7) is found in many
devices today. It contains 7 LED’s that have been
combined into one case to make a convenient
device for displaying numbers and some letters. The
display is a common anode version. That means
that the positive leg of each LED is connected to a
common point which is the snap marked “+”. Each
LED has a negative leg that is connected to one
snap. To make it work you need to connect the “+”
snap to positive three volts. Then to make each
segment light up, connect the snaps of each LED to
ground. In the projects, a resistor is always
connected to the “+”snap to limit the current.
A high
current may damage this part, so the current must
be limited by other components in the circuit.
SCR:
A - Anode
K - Cathode
G - Gate
7-segment Display:
(+) - power from batteries
A - Segment A
B - Segment B
C - Segment C
D - Segment D
E - Segment E
F - Segment F
G - Segment G
DP - Decimal Point
See project #337 for example
of proper connections.
MORE Advanced Troubleshooting (Adult supervision recommended) MORE AboutYour Snap
Circuits®Parts (continued)

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MORE DO’s and DON’Ts of Building Circuits
After building the circuits given in this booklet, you may wish to experiment on your own. Use
the projects in this booklet as a guide, as many important design concepts are introduced
throughout them. Every circuit will include a power source (the batteries), a resistance
(which might be a resistor, lamp, motor, integrated circuit, etc.), and wiring paths between
them and back. You must be careful not to create “short circuits” (very low-resistance paths
across the batteries, see examples below) as this will damage components and/or quickly
drain your batteries.Only connect the IC’s using configurations given in the projects,
incorrectly doing so may damage them. Elenco®is not responsible for parts damaged
due to incorrect wiring.
Here are some important guidelines:
ALWAYS USE EYE PROTECTION WHEN EXPERIMENTING ONYOUR OWN.
ALWAYS include at least one component that will limit the current through a circuit, such
as the speaker, lamp, whistle chip, capacitors, IC’s (which must be connected
properly), motor, microphone, photoresistor, or fixed resistors.
ALWAYS use the 7-segment display, LED’s, transistors, the high frequency IC, the SCR,
the antenna, and switches in conjunction with other components that will
limit the current through them. Failure to do so will create a short circuit
and/or damage those parts.
ALWAYS connect the adjustable resistor so that if set to its 0 setting, the current will be
limited by other components in the circuit.
ALWAYS connect position capacitors so that the “+” side gets the higher voltage.
ALWAYS disconnect your batteries immediately and check your wiring if something
appears to be getting hot.
ALWAYS check your wiring before turning on a circuit.
ALWAYS connect IC’s, the FM module, and the SCR using configurations given in
the projects or as per the connection descriptions for the parts.
NEVER try to use the high frequency IC as a transistor (the packages are similar, but the
parts are different).
NEVER use the 2.5V lamp in a circuit with both battery holders unless you are sure that
the voltage across it will be limited.
NEVER connect to an electrical outlet in your home in any way.
NEVER leave a circuit unattended when it is turned on.
NEVER touch the motor when it is spinning at high speed.
Note: If you have the more advanced Model SC-750, there are additional guidelines in your
other project manual.
For all of the projects given in this book, the parts may be arranged in different ways without
changing the circuit. For example, the order of parts connected in series or in parallel does
not matter — what matters is how combinations of these sub-circuits are arranged together.
Examples of SHORT CIRCUITS - NEVER DO THESE!!!
You are encouraged to tell us about new circuits you create. If they are
unique, we will post them with your name and state on our website at
www.snapcircuits.net/kidkreations.htm. Send your suggestions to
Elenco®.
Elenco®provides a circuit designer so that you can make your own Snap
Circuits®drawings. This Microsoft®Word document can be downloaded
from www.snapcircuits.net/SnapDesigner.doc or through the
www.snapcircuits.net web site.
WARNING: SHOCK HAZARD - Never connect Snap Circuits®to
the electrical outlets in your home in any way!
Placing a 3-snap wire directly
across the batteries is a
SHORT CIRCUIT.
This is also a
SHORT CIRCUIT.
When the slide switch (S1) is turned on, this large circuit has a SHORT
CIRCUIT path (as shown by the arrows). The short circuit prevents any
other portions of the circuit from ever working.
NEVER
DO!
Warning to Snap Rover owners: Do not connect your parts to the
Rover body except when using our approved circuits, the Rover
body has a higher voltage which could damage your parts.
!
!NEVER
DO!
!
!
!
NEVER
DO! NEVER
DO!

Project # Description Page #
306 AM Radio 8
307 Adjustable Volume FM Radio 8
308 Playback & Record 9
309 Playing Music 9
310 Light-Controlled Music 9
311 Touch-Controlled Music 9
312 Power Playback & Record 10
313 Power Amplified Playing Music 10
314 Power Light-Controlled Music 10
315 Power Touch-Controlled Music 10
316 FM Radio 11
317 Mega Circuit 11
318 SCR 2.5V Bulb 12
319 SCR & Motor 12
320 Music Alarm 13
321 Light-Music Alarm 13
322 Light-Controlled SCR 13
323 3mA Meter 14
324 0-3V Meter 14
325 Function of adjustable resistor 15
326 Function of Photoresistor 15
327 Meter Deflect by Motor 16
328 SCR 6V Bulb 16
329 Principle of Segment LED 17
330 Display #1 17
331 Display #2 17
332 Display #3 17
333 Display #4 17
334 Display #5 18
335 Display #6 18
336 Display #7 18
337 Display #8 18
338 Display #9 18
339 Display #0 18
Project # Description Page #
340 Music Meter 18
341 LED & Relay 19
342 Manual 7 Second Timer 19
343 Half Wave Rectifier Circuit 20
344 Half Wave Rectifier Circuit (II) 20
345 LED vs. Diode 20
346 Current & Resistance 20
347 Telegraph 21
348 Mosquito Sound 21
349 Mosquito Sound (II) 21
350 Mosquito Sound (III) 21
351 Touch-Control Mosquito Sound 21
352 Bulb & Relay 22
353 Relay Buzzer 22
354 Transistor Timer 23
355 Light-Controlled Relay 23
356 Bulb Alert Relay 23
357 Adjustable Light Control 24
358 Meter Deflection 24
359 AC to DC Current 25
360 Current Meter 25
361 Buzzer, Relay, & Transformer 26
362 Buzzer & Relay 26
363 Display Capital Letter “F” 27
364 Display Capital Letter “H” 27
365 Display Capital Letter “P” 27
366 Display Capital Letter “S” 27
367 Display Capital Letter “U” 27
368 Display Capital Letter “C” 27
369 Display Capital Letter “E” 27
370 Display “.” 27
371 Display Letter “b” 28
372 Display Letter “c” 28
373 Display Letter “d” 28
Project # Description Page #
374 Display Letter “e” 28
375 Display Letter “h” 28
376 Recorded Voice Transmitter 28
377 Space War Alarm by SCR 29
378 Light Space War Alarm 29
379 Alarm by SCR 29
380 Light & Alarm IC 29
381 Delay Light 30
382 Delay Fan 30
383 Sound Activated Fan 30
384 Recording LED Indicator 31
385 Playback & Record with Meter 31
386 Alarm Light 32
387 Alarm Light (II) 32
388 Night Police Car 33
389 Night Machine Gun 33
390 Night Fire Engine 33
391 Night Ambulance 33
392 Daytime Light Police Car 34
393 Daytime Light Machine Gun 34
394 Daytime Light Fire Engine 34
395 Daytime Light Ambulance 34
396 Flashing 8 35
397 Flashing 8 with Sound 35
398 Musical Space War 35
399 Electronic Noisemaker 36
400 Electronic Noisemaker (II) 36
401 Bee 36
402 Bee (II) 36
403 Bee (III) 36
404 Oscillator Sound 37
405 Oscillator Sound (II) 37
406 Oscillator Sound (III) 37
407 Oscillator Sound (IV) 37
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Project Listings

-7-
Project # Description Page #
408 Oscillator Sound (V) 37
409 Transistor Tester 38
410 Adjustable Voltage Divider 38
411
Automatic Display Capital Letter “C” 39
412
Automatic Display Capital Letter “E” 39
413
Automatic Display Capital Letter “F” 39
414
Automatic Display Capital Letter “H” 39
415
Automatic Display Capital Letter “P”
39
416
Automatic Display Capital Letter “S”
39
417
Automatic Display Capital Letter “U”
39
418
Automatic Display Capital Letter “L”
39
419 Whistle Chip Sounds 40
420 Whistle Chip Sounds (II) 40
421 Whistle Chip Sounds (III) 40
422 Whistle Chip Sounds (IV) 40
423 Whistle Chip Sounds (V) 40
424 Whistle Chip Sounds (VI) 40
425 LED Music 41
426
Light-Controlled LED Time Delay 41
427
Touch-Controlled LED Time Delay 41
428 Alarm Recorder 42
429 Alarm Recorder (II) 42
430 Machine Gun Recorder 42
431 Time Delay 1-7 Seconds 43
432 Time Delay 43
433 Manual 7 Second Timer (II) 44
434 15 Second Alarm 44
435 Flashing “1 & 2” 45
436 Flashing “3 & 4” 45
437 Flashing “5 & 6” 45
438 Flashing “7 & 8” 45
439 Flashing “9 & 0” 45
440 Flashing “b & c” 46
441 Flashing “d & e” 46
442 Flashing “h & o” 46
Project # Description Page #
443 Flashing “A & J” 46
444 Alarm Timer 46
445 Alarm Timer (II) 46
446 Alarm Timer (III) 46
447 Bird Sounds 47
448 Bird Sounds (II) 47
449 Bird Sounds (III) 47
450 Bird Sounds (IV) 47
451 Bird Sounds (V) 47
452 Touch-Control Bird Sound 47
453 Motor Sound Recording 48
454 Motor Sound Indicator 48
455 Relay & Buzzer 49
456 Relay & Speaker 49
457 Electronic Playground 49
458 Electronic Cat 50
459 Electronic Cat (II) 50
460 Electronic Cat (III) 50
461 Electronic Cat (IV) 50
462 Buzzer Cat 50
463 Buzzer Cat (II) 50
464 Buzzer Cat (III) 50
465 Lazy Cat 50
466 Meter Deflection (II) 51
467 Automatic Display #1 51
468 Automatic Display #2 51
469 Automatic Display #3 52
470 Automatic Display #4 52
471 Automatic Display #5 52
472 Automatic Display #6 52
473 Automatic Display #7 52
474 Automatic Display #8 52
475 Automatic Display #9 52
476 Automatic Display #0 52
477 Variable Oscillator 53
Project # Description Page #
478 Variable Oscillator (II) 53
479 Variable Oscillator (III) 53
480 Variable Oscillator (IV) 53
481 Photo Variable Resistor 53
482 Variable Whistle Chip Oscillator 53
483 Slow Adjusting Tone 53
484 Slow Adjusting Tone (II) 53
485 Fixed-Current Path 54
486 Simple Illumination Meter 54
487 LED Voltage Drop 55
488 Open/Closed Door Indicator 55
489 Hand-Control Meter 56
490 Light-Control Meter 56
491 Electric-Control Meter 56
492 Sound-Control Meter 56
493 Fixed-Voltage Divider 57
494 Resistor Measurement 57
495 Automatic Display Letter “b” 58
496 Automatic Display Letter “c” 58
497 Automatic Display Letter “d” 58
498 Automatic Display Letter “e” 58
499 Automatic Display Letter “h” 58
500 Automatic Display Letter “o” 58
501 Hand-Control Display 1 & 4 59
502 Hand-Control Display 1 & 0 59
503 Hand-Control Display 1 & 7 59
504 Hand-Control Display 1 & 8 59
505 Hand-Control Display 1 & 9 59
506
Monitor Capacitor Charging & Discharging
60
507 Hand-Control Space Meter 60
508 Rhythm Swinging Meter 61
509
Police Car Sound with Whistle Chip
61
510
Fire Engine Sound with Whistle Chip
61
511
Ambulance Sound with Whistle Chip 61
Project Listings

-8-
Project #306
OBJECTIVE: To build a one-IC AM radio.
Turn on the slide switch (S1) and adjust the variable capacitor (CV) for
a radio station. Make sure you set the variable resistor (RV) control to
the left for louder sound.
AM Radio
Project #307
OBJECTIVE: To build a working FM radio with adjustable
volume.
Turn on the slide switch (S1) and press the R button. Now press the
T button and FM module (FM) scans for a radio station. When a
station is found, it locks on to it and you hear it on the speaker (SP).
Adjust the volume using the adjustable resistor (RV). The resistor
controls the amount of signal into the power amplifier IC (U4). Press
the T button again for the next radio station. The module will scan up
to 108MHz, the end of the FM band, and stop. You must then press
reset (R) to start at 88MHz again.
Adjustable Volume
FM Radio

-9-
Project #308
Build the circuit shown. Turn on the slide switch (S1), you hear a beep
signaling that you may begin recording. Talk into the microphone (X1)
up to 5 seconds, and then turn off the slide switch (it also beeps after
the 5 seconds expires).
Press the press switch (S2) for playback. It plays the recording you
made followed by one of three songs. If you press the press switch
before the song is over, music will stop. You may press the press
switch several times to play all three songs. The lamp (L2) is used to
limit current and will not light.
Playback & Record
OBJECTIVE: To demonstrate the capabilities of the recording
integrated circuit.
OBJECTIVE: To play the three built-in
songs on the recording IC.
Use the circuit in project #308. Turn on the
slide switch (S1), then press the press switch
(S2) to start the first song. When the music
stops, press the press switch again to hear the
second song. When the second song stops,
press the press switch again, the third song
plays.
Playing Music
Project #309
OBJECTIVE: To build a circuit that uses
light to control the recording IC.
Light-
Controlled
Music
Project #310
OBJECTIVE: To build a circuit that lets you
control the recording IC with your fingers.
Touch-
Controlled
Music
Project #311
Use the circuit in project #308. Replace the
press switch (S2) with the photoresistor (RP),
then turn on the slide switch (S1). Turn the
music on and off by waving your hand over
photoresistor.
Use the circuit in project #308. Place a single
snap on base grid point F1. Replace the
press switch (S2) with the PNP transistor (Q1,
with the arrow on point E2) and then turn on
the slide switch (S1). Turn the music on and
off by touching points F1 & G2 at the same
time. You may need to wet your fingers.
Visit www.snapcircuits.net or page 62 to learn about Snap Circuits®upgrade kits, which have more parts and circuits.

-10-
Project #312
Connecting the power amplifier IC (U4) to the output of the recording
IC (U6), you can make much louder music than project #308.
Turn on the switch (S1), you hear a beep signaling that you may begin
recording. Talk into the microphone up to 5 seconds, and then turn
open the switch (it also beeps after the 5 seconds expires).
Press the press switch (S2) for playback. It plays the recording you
made followed by one of three songs. If you press switch (S2) before
the song is over, music will stop. You may press the press switch
several times to play all three songs.
Power Playback &
Record
OBJECTIVE: To build a circuit that amplifies the recording IC.
OBJECTIVE: To amplify the output of the
recording IC.
Use the circuit in project #312. Turn on the
switch (S1), then press the press switch (S2)
to start the first song. When the music stops,
press the press switch again to hear the
second song. When the second song stops,
press the press switch again, the third song
plays.
Power
Amplified
Playing Music
Project #313
OBJECTIVE: Show variations of project
#312.
Power Light-
Controlled
Music
Project #314
OBJECTIVE: Show variations of project
#312.
Power Touch-
Controlled
Music
Project #315
Use the circuit in project #312. Replace the
press switch (S2) with the photoresistor (RP),
then turn on the switch (S1). Turn the music
on and off by waving your hand over
photoresistor.
Use the circuit in project #312. Place a single
snap on base grid point F1. Replace the
press switch (S2) with the PNP transistor (Q1,
with the arrow on point E2) and then turn on
the slide switch (S1). Turn the music on and
off by touching points F1 & G2 at the same
time. You may need to wet your fingers.

-11-
Project #316
OBJECTIVE: To build a working FM radio.
The FM module (FM) contains a scan (T) and a reset (R) button. The
R button resets the frequency to 88MHz. This is the beginning of the
FM range. Press the T button, the module scans for the next available
radio station.
Turn on the slide switch (S1) and press the R button. Now press the
T button and the FM module scans for an available radio station.
When a station is found, it locks on to it and you hear it on the speaker.
Press the T button again for the next radio station. The module will
scan up to 108MHz, the end of the FM band, and stop. You must then
press the reset (R) button to start at 88MHz again.
FM Radio
Project #317
OBJECTIVE: To build a complex circuit.
Note that there is a 3-snap wire between RV and U4, partially hidden
under R4.
This is an example of using many parts to create an unusual circuit.
Set the meter (M2) to the LOW (or 10mA) scale. Turn on the slide
switch (S1). As the circuit oscillates, the 7-segment display (D7)
flashes the number 5 and the LED’s (D1 & D2) flash as well. The
meter deflects back and forth and the speaker (SP) sounds a low tone
at the same rate. The frequency of the circuit can be changed by
adjusting the adjustable resistor (RV).
Next, place the 100Ωresistor (R1) directly over the diode (D3) using a
1-snap. See how this changes the circuit performance.
Mega Circuit

-12-
Project #318
OBJECTIVE: To learn the principle of an SCR.
This circuit demonstrates the principle of the SCR (Q3). The SCR can
be thought of as an electronic switch with three leads: anode, cathode,
and gate. Like a standard diode, it permits current flow in only one
direction. It will only conduct in the forward direction when triggered
by a short pulse or steady voltage applied between the gate and
cathode terminals. One set of batteries powers the lamp, the other is
used to trigger the SCR.
Turn on the slide switch (S1) and the bulb (L1) should not light. Now
press the press switch (S2); the SCR turns on and lights the bulb. To
turn off the bulb you must turn off the slide switch (S1).
SCR 2.5V Bulb
Project #319
OBJECTIVE: To activate a motor using an SCR.
SCR & Motor
Place the fan onto the motor (M1). In this circuit, the gate is connected
to the battery (B1) through the 1KΩresistor (R2). When the slide
switch (S1) is turned on, it triggers the gate, the SCR (Q3) conducts,
and the motor spins. The motor continues to spin until the switch is
turned off.
!WARNING: Moving parts. Do not touch the fan or
motor during operation.Do not lean over the motor.
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Project #320
OBJECTIVE: To build a music alarm.
The alarm circuit activates when you remove the jumper wire from
points A & B. The jumper wire shorts the SCR’s (Q3) gate to ground
and the SCR does not conduct. Removing the jumper wire places a
voltage on the gate and the SCR conducts. This connects the battery
to the music IC (U1) and music is played.
Construct the circuit and you should hear no music. Now remove the
jumper wire and the music starts playing.
Music Alarm
Project #321
OBJECTIVE: To build a light-music alarm.
Light-Music Alarm
Use the circuit in project #320. Replace the resistor R3 with the
photoresistor (RP) and remove the jumper wire. Cover the
photoresistor with your hand. Now slowly remove your hand. When
enough light hits the resistor, the music plays.
Project #322
OBJECTIVE: To build a circuit that activates a bulb and motor
with the amount of light present.
Cover the photoresistor (RP) with your finger. Turn on the switch (S1),
and only the LED (D1) lights. The relay (S3) connects the motor (M1)
and the bulb (L2) to the batteries, but the motor and bulb are
powerless until a voltage is applied to the SCR's gate.
Remove your finger, as light hits the photoresistor, its resistance
decreases and a voltage appears on the gate of the SCR (Q3). The
SCR conducts and the motor and bulb work now.
Light-controlled SCR
!WARNING: Moving parts. Do not touch the fan or
motor during operation.Do not lean over the motor.

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Project #323
OBJECTIVE: To build a 3mA meter circuit.
3mA Meter
Project #324
OBJECTIVE: To build a voltmeter.
0-3V Voltmeter
Build this 0-3V voltmeter circuit. Set the meter (M2) to the LOW (or
10mA) setting. Using new batteries, place the battery holder between
points A & B. Adjust the adjustable resistor (RV) so the meter deflects
full scale.
Now you can check your other“AA” batteries by inserting them into the
battery holder.
Set the meter (M2) to the LOW (or 10mA) scale. Inside the meter,
there is a fixed magnet and a moveable coil around it. As current flows
through the coil, it creates a magnetic field. The interaction of the two
magnetic fields cause the coil (connected to the pointer) to move
(deflect). By itself, the meter can measure 300μA. To increase its
range, resistors are connected in parallel or in series to the meter.
Build the circuit shown. Placing the 100Ωresistor (R1) in parallel with
the meter increases the range by 10 times to 3mA. More current flows
through the resistor than the meter. The lower the resistor value, the
wider the range of the meter.

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Project #325
OBJECTIVE: To understand the function of the adjustable resistor.
An adjustable resistor is a normal resistor with an additional arm contact.
The arm moves along the resistive material and taps off the desired
resistance.
The slider on the adjustable resistor moves the arm contact and sets the
resistance between the bottom (point C1) pin and the center pin (point
B2). The remaining resistance is between the center and top pin. For
example, when the slider is all the way down, there is minimal resistance
between the bottom and center pins (usually 0Ω) and maximum
resistance between the center and top pins. The resistance between the
top (point A1) and bottom (point A3) pins will always be the total
resistance, (50kΩfor your part).
Set the meter (M2) to the LOW (or 10mA) scale. Adjust the adjustable
resistor (RV) for maximum resistance by setting the slider to the top. The
meter only deflects part of the way. As you move the slider down,
decreasing the resistance, the meter deflects more.
Function of
Adjustable Resistor
Project #326
OBJECTIVE: To understand the function of the photoresistor.
Build the circuit shown. Set the meter (M2) to the LOW (or 10mA)
scale. The photoresistor (RP) is a light-sensitive resistor. Its value
changes from nearly infinite in total darkness to about 1,000Ωwhen a
bright light shines on it.
The meter reading changes as the resistance changes in the circuit.
When the lights are on, the meter points to a higher number on the
scale. When the lights are OFF, the pointer will point to a lower number
on the scale. This means that the resistance of the photoresistor is
changing according to the amount of light in the room.
Function of
photoresistor
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Project #328
OBJECTIVE: To learn the principle of an SCR.
In this circuit, the 6-volt bulb (L2) will not light until the SCR (Q3) is
triggered. Turn on the slide switch (S1) and the bulb will not light. Now
press the press switch (S2) to light the bulb. The bulb will stay lit until
the slide switch is turned off. To protect the SCR, a current limiting 1kΩ
resistor (R2) is placed in series with the gate.
SCR 6V Bulb
Project #327
OBJECTIVE: To change the direction of current flow using a
motor.
Set the meter (M2) to the LOW (or 10mA) setting. A motor generates
a current when it rotates. The rotation of the motor determines the
direction current flows. Quickly spin the motor (M1) clockwise with
your hand; the meter deflects to the right. Now spin the motor
counterclockwise, and the meter deflects to the left.
Meter Deflect
by Motor

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Project #329
OBJECTIVE: To demonstrate how a seven segment LED works.
The display (D7) is made up of seven segments. Each segment
contains an LED connected to an input snap. When the snap is
connected to the negative of the battery the segment lights. For
example, connect the circuit as shown and the letter “L” lights.
Principle of
Segment LED
Project #330
OBJECTIVE: To configure the seven
segment to display the number 1.
Connect B & C to the negative of the
battery.
Display #1
OBJECTIVE: To configure the seven
segment to display the number 2.
Connect A, B, G, E, & D to the negative
of the battery.
Display #2
OBJECTIVE: To configure the seven
segment to display the number 3.
Connect A, B, G, C, & D to the negative
of the battery.
Display #3
OBJECTIVE: To configure the seven
segment to display the number 4.
Connect B, C, F, & G to the negative of
the battery.
Display #4
Project #331
Project #332 Project #333

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Project #334
OBJECTIVE: To configure the seven
segment to display the number 5.
Connect A, F, G, C, & D to the negative of the
battery.
Display #5
Project #335
OBJECTIVE: To configure the seven
segment to display the number 6.
Connect A, C, D, E, F, & G to the negative of
the battery.
Display #6
Project #336
OBJECTIVE: To configure the seven
segment to display the number 7.
Connect A, B, & C to the negative of the
battery.
Display #7
Project #337
OBJECTIVE: To configure the seven
segment to display the number 8.
Connect A, B, C, D, E, F & G to the negative
of the battery.
Display #8
Project #338
OBJECTIVE: To configure the seven
segment to display the number 9.
Connect A, B, C, D, F, & G to the negative of
the battery.
Display #9
Project #339
OBJECTIVE: To configure the seven
segment to display the number 0.
Connect A, B, C, D, E, & F to the negative of
the battery.
Display #0
Project #340
OBJECTIVE: See and hear the output of the music IC.
Set the meter (M2) to the LOW (or 10mA) setting. In this circuit, the
output of the music IC (U1) is applied to the less windings side of the
transformer (T1), which lights the LED (D1) and deflects the meter.
Place the adjustable resistor (RV) to the bottom position and turn on
the switch (S1). Adjust the adjustable resistor upwards. This
increases the voltage across the LED and meter. The LED brightens
and the meter deflects more towards 10. Place the speaker (SP)
across points A & B and use a jumper wire to complete the connection.
Now you can hear and see the output of the music IC.
Music Meter
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Project #341
OBJECTIVE: Turn on and off LED’s using a relay.
A relay is an electronic switch with contacts that are opened or closed
using voltage. It contains a coil that generates a magnetic field when
a current flows through it. The magnetic field attracts an iron armature
which switches the contacts. Contact #2 is normally closed,
connecting the green LED (D2) and the resistor across the batteries.
With the slide slide switch (S1) turned off, the green LED should light.
Now turn on the switch, contact #1 on the relay (S3) will switch to
contact #3, lighting the red LED (D1).
LED & Relay
Project #342
OBJECTIVE: To build a manual timer using a relay.
The transistor (Q2) acts as a switch, connecting the relay (S3) to the
batteries. As long as there is positive voltage on the transistor’s base,
the bulb (L2) will light.
Turn on the slide switch (S1) and hold down the press switch (S2). The
transistor turns on, capacitor C5 charges up, and the bulb lights.
When the press switch is released, the capacitor discharges through
the base, keeping the transistor on. The transistor will turn off when
the capacitor is almost discharged, about 7 seconds. The relay
contacts will switch and the bulb will turn off.
Change the value of the capacitor and see what happens.
Manual
7 Second Timer