Elenco Projects 102-305 User Manual

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REV-H Revised 2012

Patent #‘s: 7,144,255, 7,273,377, & other patents pending

Project 242

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Table of Contents

Basic T roubleshooting 1 Parts List 2

About Your Snap Circuits®Parts 3

DO’s and DON’Ts of Building Circuits 4

Advanced T roub leshooting 5 Project Listings 6, 7 Projects 102 - 305 8 - 73 Other Fun Elenco®Products 74

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 T roub leshooting

Note: If you suspect you have damaged parts, you can

follow the Advanced Troubleshooting procedure on page 5 to determine which ones need replacing.

Review of How To 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 (carbonzinc), 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

ary 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 Par t # Qty. ID Name Symbol Par t #

r 3

1-Snap Wire 6SC01

r 1

10μF Capacitor 6SCC3

r 3

2-Snap Wire 6SC02

r 1

100μF Capacitor 6SCC4

r 1

3-Snap Wire 6SC03

r 1

470μF Capacitor 6SCC5

r 1

4-Snap Wire 6SC04

r 1

1kΩ Resistor 6SCR2

r 1

7-Snap Wire 6SC07

r 1

5.1kΩ Resistor 6SCR3

r 1

Battery Holder - uses 2 1.5V type AA (not

Included)

6SCB1

r 1

10kΩ Resistor 6SCR4

r 1

Antenna Coil 6SCA1

r 1

100kΩ Resistor 6SCR5

r 1

Green Light Emitting Diode (LED)

6SCD2

r 1

High Frequency Integrated Circuit

6SCU5

r 1

6V Lamp 6SCL2

r 1

PNP Transistor 6SCQ1

r 1

Microphone 6SCX1

r 1

NPN Transistor 6SCQ2

r 1

Power Amplifier Integrated Circuit

6SCU4

r 1

Adjustable Resistor 6SCRV

r 1

0.02μF Capacitor 6SCC1

r 1

Variable Capacitor 6SCCV

r 1

0.1μF Capacitor 6SCC2

You may order additional / replacement parts at our website: www.snapcircuits.net

Note: There are additional part lists in your other project manuals.

Important: If any parts are missing or damaged, DO NOT RETURN TO RETAILER. Call toll-free (800) 533-2441 or e-mail us at:

help@elenco.com. Customer Ser vice • 150 Car penter 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).

Note: There is additional information in your other project manual.

The green LED (D2) works the same as the red LED (D1) and the

6V lamp (L2) works the same as the 2.5V lamp; these are

descr

ibed in the projects 1-101 manual.

Resistors “resist” the flow of electricity and are used to control or limit the electricity in a circuit. Snap Circuits

includes 100Ω (R1),

1KΩ (R2), 5.1KΩ (R3), 10KΩ (R4), and 100KΩ (R5) resistor s (“K”

symboliz

es 1,000, so R3 is really 5,100Ω). Materials like metal have very low resistance (<1Ω) and are called conductors, while materials like paper, plastic, and air have near-infinite resistance and are called insulators.

The adjustable resistor (RV) is a 50KΩ resistor b

ut with a center tap that can be adjusted between 0Ω and 50KΩ. At the 0Ω setting, the current must be limited by the other components in the circuit.

The microphone (X1) is actually a resistor that changes in value when changes in air pressure (sounds) apply pressure to its surf

ace. Its resistance typically varies from around 1KΩ in silence

to around 10KΩ when you blow on it. Capacitors are components that can store electrical pressure

(voltage) for periods of time, higher values have more storage. Because of this storage ability they block unchanging voltage signals and pass fast changing voltages. Capacitors are used for filtering and oscillation circuits. Snap Circuits

includes 0.02μF

(C1), 0.1μF (C2), 10μF (C3), 10μF (C4), 470μF (C5) capacitors, and a variable capacitor (CV). The variable capacitor can be

adjusted from .00004 to .00022μF and is used in high frequency r

adio circuits for tuning. The whistle chip (WC) also acts like a

0.02μF capacitor in addition to its sound properties.

The antenna (A1) contains a coil of wire wrapped around an iron bar

. Although it has magnetic effects similar to those in the motor, those effects are tiny and may be ignored except at high frequencies (like in AM radio). Its magnetic proper ties allow it to concentrate radio signals for reception. At lower frequencies the antenna acts like an ordinary wire.

The PNP (Q1) and NPN (Q2) transistorsare components that use a small electr

ic current to control a large current, and are used in switching, amplifier, and buffering applications. They are easy to miniaturize, and are the main building blocks of integrated circuits including the microprocessor and memory circuits in computers. Projects #124-125 and #128-133 demonstrate their properties. A high current may damage a transistor, so the current must be limited by other components in the circuit.

The power amplifier IC (U4) is a module containing an integrated circuit amplifier and suppor

ting components that are always

needed with it. A description of it is giv en here f or those interested:

About Your Snap Circuits®Parts

The high frequency IC (U5) is a specialized amplifier used only in high frequency radio circuits. A description of it is given here for those interested:

INP

FIL

(+)

OUT

(–)

Power Amplifier IC:

(+) - power from batteries (–) - power return to batteries FIL - filtered power from batteries INP - input connection OUT - output connection

See project #242 for example of connections.

High Frequency IC:

INP - input connection (2 points are same) OUT - output connection (–) power return to batteries

See project #242 for example of connections.

INP INP(–)

OUT

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 74 for more information.

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DO’s and DON’Ts of Building Circuits

After building the circuits given in this booklet, you ma y wish to e xperiment 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 batter

ies, see examples below) as this will damage components and/or quickly

drain your batteries

. Only connect the ICs 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 ON YOUR OWN.

ALWAYS

include at least one component that will limit the current through a circuit, such as the speaker, lamp, whistle chip, capacitors, ICs (which must be connected properly), motor, microphone, photoresistor, or resistors (the adjustable resistor doesn’t count if it’s set at/near minimum resistance).

ALWAYS

use LEDs, transistors, the high frequency IC, 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 ICs 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 Models SC-500 or SC-750, there are additional guidelines in your other project manual(s).

For all of the projects given in this book, the parts may be arranged in diff erent 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 website.

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!

Advanced Troubleshooting (Adult supervision recommended)

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. - 9. Refer to project manual 1 (projects 1-101) for testing steps 1-9, then continue below. Test both lamps (L1, L2) and battery holders in test step 1, all blue snap wires in step 3, and both LEDs (D1, D2) in step 5.

10. 1KΩ (R2),

5.1KΩ (R3), and 10KΩ (R4) resistors: Build

project #7 but use each of these resistors in place of the 100Ω resistor (R1), the LED should light and the brightness decreases with the higher value resistors.

11. Antenna (A1): Build the mini-

circuit sho

wn here, you should

hear sound.

12. NPN transistor (Q2): Build the

mini-circuit sho

wn here. The LED (D2) should only be on if the press switch (S2) is pressed. If otherwise, then the NPN is damaged.

13. PNP transistor (Q1): Build the mini-circuit sho

wn here. The LED (D1) should only be on if the press switch (S2) is pressed. If otherwise, then the PNP is damaged.

14. Adjustable resistor (R V): Build project #261 but use the 100Ω resistor (R1) in place of the photoresistor (RP), the resistor control can tur

n the LED (D1) on and off.

15. 100ΩK resistor (R5) and 0.02μF (C1),

0.1μF (C2), and 10μF

(C3) capacitors: Build project #206, it makes sound unless

the resistor is bad.

Place the 0.02μF capacitor on top of the whistle chip (WC) and the sound changes (pitch is lower). Replace the 0.02μF with the 0.1μF and the pitch is even lower. Replace the 0.1μF with the 10μF and the circuit will “click” about once a second.

16. 100μF (C4) and 470μF (C5) capacitor

s: Build project #225,

press the press switch (S2) and turn on the slide switch (S1). The LED (D1) should be lit for about 15 seconds then go out (press the press switch again to reset this). Replace the 470μF with the 100μF and the LED is only lit for about 4 seconds now.

17. Power Amplifier IC (U4): Build project #293, the sound from the speak

er (SP) should be loud.

18. Microphone (X1): Build project #109, blowing into the microphone should tur

n off the lamp (L2).

19. Variable Capacitor (CV): Build project #213 and place it near an AM r

adio, tune the radio and the capacitor to verify you hear

the music on your radio.

20. High Frequency IC (U5): Build project #242 and adjust the v

ariable capacitor (CV) and adjustable resistor (RV) until you

hear a radio station.

Note: If you have the more advanced Models SC-500 or SC-750, there are additional tests in your other project manuals.

ELENCO

150 Carpenter Avenue

Wheeling, IL 60090 U.S.A.

Phone: (847) 541-3800

Fax: (847) 520-0085

e-mail: help@elenco.com

Web site: www.elenco.com

You may order additional / replacement parts at:

www

.snapcircuits.net

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Project # Description Page #

102 Batteries in Series 8 103 Ticking Screecher 8 104 Spacey Fan 9 105 Two-Transistor Light Alarm 9 106 Light-Controlled Alarm 9 107 Automatic Street Lamp 10 108 Voice-Controlled Rays of Light 10 109 Blowing Off the Electric Light 10 110 Adjustable Tone Generator 11 111 Photosensitive Electronic Organ 11 112 Electronic Cicada 11 113 Light & Sounds 12 114 More Light & Sounds 12 115 More Light & Sounds (II) 12 116 More Light & Sounds (III) 12 117 More Light & Sounds (IV) 12 118 Motor Speed Detector 13 119 Old-Style Typewriter 13 120 Optical Transmitter & Receiver 14 121

Space War Sounds Controlled by Light

14 122 Space War Radio 15 123 The Lie Detector 15 124 NPN Amplifier 16 125 PNP Amplifier 16 126 Sucking Fan 17 127 Blowing Fan 17 128 PNP Collector 17 129 PNP Emitter 17 130 NPN Collector 18 131 NPN Emitter 18 132 NPN Collector - Motor 18 133 NPN Emitter - Motor 18 134 Buzzing in the Dark 19 135 Touch Buzzer 19

Project # Description Page #

136 High Frequency Touch Buzzer 19 137

High Frequency Water Buzzer 19 138 Mosquito 19 139 High Sensitivity Voice Doorbell 20 140 Louder Doorbell 20 141 Very Loud Doorbell 20 142 Doorbell with Button 20 143 Darkness Announcer 20 144 Musical Motion Detector 20 145 Radio Music Alarm 21 146 Daylight Music Radio 21 147 Night Music Radio 21 148 Night Gun Radio 21 149 Radio Gun Alarm 21 150 Daylight Gun Radio 21 151 Blow Off a Space War 22 152 Series Lamps 22 153 Parallel Lamps 22 154 Fire Fan Symphony 23 155 Fire Fan Symphony (II) 23 156 Fan Symphony 23 157 Fan Symphony (II) 23 158 Police Car Symphony 24 159 Police Car Symphony (II) 24 160 Ambulance Symphony 24 161 Ambulance Symphony (II) 24 162 Static Symphony 25 163 Static Symphony (II) 25 164 Capacitors in Series 25 165 Capacitors in Parallel 25 166 Water Detector 26 167 Salt Water Detector 26 168 NPN Light Control 27 169 NPN Dark Control 27

Project # Description Page #

170 PNP Light Control 27 171 PNP Dark Control 27 172 Red & Green Control 28 173 Current Controllers 28 174 Current Equalizing 28 175 Battery Polarity Tester 28 176 Blow Off a Doorbell 29 177 Blow Off a Candle 29 178 Blow On a Doorbell 29 179 Blow On a Candle 29 180 Screaming Fan 30 181 Whining Fan 30 182 Light Whining 30 183 More Light Whining 30 184 Motor Than Won’t Start 30 185 Whiner 31 186 Lower Pitch Whiner 31 187 Hummer 31 188 Adjustable Metronome 31 189 Quiet Flasher 31 190 Hissing Foghorn 32 191 Hissing & Clicking 32 192 Video Game Engine Sound 32 193 Light Alarm 33 194 Brighter Light Alarm 33 195 Lazy Fan 33 196 Laser Light 33 197 Water Alarm 34 198 Radio Announcer 34 199 Pitch 35 200 Pitch (II) 35 201 Pitch (III) 35 202 Flooding Alarm 35 203 Make Your Own Battery 36

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Project Listings

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Project # Description Page #

204 Make Your Own Battery (II) 36 205 Make Your Own Battery (III) 36 206 Tone Generator 37 207 Tone Generator (II) 37 208 Tone Generator (III) 37 209 Tone Generator (IV) 37 210 More Tone Generator 38 211 More Tone Generator (II) 38 212 More Tone Generator (III) 38 213 Music Radio Station 39 214 Alarm Radio Station 39 215 Standard Transistor Circuit 39 216 Motor & Lamp by Sound 40 217 Fading Siren 40 218 Fast Fade Siren 40 219 Laser Gun with Limited Shots 41 220 Symphony of Sounds 41 221 Symphony of Sounds (II) 41 222 Transistor Amplifiers 42 223 Pressure Meter 42 224 Resistance Meter 42 225 Auto-Off Night-Light 43 226 Discharging Caps 43 227 Changing Delay Time 43 228 Morse Code Generator 44 229 LED Code Teacher 44 230 Ghost Shriek Machine 44 231 LED & Speaker 44 232 Dog Whistle 44 233 Mind Reading Game 45 234 Enhanced Quiet Zone Game 46 235 Capacitor Charge & Discharge 46 236 Sound Wave Magic 47 237 Space War Amplifier 47

Project # Description Page #

238 Trombone 48 239 Race Car Engine 48 240 Power Amplifier 49 241 Feedback Kazoo 49 242 AM Radio 50 243 Fire Engine Symphony 51 244 Fire Engine Symphony (II) 51 245 Vibration or Sound Indicator 51 246 Two-Finger Touch Lamp 52 247 One-Finger Touch Lamp 52 248 Space Battle 53 249 Space Battle (II) 53 250 Multi-Speed Light Fan 53 251 Light & Finger Light 53 252 Storing Electricity 54 253 Lamp Brightness Control 54 254 Electric Fan 54 255 Radio Music Burglar Alarm 55 256 Light Dimmer 55 257 Motion Detector 56 258 Fan Modulator 56 259 Oscillator 0.5 - 30Hz 57 260 Sound Pulse Oscillator 57 261 Motion Detector (II) 57 262 Motor Rotation 58 263 Motor Delay Fan 58 264 Motor Delay Fan (II) 58 265 High Pitch Bell 59 266 Steamboat Whistle 59 267 Steamship 59 268 Light NOR Gate 59 269 Noise-Activated Burglar Alarm 60 270 Motor-Activated Burglar Alarm 60 271 Light-Activated Burglar Alarm 60

Project # Description Page #

272 Photoresistor Control 61 273 Microphone Control 61 274 Pressure Alarm 62 275 Power Microphone 62 276 LED Fan Rotation Indicator 63 277 Space War Sounds with LED 63 278 Sound Mixer 64 279 Sound Mixer Fan Driver 64 280 Electric Fan Stopped by Light 65 281 Motor & Lamp 65 282 Start-Stop Delay 66 283 Mail Notifying System 66 284 Mail Notifying Electronic Bell 67 285 Mail Notifying Electronic Lamp 67 286 Twice-Amplified Oscillator 67 287 Quick Flicking LED 67 288 AM Radio with Transistors 68 289 AM Radio (II) 68 290 Music Amplifier 69 291 Delayed Action Lamp 69 292 Delayed Action Fan 69 293 Police Siren Amplifier 70 294 Lasting Doorbell 70 295 Lasting Clicking 70 296 Quieting a Motor 71 297 Transistor Fading Siren 71 298 Fading Doorbell 71 299 Blowing Space War Sounds 72 300 Adjustable Time Delay Lamp 72 301 Adjustable Time Delay Fan 72 302

Adjustable Time Delay Lamp (II)

73 303 Adjustable Time Delay Fan (II) 73 304 Watch Light 73 305 Delayed Bedside Fan 73

Project Listings

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Project #102

OBJECTIVE: To show the increase in voltage when batteries are connected in series.

When you turn on the slide switch (S1), current flows from the batteries through the slide switch, the 100Ω resistor (R1), the LED (D1), through the LED (D2), and back to the second group of batteries (B1). Notice ho w both LED’s are lit. The v oltage is high enough to turn on both LED’s when the batteries are connected in series. If only one set of batteries is used, the LED’s will not light up.

Some devices use only one 1.5 volt battery, but they make hundreds of volts electronically from this small source. A flash camera is an example of this.

Batteries in Series

Project #103

OBJECTIVE: To make fun sounds using light.

Build the circuit as shown, and turn on the slide switch (S1). Var y the amount of light to the photoresistor (RP) by partially covering it with your hand. You can make screeching sounds by allowing just a little light to reach the photoresistor.

If you replace the 10μF capacitor (C3) with a 3-snap wire or any of the other capacitors (C1, C2, C4, or C5), then the sound will be a little different.

Ticking Screecher

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Project #104

Spacey Fan

OBJECTIVE: To build a fan with sound that is activated by light.

Place the fan onto the motor (M1). Sounds are heard if light shines on the photoresistor (RP) OR if you press the press switch (S2), the fan may start to spin, but will only get to high speed if you do BOTH. Try various combinations of shining light and holding down the press switch.

Project #106

OBJECTIVE: To show how light is used to turn an alarm.

The alarm will sound, as long as light is present. Slowly cover the photoresistor (RP), and the volume goes down. If you turn off the lights, the alarm will stop. The amount of light changes the resistance of the photoresistor (less light means more resistance). The photoresistor and transistor (Q2) act like a dimmer switch, adjusting the voltage applied to the alarm.

This type of circuit is used in alarm systems to detect light. If an intruder turned on a light or hit the sensor with a flashlight beam, the alarm would trigger and probably force the intruder to leave.

Light-controlled Alarm

Project #105

Two-Transistor Light Alarm

OBJECTIVE: To compare transistor circuits.

This light alarm circuit uses two transistors (Q1 & Q2) and both sets of batteries. Build the circuit with the jumper connected as shown, and turn it on. Nothing happens. Break the jumper connection and the lamp (L2) turns on. You could replace the jumper with a longer wire and run it across a doorway to signal an alarm when someone enters.

WARNING: Moving parts. Do

not touch the fan or motor during operation. Do not lean over the motor.

Visit www.snapcircuits.net or page 74 to learn about Snap Circuits®upgrade kits, which have more parts and circuits.

-10-

Project #107

OBJECTIVE: To show how light is used to control a street lamp.

Press the press switch (S2) on and set the adjustable resistor (RV) so the lamp (L2) just lights. Slowly cover the photoresistor (RP) and the lamp brightens. If you place more light at the photoresistor the light dims.

This is an automatic street lamp that you can turn on by a certain darkness and turn off by a certain br ightness. This type of circuit is installed on many outside lights and forces them to turn off and save electricity. They also come on when needed for safety.

Automatic

Street Lamp

Project #108

Voice-controlled Rays of Light

OBJECTIVE: To show how light is stimulated by sound.

Turn the slide switch (S1) on. There will be only a weak light emitting from the green LED (D2). By blowing on the mic (X1) or putting it near a radio or TV set, the green LED will emit light, and its brightness changes as the loudness changes.

Project #109

Blowing Off the Electric Light

OBJECTIVE: To show how light is stimulated by sound.

Install the parts. The lamp (L2) will be on. It will be off as long as you blow on the mic (X1). Speaking loud into the mic will change the brightness of the lamp.

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Project #110

OBJECTIVE: To show how resistor values change the frequency of an oscillator.

Turn on the slide switch (S1); the speaker (SP) will sound and the LED (D1) will light. Adjust the adjustable resistor (RV) to make different tones. In an oscillator circuit, changing the values of resistors or capacitors can vary the output tone or pitch.

Adjustable Tone

Generator

OBJECTIVE: To show how resistor values change the frequency of an oscillator.

Project #112

Electronic Cicada

OBJECTIVE: To show how capacitors in parallel change the frequency of an oscillator.

Use the circuit from project #110 shown above, replace the photoresistor (RP) back to the 10kΩ resistor (R4). Place the 0.02μF capacitor (C1) on top of the whistle chip (WC). Place the slide switch (S1) on and adjust the adjustable resistor (R V). The circuit produces the sound of the cicada insect. By placing the 0.02μF capacitor on top of the whistle chip, the circuit oscillates at a lower frequency. Notice that the LED (D1) flashes also at the same frequency.

It is possible to pick resistors and capacitors that will make the pitch higher than humans can hear. Many animals, however, can hear these tones. For example, a parakeet can hear tones up to 50,000 cycles per second, but a human can only hear to 20,000.

Use the circuit from project #110 shown above. Replace the 10kΩ resistor (R4) with the photoresistor (RP). Turn on the slide switch (S1). The speaker (SP) will sound and the LED (D1) will light. Move your hand up and down over the photoresistor and the frequency changes. Decreasing the light on the photoresistor increases the resistance and causes the circuit to oscillate at a lower frequency. Notice that the LED flashes also at the same frequency as the sound.

By using your finger , see if you can v ary the sounds enough to make this circuit sound like an organ playing.

Project #111

Photosensitive

Electr

onic Organ

-12-

OBJECTIVE: To build a police siren with light.

Turn on the slide switch (S1). A police siren is heard and the lamp (L1) lights.

Project #114

More Light &

Sounds

OBJECTIVE: To show a variation of the circuit in project #113.

Modify the last circuit by connecting points X & Y. The circuit works the same way but now it sounds like a machine gun.

OBJECTIVE: To show a variation of the circuit in project #113.

Project #116

More Light &

Sounds (III)

OBJECTIVE: To show a variation of the circuit in project #113.

Project #117

More Light &

Sounds (IV)

OBJECTIVE: To show a variation of the circuit in project #113.

Project #113 Light & Sounds

Project #115

More Light &

Sounds (II)

Now remove the connection between X & Y and then make a connection between T & U. Now it sounds like a fire engine.

Now remove the connection between T & U and then make a connection between U & Z. Now it sounds like an ambulance.

Now remove the connection between U & Z, then place the 470μF capacitor (C5) between T & U (“+” side to T). The sound changes after a few seconds.

To learn more about how circuits work, visit www.snapcircuits.net or page 74 to find out about our Student Guides.

-13-

Project #118

OBJECTIVE: To show how to make electricity in one direction.

When building the circuit, be sure to position the motor (M1) with the positive (+) side snapped to the 470μF capacitor (C5). Tur n on the slide switch (S1), nothing will happen. It is a motor speed detector, and the motor isn’t moving. Watch the LED (D2) and give the motor a good spin CLOCKWISE with your fingers (don’t use the fan b lade); you should see a flash of light. The faster you spin the motor, the brighter the flash will be. As a game, see who can make the brightest flash.

Now try spinning the motor in the opposite direction (counterclockwise) and see how bright the flash is — it won’t flash at all because the electricity it produces, flows in the wrong direction and won’t activate the diode. Flip the motor around (positive (+) side snapped to the 3-snap wire) and try again. Now the LED lights only if you spin the motor counter-clockwise.

Motor Speed Detector

Project #119

OBJECTIVE: To show how a generator works.

Turn on the slide switch (S1), nothing will happen. Turn the motor (M1) slowly with your fingers (don’t use the fan blade), you will hear a clicking that sounds like an old-time manual typewriter keystrokes. Spin the motor faster and the clicking speeds up accordingly.

This circuit works the same if you spin the motor in either direction (unlike the Motor Speed Detector project).

By spinning the motor with your fingers, the physical effort you exert is converted into electricity. In electric power plants, steam is used to spin large motors like this, and the electricity produced is used to run everything in your town.

Old-Style Typewriter

-14-

Project #120

OBJECTIVE: To show how information can be transmitted using light.

Build the circuit shown. Connect the photoresistor (RP) to the circuit using the red & black jumper wires. Place the photoresistor upside down over the red LED (D1), so the LED goes inside the photoresistor . Turn on both switches (hold down the press switch button). Music pla ys on the speaker, even though the two parts of the circuit are not electrically connected.

The left circuit, with the LED and music IC (U1) creates a music signal and transmits it as light. The right circuit, with the photoresistor and speaker, receives the light signal and converts it back to music. Here the photoresistor has to be on top of the LED for this to work, but better communication systems (such as fiber optic cables), can transmit information over enormous distances at very high speeds.

Optical Transmitter &

Receiver

Project #121

OBJECTIVE: To change the sounds of a multiple space war with light.

The space war IC (U3) will play a sound continuously. Block the light to the photoresistor (RP) with your hand. The sound will stop . Remove your hand and a different sound is played. Wave your hand over the photoresistor to hear all the different sounds.

Press the press switch down and now two space war sounds are played. If you hold the press switch down the sound repeats. Press the press switch again and a different sound is played. Keep pressing the press switch to hear all the different combinations of sounds.

Space War Sounds

Controlled By Light

-15-

Project #122

OBJECTIVE: To transmit Space War sounds to a AM radio.

Place the circuit next to an AM radio . Tune the radio so no stations are heard and turn on the slide switch (S1). You should hear the space war sounds on the radio. The red LED (D1) should also be lit. Adjust the variable capacitor (CV) for the loudest signal. Push the press switch (S2) to change the sound.

You have just performed the experiment that took Marconi (who invented the radio) a lifetime to invent. The technology of radio transmission has expanded to the point that we take it for granted. There was a time, however, when news was only spread by word of mouth.

Space War Radio

Project #123

OBJECTIVE: To show how sweat makes a better conductor.

Turn on the slide switch (S1) and place your finger across points A & B. The speaker (SP) will output a tone and the LED (D2) will flash at the same frequency. Your finger acts as a conductor connecting points A & B. When a person is lying, one thing the body starts to do is sweat. The sweat makes the finger a better conductor by reducing its resistance.

As the resistance drops, the frequency of the tone increases. Lightly wet your finger and place it across the two points again. Both the output tone and LED flashing frequency increase, and the lamp (L2) may begin to light. If your finger is wet enough, then the lamp will be bright and the sound stops - indicating you are a big liar! Now change the wetness of your finger by drying it and see how it affects the circuit. This is the same principle used in lie detectors that are sold commercially.

The Lie Detector

Visit www.snapcircuits.net or page 74 to learn about more Snap Circuits®products to add to your collection.

-16-

Project #124

OBJECTIVE: To compare transistor circuits.

There are three connection points on an NPN transistor (Q2), called base (marked B), emitter (marked E), and collector (marked C). When a small electric current flows from the base to the emitter, a larger (

amplified

) current will flow from the collector to the emitter. Build the circuit and slowly move up the adjustable resistor (RV) control. When the LED (D2) becomes bright, the lamp (L2) will also turn on and will be much brighter.

NPN Amplifier

Project #125

OBJECTIVE: To compare transistor circuits.

The PNP transistor (Q1) is similar to the NPN transistor (Q2) in project #166, except that the electric currents flow in the opposite directions. When a small electric current flows from the emitter to the base, a larger (

amplified

) current will flow from the emitter to the collector. Build the circuit and slowly move up the adjustable resistor (RV) control. When the LED (D1) becomes br ight, the lamp (L2) will also turn on and will be much brighter.

PNP Amplifier

-17-

Project #126 Sucking Fan

OBJECTIVE: To adjust the speed of a fan.

Project #128 PNP Collector

OBJECTIVE: To demonstrate adjusting the gain of a transistor circuit.

OBJECTIVE: To build a fan that won’t come off.

Modify the circuit from project #126 by reversing the position of the motor (M1), so the positive (+) side is towards the PNP (Q1). Turn it on, and set the adjustable resistor (R V) for the fan speed you like best. Set it for full speed and see if the fan flies off - it won’t! The fan is blowing air upward now! Try holding a piece of paper just above the fan to prove this.

Project #127

Blowing Fan

Project #129

PNP Emitter

OBJECTIVE: To compare transistor circuits.

Compare this circuit to that in project #128. The maximum lamp (L2) brightness is less here because the lamp resistance reduces the emitter-base current, which contacts the emittercollector current (as per project #128). The point on the PNP (Q1) that the lamp is now connected to (grid point C4) is called the emitter.

Build the circuit, and be sure to orient the motor (M1) with the positive (+) side down as shown. Turn it on, and set the adjustable resistor (RV) for the fan speed you like best. If you set the speed too fast then the fan may fly off the motor. Due to the shape of the fan blades and the direction the motor spins, air is sucked into the fan and towards the motor. Try holding a piece of paper just above the fan to prove this. If this suction is strong enough then it can lift the fan blades, just like in a helicopter.

The fan will not move on most settings of the resistor, because the resistance is too high to overcome friction in the motor. If the fan does not move at any resistor setting, then replace your batteries.

Build the circuit and vary the lamp (L2) brightness with the adjustable resistor (RV), it will be off for most of the resistor’s range. The point on the PNP (Q1) that the lamp is connected to (point E4 on the base grid) is called the collector, hence the name for this project.

WARNING: Moving par ts. Do not touch the fan or

motor during operation. Do not lean o ver the motor.

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Project #130

NPN Collector

OBJECTIVE: To compare transistor circuits.

Project #131

NPN Emitter

Compare this circuit to that in project #128, it is the NPN transistor (Q2) version and works the same way. Which circuit makes the lamp (L2) brighter? (They are about the same because both transistors are made from the same materials).

OBJECTIVE: To compare transistor circuits.

Compare this circuit to that in project #129. It is the NPN transistor (Q2) version and works the same way. The same principles apply here as in projects #128-#130, so you should expect it to be less bright than #130 but as bright as #129.

Project #132

NPN Collector - Motor

OBJECTIVE: To compare transistor circuits.

Project #133

NPN Emitter - Motor

This is the same circuit as in project #130, except that it has the motor (M1) instead of the lamp. Place the motor with the positive (+) side touching the NPN and put the fan on it.

OBJECTIVE: To compare transistor circuits.

This is the same circuit as in project #131, except that it has the motor (M1) instead of the lamp. Place the motor with the positive (+) side to the right and put the fan on it. Compare the fan speed to that in project #132. Just as the lamp was dimmer in the emitter configuration, the motor is not as fast now.

WARNING: Moving parts. Do not touch

the fan or motor during operation.

not lean over the motor.

Visit www.snapcircuits.net or page 74 to learn about Snap Circuits®upgrade kits, which have more parts and circuits.

WARNING: Moving parts. Do not touch the fan or

motor during operation.

Do not lean over the motor.

-19-

Project #134

OBJECTIVE: To make a circuit that buzzes when the lights are off.

Buzzing in

the Dark

Project #136

High Frequency

Touch Buzzer

OBJECTIVE: To build a high frequency human buzzer oscillator.

Replace the speaker (SP) with the 6V lamp (L2). Now touching your fingers between B1 and D1 creates a quieter but more pleasant buzzing sound.

Project #137

High Frequency

Water Buzzer

OBJECTIVE: To build a high frequency water buzzer oscillator.

Now connect two (2) jumpers to points B1 and D1 (that you were touching with your fingers) and place the loose ends into a cup of water. The sound will not be much different now, because your body is mostly water and so the circuit resistance has not changed much.

Project #138

Mosquito

OBJECTIVE: To make a buzz like a mosquito.

Place the photoresistor (RP) into the circuit in project #137 across where you were connecting the jumpers (points B1 and D1 on the grid, and as shown in project #134). Now the buzz sounds like a mosquito.

Project #135

Touch Buzzer

OBJECTIVE: To build a human buzzer oscillator.

Remove the photoresistor (RP) from the circuit in project #134 and instead touch your fingers across where it used to be (points B1 and D1 on the grid) to hear a cute buzzing sound. The circuit works because of the resistance in your body. If you put back the photoresistor and partially cover it, you should be able to make the same resistance your body did, and get the same sound.

This circuit makes a high-frequency screaming sound when light shines on the photoresistor (RP), and makes a buzzing sound when you shield the photoresistor.

-20-

Project #139

Project #141

Very Loud

Doorbell

OBJECTIVE: To build a very loud, highly-sensitive, voiceactivated doorbell.

Replace the antenna coil (A1) with the speaker (SP), the sound is much louder now.

OBJECTIVE: To build a pressactivated doorbell.

Project #143

Darkness

Announcer

OBJECTIVE: To play music when it gets dark.

OBJECTIVE: To detect when someone spins the motor.

Project #142

Doorbell

with Button

Replace the microphone (X1) with the press switch (S2) and wait until the music stops. Now you have to press the slide s witch (S1) to activate the music, just like the doorbell on your house.

Replace the press switch (S2) with the photoresistor (RP) and wait until the sound stops. If you cover the photoresistor now the music will play once, signaling that it has gotten dark. If the speaker (SP) is too loud then you may replace it with the antenna coil (A1).

Replace the photoresistor (RP) with the motor (M1), oriented in either direction. No w spinning the motor will re-activate the music.

Project #144

Musical

Motion Detector

OBJECTIVE: To build a loud highly sensitive voice-activated doorbell.

Replace the 6V lamp (L2) with the antenna coil (A1), the sound is louder now.

Project #140

Louder

Doorbell

OBJECTIVE: To build a highly sensitive voice-activated doorbell.

Build the circuit and wait until the sound stops. Clap or talk loud a few feet away and the music plays again. The microphone (X1) is used here because it is very sensitive.

High

Sensitivity

Voice Doorbell

-21-

Project #145 Radio Music

Alarm

OBJECTIVE: To build a radio music alarm.

Project #147

Night Music

Radio

OBJECTIVE: To build a darkcontrolled radio transmitter.

Put the 100kΩ resistor back in as before and instead connect the photoresistor between X & Y (you also need a 1-snap and a 2-snap wire to do this). Now your radio plays music when it is dark.

OBJECTIVE: To build a darkcontrolled radio transmitter.

Project #149

Radio Gun

Alarm

OBJECTIVE: To build a radio alarm.

OBJECTIVE: To build a lightcontrolled radio transmitter.

Project #148

Night Gun

Radio

Replace the music IC (U1) with the alarm IC (U2). Now your radio plays the sound of a machine gun when it is dark.

Remove the photoresistor (RP). Now connect a jumper wire between X & Y on the drawing. If you remove the jumper now, the machine gun sound will play on the radio indicating your alarm wire has been triggered.

Remove the jumper wire. Replace the 100kΩ resistor (R5) with the photoresistor (RP). Now your AM radio will play the machine gun sound as long as there is light in the room.

Project #150

Daylight Gun

Radio

OBJECTIVE: To build a lightcontrolled radio transmitter.

Project #146

Daylight

Music Radio

Remove the jumper wire. Replace the 100kΩ resistor (R5) with the photoresistor (RP). Now your AM radio will play music as long as there is light in the room.

You need an AM radio for this project. Build the circuit on the left and turn on the slide switch (S1). Place it ne xt to y our AM radio and tune the radio frequency to where no other station is transmitting. Then, tune the adjustable capacitor (CV) until your music sounds best on the radio. Now connect a jumper wire between X and Y on the drawing, the music stops.

If you remove the jumper now, the music will play indicating your alarm wire has been triggered. You could use a longer wire and wrap it around a bike, and use it as a burglar alarm!

To learn more about how circuits work, visit www.snapcircuits.net or page 74 to find out about our Student Guides.

-22-

Project #151

OBJECTIVE: To turn off a circuit by blowing on it.

Blow Off a Space War

Project #152

Series Lamps

OBJECTIVE: To compare types of circuits.

Turn on the slide switch (S1) and both lamps (L1 & L2) will light. If one of the bulbs is broken then neither will be on, because the lamps are in series. An example of this is the strings of small Christmas lights; if one bulb is damaged then the entire string does not work.

Project #153

Parallel Lamps

OBJECTIVE: To compare types of circuits.

Build the circuit and turn it on, you hear a space war. Since it is loud and annoying, try to shut it off by blowing into the microphone (X1). Blowing hard into the microphone stops the sound, and then it starts again.

Turn on the slide switch (S1) and both lamps (L1 & L2) will light

. If one of the bulbs is broken then the other will still be on, because the lamps are in parallel. An example of this is most of the lights in your house; if a bulb is broken on one lamp then the other lamps are not affected.

-23-

Project #154 Fire Fan Symphony

OBJECTIVE:

To combine sounds from the music, alarm, and space war integrated circuits.

OBJECTIVE: See project #156.

The preceding circuit may be too loud, so replace the speaker (SP) with the whistle chip (WC).

Project #157

Fan

Symphony (II)

OBJECTIVE: See project #154.

Project #155

Fire Fan

Symphony (II)

Project #156

Fan Symphony

OBJECTIVE:

To combine sounds from the music, alarm, and space war integrated circuits.

Modify the circuit from project #154 to match the circuit shown on the left. The only differences are the connections around the alarm IC (U2). It works the same way.

The preceding circuit may be too loud, so replace the speaker (SP) with the whistle chip (WC).

Build the circuit shown and add the jumper to complete it. Note that in one place two (2) single snaps are stacked on top of each other. Also, note that there is a 2-snap wire on layer 2 that does not connect with a 4-snap wire that runs over it on layer 4 (both touch the music IC). T urn it on and press the press switch (S2) several times and wave your hand over the photoresistor (RP) to hear the full spectrum of sounds that this circuit can create. Have fun!

WARNING: Moving parts. Do not touch

the fan or motor during operation. Do not lean over the motor.

WARNING: Moving parts. Do not touch

the fan or motor during operation. Do not lean over the motor.

-24-

Project #158 Police Car Symphony

OBJECTIVE: To combine sounds from the integrated circuits.

OBJECTIVE: See project #160.

The preceding circuit may be too loud, so replace the speaker (SP) with the whistle chip (WC).

Project #161

Ambulance

Symphony (II)

OBJECTIVE: See project #158.

Project #159

Police Car

Symphony (II)

Project #160 Ambulance Symphony

OBJECTIVE:

To combine sounds from the music, alarm, and space war integrated circuits.

Modify the circuit from project #158 to match the circuit shown on the left. The only differences are the connections around the alarm IC (U2). It works the same way.

The preceding circuit may be too loud, so replace the speaker (SP) with the whistle chip (WC).

Build the circuit shown and add the two (2) jumper wires to complete it. Note that in one place two (2) single snaps are stacked on top of each other. Turn it on and press the press switch (S2) several times and wave your hand over the photoresistor (RP) to hear the full spectrum of sounds that this circuit can create. Have fun! Do you know why the antenna (A1) is used in this circuit? It is being used as just a 3snap wire, because it acts like an ordinary wire in low frequency circuits such as this. Without it, you don’t have enough parts to build this complex circuit.

Visit www.snapcircuits.net or page 74 to learn about more Snap Circuits®products to add to your collection.

-25-

Project #162 Static Symphony

OBJECTIVE: See project #162.

Project #163

Static

Symphony (II)

Project #164 Capacitors in Series

OBJECTIVE: To compare types of circuits.

Project #165 Capacitors in Parallel

OBJECTIVE: To compare types of circuits.

Tur n on the slide switch (S1), then press and release the press switch (S2). The LED (D1) becomes bright when the 470μF capacitor charges up with the press switch on, then the LED slowly gets dim after you release the press switch.

Now turn off the slide switch. Repeat the test with the slide s wtich off; you’ll notice the LED goes out much faster after you release the press switch. The much smaller 100μF capacitor (C4) is now in series with the 470μF and so reduces the total capacitance (electrical storage capacity), and they discharge much faster. (Note that this is opposite to how resistors in series work).

Tur n off the slide switch (S1), then press and release the press switch (S2). The LED (D1) becomes bright when the 100μF capacitor charges up with the press switch on, then the LED slowly gets dim after you release the press switch.

Now turn on the slide switch and repeat the test; y ou’ll notice the LED goes out much slower after you release the press switch. The much larger 470μF capacitor (C5) is now in parallel with the 100μF and so increases the total capacitance (electrical storage capacity), and they discharge much slower. (Note that this is opposite to how resistors in parallel work.)

OBJECTIVE: To combine sounds from the integrated circuits.

For a variation on the preceding circuit, you can replace the 6V lamp (L2) with the LED (D1), with the positive (+) side up, or the motor (M1) (do not place the fan on it).

Build the circuit shown. Note that in some places parts are stacked on top of each other. Turn it on and press the press switch (S2) several times and wave your hand over the photoresistor (RP) to hear the full spectrum of sounds that this circuit can create. Have fun!

-26-

Project #166

OBJECTIVE: To show how water conducts electricity.

Build the circuit at left and connect the two jumpers to it, but leave the loose ends of the jumpers lying on the table initially. Tur n on the slide switch (S1) - the LED (D1) will be dark because the air separating the jumpers has very high resistance. Touch the loose jumper ends to each other and the LED will be bright, because with a direct connection there is no resistance separating the jumpers.

Now take the loose ends of the jumpers and place them in a cup of water, without letting them touch each other. The LED should be dimly lit, indicating you have detected water!

For this experiment, your LED brightness may vary depending upon your local water supply. Pure water (like distilled water) has very high resistance, but drinking water has impurities mixed in that increase electrical conduction.

Water Detector

Project #167

OBJECTIVE: To show how adding salt to water changes water’s electrical characteristics.

Place the jumpers in a cup of water as in the preceding project; the LED (D1) should be dimly lit. Slo wly add salt to the water and see ho w the LED brightness changes, mix it a little so it dissolves. It will slowly become very bright as you add more salt. You can use this bright LED condition as a saltwater detector! You can then reduce the LED brightness by adding more water to dilute the salt.

Take another cup of water and try adding other household substances like sugar to see if they increase the LED brightness as the salt did.

Saltwater Detector

-27-

Project #168

NPN Light Control

OBJECTIVE: To compare transistor circuits.

Project #169

NPN Dark Control

Turn on the slide switch (S1), the brightness of the LED (D2) depends on how much light shines on the photoresistor (RP). The resistance drops as more light shines, allowing more current to the NPN (Q2).

OBJECTIVE: To compare transistor circuits.

Turn on the slide switch (S1), the brightness of the LED (D2) depends on how LITTLE light shines on the photoresistor (RP). The resistance drops as more light shines, diverting current away from the NPN (Q2).

Project #170

PNP Light Control

OBJECTIVE: To compare transistor circuits.

Project #171

PNP Dark Control

Turn on the slide switch (S1), the brightness of the LED (D1) depends on how much light shines on the photoresistor (RP). The resistance drops as more light shines, allowing more current through the PNP (Q1). This is similar to the NPN (Q2) circuit above.

OBJECTIVE: To compare transistor circuits.

Turn on the slide switch (S1), the brightness of the LED (D1) depends on how LITTLE light shines on the photoresistor (RP). The resistance drops as more light shines, so more current gets to the 100kΩ resistor (R5) from the photoresistor path and less from the PNP-diode path. This is similar to the NPN circuit above.

Visit www.snapcircuits.net or page 74 to learn about Snap Circuits®upgrade kits, which have more parts and circuits.

-28-

Project #172

Red & Green Control

OBJECTIVE: To demonstrate how the adjustable resistor works.

Project #173

Current Controllers

Turn on the circuit using the slide switch (S1) and/or the press switch (S2) and move the adjustable resistor’s (RV) control lever around to adjust the brightness of the LED’s (D1 & D2). When the adjustable resistor is set to one side, that side will have low resistance and its LED will be bright (assuming the switch on that side is ON) while the other LED will be dim or OFF.

OBJECTIVE: To compare types of circuits.

Build the circuit and turn on the slide switch (S1), the LED (D1) will be lit. To increase the LED brightness, turn on the press switch (S2). To decrease the LED brightness, turn off the slide switch.

With the slide switch on, the 5.1KΩ resistor (R3) controls the current. Turning on the press switch places the 1KΩ resistor (R2) in parallel with it to decrease the total circuit resistance. Turning off the slide switch places the 10KΩ resistor (R4) in series with R2/R3 to increase the total resistance.

Project #174

Current Equalizing

OBJECTIVE: To compare types of circuits.

Project #175

Battery Polarity Tester

In this circuit the LED’s (D1 & D2) will have the same brightness, but the lamp (L1) will be off. When connected in series, all components will have equal electric current through them. The lamp is off because it requires a higher current through the circuit to turn on than the LED’s do.

OBJECTIVE: To test the polarity of a battery.

Use this circuit to check the polarity of a battery. Connect your battery to X & Y on the drawing using the jumper cables (your 3V battery pack (B1) can also be snapped on directly instead). If the positive (+) side of your battery is connected to X, then the red LED (D1) will be on, if the negative (–) side is connected to X then the green LED (D2) will be on.

-29-

Project #176 Blow Off a Doorbell

OBJECTIVE: To turn off a circuit by blowing on it.

OBJECTIVE: To turn on a circuit by blowing on it.

Replace the speaker (SP) with the 6V lamp (L2). Blowing into the microphone (X1) turns on the light, and then it goes off again.

Project #179

Blow On a

Candle

OBJECTIVE: To turn off a circuit by blowing on it.

Project #177

Blow Off a

Candle

Project #178 Blow On a Doorbell

OBJECTIVE: To turn on a circuit by blowing on it.

Build the circuit and turn it on, music plays for a few moments and then stops. Blo w into the microphone (X1) and it plays; it plays as long as you keep blowing.

Replace the speaker (SP) with the 6V lamp (L2). Blowing hard into the microphone (X1) turns off the light briefly.

Build the circuit and turn it on; music plays. Since it is loud and annoying, try to shut it off by blowing into the microphone (X1). Blowing hard into the microphone stops the music, and then it starts again.

-30-

Project #180

OBJECTIVE: To have an adjustable resistance control a fan and sounds.

Screaming Fan

Project #182

Light Whining

OBJECTIVE: To make different sounds.

Replace the 100Ω resistor (R1) at the upperleft of the circuit (points A1 & A3 on the base grid) with the photoresistor (RP), and wave your hand over it. The whining sound has changed a little and can now be controlled by light.

Project #183

More Light

hining

OBJECTIVE: To make different sounds.

Replace the 0.02μF capacitor (C1) with the

0.1μF capacitor (C2). The sounds are lower in frequency and you can’t make the fan spin now.

Project #184

Motor That

on’t Start

OBJECTIVE: To make different sounds.

Replace the 0.1μF capacitor (C2) with the 10μF capacitor (C3), put the positive (+) side towards the left). It now makes clicking sounds and the fan moves only in small bursts, like a motor that won’t start.

Project #181

Whining Fan

OBJECTIVE: To make different sounds.

Replace the 0.1μF capacitor (C2) with the

0.02μF capacitor (C1). The sounds are now a high-pitch whine and the motor (M1) starts a little sooner.

Build the circuit on the left and place the fan onto the motor (M1). T urn on the slide switch (S1) and move the setting on the adjustable resistor (RV) across its range. You hear screaming sounds and the fan spins.

WARNING: Moving parts. Do not

touch the fan or motor during operation. Do not lean over the motor.

To learn more about how circuits work, visit www.snapcircuits.net or page 74 to find out about our Student Guides.

-31-

Project #185

OBJECTIVE: To build a circuit that makes a loud whine.

Whiner

Project #187

Hummer

OBJECTIVE: To show how adding capacitance reduces frequency.

Now place the 0.1μF capacitor (C2) above the whistle chip (WC) and vary the adjustable resistor (RV) again. The frequency (or pitch) of the whine has been reduced by the greater added capacitance and it sounds more like a hum now.

Project #188

Adjustable

Metr

onome

OBJECTIVE: To build an adjustable electronic metronome.

Now place the 10μF capacitor (C3, “+” side on right) above the whistle chip (WC) and vary the adjustable resistor (RV) again. There is no hum now but instead there is a click and a flash of light repeating about once a second, like the “beat” of a sound. It is like a metronome, which is used to keep time for the rhythm of a song.

Project #189

Quiet Flasher

OBJECTIVE: To make a blinking flashlight.

Leave the 10μF capacitor (C3) connected but replace the speaker (SP) with the 2.5V lamp (L1).

Project #186

Lower Pitch

hiner

OBJECTIVE: To show how adding capacitance reduces frequency.

Place the 0.02μF capacitor (C1) above the whistle chip (WC) and vary the adjustable resistor (RV) again. The frequency (or pitch) of the whine has been reduced by the added capacitance.

Build the circuit, turn it on, and move the setting on the adjustable resistor (RV). It makes a loud, annoying whine sound. The green LED (D2) appears to be on, but it is actually flashing at a very fast rate.

-32-

Project #190

OBJECTIVE: To build a transistor oscillator that can make a foghorn sound.

Hissing Foghorn

Project #191

Hissing & Clicking

OBJECTIVE: To build an adjustable clicking oscillator.

Modify the circuit in project #190 by replacing the 100kΩ resistor (R5) with the photoresistor (RP). Move the adjustable resistor (RV) setting until you hear hissing sounds, and then shield the photoresistor while doing so and you hear clicking sounds.

OBJECTIVE: To build a human oscillator.

Build the circuit on the left and move the adjustable resistor (RV) setting. Sometimes it will make a foghorn sound, sometimes it will make a hissing sound, and sometimes it will make no sound at all.

Project #192

Video Game

Engine Sound

Remove the photoresistor (RP) from the circuit in project #191 and instead touch your fingers between the contacts at points A4 and B2 on the base grid while moving the adjustable resistor (RV). You hear a clicking that sounds like the engine sound in autoracing video games.

-33-

Project #193 Light Alarm

OBJECTIVE: To build a transistor light alarm.

OBJECTIVE: To build a simple laser.

Replace the motor (M1) with the 6V lamp (L2). Now pressing the press switch (S2) creates a blast of light like a laser.

Project #196

Laser Light

OBJECTIVE: To build a brighter transistor light alarm.

Project #195 Lazy Fan

OBJECTIVE: To build a fan that doesn’t work well.

Press the press switch (S2) and the fan will be on for a few turns. Wait a few moments and press again, and the fan will make a few more turns.

Modify the circuit in project #193 by replacing the LED (D1) with the 2.5V lamp (L1) and replacing the 5.1kΩ resistor (R3) with the 100Ω resistor (R1). It works the same way but is brighter now.

Build the circuit with the jumper connected as shown, and turn it on. Nothing happens. Break the jumper connection and the light turns on. You could replace the jumper with a longer wire and run it across a doorway to signal an alarm when someone enters.

Project #194

Brighter

Light Alarm

WARNING: Moving parts. Do not

touch the fan or motor during operation. Do not lean over the motor.

Visit www.snapcircuits.net or page 74 to learn about more Snap Circuits®products to add to your collection.

-34-

Project #197

OBJECTIVE: To sound an alarm when water is detected, tone will vary with salt content.

Build the circuit at left and connect the two (2) jumpers to it, place the loose ends of the jumpers into an empty cup (without them touching each other). Press the press switch (S2) - nothing happens. Add some water to the cup and an alarm will sound. Add salt to the water and the tone changes.

You can also test different liquids and see what tone they produce.

Water Alarm

Project #198

OBJECTIVE: To hear your voice on the radio.

You need an AM radio for this project. Build the circuit shown but do not turn on the slide switch (S1). Place it within a foot of your AM radio and tune the radio frequency to the middle of the AM band (around 1000 kHz), where no other station is transmitting. Turn the volume up so you can hear the static. Set the adjustable resistor (RV) control to the middle setting. Turn on the slide switch and slowly tune the adjustable capacitor (CV) until the static on the radio becomes quiet. You may hear a whistle as you approach the proper tuning. In some cases you may also need to set the adjustable resistor slightly offcenter.

When the radio static is gone, tap on the speaker (SP) with your finger and you should hear the sound of tapping on the radio . No w talk loudly into the speaker (used here as a microphone) and you will hear your voice on the radio . Set the adjustable resistor for best sound quality at the radio.

Radio Announcer

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Project 201

Pitch (III)

OBJECTIVE: See project #199.

Project #202

OBJECTIVE: To sound an alarm when water is detected.

Flooding Alarm

Project #199 Pitch

OBJECTIVE: To show how to change the pitch of a sound.

Project 200

Pitch (II)

OBJECTIVE: See project #199.

Remove the 0.1μF (C2) capacitor and replace the 100kΩ resistor (R5) wth the photoresistor (RP). Wave your hand up and down over the photoresistor to change the sound. Changing the light on the photoresistor changes the circuit resistance just like varying the adjustable resistance does. Note: If you have the adjustable resistor (RV) set to the right and light shining on the photoresistor, then you may not get any sound because the total resistance is too low for the circuit to operate.

Build the circuit on the left, turn it on, and vary the adjustable resistor (RV). The

frequency

pitch

of the sound is changed. Pitch is the musical profession’ s word for frequency. If you’ve had music lessons, you may remember the music scale using chords such as A3, F5, and D2 to express the

pitch

of a sound. Electronics prefers the term

frequency

, as in when you adjust the frequency on your radio.

Build the circuit on the left and connect the two (2) jumpers to it, place the loose ends of the jumpers into an empty cup (without them touching each other). T urn on the slide s witch (S1) - nothing happens. This circuit is designed to detect water and there is none in the cup. Add some water to the cup - an alarm sounds!

You can use longer jumper wires and hang them near your basement floor or next to your sump pump to give a warning if your basement is being flooded. Note that if the loose jumper ends accidentally touch then you will have a false alar m.

Since we’ve seen we can adjust the frequency by varying the resistance in the adjustable resistor, are there other ways to change frequency? You can also change frequency by changing the capacitance of the circuit. Place the 0.1μF capacitor (C2) on top of the

0.02μF capacitor (C1); notice how the sound has changed.

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Project #203

OBJECTIVE: To demonstrate how batteries can store electricity.

Build the circuit, then connect points Y & Z (use a 2-snap wire) for a moment. Nothing appears to happen, but you just filled up the 470μF capacitor (C5) with electricity. Now disconnect Y & Z and instead touch a connection between X & Y. The green LED (D2) will be lit and then go out after a few seconds as the electricity you stored in it is discharged through the LED and resistor (R2).

Notice that a capacitor is not very efficient at storing electricity compare how long the 470μF kept the LED lit for with how your batteries run all of your projects! That is because a capacitor stores electrical energy while a battery stores chemical energy.

Make Your Own

Battery

OBJECTIVE: To demonstrate how batteries can store electricity. OBJECTIVE: To demonstrate how batteries can store electricity.

Now replace the 1kΩ resistor (R2) with the 100Ω resistor (R1) and try it. The LED (D2) gets brighter but goes out faster because less resistance allows the stored electricity to dissipate faster.

In the preceding circuit, replace the 470μF capacitor (C5) with the 100μF capacitor (C3) and repeat the test. You see that the LED (D2) goes out faster, because the 100μF capacitor does not store as much electricity as the 470μF.

Project #204

Make Your Own

ttery (II)

Project #205

Make Your Own

ttery (III)

Visit www.snapcircuits.net or page 74 to learn about Snap Circuits®upgrade kits, which have more parts and circuits.

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Project #206

OBJECTIVE: To build a high-frequency oscillator.

Tone Generator

Project #207

Tone

Generator (II)

OBJECTIVE: To lower the frequency of a tone by increasing circuit capacitance.

Place the 0.02μF capacitor (C1) on top of the whistle chip (WC) in the preceding circuit, you hear a middle-frequency sound. Why? The whistle chip is used here as a capacitor and by placing the 0.02

F on top (in parallel) we have increased the capacitance, and doing so lowers the frequency.

Project #208

Tone

Gener

ator (III)

OBJECTIVE: To lower the frequency of a tone by increasing circuit capacitance.

Next, replace the 0.02μF capacitor (C1) and the whistle chip (WC) with the larger 0.1

F capacitor (C2). You now hear a low frequency sound, due to yet more capacitance.

Project #209

Tone

Gener

ator (IV)

OBJECTIVE: To lower the frequency of a tone by increasing circuit capacitance.

Now replace the 0.1μF (C2) with the much larger 10

F capacitor (C3), (orient with the positive (+) side towards the left); the circuit just clicks about once a second. There isn’t a constant tone anymore due to other transistor properties. You need a different type of circuit to create very low frequency tones.

Build the circuit and turn it on, you hear a high-frequency sound.

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Project #210

OBJECTIVE: To build a middle-frequency oscillator.

Build the circuit, as the name suggests this circuit is similar to that in project #206. Turn it on, you hear a middle-frequency sound.

More Tone Generator

OBJECTIVE: To lower the frequency of a tone by increasing circuit capacitance.

Now place the 10μF capacitor (C3) on top of the whistle chip (WC). You hear a clicking sound as the LED’s blink about once a second.

Place the 0.02μF capacitor (C1) or the 0.1μF capacitor (C2) on top of the whistle chip (WC). The sound is different now because the added capacitance has lowered the frequency. The LED’s appear to be on, but are actually blinking at a very fast rate.

Project #211

More Tone

Gener

ator (II)

Project #212

More Tone

Gener

ator (III)

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Project #213 Music Radio Station

OBJECTIVE: To create music and transmit it to a radio.

OBJECTIVE: To create music

and transmit it to a radio.

Project #214

Alarm Radio

Station

Project #215 Standard Transistor Circuit

OBJECTIVE: To save some electricity for later use.

Turn on the slide switch (S1) and move the adjustable resistor (RV) control lever across its range. When the lever is all the way down the LED (D1) will be off, as you move the lever up it will come on and reach full brightness.

This circuit is considered the standard transistor configuration for amplifiers. The adjustable resistor control will normally be set so that the LED is at half brightness, since this minimizes distortion of the signal being amplified.

Replace the music IC (U1) with the alarm IC (U2), and then you will hear a machine gun sound on the radio. You may need to retune the variable capacitor (CV).

You need an AM radio for this project. Build the circuit shown on the left and turn on the slide switch (S1). Place it next to your AM radio and tune the radio frequency to where no other station is transmitting.

Then, tune the variable capacitor (CV) until your music sounds best on the radio.

To learn more about how circuits work, visit www.snapcircuits.net or page 74 to find out about our Student Guides.

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Project #217

Fading Siren

OBJECTIVE: To produce sound of a siren driving away into the distance.

Replace the 470μF capacitor (C5) with the 100

F capacitor

(C4), the siren fades faster.

Press the press switch (S2), the alarm IC (U2) should make the sound of an up-down siren that gets weaker with time. The fading is produced by the charging of the 470

F capacitor (C5). After it is charged the current stops and the sound is very weak.

To repeat this effect you must release the press switch, remove the capacitor, and discharge it by placing it across the snaps on the bottom bar marked A & B. Then, replace the capacitor and press the switch again.

Project #218

Fast Fade

Siren

Project #216

OBJECTIVE: To control a motor using light.

Turn the slide switch (S1) on, the motor (M1) spins and the lamp (L2) lights. As you move your hand over the photoresistor (RP), the motor slows. Now place finger onto the photoresistor to block the light. The motor slows down. In a few seconds, the motor speeds up again.

Motor & Lamp

by Sound

WARNING: Moving par ts. Do not touch the fan or

motor during operation. Do not lean o ver the motor.

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Project #219 Laser Gun with

Limited Shots

OBJECTIVE: To build a circuit with laser gun sounds and a limited amount of shots.

Project #220 Symphony of Sounds

OBJECTIVE: To combine sounds from the music, alarm, and space war integrated circuits.

OBJECTIVE: See project #220.

The preceding circuit may be too loud, so replace the speaker (SP) with the whistle chip (WC).

Build the circuit shown. Turn it on and press the press switch (S2) several times and wave your hand over the photoresistor (RP) to hear the full symphony of sounds that this circuit can create. Have fun!

When you press the press switch (S2), the alarm IC (U2) should start sounding a very loud laser gun sound. The speaker (SP) will sound, simulating a burst of laser energy. You can shoot long repeating laser burst, or short zaps by tapping the trigger switch. But be careful, this gun will run out of energy and you will have to wait for the energy pack (C5) to recharge. This type of gun is more like a real life laser gun because power would run out after a fe w shots due to energy drain. In a real laser, the energy pac k would hav e to be replaced. Here you only have to wait a few seconds for recharge.

Project #221

Symphony of

Sounds (II)

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Project #222

OBJECTIVE: To learn about the most important component in electronics.

Transistor Amplifiers

OBJECTIVE: To show how electronic amplifiers can detect skin pressure on two contacts.

OBJECTIVE: To show how electronic amplifiers can detect different values of resistance.

Use the circuit from project #222 shown above. When you placed your fingers across the two snaps marked X & Y you

noticed the LED (D1) came on in project #222. Repeat this process , b ut this time press very lightly on the two snaps marked X & Y. Notice how the brightness of the LED is dependent on the amount of pressure you use. Pressing hard makes the LED bright while pressing very gently makes it dim or even flash. This is due to what technicians call “contact resistance”. Even switches made to turn your lights on and off have some resistance in them. When large currents flow, this resistance will drop the voltage and produce the undesirable side effect of heat.

Project #223

Pressure Meter

Project #224

Resistance Meter

When you place one or more fingers across the two snaps marked X & Y you will notice the LED (D1) turns on. The two transistors are being used to amplify the very tiny current going through your body to turn on the LED. Transistors are actually electrical current amplifiers. The PNP transistor (Q1) has the arrow pointing into the transistor body. The NPN transistor (Q2) has the arrow pointing out of the transistor body. The PNP amplifies the current from your fingers first, then the NPN amplifies it more to turn on the LED.

Use the circuit from project #222 shown above When you placed your fingers across the two snaps marked X & Y you

noticed the LED (D1) came on in project #222. In this project, you will place different resistors across R & Z and see how bright the LED glows. Do not snap them in; just press them up against the snaps labeled R & Z in the diagram above. First, place the 100kΩ resistor (R5) across the R & Z snaps and note the brightness of the LED. Next, press the 5.1kΩ resistor (R3) across R & Z. Notice ho w the LED gets brighter when the resistance is less. This is because the NPN amplifier (Q2) gets more current at its input when the resistance is lower. The PNP amplifier (Q1) is not used in this test.

Visit www.snapcircuits.net or page 74 to learn about more Snap Circuits®products to add to your collection.

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Project #225

OBJECTIVE: To learn about one device that is used to delay actions in electronics.

Auto-Off Night-Light

OBJECTIVE: To show how capacitor delays can be repeated by discharging the capacitor.

OBJECTIVE: To show how the size of the capacitor effects the delay time.

Use the circuit from project #225 shown above. When you first turned on the slide switch (S1) in project #225, the LED

(D1) came on and very slowly got dimmer and dimmer. When you turned the slide switch (S1) off and back on after the light went out, it did NOT come on again. The 470μF capacitor (C5) was charged and everything stopped. This time turn the slide switch off. Then press the press switch (S2) for a moment to discharge the 470μF capacitor. Now when you turn the slide switch back on the delay repeats. Shorting a capacitor with a low resistance will allow the charges on the capacitor to leave through the resistance. In this case, the low resistance was the press switch.

Project #226

Discharging Caps

Project #227

Changing Delay Time

When you turn on the slide switch (S1) the first time the LED (D1) will come on and very slowly get dimmer and dimmer. If you turn the slide switch (S1) off and back on after the light goes out it will NOT come on again. The 470μF capacitor (C5) has charged up and the NPN transistor amplifier (Q2) can get no current at its input to turn it on.

This circuit would make a good night-light. It would allow you to get into bed, and then it would go out. No further current is taken from the battery so it will not drain the batteries (B1) even if left on all night.

Use the circuit from project #225 shown above. Change the 470μF capacitor (C5) to the 100μF capacitor (C4). Make

sure the capacitor (C4) is fully discharged by pressing the press switch (S2) before closing the on-off slide switch (S1). When slide switch is turned on, notice how much quicker the LED (D1) goes out. Since 100μF is approximately 5 times smaller than 470μF, the LED will go out 5 times faster. The bigger the capacitor the longer the delay.

In electronics, capacitors are used in every piece of equipment to delay signal or tune circuits to a desired frequency.

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Project #228 Morse Code Generator

OBJECTIVE: To make a Morse code generator and learn to generate code.

Project #229

LED Code

Teacher

OBJECTIVE: A method of learning the Morse code without all the noise.

Use the circuit from project #228 shown above. Replace the speaker with a 100Ω resistor (R1) so you can practice generating the Morse code without the loud speaker. Have someone transmit code and watch the LED. Tell them the letter or number after each is generated. When you have learned code, replace the speaker.

OBJECTIVE:

To make a ghost like special effect from the Morse code generator.

Project #231

LED &

Speaker

OBJECTIVE: To improve Morse code skills and visual recognition.

OBJECTIVE: To make an oscillator that only a dog can hear.

Project #230

Ghost Shriek

Machine

Use the circuit from project #228 shown above , but change the 1kΩ resistor (R2) to a 10kΩ resistor (R4), and 0.1μF capacitor (C2) to the whistle chip (WC). While holding the press switch (S2) down, adjust both the adjustable resistor (RV) and the whistle chip for a ghost like sound. At cer tain settings, sound may stop or get very faint.

Use the circuit from project #228 shown above. Try and find a person that already knows the Morse code to send you a message with both sound and LED flashing. Try in a dark room first so LED (D1) is easier to see. Morse code is still used by many amateur radio operators to send messages around the world.

Use the circuit from project #228 shown above, but change the 1k

resistor (R2) to the 100Ωresistor (R1). While holding down the press switch (S2), move the slider on the adjustable resistor (RV) around. When the slider is near the 100

resistor you won’t hear any sound, but the circuit is still working. This oscillator circuit is making sound waves at a frequency too high for your ears to hear. But your dog may hear it, because dogs can hear higher frequencies than people can.

Project #232

Dog Whistle

When you press down on the press switch (S2) you will hear a tone. By pressing and releasing the press switch you can generate long and short tones called Morse code. For International code, a short tone is represented by a “+”, and a long tone by a “–”. See the chart below for letter or number followed by code.

A+– B–+++ C–+–+ D–++ E+ F++–+

G––+ H++++ I++ J+––– K–+– L+–++

M–– N–+ O––– P+––+ Q––+– R+–+

S+++ T– U++– V+++– W+–– X–++–

Y–+–– Z––++ 1+–––– 2++––– 3+++–– 4++++–

5+++++ 6–++++ 7––+++ 8–––++ 9––––+ 0–––––

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Project #233 Mind Reading Game

OBJECTIVE: To make an electronic game of mind reading.

Build the circuit shown on the left. It uses two (2) 2-snap wires as shorting bars.

Setup: Player 1 sets up by placing one shorting bar under the paper on row A, B, C, or D. Player 2 must NOT know where the shorting bar is located under the paper.

The object is for Player 2 to guess the location by placing his shorting bar at positions W, X, Y, or Z. In the drawing on the left, Player 1 set up at position “D”. If Player 2 places his shorting bar across “Z” on the first try, then he guessed correctly and marks a 1 on the score card sheet under that round number. If it takes three tries, then he gets a three. Player 2 then sets the A, B, C, D side and Player 1 tries his luck. Each player records his score for each round. When all 18 rounds have been played, the player with the lowest score wins. Additional players can play. Use the score card below to determine the winner.

Round # 123456789101112131415161718 Total

Player 1 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ _____ Player 2 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ _____ Player 3 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ _____ Player 4 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ _____

Shorting Bar for A, B, C, or D.

Paper Sheet to hide position of shorting bar.

Shorting Bar for W, X, Y, or Z.

Visit www.snapcircuits.net or page 74 to learn about Snap Circuits®upgrade kits, which have more parts and circuits.

-46-

Project #234

OBJECTIVE: Make and play the electronic game of “Quiet Zone”.

Use the circuit from project #233, but place three (3) 2-snap wires (“shorting bars”) under paper as shown on left.

Setup: Player 1 sets the “Quiet Zone” by placing

three (3)

shorting bars under the paper on row A, B, C, or D, leaving only one open. Player 2 must NOT know where the shor ting bars are located under the paper.

Both Player 1 and Pla yer 2 are giv en 10 points . The object is for Player 2 to guess the location of the “Quiet Zone” by placing his shorting bar at positions W, X, Y, or Z. In the drawing on the left Player 1 set up the “Quiet Zone” at position “C”. If Player 2 places his shorting bar across “Z” on the first try, the sounds played mean he has not found the “Quiet Zone” and he loses 1 point. He has 3 tr ies to find the zone on each turn. Each time sounds are made he loses a point. Player 2 then sets the A, B, C, D side and Player 1 starts searching. Play continues until one player is at zero points and makes sound during that players turn.

Enhanced Quiet Zone Game

Project #235

OBJECTIVE: To show how capacitors store and release electrical charge.

Turn on the slide switch (S1) for a few seconds, then turn it off. The green LED (D2) is initially bright but goes dim as the batteries (B1) charge up the 470μF capacitor (C5). The capacitor is storing electrical charge.

Now press the press switch (S2) for a few seconds. The red LED (D1) is initially bright but goes dim as the capacitor discharges itself through it.

The capacitor value (470μF) sets how much charge can be stored in it, and the resistor value (1kΩ) sets how quickly that charge can be stored or released.

Capacitor Charge &

Discharge

Shorting Bar for A , B , C, or D.

Paper Sheet to hide position of shorting bar.

Shorting Bar for W, X, Y, or Z.

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Project #236

OBJECTIVE: To show how sound waves travel on a paper surface.

Sound Wave Magic

Project #237

OBJECTIVE: To amplify sounds from the space

war integrated circuit.

Build the circuit, turn on the slide switch (S1), and press the press switch (S2) several times. You will hear loud space war sounds, since the sound from the space war IC (U3) is amplified by the power amplifier IC (U4). Nearly all toys that make sound use a power amplifier of some sort.

Space War

Amplifier

Build the circuit shown on the left and connect the speaker (SP) using the two (2) jumper wires. Then, lay the speaker on a flat hard surface.

Setup: Use some paper and scissors to cut out a rectangular pattern. Use the one shown below as a guide. Use colored paper if available. Fold at the points shown. Scotch tape the cor ners so the tray has no cracks at the corners. Place the tray over the speaker and sprinkle a small amount of white table salt in the tray. There should be enough salt to cover the bottom with a little space between each salt grain.

Sound Magic: Turn on the circuit by turning on the slide switch (S1). Adjust the adjustable resistor (RV) for different pitches and watch the salt particles. Particles that bounce high are directly over the vibrating paper and ones that do not move are in the nodes where the paper is not vibrating. Ev entually, all the salt will move to the areas that hav e no vibration, and stay there. Change the position of the tray and the material used to create different patterns due to the sound. Try sugar and coffee creamer, for example, to see if they move differently due to the sound waves.

Paper Tray

Salt

Sample Cut-out Pattern

(fold)

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Project #238

Trombone

OBJECTIVE: To build an electronic trombone that changes pitch of note with slider bar.

When you turn on the slide switch (S1) the trombone should start playing. To change the pitch of the note, simply slide the adjustable resistor (RV) control back and forth. By turning the slide switch on and off and moving the slider, you will be able to play a song much like a trombone player makes music. The switch represents air going through the trombone, and the adjustable resistor control is the same as a trombone slider bar. The circuit may be silent at some positions of the resistor control.

Project #239

Race Car Engine

OBJECTIVE: To show how changing frequency changes the sound to a different special effect.

Use the circuit from project #238 shown on the left, but change the

0.02μF capacitor (C1) to a 10μF capacitor (C3). Make sure the positive (+) mark on the capacitor is NOT on the resistor (R2) side when you snap it in.

When the slide switch (S1) is turned on, you should hear a very low frequency oscillation. By sliding the adjustable resistor (RV) control up and down, you should be able to make the sound of a race car engine as it’s motor speeds up and slows down.

To learn more about how circuits work, visit www.snapcircuits.net or page 74 to find out about our Student Guides.

-49-

Project #240

Power Amplifier

OBJECTIVE: To check stability of power amplifier with open input.

When you turn on the slide switch (S1), the power amplifier IC (U4) should not oscillate. You should be able to touch point X with your finger and hear static. If you do not hear anything, listen closely and wet your finger that touches point X. High frequency clicks or static should be coming from speaker (SP) indicating that the amplifier is powered on and ready to amplify signals.

The power amplifier may oscillate on its o wn. Do not worry, this is normal with high gain high-powered amplifiers.

Project #241

Feedback Kazoo

OBJECTIVE: To show how electronic feedback can be used to make a musical instrument.

Use the circuit from project #240 shown on the left. When you place one finger on point X and a finger from your other hand

on the speaker (SP) snap that is not connected to the battery (B1), what happens? If the amplifier starts to oscillate it is due to the fact that you just provided a feedback path to make the amplifier into an oscillator. You may ev en be ab le to change the pitch of the oscillation b y pressing harder on the snaps.

This is the principle used to make an electronic kazoo. If you practice and learn the amount of pressure required to make each note, you may even be able to play a few songs.

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Project #242

OBJECTIVE: To make a complete working AM radio.

When you turn on the slide switch (S1), the integrated circuit (U5) should amplify and detect the AM radio waves all around you. The variable capacitor (CV) can be tuned to the desirable station. V arying the adjustable resistor (RV) will make the audio louder or softer. The power amplifier IC (U4) drives the speaker (SP) to complete the AM radio project.

AM Radio

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Project #243 Fire Engine Symphony

OBJECTIVE: To combine sounds from the music, alarm, and space war integrated circuits.

OBJECTIVE: See project #243.

Project #244

Fire Engine

Symphony (II)

Project #245

Vibration or Sound Indicator

OBJECTIVE: To build a circuit that is activated by vibration or sound.

Turn on the slide switch (S1), the war sounds start playing and the LED (D1) flashes. When all of the sounds are played, the circuit stops. Clap your hands next to the whistle chip (WC) or tap on it. Any loud sound or vibration causes the whistle chip to produce a small voltage, which activates the circuit. You can repeat a sound by holding down the press switch (S2) while it is playing.

The preceding circuit may be too loud, so replace the speaker (SP) with the whistle chip (WC).

Can you guess why the jumper is used in this circuit? It is being used as just a 6-snap wire, because without it you don’t have enough parts to build this complex circuit.

Build the circuit shown and add the jumper to complete it. Note that in two places two single snaps are stacked on top of each other. Also, note that there is a 2-snap wire on layer 2 that does not connect with a 4-snap wire that runs over it on layer 4 (both touch the music IC, U1). Turn it on and press the press switch (S2) several times and wave your hand over the photoresistor (RP) to hear the full spectrum of sounds that this circuit can create. Have fun!

Visit www.snapcircuits.net or page 74 to learn about more Snap Circuits®products to add to your collection.

-52-

Project #246

OBJECTIVE: To show that your body can be used as an electronic component.

Build the circuit on the left. You’re probably wondering how it can work, since one of the points on the NPN transistor (Q2) is unconnected. It can’t, but there is another component that isn’t shown. That component is you.

Touch points X & Y with your fingers. The LED (D1) may be dimly lit. The problem is your fingers aren’t making a good enough electrical contact with the metal. Wet your fingers with water or saliva and touch the points again. The LED should be very br ight now. Think of this circuit as a touch lamp since when you touch it, the LED lights. You may have seen such a lamp in the store or already have one in your home.

Two-Finger Touch Lamp

Project #247

OBJECTIVE: To show you how finger touch lamps work.

The touch lamps you see in stores only need to be touched by one finger to light, not two. So let’s see if we can improve the last circuit to only need one finger. Build the new circuit, note that near point X there is a 2-snap wire that is only mounted on one side, swing it so the plastic touches point X. Wet a large area of one of your fingers and touch it to both metal contacts at point X at the same time; the LED (D2) lights. To make it easier for one finger to touch the two contacts, touch lamps or other touch devices will have the metal contacts interweaved as shown below and will also be more sensitive so that you don’t have to wet your finger to make good contact.

One-Finger Touch Lamp

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Project #248 Space Battle

OBJECTIVE: To make space battle sounds.

Project #250 Multi-Speed Light Fan

OBJECTIVE: To vary the speed of a fan activated by light.

OBJECTIVE: To show how light can turn “ON” an electronic device.

Replace the slide switch (S1) with the photoresistor (RP). No w cov ering and uncovering the photoresistor will change the sound.

Project #249

Space Battle (II)

Project #251

Light & Finger Light

OBJECTIVE: To show another way the Space War IC may be used.

In the circuit at left, replace the motor (M1) with the 2.5V lamp (L1) shown below. Vary the brightness of the lamp by covering the photoresistor (RP) and holding down the press switch (S2) in v arious combinations. Notice that pressing the press switch when the photoresistor is covered still turns on the lamp, while in project #250, doing this would turn off the motor.

Build the circuit shown on the left. Activate the circuit by turning on the slide switch (S1) or pressing the press switch (S2), do both several times and in combination. You will hear exciting sounds and see flashing lights, as if a space battle is raging!

Build the circuit shown on the left, with the fan on the motor (M1).

This circuit is activated by light on the photoresistor, (RP) though the fan will barely turn at all. Press the press switch (S2) and the fan will spin. If you hold the press switch down, the fan will spin faster. If you cover the photoresistor, the fan will stop unless the press switch is pressed.

WARNING: Moving par ts. Do not touch the fan or

motor during operation. Do not lean o ver the motor.

-54-

Project #252 Storing Electricity

OBJECTIVE: To store electricity in a capacitor.

Project #253

Lamp Brightness Control

OBJECTIVE: To use a transistor combination to control a lamp.

OBJECTIVE: To make an electric fan using a transistor circuit.

Use the circuit from project #253. Replace the lamp (L1) with the motor (M1) and install the fan. By controlling the adjustable resistor (RV), the speed of the fan changes. Now you can make your own speed changing electric fan.

Here is a combination with two transistors. This combination increases the amplifying power. By changing the resistance, the current at the base of the transistor is also changed. With this amplifying ability of the combination, there is a greater change of current to the lamp (L1). This changes the brightness.

Turn the slide switch (S1) on and connect points A & B with a 2-snap wire. The green LED (D2) will flash and the 470μF capacitor (C5) will be charged with electricity. The electricity is now stored in the capacitor. Disconnect points A & B. Connect points B & C and there will be a flash from the 6V lamp (L2).

The capacitor discharges through the resistor to the base of the NPN transistor (Q2). The positive current turns on the transistor like a switch, connecting the lamp to the negative (–) side of the batteries. The light will go out after the capacitor discharges, because there is no more current at the base of the transistor.

Project #254

Electric Fan

WARNING: Moving parts.

Do not touch the fan or motor during operation. Do not lean over the motor.

Visit www.snapcircuits.net or page 74 to learn about Snap Circuits®upgrade kits, which have more parts and circuits.

-55-

Project #255

OBJECTIVE: To build an alarm that plays music on the radio.

Place the circuit next to an AM radio . Tune the radio so no stations are heard. Set the slide switch (S1) on. You should hear the song play. The red LED (D1) should also be lit. Adjust the v ariable capacitor (CV) for the loudest signal.

Connect a jumper wire across points A & B and the music stops. The transistor (Q2) acts like a switch connecting power to the music IC (U1). Positive voltage on the base turns on the switch and negative voltage opens it. Connect a string to the jumper wire and the other end of the string to a door or window. Turn the slide switch on. If a thief comes in through the door or window, the string pulls the jumper off and the music plays on the radio.

Radio Music

Burglar Alarm

Project #256

OBJECTIVE: To build a light dimmer.

Press the press switch (S2) to complete the current’s path flow. You might expect the LED (D1) to light instantly but it doesn’t. The charging current flows into the 100μF capacitor (C4) first. As the capacitor charges, the charging current decreases, input current to the PNP transistor (Q1) increases. So current begins to flow to the LED and the LED gradually brightens.

Now release the press switch. The capacitor begins to discharge, sending input current to the transistor. As the capacitor discharges, the input current reduces to zero and gradually turns off the LED and the transistor.

Light Dimmer

-56-

Project #257

OBJECTIVE: Build a circuit that detects motion.

Set the adjustable resistor (RV) to the center position. Turn the slide switch (S1) on and the LED (D1) lights. Wave your hand over the photoresistor (RP) and the LED turns off and on. The resistance changes as the amount of light strikes the photoresistor. As the light decreases, the resistance increases. The increased resistance lowers the voltage at the base of the NPN transistor (Q2). This turns off the transistor, preventing current flowing through the LED to the negative (–) side of the battery (B1). Wave your hand over photoresistor at different distances. The LED gets brighter the farther away your hand is.

Motion Detector

Project #258

OBJECTIVE: To modulate the brightness of an LED.

Using the fan outline as a guide, cut a 3” circle out of a piece of paper. Then, cut a small triangle in it as shown. Tape the circle onto the fan and then place it onto the motor (M1). Set the

adjustable

resistor (RV) to the center position and turn the slide switch (S1) on. Press the press switch (S2), the fan spins and the lamp (L1) lights. As the triangle opening moves over the photoresistor (RP), more light strikes it. The brightness of the LED changes, or is

modulated

. As in AM or FM radio, modulation uses one signal to modify the amplitude or frequency of another signal.

Fan Modulator

3” dia.

WARNING: Moving par ts. Do not touch the fan or

motor during operation. Do not lean o ver the motor.

-57-

Project #261

OBJECTIVE: To build a motion detector that senses an objects movement.

Turn the slide switch (S1) on and move the adjustable resistor (RV) control all the way up. The brightness of the LED (D1) is at maximum. Now, move the adjustable resistor control down until the LED goes out. Set the control up a little and the LED lights dimly.

Move your hand from side to side over the photoresistor (RP). As your hand blocks the light, the LED goes out.

The amount of light changes the resistance of the photoresistor and the current flow to the base of the NPN transistor (Q2). The transistor acts like a switch. Its base current is supplied through the photoresistor. As the base current changes, so does the current flow through the LED. With no base current, the LED goes out.

Motion Detector (II)

Project #259

Oscillator 0.5 - 30Hz

OBJECTIVE: To build a 0.5Hz - 30Hz oscillator that will light an LED.

Set the adjustable resistor (RV) to the bottom position and then turn the slide switch (S1) on. The LED (D1) will start flashing at a frequency of 0.5Hz (once every two seconds). Slowly adjust the adjustable resistor and the LED flashes faster. As the frequency increases, the LED flashes faster. Eventually, the LED flashes so fast, it looks like it is on all of the time.

Project #260

Sound Pulse Oscillator

OBJECTIVE: To build a 0.5Hz - 30Hz oscillator and hear it on a speaker.

Use the circuit from project #259. Connect a single snap under the speaker (SP) and then connect it across the LED (on level 4). Turn the slide switch (S1) on and now you can hear the oscillator. Adjust the adjustable resistor (RV) to hear the different frequencies. Now you can hear and see the frequencies. Note: You may not hear sounds at all settings of the adjustable resistor.

To learn more about how circuits work, visit www.snapcircuits.net or page 74 to find out about our Student Guides.

-58-

Project #262

OBJECTIVE: To show how voltage polarity affects a DC motor.

Place the fan onto the motor (M1). Press the press switch (S2). The fan rotates clockwise. When you connect the positive (+) side of the battery (B1) to the positive (+) side of the motor, it spins clockwise. Release the press switch and turn on the slide switch (S1). Now the fan spins the other way. The positiv e (+) side of the battery is connected to the negative (–) side of the motor. The polarity on the motor determines which way it rotates.

Motor Rotation

OBJECTIVE: To build a circuit that controls how long the fan is on.

Place the fan onto the motor (M1) and set the adjustable resistor (RV) control to the far right. Turn the slide switch (S1) on and then press the press switch (S2) once. The motor will spin and then stop. Now set the resistor control to the f ar left and press the press s witch again. The time the fan spins is much less now.

When the press switch is pressed, the current flows through the circuit and the fan spins. The 100μF capacitor (C4) charges up also. When the press switch is released, the capacitor discharges and supplies the current to keep the transistors (Q1 & Q2) on. The transistor acts like a switch connecting the fan to the battery. When the capacitor fully discharges, the transistors turn off and the motor stops. The adjustable resistor controls how fast the capacitor discharges. The more resistance, the longer the discharge time.

Project #264

Motor Delay Fan (II)

OBJECTIVE: To change capacitance to affect time.

Use the circuit from project #263. Connect a single snap under the positive (+) side of the 470μF capacitor (C5) and then connect it over the top of the 100μF capacitor (C4). Turn the slide switch (S1) on and press the press switch (S2). Notice that the fan spins longer now. When capacitors are in parallel, the values are added, so now you have 570μF. Th e time it takes to discharge the capacitors is longer now, so the fan keeps spinning.

Project #263

Motor Delay Fan

WARNING: Moving par ts. Do not touch the fan or

motor during operation. Do not lean o ver the motor.

WARNING: Moving parts.

Do not touch the fan or motor during operation. Do not lean over the motor.

-59-

OBJECTIVE: To build a high pitch bell.

Build the circuit shown and press the press switch (S2). The circuit starts to oscillate. This generates the sound of a high pitch bell.

Project #266

Steamboat Whistle

OBJECTIVE: To build a steamboat whistle.

Using the circuit in project #265, connect the 0.02μF capacitor (C1) across the whistle chip (WC). Press the press switch (S2). The circuit now generates the sound of a steamboat.

Project #267

Steamship

OBJECTIVE: To generate the sound of a steamship.

Using the circuit in Project #265, connect the 0.1μF capacitor (C2) across the whistle chip. Press the press switch (S2). The circuit now generates the sound of a steamship.

Project #268 Light NOR Gate

OBJECTIVE: To build a NOR gate.

Build the circuit on the left. You will find that the lamp (L1) is on when neither the slide switch (S1) NOR the press switch (S2) are on. This is referred to as an NOR gate in electronics and is important in computer logic.

Example: If neither condition X NOR condition Y are true, then execute instruction Z.

Project #265 High Pitch Bell

-60-

Project #269

OBJECTIVE: To build a noise activated alarm.

Noise-Activated

Burglar Alarm

OBJECTIVE: To build a motor-activated burglar alarm. OBJECTIVE: To build a light-activated burglar alarm.

Use the circuit from project #269 shown above. Replace the whistle chip (WC) with the motor (M1). Wind a piece of string around the axis of the motor so when you pull it the axes spins. Connect the other end of the string to a door or window. Turn the slide switch (S1) on and wait f or the sound to stop . If a thief comes in through the door or window the string pulls and the axes spins. This will activate the sound.

Project #270

Motor-Activated

Bur

glar Alarm

Project #271

Light-Activated

Bur

glar Alarm

Turn the slide switch (S1) on and wait for the sound to stop. Place the circuit into a room you want guarded. If a thief comes into the room and makes a loud noise, the speaker (SP) will sound again.

If you find that the sound does not turn off, then vibrations created by the speaker may be activ ating the whistle chip. Set the speak er on the table near the circuit and connect it to the same locations using the jumper wires to prevent this.

Use the circuit from project #269 shown above. Connect a photoresistor (RP) across points A & B and cover it or turn off the lights. Turn the slide switch (S1) on and wait for the sound to stop. At night, when the thief comes in and turns on the light, the speaker (SP) makes the sound of a machine gun.

Visit www.snapcircuits.net or page 74 to learn about more Snap Circuits®products to add to your collection.

-61-

Project #272

Photoresistor Control

OBJECTIVE: To use a photoresistor to control the brightness of an LED.

In this circuit, the brightness of the LED (D1) depends on how much light shines directly on the photoresistor (RP). If the photoresistor were held next to a flashlight or other bright light, then the LED would be very bright.

The resistance of the photoresistor decreases as more light shines on it. Photoresistors are used in applications such as streetlamps, which come on as it gets dark due to night or a severe storm.

Project #273

Microphone Control

OBJECTIVE: To use a microphone to control the brightness of an LED.

In this circuit, blowing on the microphone (X1) changes the LED (D1) brightness.

The resistance of the microphone changes when you blow on it. You can replace the microphone with one of the resistors to see what resistor value it is closest to.

-62-

Project #274

Pressure Alarm

OBJECTIVE: To build a pressure alarm circuit.

Connect two jumper wires to the whistle chip (WC) as shown. Set the control of the adjustable resistor (RV) to the far left and turn on the switch. There is no sound from the speak er (SP) and the LED (D1) is off. Tap the center of the whistle chip. The speaker sounds and the LED lights. The whistle chip has a piezocrystal between the two metal plates. The sound causes the plates to vibrate and produce a small voltage. The voltage is amplified by the power amplifier IC (U4), which drive the speaker and LED.

Place a small object in the center of the whistle chip. When you remove the object the speaker and LED are activated. In alarm systems, a siren would sound to indicate the object has been removed.

Project #275

Power Microphone

OBJECTIVE: To build a power microphone.

Use the circuit from project #274. Replace the whistle chip with the microphone (X1), and hold it away from

the speaker (SP). Set the control of the adjustab le resistor (RV) to the far left. Turn on the slide switch (S1) and talk into the microphone. You now hear your voice on the speaker. The sound w av es from y our voice vibr ate the microphone and produce a voltage. The voltage is amplified by the power amplifier IC (U4) and your voice is heard on the speaker.

-63-

Project #277

OBJECTIVE: To build a circuit that uses a programmed sound

integrated circuit (IC).

Space War Sounds

with LED

Project #276

OBJECTIVE: To build an LED fan rotation indicator.

Do not place the fan onto the motor (M1). T urn the slide switch (S1) on. The motor rotates clockwise, and the green LED (D2) lights. When you connect the positive (+) side of the battery (B1) to the positive (+) side of the motor, it spins clockwise. Turn the slide switch off and press the press switch (S2). Now the fan spins the other way and the red LED (D1) lights. The positive (+) side of the battery is connected to the negative (–) side of the motor. The polar ity on the motor determines which way it rotates.

Now place the fan on the motor, and turn on S1 or S2 (not both). Now one of the lamps (L1 or L2) lights as the motor spins, but the LED is dim.

The motor needs a lot of current to spin the fan, but only a little current to spin without it. In this circuit, a lamp lights when the motor current is high, and an LED lights when the motor current is low. The lamps also prevent a short circuit if both switches are on.

LED Fan Rotation Indicator

Build the circuit shown on the left, which uses the space war integrated circuit (U3). Turn the slide switch (S1) on. A space war sound plays, and the LED (D1) flashes. If there is no light on the photoresistor (RP) then the sound will stop after a while.

You also make sounds by pressing the press switch (S2). See how many sounds are programmed into the space war sound IC.

Visit www.snapcircuits.net or page 74 to learn about Snap Circuits®upgrade kits, which have more parts and circuits.

WARNING: Moving par ts. Do not touch the fan or

motor during operation. Do not lean o ver the motor.

-64-

Project #278

OBJECTIVE: To connect two sound IC’s together.

In the circuit, the outputs from the alarm (U2) and music (U1) IC’s are connected together. The sounds from both IC’s are pla yed at the same time.

Sound Mixer

Project #279

OBJECTIVE: To connect two sound IC’s together to drive two

LED’s and a motor.

Build the circuit shown on the left. Place the fan onto the motor (M1). In the circuit, the alarm IC (U2) and the music IC (U1) are connected

together. The sounds from both IC’s can be played at the same time. Press the press switch (S2). The music IC plays and the green LED (D2) lights. Now turn on the slide switch (S1) and press the press switch again. You should hear the sounds from both IC’s playing. As the alarm IC plays, it also drives the fan and the red LED (D1).

Sound Mixer Fan

Driver

WARNING: Moving par ts. Do not touch the fan or

motor during operation. Do not lean o ver the motor.

-65-

Project #280

OBJECTIVE: To show how light can control a motor.

Turn on the slide switch (S1) and set the adjustable resistor (RV) control so the motor (M1) just starts spinning. Slowly cover the photoresistor (RP) and the motor spins faster. By placing more light over the photoresistor, the motor slows.

Electric Fan Stopped

by Light

Project #281

OBJECTIVE: To control large currents with a small one.

Place the fan on the motor (M1). Turn on the slide switch (S1) and the motor spins. The transistors are like two switches connected in series. A small current turns on the NPN transistor (Q2), which turns on the PNP transistor (Q1). The large current used to spin the motor now flows through the PNP. The combination allows a small current to control a much larger one.

Press the press switch (S2) and the lamp (L2) lights and slows the motor. When the lamp lights, the voltage across the motor decreases and slows it down.

Motor & Lamp

WARNING: Moving par ts. Do not touch the fan or

motor during operation. Do not lean o ver the motor.

WARNING: Moving par ts. Do not touch the fan or

motor during operation. Do not lean o ver the motor.

-66-

Project #282

OBJECTIVE: To start and stop a motor with light.

Place the fan on the motor (M1). Tur n on the slide switch (S1), the motor starts spinning. As you move your hand over the photoresistor, (RP) the motor slows. Now place a finger on top of the photoresistor to block the light. The motor slows down. In a few seconds the motor speeds up again.

Start-Stop Delay

Project #283

OBJECTIVE: To build a circuit to indicate if you have mail.

Turn on the slide switch (S1). If there is light on the photoresistor (RP) the red LED (D1) will not light. Place y our finger o v er the photoresistor and now the red LED lights. A simple mail notifying system can be made using this circuit. Install the photoresistor and the green LED (D2) inside the mailbox facing each other. Place the red LED outside the mailbox. When there is mail, the light is blocked from the photoresistor and the red LED turns on.

Mail Notifying System

WARNING: Moving par ts. Do not touch the fan or

motor during operation. Do not lean o ver the motor.

To learn more about how circuits work, visit www.snapcircuits.net or page 74 to find out about our Student Guides.

-67-

Project #284 Mail Notifying Electronic Bell

OBJECTIVE: To build a circuit to indicate if you have mail by sounding a tone.

OBJECTIVE: To build a flicking LED circuit.

Use the circuit from project #286. Replace the speaker (SP) with a red LED (D1, the “+” sign on top). Now you see the frequency of the oscillator. Install different values of capacitors to change the frequency.

Project #287

Quick Flicking LED

OBJECTIVE: To build a circuit to indicate if you have mail by activating the lamp.

Project #286

OBJECTIVE: To build an oscillating circuit.

The tone you hear is the frequency of the oscillator. Install different values of capacitors in place of the 0.1μF capacitor (C2) to change the frequency.

Replace the speaker (SP) with the lamp (L2). When there is mail, the light is blocked from the photoresistor (RP) and the lamp lights.

Turn on the slide switch (S1). If there is enough light on the photoresistor (RP), the speaker (SP) will not make any sound. Place your finger o ver the photoresistor and now the speaker sounds. The sound will stay on until you turn off the slide switch. A simple mail notifying system can be made using this circuit. Install the photoresistor and the green LED inside the mailbox facing each other. When there is mail, the light is blocked from the photoresistor and the speaker turns on.

Project #285

Mail Notifying Electronic Lamp

Twice-

Amplified

Oscillator

-68-

Project #288

OBJECTIVE: To build a complete, working AM radio with

transistor output.

AM Radio with Transistors

Project #289

OBJECTIVE: To build a complete, working AM radio.

When you close the slide switch (S1), the integr ated circuit (U5) should detect and amplify the AM radio waves. The signal is then amplified using the power amplifier (U4), which drives the speaker (SP). Tune the variable capacitor (CV) to the desirable station.

AM Radio (II)

When you turn on the slide switch (S1), the integrated circuit (U5) should amplify and detect the AM radio waves. Tune the variable capacitor (CV) to the desirable station. Set the adjustab le resistor (R V) for the best sound. The two transistors (Q1 & Q2) drive the speaker (SP) to complete the radio. The radio will not be very loud.

-69-

Project #290

OBJECTIVE: To amplify sounds from the music integrated circuit.

Build the circuit and turn on the slide switch (S1). You will hear loud music, since the sound from the music IC (U1) is amplified by the power amplifier IC (U4). All radios and stereos use a power amplifier.

Music Amplifier

Project #291 Delayed Action Lamp

OBJECTIVE: To build a lamp that

stays on for a while.

OBJECTIVE: To build a fan

that stays on for a while.

Replace the lamp (L1) with the motor (M1), positive (+) side up. Be sure to put on the fan. Turn on the slide switch (S1) and press the press switch (S2). The fan turns on slowly but stays on for a while after you release the press switch.

Turn on the slide switch (S1) and press the press switch (S2). The lamps (L1 & L2) turn on slowly, but stay on for a while after you release the press switch.

Project #292

Delayed

Action Fan

Visit www.snapcircuits.net or page 74 to learn about more Snap Circuits®products to add to your collection.

-70-

Project #293 Police Siren Amplifier

OBJECTIVE: To amplify sounds from the music integrated circuit.

Build the circuit and turn on the slide switch (S1). You will hear a very loud siren, since the sound from the alarm IC (U2) is amplified by the power amplifier IC (U4). Sirens on police cars use a similar circuit, with an IC to create the sound and a power amplifier to make it very loud.

Project #294 Lasting Doorbell

OBJECTIVE: To build a doorbell that stays on for a while.

OBJECTIVE: To build a clicker that stays on for a while.

Place the 10μF capacitor (C3) on top of the whistle chip (WC). Press and release the press switch (S2). It makes a clicking sound that repeats for a while.

Build the circuit at left, note that there is a 4-snap wire on layer 1 that is not connected to a 3-snap wire that runs over it on layer 3. Turn on the slide switch (S1), then press and release the

press switch

(S2). There is a

doorbell sound that slowly fades aw a y. When the press switch is pressed,

the transistors are supplied with current for oscillation. At the same time, the 100μF capacitor (C4) is being charged. When the press switch is released, the capacitor discharges and keeps the oscillation going for a while.

Project #295

Lasting

Clicking

-71-

Project #296

OBJECTIVE: To show how capacitors can filter out electrical disturbances.

Place the fan on the motor (M1) and turn off the slide switch (S1). Press the press switch (S2) and listen to the motor.

As the motor shaft spins around it connects/ disconnects several sets of electrical contacts. As these contacts are switched, an electrical disturbance is created, which the speaker converts into sound.

Turn on the slide switch and push the press switch again. The fan spins just as fast, but the sound is not as loud. Capacitors, like the 470μF capacitor (C5), are often used to filter out undesired electrical disturbances. If y ou replace C5 with one of the other capacitors in y our set then the sound will not be changed as much.

Quieting a Motor

Project #297 Transistor Fading Siren

OBJECTIVE: To build a siren that slowly fades away.

OBJECTIVE: To build a doorbell that slowly fades away.

Replace the alarm IC (U2) with the music IC (U1). The circuit has a doorbell sound that plays and stops.

Turn on the slide switch (S1), then press and release the press switch (S2). You hear a siren that slowly fades away and eventually goes off. You can modify this circuit to make machine gun or ambulance sound instead like in the other projects. You can also replace the 10μF capacitor (C3) with the 100μF (C4) or 0.1μF (C2) to greatly slow down or speed up the fading.

Project #298

Fading

Doorbell

WARNING: Moving parts. Do not touch the fan or

motor during operation. Do not lean o ver the motor.

-72-

Project #299

OBJECTIVE: To change space war sounds by blowing.

Turn on the slide switch (S1) and you will hear explosion sounds and the lamp is on or flashing. Blo w into the microphone (X1) and you can change the sound pattern.

Blowing Space War Sounds

Project #300 Adjustable Time Delay Lamp

OBJECTIVE: To build a lamp that stays on for a while.

OBJECTIVE: To build a fan that stays on for a while.

Replace the lamp (L1) with the motor (M1), be sure to put on the fan. Turn on the slide switch (S1) and press the press switch (S2). The f an sta ys on for a while after you release the press switch. You can change the delay time with the adjustable resistor (RV).

Turn on the slide switch (S1) and press the press switch (S2). The lamps stay on for a while after you release the press switch. You can change the delay time with the adjustable resistor (RV).

Project #301

Adjustable

Time Delay Fan

WARNING: Moving parts. Do not

touch the fan or motor during operation. Do not lean over the motor.

Visit www.snapcircuits.net or page 74 to learn about Snap Circuits®upgrade kits, which have more parts and circuits.

-73-

Project #302

OBJECTIVE: To build a lamp that stays on for a while.

OBJECTIVE: To build a fan that stays on for a while.

Replace the lamp (L1) with the motor (M1, positive (+) side up), be sure to put on the fan. Turn on the switch and press the press switch (S2). The fan stays on for a while after you release the press switch. This could have a longer dela y and be near your bed, to turn off after you fall asleep.

Project #305

Delayed

Bedside Fan

OBJECTIVE: To build a fan that stays on for a while.

Project #304 Watch Light

OBJECTIVE: To build a lamp that stays on for a while.

Turn on the switch and press the press switch (S2). The lamp stays on for a few seconds after you release the press switch.

A miniature version of a circuit like this might be in your wristwatch when you press a light button on the watch to read the time in the dark, a light comes on but automatically turns off after a few seconds to avoid draining the battery.

Replace the lamp (L1) with the motor (M1), be sure to put on the fan. Turn on the switch and press the press switch (S2). The fan stays on for a while after you release the press switch. You can change the delay time with the adjustable resistor (RV).

Be sure to use the 2.5V lamp (L1) for this circuit. Turn on the switch and press the press switch (S2). The lamp stays on for a few seconds after you release the press switch. You can change the delay time with the adjustable resistor (RV).

Project #303

Adjustable Time Delay Fan (II)

Adjustable

Time Delay

Lamp (II)

WARNING: Moving parts. Do not

touch the fan or motor during operation. Do not lean o v er the motor.

WARNING: Moving parts. Do not

touch the fan or motor during operation. Do not lean o v er the motor.

-74-

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