SCS 185_Manual 185 Manual

User Manual: SCS-185_Manual

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Project 47

Copyright © by Elenco® Electronics, Inc. All rights reserved. No part of this book shall be reproduced by
any means; electronic, photocopying, or otherwise without written permission from the publisher.

Patents: 7,144,255; 7,273,377; & other patents pending

753120

Table of Contents
Basic Troubleshooting
Parts List
How to Use Snap Circuits®
About Your Snap Circuits® SOUND Parts
Introduction to Electricity
Sound in Our World

1
2, 3
4
5-7
8
9-14

WARNING: SHOCK HAZARD - Never connect Snap
Circuits® to the electrical outlets in your home in any way!

Basic Troubleshooting
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 flexible sheet in the sound energy demo container is
damaged, replace it with a spare (if one was included), or use
household plastic wrap.
6. If the echo IC (U28) stops working, turn the circuit off and on
to reset it.
ELENCO® is not responsible for parts damaged due to incorrect wiring.
Note: If you suspect you have damaged parts, you can follow the
Advanced Troubleshooting procedure on pages 16 and 17 to determine
which ones need replacing.

-1-

WARNING: Some projects are intended for use with
headphones (not included in this set). Headphones
performance varies, so you should use caution.
Permanent hearing loss may result from long-term
exposure to sound at high volumes. Start with as
low a volume as possible, then carefully increase to
a comfortable level. Ringing or discomfort in the
ears may indicate that the sound levels are too high;
immediately discontinue using the headphones with
this product and consult a physician.

DO’s and DON’Ts of Building Circuits
Advanced Troubleshooting
Project Listings
Projects 1 - 188
Other Snap Circuits® Projects

WARNING: CHOKING HAZARD Small parts. Not for children under 3 years.

WARNING: Always check your wiring
before turning on a circuit. Never leave
a circuit unattended while the batteries
are installed. Never connect additional
batteries or any other power sources to
your circuits. Discard any cracked or
broken parts.
Adult Supervision: Because children’s
abilities vary so much, even with age
groups,
adults
should
exercise
discretion as to which experiments are
suitable and safe (the instructions
should enable supervising adults to
establish the experiment’s suitability for

15
16, 17
18, 19
20-85
86

Conforms to all applicable
U.S. government
requirements.

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.

Batteries:

• Use only 1.5V “AA” type, alkaline batteries
(not included).
• Insert batteries with correct polarity.

• Do not mix alkaline, standard (carbonzinc), or rechargeable (nickel-cadmium)
batteries.

• 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.

• Remove batteries when they are used up.

• Do not mix old and new batteries.

• Batteries are harmful if swallowed, so keep
away from small children.

• Do not connect batteries or battery holders
in parallel.

• Do not short circuit the battery terminals.
• Never throw batteries in a fire or attempt to
open its outer casing.

Parts List (Colors and styles may vary) Symbols and Numbers (page 1)
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 Service • 150 Carpenter Ave. • Wheeling, IL 60090 U.S.A.
Qty.

Name

Symbol

Part #

Base Grid
(11.0” x 7.7”)

6SCBG

1-Snap Wire

6SC01

2-Snap Wire

6SC02

3-Snap Wire

6SC03

4-Snap Wire

6SC04

5-Snap Wire

6SC05

6-Snap Wire

6SC06

Battery Holder - uses
two (2) 1.5V type “AA”
(not included)

6SCB1

Qty.
r1

Name

0.1mF Capacitor

6SCC2

470mF Capacitor

6SCC5

1mF Capacitor

6SCC7

Color Light Emitting
Diode (LED)

6SCD8

Egg LED Attachment

6SCEGG

Jumper Wire (black)

6SCJ1

Jumper Wire (red)

6SCJ2

Audio Jack

6SCJA

Symbol

Part #

You may order additional / replacement parts at our website: www.snapcircuits.net
-2-

Parts List (Colors and styles may vary) Symbols and Numbers (page 2)
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 Service • 150 Carpenter Ave. • Wheeling, IL 60090 U.S.A.
Qty.

Name

Part #

Qty.

NPN Transistor

6SCQ2

Tube for Sound
Energy Demo
Container

6SCSEDCT

100W Resistor

6SCR1

Flexible Sheet for Sound
Energy Demo Container
(may include spare)

6SCSEDCF

5.1kW Resistor

6SCR3

SP2

Speaker

6SCSP2

Adjustable Resistor

6SCRV

U26

Keyboard

6SCU26

RV3

500kW Adjustable
Resistor

6SCRV3

U27

Voice Changer

6SCU27

Photoresistor

6SCRP

U28

Echo IC

6SCU28

Slide Switch

6SCS1

Microphone

6SCX1

Press Switch

6SCS2

Stereo Cable

9TLSCST

Symbol

Base for Sound
Energy Demo
Container

Name

Symbol

6SCSEDCB

You may order additional / replacement parts at our website: www.snapcircuits.net
-3-

Part #

How to Use Snap Circuits®
Snap Circuits® uses building blocks with snaps
to build the different electrical and electronic
circuits in the projects. Each block has a
function: there are switch blocks, light blocks,
battery blocks, different length wire blocks, etc.
These blocks are different colors and have
numbers on them so that you can easily
identify them. The blocks you will be using are
shown as color symbols with level numbers
next to them, allowing you to easily snap them
together to form a circuit.

You need a power source to build each circuit.
This is labeled B1 and requires two (2) 1.5V
“AA” batteries (not included).

Egg

(Adult supervision recommended)

This set contains a sound energy
demonstration container, which will sometimes
be placed over the speaker. Its use is
explained in project 13.

This is the switch block, which is green and has
the marking S2 on it. The part symbols in this
booklet may not exactly match the appearance
of the actual parts, but will clearly identify them.

There is also a 1-snap wire that is used as a
spacer or for interconnection between different
layers.

Egg LED attachment
mounted to D8

Sound Energy Demonstration
Container Assembly

For Example:

This is a wire block, which is blue and comes
in different wire lengths.
This one has the number 2 , 3 , 4 , 5 ,
or 6 on it depending on the length of the wire
connection required.

This set contains an egg LED attachment,
which can be mounted on the color LED (D8)
to enhance its light effects.

To assemble it, lay the tube and flexible sheet
over the base, and then push the tube into the
base, as shown. Do not disassemble it except
to repair it. This set may include a spare for the
flexible sheet, and household plastic wrap also
works.
A large clear plastic base grid is included with
this kit to help keep the circuit blocks properly
spaced. You will see evenly spaced posts that
the different blocks snap into. The base has
rows labeled A-G and columns labeled 1-10.
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.
Some circuits use the jumper wires to make
unusual connections. Just clip them to the
metal snaps or as indicated.

Tube

Flexible
sheet

Base

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.

-4-

About Your Snap Circuits® SOUND Parts
(Part designs are subject to change without
notice).

BASE GRID
The base grid is a platform for mounting parts
and wires. It functions like the printed circuit
boards used in most electronic products, or like
how the walls are used for mounting the electrical
wiring in your home.

BATTERY HOLDER
The batteries (B1) produce an electrical voltage
using a chemical reaction. This “voltage” can be
thought of as electrical pressure, pushing
electricity through a circuit just like a pump
pushes water through pipes. This voltage is
much lower and much safer than that used in
your house wiring. Using more batteries
increases the “pressure”, therefore, more
electricity flows.

RESISTORS

Resistors “resist” the flow of electricity and are
used to control or limit the current in a circuit.
Snap Circuits® SOUND includes 100W (R1) and
5.1kW (R3) resistors (“k” symbolizes 1,000, so
R3 is really 5,100W). Materials like metal have
very low resistance (<1W), while materials like
paper, plastic, and air have near-infinite
resistance. Increasing circuit resistance reduces
the flow of electricity.

SNAP WIRES & JUMPER WIRES
The blue snap wires
are wires used to
connect components.
They are used to
transport electricity and do
not affect circuit performance.
They come in different lengths to
allow orderly arrangement of connections
on the base grid.
The red and black
jumper wires make
flexible connections for
times when using the snap wires
would be difficult. They also are
used to make connections off the base grid.
Wires transport electricity just like pipes are used
to transport water. The colorful plastic coating
protects them and prevents electricity from
getting in or out.

Resistors (R1 & R3)
Battery Holder (B1)

SLIDE & PRESS SWITCHES
The slide & press switches (S1 & S2) connect
(pressed or “ON”) or disconnect (not pressed or
“OFF”) the wires in a circuit. When ON they have no
effect on circuit performance. Switches turn on
electricity just like a faucet turns on water from a pipe.

The
adjustable
resistor (RV) is a
50kW resistor but
with a center tap
that can be adjusted
between 200W and
50kW.
Adjustable Resistor (RV)
The 500kW adjustable resistor (RV3) is a
500kW resistor that can be adjusted between
200W and 500kW.

Slide & Press
Switches
(S1 & S2)
500kW Adjustable Resistor (RV3)

-5-

About Your Snap Circuits® SOUND Parts
The photoresistor (RP) is a light-sensitive
resistor, its value changes from nearly infinite in
total darkness to about 1000W when a bright light
shines on it.

Photoresistor (RP)

SPEAKER

The speaker (SP) converts electricity into sound
by making mechanical vibrations. These
vibrations create variations in air pressure, which
travel across the room. You “hear” sound when
your ears feel these air pressure variations.

LED

TRANSISTORS

The color LED (D8) is a light emitting diode, and
may be thought of as a special one-way light
bulb. In the “forward” direction, (indicated by the
“arrow” in the symbol) electricity flows if the
voltage exceeds a turn-on threshold (about 1.5V
for red, about 2.0V for green, and about 3.0V for
blue); brightness then increases. The color LED
contains red, green, and blue LEDs, with a microcircuit controlling then. A high current will burn
out an LED, so the current must be limited by
other components in the circuit. LED’s block
electricity in the “reverse” direction.

The NPN transistor (Q2) is a component that
uses a small electric current to control a large
current, and is used in switching, amplifier, and
buffering applications. Transistors are easy to
miniaturize, and are the main building blocks of
integrated circuits including the microprocessor
and memory circuits in computers.

Color LED
(D8)

ELECTRONIC MODULES

CAPACITOR

Speaker (SP2)

NPN Transistor (Q2)

The 0.1mF, 1mF, and 470mF capacitors (C2, C7,
& C5) can store electrical pressure (voltage) for
periods of time. This storage ability allows them
to block stable voltage signals and pass
changing ones. Capacitors are used for filtering
and delay circuits.

The keyboard (U26) contains resistors,
capacitors, switches, and an integrated circuit. It
can produce two adjustable audio tones at the
same time. The tones approximate musical
notes, and may not be exact. The tone of the
green keys can be adjusted with the tune knob
or using external resistors and capacitors. A
schematic
for
it
is
available
at
www.snapcircuits.net/faq.

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

Microphone (X1)

Capacitors (C2, C5, & C7)

Connections:
(+) - power from batteries
RES - resistor freq adjust
CAP - capacitor freq adjust
OUT - output connection
(–) - power return to batteries

Keyboard (U26)

See projects 1, 6, & 25 for example of proper connections.

-6-

About Your Snap Circuits® SOUND Parts
The echo IC (U28) contains resistors, capacitors, and
integrated circuits that are needed to add echo effects to
a sound. A schematic for it is available at
www.snapcircuits.net/faq.
Connections:
(+) - power from batteries
G+ - gain control
G– - gain control
ADJ - echo adjust
INP - input connection
OUT - output connection
(–) - power return to
batteries

See projects 10 & 41 for
examples
of
proper
connections.

The voice changer (U27) contains resistors, capacitors,
and an integrated circuit that are needed to record and
play back sound at different speeds. A schematic for it is
available at www.snapcircuits.net/faq.
Connections:
(+) - power from batteries
SPD - speed adjust
SP+ - speaker (+)
SP– - speaker (–)
MIC+ - microphone (+)
MIC– - microphone (–)
REC - record
PLY - play
(–) - power return to batteries

See project 7 for example of
proper connections.

-7-

OTHER PARTS
The egg LED attachment can be used
with the color LED (D8) to enhance the
light effects.

The stereo cable is used to connect the
audio jack (JA) to your music device or
external speaker.

Egg

The audio jack (JA) is a connector
mounted on snaps, and is used for
interfacing your music device or external
speaker to Snap Circuits®.

Audio Jack (JA)

The sound energy demonstration
container is used to show that sound
waves have energy, and can move
things around. See project 13.

Introduction to Electricity
What is electricity? Nobody really knows. We only know how to produce it,
understand its properties, and how to control it. Electricity is the movement of subatomic charged particles (called electrons) through a material due to electrical
pressure across the material, such as from a battery.

There are two ways of arranging parts in a circuit, in series or
in parallel. Here are examples:

Power sources, such as batteries, push electricity through a circuit, like a pump
pushes water through pipes. Wires carry electricity, like pipes carry water. Devices
like LEDs, motors, and speakers use the energy in electricity to do things. Switches
and transistors control the flow of electricity like valves and faucets control water.
Resistors limit the flow of electricity.
The electrical pressure exerted by a battery or other power source is called
voltage and is measured in volts (V). Notice the “+” and “–” signs on the battery;
these indicate which direction the battery will “pump” the electricity.

Series Circuit

The electric current is a measure of how fast electricity is flowing in a wire, just
as the water current describes how fast water is flowing in a pipe. It is expressed
in amperes (A) or milliamps (mA, 1/1,000 of an ampere).
The “power” of electricity is a measure of how fast energy is moving through a
wire. It is a combination of the voltage and current (Power = Voltage x Current). It
is expressed in watts (W).
The resistance of a component or circuit represents how much it resists the
electrical pressure (voltage) and limits the flow of electric current. The relationship
is Voltage = Current x Resistance. When the resistance increases, less current
flows. Resistance is measured in ohms (W), or kilo ohms (kW, 1,000 ohms).
Nearly all of the electricity used in our world is produced at enormous generators
driven by steam or water pressure. Wires are used to efficiently transport this
energy to homes and businesses where it is used. Motors convert the electricity
back into mechanical form to drive machinery and appliances. The most important
aspect of electricity in our society is that it allows energy to be easily transported
over distances.
Note that “distances” includes not just large distances but also tiny distances. Try
to imagine a plumbing structure of the same complexity as the circuitry inside a
portable radio - it would have to be large because we can’t make water pipes so
small. Electricity allows complex designs to be made very small.

Parallel Circuit

Placing components in series increases the resistance; highest
value dominates. Placing components in parallel decreases the
resistance; lower value dominates.
The parts within these series and parallel sub-circuits may be
arranged in different ways without changing what the circuit
does. Large circuits are made of combinations of smaller series
and parallel circuits.

-8-

Sound in Our World
Sound is a variation in air pressure created by
a mechanical vibration. See projects 13 & 51
for a demonstration of this. These air pressure
variations travel across the room like waves,
so we call them sound waves. You “hear”
sound when your ears feel these air pressure
variations, and convert them to nerve pulses
that your brain interprets. Eventually the
energy of a sound wave is absorbed, and
becomes heat.
Sound waves can also be thought of as waves
of temporary compression that travel through
materials. Notice that at a loud concert you can
sometimes feel the pressure waves, in
addition to hearing them. Sound waves can
travel through liquids and solids but their
speed may change and their energy may be
reduced, depending on the characteristics of
the material. Sound waves can only travel
through a compressible material, and so
cannot travel through a vacuum. Outer space
is silent, because there is no air or other
material for sound waves to travel through.
The “hearing” part of your ear is inside your
skull; the flaps you see are just funnels to
collect the sound and pass it along to your
eardrum inside. When you were young your
brain learned to interpret the difference in the
information collected from your two ears, and
use it to know which direction a sound came
from. If one of your ears is clogged, then it is
difficult to determine a sound’s direction.
You can compare sound waves from your
voice to waves in a pond. When you speak,
the movements in your mouth create sound
waves just as tossing a rock into the pond
creates water waves. Sound waves travel
through air as water waves travel across the
pond. If someone is nearby, then their ears will
feel the air pressure variations caused by your
-9-

sound waves just as a small boat at the other
side of the pond will feel the water waves.
Sound and water waves

If the mechanical vibration causing the sound
wave occurs at a constant rate, then the sound
wave will repeat itself at the same rate; we
refer to this as the frequency of the sound
wave. Nearly all sound waves have their
energy spread unevenly across a range of
frequencies. When you say a word, you create
a sound wave with energy at various
frequencies, just as tossing a handful of
various-sized rocks into the pond will create a
complicated water wave pattern.
Frequency measures how many times
something occurs per second, expressed in
units called hertz (Hz). The metric prefixes can
be used, so 1,000 repetitions per second is 1
kilohertz (kHz) and 1,000,000 repetitions per
second is 1 megahertz (MHz). The range of
frequencies that can be heard by the human
ear is approximately 20 to 20,000 Hz and is
referred to as the audio range.
Just as there are sound waves caused by
mechanical vibrations, there are also electrical
waves caused by electrical variations. Just as
sound waves travel through air, electrical
waves travel through wires. A microphone
senses pressure variations from sound waves
and creates electrical waves at the same
frequencies. A speaker converts electricity into

sound, by using the energy in electrical waves
to create mechanical vibrations (sound waves)
at the same frequencies.
How does the speaker make sound? An
electric current flowing through a wire has a
very, very tiny magnetic field. Inside the
speaker is a coil of wire and a magnet. The coil
of wire concentrates the magnetic field from
the flowing electric current, enough to make
the magnet move slightly, like a vibration. The
magnet’s vibration creates the air pressure
variations that travel to your ears.
Speaker
sound waves

Your speaker can only create sound from a
CHANGING electrical signal, for unchanging
electrical signals it acts like a 32 ohm resistor.
(An unchanging signal does not cause the
magnet in the speaker to move, so no sound
waves are created). Electrical variations at
high frequencies (referred to as radio
frequencies) cannot be heard by your ears, but
can be used to create electromagnetic radio
waves, which travel through air and are used
for many forms of communication. In AM and
FM radio, voice or music is superimposed on
radio waves, allowing it to be transmitted over
great distances, to later be decoded and
listened to.

Sound in Our World
In stereo, sound is produced on several
speakers (or earphones) with varying
frequencies/loudness on each. This gives the
impression that the sound is coming from
different directions, and is more pleasing to
listen to. Mono sound is the same on all
speakers, and is easier to produce. Note that
a “stereo speaker” can be several speakers
(possibly of different sizes) in one package.
Your Snap Circuits® speaker (SP2) is a mono
speaker. Surround sound is a technique for
placing several speakers (with different
sounds from each) around the listener, to
create a more interesting listening experience.
Surround sound

It’s hard to perceive
sound direction
underwater.

The loudness of sound waves is a measure of
the pressure level, and is expressed in
decibels (dB, a logarithmic scale). Long-term
exposure to loud sounds can lead to hearing
loss. Here are some examples of sound levels:
Sound Source
Threshold of pain
Chain saw
Normal conversation
Calm breathing
Hearing threshold

Sound waves travel very fast, but sometimes
you can perceive the effects of their speed.
Ever notice how sometimes you see lightning
before you hear the thunder? The reason is
because light travels at about 186,000 miles
per second, while sound travels at only about
1,100 feet per second in air. Sound can travel
through liquids and solids, but with increased
speed (the speed depends on the material’s
compressibility and density). Sound travels 4.3
times faster in water than in air; this difference
in speed confuses our ears, making it difficult
to perceive the direction of sound while
underwater.

Level
130dB
110dB
50dB
10dB
0dB

A sonic boom is a shock wave that occurs
when an object travels through air at
supersonic speeds (faster than the speed of
sound). These sonic shock waves are similar
to how the bow of a boat produces waves in
the water. Sonic shock waves can carry a lot
of sound energy and can be very unpleasant
to hear, like an explosion. Aircraft can fly at
supersonic speeds, and the sonic boom
produced is so unpleasant that aircraft are
rarely permitted to fly at supersonic speeds
over populated areas.

Sonic boom

Sound waves can reflect off walls and go
around corners, though their energy may be
reduced depending on the angle and the
roughness of the surface. Sometimes sound
waves can be channeled to focus in a certain
direction. As an example, get a long tube, like
the ones for wrapping paper. Use one of the
projects that make a continuous tone, such as
projects 6 or 92. Hold one end of the tube next
to the speaker (use the yellow side with the
grating) and the other end near your ear, then
remove the tube and compare the sound
volume at the same distance from the speaker.
The long tube should make the sound
reaching your ear louder, because sound
waves reflect off the tube walls and stay
concentrated, instead of spreading out across
the room.
Speaker

Placing a long tube next to
the speaker keeps its sound
waves together longer.

Long tube

Sound waves

-10-

Sound in Our World
Some of a sound wave’s energy can reflect off
walls or objects and come back to you.
Normally you don’t notice these reflections
when you are speaking because not all of the
energy is reflected, and the delay is so short
that your ears can’t distinguish it from the
original sound, but sometimes (such as in a
very large open room) you can hear them these are echoes! You hear an echo when a
lot of the energy of your voice is reflected back
to you after a noticeable delay. The delay time
is the distance (to the reflection point and
back) divided by the speed of sound. Most
people cannot distinguish reflected sound
waves with delays of less than 1/15 of a
second, and perceive them as being part of
the original sound. Echoes can be simulated
electronically by replaying a recorded sound
with a small delay and at reduced volume. See
project 10 and others for examples.

Engineers developing sensitive audio
equipment need to make very accurate sound
measurements. They need rooms that are
sealed from outside sounds, and need to
minimize the measured signal’s reflections off
the walls/ceiling/floor. Specialized rooms have
been designed for this, called anechoic
chambers. These chambers are virtually
soundproof and have specially shaped
materials (usually made of foam) on the walls
to absorb sound waves without producing any
echoes. These chambers simulate a quiet,
open space, allowing the engineers to
accurately measure the equipment being
tested.

Small pushes at the right
moment will make the swing
go higher.

Sound waves reflecting off a wall

Resonance is an important consideration in
the design of musical instruments, and also in
construction. If high winds blow on a tall
building or a bridge at the structure’s resonant
frequency, vibrations can slowly increase until
the structure is torn apart and collapses.
Anechoic chamber

In project 10, if your speaker is too close to
your microphone then the echo sound can be
picked up by the microphone and echoed
again and again until you can’t hear anything
else. The same thing can occur in telephone
systems, and these systems sometimes have
echo-cancelling circuitry to prevent problems
(especially in overseas calls, where the
transmission delay times may be longer).
-11-

need to keep adding energy at the right
moment. In project 13 (Sound Energy
Demonstration), the frequency is tuned to the
speaker’s natural frequency, making it vibrate
noticeably.

Everything has a natural frequency, its
resonance frequency, at which it will vibrate
more easily. When sound waves strike an
object at its natural frequency, the object can
absorb and store significantly more energy
from the sound waves, as vibration. To help
understand this concept, think of a playground
swing, which tends to always swing back and
forth at the same rate. If you push the swing at
the ideal moment, it will absorb energy from
you and swing higher. You don’t need to push
the swing very hard to make it go high, you just

A cone can help you project your voice. A cone
keeps the sound waves (air pressure
variations) together longer, so they don’t
spread out so quickly. Long ago, people who
had trouble hearing used an ear trumpet,
which helps collect sound waves. A person
would speak into the wide end of the ear
trumpet, and the trumpet makes the sound
louder at the listening person’s ear. Electronic
hearing aids have replaced ear trumpets.
Doctors use a stethoscope to hear inside
patient’s bodies. A stethoscope uses a conelike structure to collect sound waves; then
passes them into the doctor’s ear.

Sound in Our World
Electronically we amplify sound by converting
the sound waves into an electrical signal,
amplify the electrical signal, and then convert
that back to sound waves.

Ultrasound waves are above 20 kHz, beyond
the range of human hearing. Bats use
ultrasound waves to effectively “see” in the
dark. Ultrasound waves are also used in
medical imaging, to create pictures of muscles
and organs in the human body. Ultrasound
waves are sometimes used in cleaning items
like jewelry.

Cone
Ear Trumpet

Stethoscope

There are many other applications for sound
waves. Here are some examples:
In SONAR (short for SOund Navigation And
Ranging), sound waves are sent out underwater
at various frequencies and the echoes are
measured; the distance to any objects can be
determined using the time for the echoes to
arrive, and the speed of sound. SONAR is used
for navigating around underwater obstacles and
for detecting other ships, especially submarines.
SONAR is also used by the fishing industry to
help find and harvest fish. Sound waves can
also be used to determine the depth of an oil
well. RADAR (RAdio Detection And Ranging) is
similar to SONAR but uses radio waves instead
of sound waves.
SONAR

Ultrasound photo of a heart (echocardiogram)

Ultrasonic welding is used in industry to bond
materials (usually plastics) together using high
frequency sound waves. The energy of the
sound waves is concentrated at the points to
be bonded, and basically melts the material at
the contact points. This can create a strong
bond, without using glue or nails. Ultrasonic
welding has been used to bond the bottoms of
Snap Circuits® parts in the past, and might still
be used for the speaker (SP2) and
microphone (X1).
Phase 1

Phase 2

Pressure is applied The horn vibrates
the plastic parts
by the horn.
very quickly.

Horn

Plastic
parts

Anvil or jig
Ultrasonic welding

Phase 3
The plastic parts
melt together from
the friction created.

Earthquakes are compression waves, similar
to sound waves but with enormous power.
Using triangulation from several measurement
points, and knowing how fast these waves can
travel across the earth’s surface, scientists can
determine where the earthquake began (called
the epicenter).

Music

The subject of music is one where the worlds
of art and science come together.
Unfortunately, the artistic/musician field works
with qualities that depend on our feelings and
so are difficult to express using numbers while
science/engineering works with the opposite clearly defined, measurable qualities. As a
result, some of the terms used may seem
confusing at first, but you will get used to them.
Music is when vibrations (creating sound
waves) occur in an orderly and controlled
manner forming a pattern with their energy
concentrated at specific frequencies, usually
pleasant to listen to. Noise is when the
vibrations occur in an irregular manner with
their energy spread across a wide range of
frequencies, usually annoying to hear (static
on a radio is a good example). Notice how
some people refer to music that they don’t like
as noise. In electrical systems, noise is
undesired interference that can obscure the
signal of interest.
Another way to think of this is that the ear tries
to estimate the next sounds it will hear. Music
with a beat, a rhythm, and familiar instruments
can be thought of as very predictable, so we
find it pleasant to listen to. Notice also that we
always prefer familiar songs to music that we
are hearing for the first time. Sudden, loud,
unpredictable sounds (such as gunfire, a glass
breaking, or an alarm clock) are very
-12-

Sound in Our World
unnerving and unpleasant. Most electronic
speech processing systems being developed
use some form of speech prediction filters.

relationships between both of your ears. The
same thing applies to stereo sound. You may
have heard the term acoustics; this is the
science of designing rooms for best sound
effects.

Take a piece of string or rope roughly 4 feet
long and tie one end of it to a chair or other
piece of furniture. Swing the other end up and
down so that you have a cyclic pattern, as
shown:

Now swing it three times as fast (three times
the frequency), to produce this pattern:

Now try to swing it five times as fast (five times
the frequency), to produce this pattern:

Since the later patterns are frequency
multiples of the first, we refer to them as
overtones (the music term) or harmonics (the
electronics term) and the original pattern is
called the fundamental. If you could combine
all three of the above patterns onto the string
then you would get a pattern, which looks like
this:
-13-

This combined pattern (a single fundamental
with overtones) is called a tone (and a pure
tone is a single fundamental with no
overtones). Notice that each pattern is more
difficult to produce than the one before it, with
the combined pattern being quite complicated.
And also notice that the more complicated
patterns are much more interesting and
pleasing to look at than the simpler ones. Well
the same thing applies to sound waves.
Complex patterns that have many overtones
for each fundamental are more pleasant to
listen to than simple patterns. If many
overtones were combined together, the results
would approximate a square wave shape.
All traditional music instruments use this
principle, with the instrument shapes and
materials perfected through the years to
produce many overtones for each fundamental
chord or key that is played by the user. Grand
pianos sound better than upright pianos since
their larger shape enables them to produce
more overtones, especially at lower
frequencies. Concert halls sound better than
small rooms because they are designed for
best overtone performance and to take
advantage of the fact that sound waves can
reflect off walls to produce different overtone

A commonly used musical scale (which
measures pitch) will now be introduced. This
scale is called the equal temperament scale,
expressed in hertz. You might think of this as
a conversion table between the artistic and
scientific worlds since it expresses pitch in
terms of frequency. Each overtone (overtone
0 being the fundamental) is divided into 12
semitones: C, C# (“C-flat”), D, D#, E, F, F#, G,
G#, A, A#, and B. The semitones increase by
the ratio 12:2, or 1.05946. Musical notes
(tones) are the measure of pitch and are
expressed using both the semitone and the
overtone, such as A3, G#4, D6, A#1, and E2.
(frequency in hertz and rounded off)
Overtone
0
1
2
3
4
5
6
7
8
9
Overtone
0
1
2
3
4
5
6
7
8
9

C
C#
D
D#
E
F
16.4
17.3
18.4
19.4
20.6
21.8
32.7
34.6
36.7
38.9
41.2
45.7
65.4
69.3
73.4
77.8
82.4
87.3
130
139
147
156
165
175
262
278
294
311
330
349
523
554
587
622
659
698
1047 1109 1174 1245 1319 1397
2093 2217 2344 2489 2637 2794
4186 4435 4698 4978 5274 5588
8372 8870 9397 9956 10548 11175
F#
G
G#
A
A#
B
23.1
24.5
26.0
27.5
29.1
30.9
46.2
49.0
51.9
55.0
58.3
61.7
92.5
98.0
104
110
117
123
185
196
208
220
233
247
370
392
415
440
466
494
740
784
831
880
932
988
1480 1568 1661 1760 1865 1976
2960 3136 3322 3520 3729 3951
5920 6271 6645 7040 7459 7902
11840 12542 13290 14080 14917 15804

Sound in Our World
On your U26 keyboard, the blue keys
approximate the 5th overtone notes, and the
green keys approximate the 6th overtone
notes; actual frequency may vary from the
musical scale. The tone of the green keys can
be adjusted with the tune knob, allowing them
to be in tune with the blue keys, or out of tune
with them. The tone of the green keys may
also be adjusted using external resistors and
capacitors, which can change the frequency
range dramatically (and even beyond the
hearing range of your ears), and can create an
optical theremin. Your keyboard can play one
blue note and one green note at the same
time; if you press two keys of the same color
at the same time, only the higher note will be
played. Projects 1-4 and 25-27 demonstrate
the capabilities of the U26 keyboard.
On most instruments, when you play a note
the sound produced is initially loud and then
decreases with time. On your U26 keyboard,
a note ends when you release the key, unless
you connected external resistors to produce a
continuous tone. More complex electronic
instruments can simulate more notes at the
same time, have more advanced techniques
for producing overtones, and continue to play
the note with decreasing loudness after the
key has been released.
The musical world’s equivalent to frequency
is pitch. The higher the frequency, the higher
the pitch of the sound. Frequencies above
2,000 Hz can be considered to provide treble
tone. Frequencies about 300 Hz and below
provide bass tone.

example, the sound of a guitar compared to
that of a piano for the same musical note. The
difference is a quality known as timbre. Timbre
describes how a sound is perceived, its
roughness. Scientifically it is due to differences
in the levels of the various overtones, and so
cannot be expressed using a single number.
Now consider the following two tones, which
differ slightly in frequency:

Notice that the combined wave has a regular
pattern of where the two tones add together
and where they cancel each other out. This is
the effect that produces the beat you hear in
music. Two tones (that are close in frequency
and have similar amplitude for their
fundamental and for each of their overtones)
will beat at the rate of their frequency
difference. Rhythm is the pattern of regular
beat that a song has.
Now observe this tone:

If they are played at the same time then their
sound waves would be added together to
produce:

The frequency is slowly increasing and
decreasing in a regular pattern. This is an
example of vibrato. If the frequency is
changing slowly then it will sound like a varying
pitch; a fast vibrato (several times a second)
produces an interesting sound effect. The
alarm IC (U2, included in Snap Circuits®
models SC-100, 300, 500, or 750) produces
sounds using the vibrato effect.
Tempo is a musical term, which simply
describes how quickly a song is played.

Up to now, the musical measures of pitch and
loudness have been discussed. But many
musical sounds have the same pitch and
loudness and yet sound very different. For
-14-

DO’s and DON’Ts of Building Circuits
After building the circuits given in this booklet, you may wish to experiment on your own.
Use the projects in this booklet as a guide, as many important design concepts are
introduced throughout them. Every circuit will include a power source (the batteries), a
resistance (which might be a resistor, capacitor, speaker, integrated circuit, etc.), and wiring
paths between them and back. You must be careful not to create “short circuits” (very lowresistance paths across the batteries, see examples at right) as this will damage
components and/or quickly drain your batteries. Only connect the keyboard (U26), voice
changer (U27), and echo IC (U28) 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, capacitors, ICs (which must be connected properly),
microphone, or resistors.

ALWAYS

use LEDs, transistors, 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 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 the keyboard (U26), voice changer (U27), and echo IC (U28) using
configurations given in the projects or as per the connection description on
pages 6 and 7.

NEVER

connect to an electrical outlet in your home in any way.

NEVER

leave a circuit unattended when it is turned on.

NEVER

use headphones at high sound levels.

For all of the projects given in this book, the parts may be arranged in different ways without
changing the circuit. For example, the order of parts connected in series or in parallel does
not matter — what matters is how combinations of these sub-circuits are arranged together.

You are encouraged to tell us about new programs and circuits you
create. If they are unique, we will post them with your name and state
on our website at:
www.snapcircuits.net/learning_center/kids_creation
Send your suggestions to ELENCO®: elenco@elenco.com.
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/learning_center/kids_creation
or through the www.snapcircuits.net website.
-15-

Examples of SHORT CIRCUITS - NEVER DO THESE!!!
Placing a 3-snap wire directly
across the batteries is a
SHORT CIRCUIT.

NEVER
DO!

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: SHOCK HAZARD - Never connect Snap Circuits®
to the electrical outlets in your home in any way!

Warning to Snap Circuits® owners: Do not connect
additional voltage sources from other sets, or you
may damage your parts. Contact Elenco® if you have
questions or need guidance.

Advanced Troubleshooting (Adult supervision recommended)
ELENCO® is not responsible for parts
damaged due to incorrect wiring.

3. Snap wires: Use this mini-circuit to test
each of the snap wires, one at a time. The
LED should light.

If you suspect you have damaged parts,
you can follow this procedure to
systematically determine which ones
need replacing:
(Note: Some of these tests connect an LED
directly across the batteries without another
component to limit the current. Normally this
might damage the LED, however Snap Circuits®
LEDs have internal resistors added to protect
them from incorrect wiring, and will not be
damaged.)

1. Color LED (D8), speaker (SP2), and
battery holder (B1): Place batteries in
holder. Place the color LED directly across
the battery holder (LED + to battery +), it
should light and be changing colors. “Tap”
the speaker across the battery holder
contacts; you should hear static as it
touches. If neither works, then replace
your batteries and repeat. If still bad, then
the battery holder is damaged. Test both
battery holders.
2. Red & black jumper wires: Use this
mini-circuit to test each jumper wire; the
LED should light.

4. Slide switch (S1) and Press switch (S2):
Use this mini-circuit; if the LED doesn’t
light then the slide switch is bad. Replace
the slide switch with the press switch to
test it.

5. 100W (R1) and 5.1kW (R3) resistors, and
microphone (X1): Use this mini-circuit;
the LED will be bright if the R1 resistor is
good. Next use the 5.1kW resistor in place
of the 100W resistor; the LED should be
much dimmer but still light. Next, replace
5.1kW resistor with the microphone (“+” to
right); the LED should flicker dimly but still
light.

6. 500kW adjustable resistor (RV3) and
Photoresistor (RP): Use the mini-circuit
from test 5 but replace the 100W resistor
with RV3. Turning RV3’s knob all the way
to the left (counter-clockwise) should make
the color LED bright and most other
settings should make the LED dim or off;
otherwise RV3 is bad. Next, replace RV3
with the photoresistor, and shine a bright
light on it. Waving your hand over the
phototransistor (changing the light that
shines on it) should change the brightness
of the color LED; otherwise the
photoresistor is bad.
7. Adjustable resistor (RV): Build project
98. Move the resistor control lever to both
sides. The color LED (D8) should be bright
if the lever is to the far left or far right, and
dim if the lever is in the middle.
8. NPN transistor (Q2): Build the minicircuit shown here. The color LED (D8)
should only be on if the press switch (S2)
is pressed. If otherwise, then Q2 is
damaged.
1

-16-

Advanced Troubleshooting (Adult supervision recommended)
9. Keyboard (U26): Build project 92, but
omit the 0.1mF capacitor (C2) and the
5.1kW resistor (R3). You should hear a
tone when you press any key. Turning the
TUNE knob while pressing any green key
should change the tone slightly. Now add
R3 to the circuit, and you should hear a
continuous tone. If any of this does not
work then the keyboard is damaged.
10. 0.1mF (C2), 1mF (C7), and 470mF (C5)
capacitors: Build project 92; removing
C2 from it should change the tone, or C2
is damaged. Next, replace C2 with C7; the
pitch of the tone should be lower now, or
C7 is damaged. Next, replace C7 with C5;
you should hear a click every few seconds,
or C5 is damaged.
11. Voice changer (U27): Build project 7.
Follow the project’s instructions to confirm
that you can make a recording and play it
back at different speeds.
12. Echo IC (U28): Build the circuit shown at
right, turn it on, and set the knob on the
500kW adjustable resistor (RV3) to the
right. Press any keys on the keyboard; you
should hear tones with echo, and be able
to adjust echo level using the lever on the
adjustable resistor (RV). Removing the
1mF capacitor (C7) should reduce the
volume a little. Sometimes an echo IC
problem can be fixed by turning the circuit
off and back on to reset it.

-17-

12. Audio Jack (JA) and stereo cable: If
you have headphones, use them to test
the audio jack using project 14. If you have
a music device, use it to test the audio jack
using project 66. Use project 66 to test
your stereo cable.
13. Sound energy demonstration container:
If the flexible sheet is damaged,
disassemble the container and replace the
flexible sheet; this set may have included
a spare for it, or you can use household
plastic wrap.

ELENCO

150 Carpenter Avenue
Wheeling, IL 60090 U.S.A.
Phone: (847) 541-3800
Fax: (847) 520-0085
e-mail: help@elenco.com
Website: www.elenco.com
You may order additional / replacement
parts at: www.snapcircuits.net

Project Listings
Project #

Description

Page #

Project #

Description

Page #

Project #

Description

Page #

Electronic Keyboard

Low Pitch Optical Keyboard Echo 33

Your Music without Echo

Aligning the Keyboard

Keyboard Echo with Stereo Effects 34

Low Power Your Music without Echo

Be a Musician

Optical Echo in Stereo

Adjustable Music without Echo

Be a Musician (II)

Color Short Light

L/R Music Amplifier

Optical Theremin

Keyboard with Optical Theremin 36

Another Transistor Amplifier

Keyboard Slider

Keyboard with Optical Theremin (II) 36

Microphone Resistance - LED

Voice Changer

Adjustable Dual Range Keyboard 36

Microphone Resistance - Audio

Voice Changer & Light

Adjustable Dual Range Keyboard (II) 36

Time Light

Color Light

Adjustable Dual Range Keyboard (III) 36

Time Light (II)

Echo

Your Music with Echo

Easier Adjust Time Light

Echo with Headphones

Your Music with Echo and Light

Small Adjust Time Light

Louder Echo with Headphones

Your Music Speed Changer

Day Light

Sound Energy Demonstration

25,26

Your Music Speed Changer (II)

Lower Day Light

Keyboard in Stereo

Your Music Speed Changer (III) 38

Dark Light

Optical Theremin in Stereo

Sound On Light

Blow Noise

Light & Sound

Super Optical Keyboard Echo

Listen to the Light Change

See Saw

Softer Optical Keyboard Echo

Adjustable Listen to the Light Change 51

Light, Sound, & Motion

Reflection Detector

Bright or Loud?

Brighter Light, Sound, & Motion

Super Optical Keyboard Echo for Headphones 40

LED Keyboard Control

Keyboard with Voice Changer

Sound is Air Pressure

LED Keyboard Control (II)

Optical Keyboard with Voice Changer 30

Sound is Air Pressure - Keyboard 41

Photo LED Keyboard Control

Keyboard Voice Changer & Light

Brightness Adjuster

Adjustable LED Keyboard Control

Voice Changer with Echo

Brightness Limiters

Capacitor Keyboard Control

Sound Controlled Light

Big Brightness Adjuster

Capacitor Keyboard Control (II)

Low Pitch Keyboard

Photo Brightness Adjuster

Voice & Keyboard Echo

Lower Pitch Keyboard

Amplified Photo Brightness Adjuster 43

LED Voice & Keyboard Echo

Very Low Pitch Keyboard

Amplified Big Brightness Adjuster 43

Photo LED Keyboard Echo

Echo Speed Changer

Cup & String Communication

Photo LED Keyboard

Keyboard Echo

Audio Amplifier

Audio Dark Light

Lower Pitch Keyboard Echo

Low Power Audio Amplifier

Oscillator

Optical Keyboard Echo

Audio Amplifier with L/R Control 45

Oscillator (II)

55
-18-

Project Listings
Project #

Description

Page #

Project #

Description

Page #

Project #

Description

Page #

Oscillator (III)

126

Daylight Voice Echo

158

Continuity Tester

Oscillator (IV)

127

Dark Voice Echo

159

High Low Light

Oscillator (V)

128

Dark Echo Light

160

Flicker Clicker

Oscillator (VI)

129

Dark Echo Variants

161

Fast Flicker Clicker

Left Right Bright Light

130

Day Echo Light

162

Slow Flicker Clicker

Adjustable Oscillator

131

Day Echo Variants

163

Timer Tone

100

Adjustable Oscillator (II)

132

Photo Light Timer

164

Little Battery

101

Adjustable Oscillator (III)

133

Adjustable Photo Light Timer

165

Tiny Battery

102

Adjustable Oscillator (IV)

134

Tone Stoppers

166

Little Battery Beep

103

Water Detector

135

Tone Stoppers (II)

167

Capacitors in Series

104

Clicker

136

Tone Stoppers (III)

168

Capacitors in Series (II)

105

Clicker with Echo

137

Tone Stoppers (IV)

169

Capacitors in Series (III)

106

3V Audio Amplifier

138

Tone Stoppers (V)

170

More Capacitors in Series

107

Mini Music Player

139

Alarm Light

171

Capacitors in Parallel

108

Voice Echo with Light

140

Voice Changer with Headphones

172

Capacitors in Parallel (II)

109

Color Sound

141

Day Keyboard

173

Capacitors in Parallel (III)

110

Color Sound (II)

142

Night Keyboard

174

More Capacitors in Parallel

111

Color Sound (III)

143

Color Keyboard

175

Resistors in Series

112

Backwards Color Sound

144

Color Keyboard (II)

176

Resistors in Parallel

113

White Light

145

Color Keyboard (III)

177

Lots of Resistors in Series

114

Red to White

146

Color Keyboard (IV)

178

Lots of Resistors in Parallel

115

Alarm

147

Color Keyboard (V)

179

Be a Loud Musician

116

Super Voice Echo with Light

148

Color Keyboard (VI)

180

Be a Loud Musician (II)

117

Press Echo

149

Adjustable Voice Changer & Light

181

Morse Code

118

Photo Echo

150

Adjustable Voice Changer & Light (II) 70

182

Transistor Audio Amplifier

119

Loud Press Photo Echo

151

Play Fast

183

Transistor Audio Amplifier (II)

120

Knob Echo

152

Red First

184

Make Your Own Parts

121

Echo Light Headphone

153

Adjustable Timer Tone

185

Color Touch Light

122

Echo Light Headphone Variants

154

Photo Timer Tone

186

Test Your Hearing

123

Press Echo Light

155

Delay Lamp

187

See the Sound

124

Photo Echo Light

156

Adjustable Delay Lamp

188

See the Spectrum

125

Another Voice Echo Light

157

Water Alarm

-19-

Project 1

Electronic Keyboard
Snap Circuits® uses electronic blocks that snap onto
a clear plastic grid to build different circuits. These
blocks have different colors and numbers on them
so that you can easily identify them.

Placement Level
Numbers

(1-snap wire is placed
under the speaker)

Placement Level
Numbers

Project 2

Build the circuit shown on the left by placing all the
parts with a black 1 next to them on the board first.
Then, assemble parts marked with a 2. Then,
assemble the part marked with a 3. Note that the 1snap wire is placed beneath the speaker (SP).
Install two (2) “AA” batteries (not included) into each
of the battery holders (B1) if you have not done so
already.
Turn on the slide switch (S1), and press any of the
keys on the keyboard (U26) to hear tones. Two
tones may be played at the same time, one tone
from the blue keys and one tone from the green
keys. If you press two keys of the same color then
the higher pitch one will be played.

Aligning the Keyboard

Use the preceding circuit. Press one of the green
keys and turn the TUNE knob on the keyboard to
adjust the pitch of the tone. The TUNE knob will
not affect the blue keys.
Now turn the TUNE knob while pressing the blue
C key and the green C key at the same time.
Slowly turn the knob across its entire range, and
see how the sound varies. At most TUNE knob
positions you will notice separate tones from the
blue and green keys, but there will be a knob
position where the blue and green tones blend
together and seem like a single musical note - this
is the best TUNE setting to play songs with. The
blue and green keys are now aligned together.

Snappy says the green keys
have approximately double
the pitch (frequency) of the
blue keys. When the blue
and green keys have been
aligned using the TUNE
knob, then they have
(almost) exactly double the
pitch, and sound good
together because they are in
harmony.

-20-

Project 3

Be a Musician

To play a song, just press the key corresponding with the letter shown. If
there is a “–” after a letter, press the key longer than usual.

Mary Had a Little Lamb
E D C D E E E– D D D–
lit-tle lamb,

Ma-ry had a

lit-tle lamb, Whose fleece was white as

ED C D

Lit-tle lamb, lit- tle lamb.

EE E

Row, Row, Row Your Boat
C– C– C D E– E D E F
Row, row,

row your boat,

CCCGGG

Mer-ri-ly, mer-ri-ly,

Gen-tly down the

EEE CCC

mer-ri-ly, mer-ri-ly,

The Farmer in the Dell
––G C C C C C–– D
The

E––
dell,

far-mer in the

G– G A

Heigh-ho the

Muffin Man
D G G A

dell,

The

GEC D

der-ry-oh, the

B C G F#

Do you know the muf-fin man, The

D G

G A

B G G

Do you know the

muf-fin man Who

E D

GGF F

Up a-bove the

C C G G

E D–

Twin-kle, twin-kle, lit-tle star,
-21-

C–––
snow.

stream.

Life is but a

dream.

E E EE

far-mer in the

E E D D C––
far-mer in the dell.

E A A G

F# D D

muf-fin man, the muf- fin man?

A A DD

lives on Dru-ry

G––

Lane?

D D C–

How I won-der what you are.

G GF F

E E D–

F FE E

D D C––

in the sky.

How I won-der what you are.

go a-way.

GG E

Come a-gain some

DD D F F D

o-ther day.

G F E D E C C–

We want to go out- side and play.

Rain, rain,

go a-way.

For He’s a Jolly Good Fellow
––C E E E D E F E E D D D C D
For

G F E D C–––

world so high, Like a dia-mond

AAG

F F

G–––

Twinkle, Twinkle, Little Star
C C G G AAG
F FE E
Twin-kle, twin-kle, lit-tle star,

Rain, rain,

E G G–

Ma-ry had a

Rain, Rain, Go Away
G E
GGE
G G E A

he’s a jol-ly good

fel-low, For

he’s a jol-ly good

E C D
–

E EED E

F– A

G G G F D C–

fel-low, For

he’s a jol-ly good

fel-low, Which no-bo-dy can de- ny.

Ring Around the Rosy
G G E A GEF GG E A

Ring a-round the

pos-ies,

F D

Ash-es,

ro-sy, A

F D F

ash-es, We

poc-ket full of

G G

all fall

C–

down!

Mystery song (see if you recognize it)
CCDC
F E–
CCDC
G F–
CCCA
FFE
A# A# A F G F–

Some songs have
been modified to make
them easier to play on
your keyboard.

Project 4 Be a Musician (II)
Use the preceding circuit and songs, but press both the blue and green keys
for each note, at the same time. Try this with the blue and green keys aligned
(as per project 2), but also try them at different TUNE knob settings (so the
keys are out of alignment.

Project 5

Optical Theremin
Build the circuit as shown. Turn on both slide switches (S1), and move
your hand over the photoresistor (RP). You can adjust the sound just
by moving your hand around. See what range of sounds you can
produce, then change the amount of light in the room, and see how
sound the range of sounds has changed. There may not be any sound
if there is too much or too little light on the photoresistor.
You can play the keyboard (U26) keys while adjusting the sound using
the photoresistor, to get a combination of sound effects. Turn off the left
slide switch to disable the photoresistor sound effects.
A theremin is an electronic musical instrument where
you change the sound by moving your hands around
near it (without touching it); using the tiny changes
your hands have on the electromagnetic field of an
antenna. This circuit is an optical theremin because
instead you adjust the sound by changing the amount
of light reaching a photosensor (the photoresistor).

Project 6

Keyboard Slider

Modify the preceding circuit to match this one. Turn on both slide
switches (S1), and move the lever on the adjustable resistor (RV)
around to change the sound. At some settings there may not be any
sound.
You can play the keyboard (U26) keys while changing the sound with
the adjustable resistor, to get a combination of sound effects. Turn off
the left slide switch to disable the adjustable resistor sound effects.

-22-

Project 7

Voice Changer
Build the circuit shown on the left by placing all the parts with a black
1 next to them on the board first. Then, assemble parts marked with
a 2. Then, assemble the part marked with a 3. Install two (2) “AA”
batteries (not included) into each of the battery holders (B1) if you
have not done so already. Be sure to install the microphone (X1)
with its “+” side positioned as shown.

+
Placement Level
Numbers

Set the 500kW adjustable resistor (RV3) to mid-range, turn OFF the
left slide switch (S1), and then turn on the right slide switch. Now
turn on the left slide switch, you hear a beep signaling that you may
begin recording. Talk into the microphone until you hear a beep
(signaling that recording time is over), then turn off the left slide
switch to exit recording mode. Push the press switch (S2) to play
back the recording, and turn the knob on RV3 to change the
playback speed. You can play your recording faster or slower by
changing the setting on RV3.
Recording time is 6 seconds at normal speed, but this can be
changed depending on the setting of RV3 when you are making the
recording.

Project 8
Voice Changer & Light

Project 9

Build the circuit as shown. Turn on the slide switch
(S1), and enjoy the light show from the color LED
(D8). For best effects, place the egg LED attachment
on the color LED, and dim the room lights.

Use the preceding circuit, but replace the
3-snap wire that is next to the speaker
(SP2) with the color LED (D8, “+” to the
left). Now when you press S2 to play the
recording, the sound will not be as sound,
but the color LED will be flashing.

Egg LED
Attachment

+
-23-

Color Light

LEDs (Light Emitting Diodes)
convert electrical energy into light;
the color of the light emitted
depends on the characteristics of
the material used in them.
The color LED actually contains
separate red, green, and blue
lights, with a micro-circuit
controlling them.

Project 10

Echo
If the speaker is too close to the
microphone, then the speaker’s sound
will be picked up by the microphone and
be echoed again and again and again,
until you can’t hear anything else. The
same thing can happen if the room is too
noisy, or if you talk too loud.

Build the circuit as shown, and place it in a quiet
room. Connect the speaker (SP2) using the red &
black jumper wires, and then hold it away from the
microphone (X1). Turn on the slide switch (S1). Talk
into the microphone, and listen the echo on the
speaker. Adjust the amount of echo using the lever
on the adjustable resistor (RV); move the lever up
for more echo or down for less echo. Try this at
different RV settings, because the effects are very
interesting with both high and low echo amounts.
Also try it while saying different words/sounds.
Note: you must hold the speaker away from the
microphone or the circuit may self-oscillate due to
feedback. You also need a quiet room, with low
background noise.

Project 11

Echo with Headphones
Build the circuit as shown, and connect your own
headphones (not included in this set) to the audio
jack (JA). Turn on the bottom slide switch (S1).
Talk into the microphone, and listen the echo on your
headphones. Set the 500kW adjustable resistor (RV3)
for most comfortable sound level (turn to the left for
higher volume, most of RV3’s range will be very low
volume), then adjust the amount of echo using the
lever on the adjustable resistor (RV); move the lever
up for more echo or down for less echo. Try this at
different RV settings, because the effects are very
interesting with both high and low echo amounts. Also
try it while saying different words/sounds.
Turn on the top slide switch to make the sound
louder, or turn it off to make the sound softer.

WARNING:
Headphones performance
varies, so use caution. Start with low volume,
and then carefully increase to a comfortable
level. Permanent hearing loss may result from
long-term exposure to sound at high volumes.

Headphones
(not included)

Turning on the top slide switch
adds the 0.1mF capacitor (C2)
to the circuit, which increases
the amplification in the echo
IC. With headphones, the
sound can be made louder
because the microhone does
not pick it up easily.

Project 12
Louder Echo
with
Headphones
Use the preceding circuit,
but replace the 0.1mF
capacitor (C2) with the 1mF
capacitor (C7). The sound is
louder now when both slide
switches (S1) are on.
If you hold your headphones
next to the microphone (X1),
you may hear a whining
sound,
because
the
headphones sound might be
picked
up
by
the
microphone and be echoed
again and again and again.
-24-

Project 13

Sound Energy Demonstration

Assemble the Sound energy demonstration container (as per page 4, or
shown on next page) if you have not done so already. Build the circuit as
shown. Turn off the left slide switch (S1) and turn on the right slide switch.
Lay the speaker (SP2) down on the unused 3-snap and 6-snap wires (to
elevate it slightly off the table); be sure it is lying flat, and place the sound
energy demonstration container over it. Pour some salt, glitter, small foam
or candy balls of 0.1 inch diameter or less (not included) or similar into the
container, but not enough to cover the bottom.
Press the keys on the keyboard to make sound. For some keys the
salt/glitter/balls will vibrate and bounce or dance around in the container,
find the key that gives the best effects. Most keys will create little or no
vibration. For the best key, adjust the TUNE knob on the keyboard for best
effects.
Now turn on the left slide switch and move the lever on the adjustable
resistor (RV) around. At some positions the salt/glitter/balls will vibrate and
bounce or dance around in the container; find the setting that gives the
best effects. Press some keyboard keys to add more sound effects.

The bouncing salt/
glitter/balls
show
that sound has
energy! Typically the
E keys and the keys
near them give the
best effects, but your
results may vary.

Experiment with different materials in the container and see which give
the most impressive results. Our engineers found that nonpareils (round
decorative candy sprinkles) of up to 0.1” work best.
Try lifting the container a little higher above the speaker with your hands,
and see how much this affects the bounce height; see where you get the
best effects. Try it at best key or RV setting, and at other keys/settings.
Also, placing the speaker directly on the table (without the 3-snap and 6snap under it) should reduce the vibration a little, but you can try it to see
the difference.
Try removing the 0.1mF capacitor (C2), and see how the sounds and
bounce effects change. Next, remove the sound energy demonstration
container from the speaker and instead lay your hand on it for the best
setting, you can feel the speaker vibrate.
Don’t eat anything you placed into the sound energy demonstration
container.

Pour salt, glitter, or small foam/candy
balls (not included) into the container,
but do not cover the bottom.

Lay the speaker on the extra 3-snap
and 6-snap wires, to elevate it. Be
sure speaker lays flat.
-25-

Part B: Optical Version
Modify the circuit to be this one, which has the
photoresistor (RP) instead of the adjustable
resistor (RV).
Turn on both slide switches and wave your hand
over the photoresistor (RP), to change how much
light shines into it. The sound changes as your
hand adjusts the light. At some hand positions the
salt/glitter/balls will vibrate and bounce or dance
around in the container; find the hand position that
gives the best effects. Press some keyboard keys
to combine their sounds with the photoresistor
sound. Try moving to an area with more or less
light, and wave your hand over the photoresistor
again.

How does this work? There is a small range of
frequency at which the sound waves resonate
with
the
mechanical
construction
characteristics of the speaker, and cause the
speaker to vibrate noticeably. The speaker’s
vibration creates changes in air pressure. The
sound energy demonstration container covers
the speaker and traps the air pressure
changes, which then push/pull the flexible
sheet up/down quickly, making the
salt/glitter/balls bounce. Raising the speaker
and container by placing them on the snap
wires (or holding them) makes the vibrations
more noticeable, because otherwise the table
can dampen the vibrations.

Sound Energy Demonstration
Container Assembly
(Adult supervision recommended)

Tube
Flexible sheet

Container base

Don’t eat anything you placed into the sound
energy demonstration container.
Speaker
Pour salt, glitter, or small
foam/candy balls into the
container, but do not cover
the bottom.

Lay the speaker on the extra 3-snap and 6-snap
wires, to elevate it. Be sure speaker lays flat.
-26-

Project 14

Keyboard in Stereo
This project requires stereo headphones or a stereo speaker; neither is included
with this set, but this set does include a stereo cable to facilitate connection to
your stereo speaker.
Build the circuit as shown. Connect your own headphones or stereo speaker to
the audio jack (JA). Turn on the slide switch (S1).
Press keys on the keyboard (U26) and listen to the sound on your headphones
or stereo speaker. Set the 500kW adjustable resistor (RV3) for most comfortable
sound level (turn to the left for higher volume, most of RV3’s range will be very
low volume), and then move the lever on the adjustable resistor (RV) to vary
the amplitude to each ear.

Headphones or
Stereo Speaker
(not included)

Project 15

WARNING:
Headphones
performance varies, so use
caution. Start with low volume,
then carefully increase to a
comfortable level. Permanent
hearing loss may result from
long-term exposure to sound
at high volumes.

In stereo, sound is produced on several
speakers with varying amplitude on each.
This gives the impression that the sound
is coming from different directions.

Optical Theremin in Stereo
Use the preceding circuit, but modify it by adding the photoresistor (RP) and
the parts next to it.
Press keys on the keyboard (U26) and wave your hand over the
photoresistor (to adjust the amount of light shining on it) while listening to
the sound on your headphones or stereo speaker. Set the 500kW adjustable
resistor (RV3) for most comfortable sound level (turn to the left for higher
volume, most of RV3’s range will be very low volume), and move the lever
on the adjustable resistor (RV) to vary the amplitude to each ear. There may
not be any sound if there is too much or too little light on the photoresistor.
Close your eyes and have a friend vary the light to the photoresistor and
moving the lever on the adjustable resistor. See if you get an impression of
the sound changing direction.

Headphones or
Stereo Speaker
(not included)
-27-

WARNING: Headphones performance varies, so use caution. Start with
low volume, then carefully increase to a comfortable level. Permanent
hearing loss may result from long-term exposure to sound at high volumes.

Project 16

Light & Sound
Build the circuit as shown; note that a 2-snap wire is placed directly
under the speaker (SP2). Turn off the left slide switch (S1) and turn on
the right slide switch. Press keys on the keyboard (U26) to make sound
on the speaker (SP2) and light on the color LED (D8). If you hold a key
down then the color LED will change colors.
Now turn on the left slide switch. If there is light on the photoresistor
(RP), or if you press keys on the keyboard, then there will be sound
from the speaker and light from the color LED. Wave your hand over
the photoresistor to change the sound, or turn off left S1 to disable
photoresistor control. Holding a key down will also make the color LED
change colors.

Project 17

See Saw

Turn on the slide switch (S1), and move the lever on the adjustable
resistor (RV) around. The pitch of the sound will be lowest with the lever
in the middle position, and higher with it set to the left or right.
You can replace the 5.1kW resistor (R3) with the 100W resistor (R1) or
500kW adjustable resistor (RV3), but there may be no sound at some
settings.

-28-

Project 18
Let’s add motion to the preceding circuit. Modify the circuit to match this
one. Turn off the left slide switch (S1) and turn on the right slide switch.
Lay the speaker (SP2) down on unused 2-snap and 6-snap wires (to
elevate it slightly off the table), be sure it is laying flat, and place the sound
energy demonstration container over it (the container should have been
assembled as per instructions on page 4). Pour some salt, glitter, small
foam or candy balls of 0.1 inch diameter or less (not included) or similar
into the container, but not enough to cover the bottom.
Press the keys on the keyboard to make sound and light the color LED
(D8). For some keys the salt/glitter/balls will vibrate and bounce or dance
around in the container, find the key that gives the best effects. Most keys
will create little or no vibration. For the best key, adjust the TUNE knob on
the keyboard for best effects. The color LED will not be very bright.
Now turn on the left slide switch and wave your hand over the photoresistor
(RP), to change how much light shines into it. The sound changes as your
hand adjusts the light, and the color LED will light if there is bright light on
the photoresistor. At some hand positions the salt/glitter/balls will vibrate

Light, Sound, & Motion
and bounce or dance around in the container; find the hand position that
gives the best effects. Press some keyboard keys to combine their sounds
with the photoresistor sound. Try moving to an area with more or less light,
and wave your hand over the photoresistor again.
Experiment with different materials in the container and see which give
the most impressive results. Our engineers found that 0.1” round non
pareils (decorative candy sprinkles) work best.
Try lifting the container a little higher above the speaker with your hands,
and see how much this affects the bounce height; see where you get the
best effects. Try it at best key or RV setting, and at other keys/settings.
Also, placing the speaker directly on the table (without the 3-snap and 6snap under it) should reduce the vibration a little, but you can try it to see
the difference.
Add the 0.1mF capacitor (C2) over the keyboard (U26) at base grid
locations D4-F4 (on level 3) and see how the circuit changed, especially
when pressing the green keys.
Place the sound energy
demonstration container over
the speaker. Pour salt, glitter,
or small foam/candy balls (not
included) into the container,
but do not cover the bottom.

Lay the speaker on the
extra 3-snap and 6-snap
wires, to elevate it. Be
sure speaker lays flat.

Project 19
Brighter Light, Sound, & Motion
Use the preceding circuit, but replace the 470mF capacitor
(C5) with the 1mF capacitor (C7). The color LED (D8) is
brighter now, but may not be changing colors.
-29-

Project 20

Keyboard with Voice Changer
Set the 500kW adjustable resistor (RV3) to mid-range, turn OFF
the left slide switch (S1), and then turn on the right slide switch.
Now turn on the left slide switch, you hear a beep signaling that
you are recording. Press keys on the keyboard (U26) until you
hear a beep (signaling that recording time is over), then turn off
the left slide switch to exit recording mode. Push the press
switch (S2) to play back the recording, and turn the knob on
RV3 to change the playback speed. You can play your
recording faster or slower by changing the setting on RV3.
The keyboard overhangs the base grid, so be sure the
connections to it stay secure as you are pressing keys.
Recording time is 6 seconds at normal speed, but this can be
changed depending on the setting of RV3 when you are making
the recording. You won’t hear the notes when you are pressing
the keys during recording; you only hear them during playback.

Project 21

Optical Keyboard
with Voice Changer

This circuit is similar to the preceding one, but adds optical
control. Modify the preceding circuit by adding the
photoresistor (RP) and the parts next to it.
When making your recording, wave your hand over the
photoresistor to change the sound recorded, in addition to
pressing keys. The photoresistor may have no effect if there is
too much or too little light on it, so adjust the light on it if
necessary.

Project 22

Keyboard Voice
Changer & Light

Use either of the preceding circuits,
but replace the 3-snap wire that is next
to the speaker (SP2) with the color
LED (D8, “+” to the left). Now when
you press S2 to play the recording, the
sound will not be as sound, but the
color LED will be flashing.
-30-

Project 23

Voice Changer with Echo
Build the circuit as shown; note that the microphone (X1) is covering a
2-snap wire, and that the 5.1kW resistor (R3) is a tight fit over the
adjustable resistor (RV) but does fit. Set the 500kW adjustable resistor
(RV3) to mid-range, set the adjustable resistor (RV) lever towards R3,
turn OFF the left slide switch (S1), and then turn on the right slide
switch.
Now turn on the left slide switch, you hear a beep signaling that you
are recording. Talk into the microphone (X1) until you hear a beep
(signaling that recording time is over), then turn off the left slide switch
to exit recording mode. Now move the lever on RV to set the echo level,
turn the knob on RV3 to change the playback speed, and push the
press switch (S2) to play back the recording. You can play your
recording faster or slower by changing the setting on RV3, and with
more or less echo by changing the setting on RV.
Recording time is 6 seconds at normal speed, but this can be changed
depending on the setting of RV3 when you are making the recording.
RV should be set for no echo when making a recording.

Project 24
+

Sound Controlled Light
Build the circuit as shown. Turn on the switch (S1) and set the lever on
the adjustable resistor (RV) so the color LED (D8) is just off. Talk loud into
the microphone (X1) or clap loudly near it to activate the color LED. Try a
long loud “ahhhhhhhh” directly into the microphone; this can make the
color LED change patterns.
The color LED may not be very bright, so this circuit works best in a dimly
lit room.
If the adjustable resistor’s lever is set too
low then the color LED will never turn
on; if it is set too high then the color LED
will never turn off.

+
-31-

Project 25 Low Pitch Keyboard
Build the circuit as shown. Turn
off the left slide switch and turn on
the right slide switch (S1), and
press some of the green keys.
Now turn on the left slide switch
to add the 0.1mF capacitor (C2) to
the circuit, and press some green
keys again. The pitch (frequency)
of the sound is lower now. The
blue keys will not be affected.

Adding the 0.1mF capacitor lowers the frequency
(pitch) of the sound produced by the green keys,
and makes them similar to the blue keys.

Compare the sound for blue and
green keys at the same place on
the keyboard (such as C to C, F#
to F#, or B to B). Turn the TUNE
knob to align a pair of blue/green
together, or to take them out of
alignment. Experiment to see
some interesting effects.

Project 26
Lower Pitch Keyboard
Use the preceding circuit, but replace the
0.1mF capacitor (C2) with the 1mF
capacitor (C7). The pitch of the green keys
is much lower now. See how the blue and
green keys sound when pressed together.

Project 27
Very Low Pitch Keyboard
Use the preceding circuit, but replace
the 1mF capacitor (C7) with the 470mF
capacitor (C5, “+” on left). Press one of
the green keys and hold it down; all you
should hear is a click every few seconds.

Project 28
Echo Speed Changer
Set the 500kW adjustable resistor (RV3) to mid-range, turn OFF the left
slide switch (S1), and then turn on the right slide switch. Set the echo
level using adjustable resistor (RV). Now turn on the left slide switch, you
hear a beep signaling that you are recording. Talk into the microphone
(X1) until you hear a beep (signaling that recording time is over), then
turn off the left slide switch to exit recording mode. Push the press switch
(S2) to play back the recording, and turn the knob on RV3 to change the
playback speed. You can play your recording faster or slower by
changing the setting on RV3, and with more or less echo by changing
the setting on RV.
Recording time is 6 seconds at normal speed, but this can be changed
depending on the setting of RV3 when you are making the recording.
C2 is only used to support RV, so is only connected on one side.
-32-

Project 29

Keyboard Echo
Build the circuit as shown,
and turn on the slide switch
(S1). Press keys on the
keyboard (U26) and hear
the sound with echo on the
speaker (SP2). RV adjusts
the amount of echo, and
RV3 adjusts the volume. Try
this at different RV settings,
because the effects are
very interesting with both
high and low echo amounts.

Project 31 Optical Keyboard Echo
Build the circuit as shown,
and turn on both slide
switches (S1). Press keys on
the keyboard (U26) or shine
light into the photoresistor
(RP) to hear sound with echo
on the speaker (SP2). RV
adjusts the amount of echo,
and RV3 adjusts the volume.
Wave your hand over the
photoresistor to adjust the
pitch of the “optical” sound.
Try this at different RV
settings, because the effects
are very interesting with both
high and low echo amounts.
There may not be any sound
if there is too much or too
little light on the photoresistor.

-33-

Project 30
Lower Pitch
Keyboard Echo
Use the preceding
circuit, but add the
0.1mF
capacitor
(C2) or the 1mF
capacitor
(C7)
across the “CAP”
and “(-)” snaps on
the keyboard using
a 1-snap wire. The
pitch of the green
keys is lower now.

Project 32
Low Pitch
Optical
Keyboard Echo
Use the preceding
circuit, but add the
0.1mF
capacitor
(C2) or the 1mF
capacitor
(C7)
across the “CAP”
and “(-)” snaps on
the keyboard. The
pitch of the green
keys is lower now.

Project 33

Keyboard Echo with
Stereo Effects
In this project you will listen to the keyboard sound both with
and without echo, at the same time (in stereo). This project
requires stereo headphones or a stereo speaker; neither is
included with this set, but this set does include a stereo
cable to help connect to your stereo speaker.
Build the circuit as shown; note that the 5.1kW resistor (R3)
is a tight fit over the adjustable resistor (RV) but does fit.
Connect your own headphones or stereo speaker to the
audio jack (JA). Turn on the slide switch (S1).

Headphones or Stereo
Speaker (not included)

WARNING: Headphones performance varies, so use caution. Start with
low volume, then carefully increase to a comfortable level. Permanent
hearing loss may result from long-term exposure to sound at high volumes.

Press keys on the keyboard (U26), and listen to the sound
on your headphones or stereo speaker. One ear (or side of
the speaker) hears the keyboard directly, set RV3 for most
comfortable sound level (turn to the left for higher volume,
most of RV3’s range will be very low volume). The other ear
(or side of the speaker) hears the sound with echo; adjust
the amount of echo using the lever on the adjustable resistor
(RV). Try this at different RV settings, because the effects
are very interesting with both high and low echo amounts.
If the echo sound is not loud enough then add the 1mF
capacitor (C7) next the echo IC (U28) as shown here:

The 100W and 5.1kW resistors (R1 &
R3) make the keyboard signal smaller,
otherwise it would be distorted by the
amplifier in the echo IC.

For best effects, try to set RV3 so that the sound level is
about equal on both sides of the headphones/speaker.

-34-

Project 34

Optical Echo in Stereo
The project is similar to the preceding one, but adds optical
control using the photoresistor (RP). Rebuild the preceding
circuit to match this one. Follow the preceding circuit’s
instructions, except also turn on the slide switch next to the
photoresistor, and then wave your hand over the
photoresistor to change the sound.
The keyboard overhangs the base grid, so be sure the
connections to it stay secure as you are pressing keys.
In the preceding circuit you could add the 1mF capacitor (C7)
to make the echo sound louder, but do not have enough
parts to add it to this circuit.
The 0.1mF capacitor (C2) is
being used as a spacer (a
1-snap wire) to support
other components.

Headphones or Stereo
Speaker (not included)

WARNING: Headphones performance varies, so use caution. Start with
low volume, then carefully increase to a comfortable level. Permanent
hearing loss may result from long-term exposure to sound at high volumes.

Project 35 Color Short Light
The light is on while the 470mF capacitor
(C5) is charging, and shuts off when the
capacitor gets fully charged. Pressing S2
discharges the capacitor. The charge-up
time is set by the capacitor’s value and
resistors R3 and RV.

Build the circuit, turn on the slide switch (S1),
and push the press switch (S2). The color LED
(D8) is on for a while and then shuts off.
Turning S1 off and back on will not get the light
back on. Push S2 to get the light back on. If
desired, place the egg attachment on the color
LED.
RV is used as a fixed resistor (50kW); so
moving its control lever will have no effect.

-35-

Project 36 Keyboard with Optical Theremin
Build the circuit as shown and
turn on the slide switch (S1).
Press keys on the keyboard
(U26), wave your hand over the
photoresistor (RP) to adjust the
amount of light shining on it, and
listen to the sound. Push the
press switch (S2) to change the
pitch of the green keys. There
may not be any sound if there is
too much or too little light on the
photoresistor.

Project 38 Adjustable Dual Range Keyboard

Build the circuit as shown and
turn on the slide switch (S1).
Press keys on the keyboard
(U26) and move the lever on the
adjustable resistor (RV) to
change the sound. Push the
press switch (S2) to change the
pitch of the green keys. There
may not be any sound at some
settings on RV.

Project 37
Keyboard with
Optical
Theremin (II)
Use the preceding circuit, but
replace the 1mF capacitor (C7) with
the 0.1mF capacitor (C2). The pitch
of the green keys is higher when
S2 is pressed.

Project 39
Adjustable Dual
Range Keyboard (II)
Use the preceding circuit, but replace
the 0.1mF capacitor (C2) with the 1mF
capacitor (C7). The pitch of the green
keys is lower when S2 is pressed.

Project 40
Adjustable Dual
Range Keyboard (III)
Use the preceding circuit, but replace the
1mF capacitor (C7) with the 470mF
capacitor (C5, “+” on left). You will hear a
click at regular intervals. The interval
depends on the RV setting, it could be
several per second or many seconds apart.

-36-

Project 41

MP3 player

Your Music with Echo
Build the circuit, and turn on the slide switch (S1). Connect
a music device (not included, but this set does include a
cable to connect it) to the audio jack (JA) as shown, and
start music on it.
Set the volume control on your music device for a
comfortable sound level, and adjust the amount of echo
using the lever on the adjustable resistor (RV); move the
lever up for more echo or down for less echo. Try this at
different RV settings, because the effects are very
interesting with both high and low echo amounts.
Try with different music, or with the touch-tones on your cell
phone.

Project 42

MP3 player

Your Music with Echo and Light
This circuit is similar to the preceding one, except
it adds light and has lower sound volume. Build the
circuit, and turn on the slide switch (S1). Connect
a music device (not included) to the audio jack (JA)
as shown, and start music on it. Set the knob on
the 500kW adjustable resistor (RV3) all the way to
the left (for loudest sound).
Set the volume control on your music device for a
comfortable sound level, and adjust the amount of
echo using the lever on the adjustable resistor
(RV). Try this at different RV settings. The color
LED (D8) will light when the sound is loud enough.
Try with different music, or with the touch-tones on
your cell phone.

-37-

Project 43

Your Music Speed Changer
Build the circuit as shown. Set the 500kW adjustable resistor
(RV3) to mid-range, turn OFF the left slide switch (S1), and then
turn on the right slide switch. Connect a music device (not
included) to the audio jack (JA) as shown, and start music on it.
Now turn on the left slide switch, you hear a beep signaling that
recording has started. Wait until you hear a beep (signaling that
recording time is over), then turn off the left slide switch to exit
recording mode. Push the press switch (S2) to play back the
recording, and turn the knob on RV3 to change the playback
speed. You can play your recording faster or slower by changing
the setting on RV3. Try with different music, or with the touchtones on your cell phone.

MP3 player

To adjust the volume, adjust it on your music device before
recording, or see the next project.
Recording time is 6 seconds at normal speed, but this can be
changed depending on the setting of RV3 when you are making
the recording.

Project 44
Your Music
Speed Changer
(II)
Use the preceding circuit, but
replace the 100W resistor (R1)
with a 3-snap wire to make the
sound louder, or with the 5.1kW
resistor (R3) to make the sound
quieter.

Project 45
Your Music
Speed Changer
(III)
Use the circuit from project 43,
but replace the 100W resistor
(R1) with the color LED (D8, “+”
to the left). Now when you press
S2 to play the recording, the
color LED will be flashing.

Project 46 Sound On Light

Build the circuit as shown
and turn on the slide switch
(S1). Set the lever on the
adjustable resistor (RV) so
the color LED (D8) just
shuts off. Talk loudly into the
microphone (X1), blow on it,
or clap near it to make the
LED flicker on.

-38-

Project 47

Super Optical Keyboard Echo
Build the circuit as shown. Turn off the left slide switch (S1), and
turn on the right slide switch. Press some of the keyboard keys
and listen to the echo. Move the lever on the adjustable resistor
(RV) to change the amount of echo (up is maximum echo, down
is no echo). Try this at different RV settings, because the effects
are very interesting with both high and low echo amounts. The
color LED (D8) will light when any green key is pressed, but will
not be very bright.
Now turn on the left slide switch to add the photoresistor (RP) to
the circuit. Wave your hand over the photoresistor to change the
sound. Try it with different levels of light shining on the
photoresistor, and at different RV settings.
This circuit is shown on the Snap
Circuits® Sound box cover; use
that picture to help in building it.

Project 48
Softer Optical
Keyboard
Echo
Use the preceding circuit, but remove the
1mF capacitor (C7) from the circuit, or
swap it with the 0.1mF capacitor (C2), or
replace it with the 470mF capacitor (C5).
The sound volume is different now.

-39-

Project 49 Reflection Detector
Build the circuit and turn the
slide switch (S1). Take it
into a dimly lit room, so that
the color LED (D8) is
flashing but there is no
sound.
Now hold a mirror directly
over the color LED and
photoresistor (RP). When
the mirror reflects the LED’s
light into the photoresistor,
a tone will be produced,
signaling that a reflection
was detected. The tone will
change as the LED flashes.

Project 50

Super Optical
Keyboard Echo for
Headphones
Build the circuit as shown. This project requires stereo
headphones or a stereo speaker (neither is included).
Turn off the left slide switch (S1), and turn on the right slide
switch. Press some of the keyboard keys and listen to the
echo. Set the 500kW adjustable resistor (RV3) for most
comfortable sound level (turn to the left for higher volume,
most of RV3’s range will be very low volume). Move the
lever on the adjustable resistor (RV) to change the amount
of echo (up is maximum echo, down is no echo). Try this
at different RV settings, because the effects are very
interesting with both high and low echo amounts. The
color LED (D8) will light when any green key is pressed,
but will not be very bright.
Now turn on the left slide switch to add the photoresistor
(RP) to the circuit. Wave your hand over the photoresistor
to change the sound. Try it with different levels of light
shining on the photoresistor, and at different RV settings.
Note that the “R” snap on the audio jack is not snapped
or connected, so there will not be any sound from the “R”
side of your headphones/speaker.

Headphones or Stereo
Speaker (not included)

You can replace the 0.1mF capacitor (C2) with the 1mF
capacitor (C7) to lower the pitch of the green keys.

WARNING: Headphones performance varies, so use caution. Start with
low volume, then carefully increase to a comfortable level. Permanent
hearing loss may result from long-term exposure to sound at high volumes.

-40-

Project 51

Sound is Air Pressure

Sound is a variation in air pressure created by a mechanical
vibration. For a demonstration of this, take a stereo speaker in
your home (the larger the better), lay it on the floor, and start
some music.
1. Place your hand on your
stereo speaker and turn up
the volume. Do you feel the
speaker vibrate?

2. Now place a piece of paper
on the speaker; if the sound is
loud enough, you will see the
paper vibrate.

Project 52

3. Take a balloon (not included) and hold
it on the speaker. You should feel it
vibrating with the sound.

4. Get your parents’ permission for this part,
because it could get messy. Place the
sound energy demonstration container
(which should have been assembled as
per instructions on page 4) on the center
of the speaker. Pour some salt, glitter,
small foam or candy balls (0.1 inch
diameter or less) or similar into the
container, but not enough to cover the
bottom. Slowly increase the music
volume. When the music is at certain
frequencies, the salt/glitter/balls will
bounce around in the container.

Sound is Air Pressure Keyboard
Your Snap Circuits®
speaker (SP2) is not
powerful enough to
use for this, unless
using
the
sound
energy demonstration
container as done in
project 13.

Stereo Speaker (not included)
-41-

If you have a stereo speaker (not included), then
you can also do the preceding demonstration
using the sounds from your keyboard (U26). Build
the circuit as shown, and connect your stereo
speaker to it. Start with the left slide switch (S1)
turned off and the right switch turned on. Press
keys to find the one that gives the best effects with
the 3 experiments in the preceding project, then
turn the tune knob on the keyboard to see if you
can make the effects even better.
Now turn on the left slide switch to add the
photoresistor (RP) to the circuit. Move your hand
over the photoresistor to adjust how much light
shines into it, to change the sound to give the best
effects for the 3 experiments in the preceding project.

Project 53

Brightness Adjuster
Build the circuit and turn on the slide switch (S1). Move the lever on the
adjustable resistor (RV) to vary the brightness of the light from the color
LED (D8). If desired, you may place the egg LED attachment on the
LED.
Resistors are used to control or limit the flow of electricity in a circuit.
Higher resistor values reduce the flow of electricity in a circuit.
In this circuit, the adjustable resistor is used to adjust the LED brightness,
to limit the current so the batteries last longer, and to protect the LED
from being damaged by the batteries.
What is Resistance? Take your hands and rub them together very fast.
Your hands should feel warm. The friction between your hands converts
your effort into heat. Resistance is the electrical friction between an
electric current and the material it is flowing through.
The adjustable resistor can be set for as low as 200W, or as high as
50,000W (50kW).

Project 54 Brightness
Limiters
Use the preceding circuit, but
replace the 3-snap with one of the
yellow resistors in this set (R1 or
R3). Observe how each changes
the LED brightness at different
settings for the adjustable resistor.
The R1 resistor (100W) will have
little effect, because the adjustable
resistor (RV) will always dominate
it. Resistor R3 (5.1kW) will
dominate when RV is set for low
values, but have little effect when
RV is set at high values.

Project 55

Big Brightness
Adjuster
Vary the brightness of the color
LED (D8) using the 500kW
adjustable resistor (RV3).

The 500kW adjustable resistor
(RV3) can be set for as low as
200W, or as high as 500,000W
(500kW), so the color LED will
only light on a small portion of
RV3’s range.
-42-

Project 56

Photo Brightness
Adjuster
Some materials, such as Cadmium Sulfide, change their
resistance when light shines on them. Electronic parts made
with these light-sensitive materials are called photoresistors.
Their resistance decreases as the light becomes brighter.
The resistance of your Snap Circuits® photoresistor changes
from nearly infinite in total darkness to about 1kW when bright
light shines directly on it. Note that a black plastic case
partially shields the Cadmium Sulfide part.

Vary the brightness
of the color LED
(D8) by varying the
amount of light
shining on the
photoresistor (RP).

Photoresistors are used in applications such as streetlamps,
which come on as it gets dark due to night or a severe storm.

Project 58
Project 57 Amplified Photo
Brightness
Amplified Big
Brightness Adjuster
Adjuster
Vary the brightness of the color LED
(D8) by varying the amount of light
shining on the photoresistor (RP). Notice
that you have to cover the photoresistor
to make the color LED dim.
In the preceding circuit the photoresistor
directly controlled the current through the
color LED. In this circuit the current
through the photoresistor is amplified by
the NPN transistor (Q2), so the light on
the photoresistor must get very dark
before the color LED brightness is
reduced.

-43-

Vary the brightness of the
color LED (D8) using the
500kW adjustable resistor
(RV3). The brightness
won’t change a lot; you
may need to view it in a
dark room to notice the
difference. Placing the egg
attachment on the color
LED may help to notice the
brightness difference.

Compare this circuit to project 55 (Big
Brightness Adjuster). In project 55 the
color LED was dark for most of RV3’s
range. In this circuit the NPN transistor
(Q2) amplifies the current through
RV3, so the color LED is bright for
most of RV3’s range.

Project 59

Cup & String Communication

Sound, radio signals, and light all travel through air like waves travel through
water. To help you understand how they are like waves, you can make a cup
& string telephone. This common trick requires some household materials (not
included with this kit): two large plastic or paper cups, some non-stretchable
thread or kite string, and a sharp pencil. Adult supervision is recommended.
Take the cups and punch a tiny hole in the center of the bottom of each with
a sharp pencil (or something similar). Take a piece of string (use between 25
and 100 feet) and thread each end through each hole. Either knot or tape the
string so it cannot go back through the hole when the string is stretched. Now
with two people, have each one take one of the cups and spread apart until
the string is tight. The key is to make the string tight, so it’s best to keep the
string in a straight line. Now if one of you talks into one of the cups while the
other listens, the second person should be able to hear what the first person
says.

Tiny hole

Cups

How it works: When you talk into the cup, the cup
bottom vibrates back and forth from your sound
waves. The vibrations travel through the string by
pulling the string back and forth, and then make
the bottom of the second cup vibrate just like the
first cup did, producing sound waves that the
listener can hear. If the string is tight, the received
sound waves will be just like the ones sent, and
the listener hears what the talker said.
Telephones work the same way, except that
electric current replaces the string. In radio, the
changing current from a microphone is used to
encode electromagnetic waves sent through the
air, then decoded in a listening receiver.

Knot

String
String threaded
through cup bottom

Pencil

Taut string

-44-

Project 60

MP3 player

Project 62

Audio Amplifier
Build the circuit, and turn
on the slide switch (S1).
Connect a music device
(not included) to the audio
jack (JA) as shown, and
start music on it. Set the
volume using the lever on
the adjustable resistor
(RV). This is a simple
amplifier, so the sound
may not be very loud.

Project 61
Low Power
Audio
Amplifier
Use the preceding circuit, but replace one
of the battery holders (B1) with a 3-snap
wire. The circuit works the same but is not
as loud now.

Audio Amplifier with L/R Control
Build the circuit, and connect the 2-snap wire between the
B1 battery holders last. Connect a music device (not
included) to the audio jack (JA) as shown, and start music
on it. Turn on both of the slide switches (S1), and set the
volume using the lever on the adjustable resistor (RV). This
is a simple amplifier, so the sound may not be very loud.

MP3 player

Turn off either of the slide switches to shut off the left or
right outputs of your music device. If the left and right
outputs of your music signal are the same, then turning off
one switch will reduce the volume a little.
When finished, remove the 2-snap wire between the
battery holders to turn off the circuit.
This circuit does not have an
on/off switch, because the slide
switches are being used to
control the music device outputs.

-45-

Project 63

MP3 player

Your Music without Echo
Build the circuit, and turn
on the slide switch (S1).
Connect a music device
(not included, but this set
does include a cable to
connect it) to the audio
jack (JA) as shown, and
start music on it.
Set the volume control on
your music device for a
comfortable sound level.

Here we are using the
amplifier inside the echo
IC (U28), without adding
any echo effects to the
music.

Project 65

MP3 player

Project 64

Low Power
Your Music
without
Echo
Use the preceding circuit, but
remove the 1mF capacitor
(C7) from the circuit, or
replace it with the 0.1mF
capacitor (C2). The volume is
not as loud now.

Adjustable Music without Echo

Modify the project 63 circuit to include a
volume control, the adjustable resistor
(RV). It works the same way, but adjust the
volume using the lever on RV.

-46-

Project 66

L/R Music Amplifier
Build the circuit, and turn on the slide switch (S1).
Connect a music device (not included) to the audio
jack (JA) as shown, and start music on it. Use the
lever on the adjustable resistor (RV) to adjust the
volume for the left and right outputs of your music
device; both won’t be loud at the same time.

MP3 player

The left and right outputs of
your music device are intended
to control separate speakers,
but are combined here
because you only have one
Snap Circuits® speaker.

Project 67

Another Transistor Amplifier
Vary the brightness of the color LED (D8) using the 500kW adjustable
resistor (RV3).

This circuit is similar to
project 58 (Amplified Big
Brightness Adjuster), but
the color LED will not be
quite as bright. In this circuit
both the controlling current
(through
RV3)
and
controlled current (through
R1) also flow through the
color LED, reducing the
amplification.

-47-

Project 68

Microphone
Resistance - LED

The microphone changes resistance when
exposed to changes in air pressure, such as
from sound waves or blowing on it. Talking
into the microphone or blowing on it will
change the LED brightness, but probably not
enough for you to notice the difference.

Build the circuit, and turn on the slide switch (S1).
The color LED (D8) is dimly lit, because the
resistance of the microphone (X1) keeps the
current low.
Push the press switch (S2) to bypass the
microphone, and the LED gets bright.
You can also try replacing the microphone with
the 5.1kW resistor (R3), to see how their
resistances compare.

Project 69

Microphone
Resistance - Audio
Build the circuit, and turn on the slide switch (S1).
The resistance of the 5.1kW resistor (R3) and
microphone (X1) determine the pitch (frequency)
of the tone.
Push the press switch (S2) to bypass the
microphone, and the tone changes.

-48-

Project 70

Time Light

Project 71
Time Light (II)

Build the circuit, and turn on the slide
switch (S1). Push the press switch (S2)
and set the 500kW adjustable resistor
(RV3) so the color LED (D8) just comes
on, then release the press switch. The
color LED will be bright for a while and
slowly get dim and go out. Push the press
switch again to reset the color LED’s timer.

Use the preceding circuit, but replace the
adjustable resistor (RV) with the 5.1kW resistor
(R3). The circuit works the same way, but the
color LED gets dim faster.

You can change RV3’s setting to keep the
color LED on much longer. The adjustable
resistor (RV) is used here as a fixed
resistor (of 50kW), so moving its lever will
have no effect.

Project 72

Easier Adjust
Time Light
Build the circuit, and turn on the slide
switch (S1) Push and release the press
switch (S2). Set the 500kW adjustable
resistor (RV3) so the color LED (D8) is on
and bright, then wait for it to get dim and
go out. Push the press switch again to
reset the color LED’s timer. The brighter
the color LED starts, the faster it gets dim.
The adjustable resistor (RV) is used here
as a fixed resistor (of 50kW), so moving its
lever will have no effect.

-49-

The 470mF capacitor (C5)
can store electricity. This
timer circuit works by slowly
charging up C5; the color
LED goes out when C5 gets
full. If you replace C5 with C2
or C7, the LED will go out
almost immediately because
these values can’t store
nearly as much electricity.

Project 73
Small Adjust
Time Light
Use the preceding circuit, but replace the
adjustable resistor (RV) with the 5.1kW resistor
(R3). The circuit works the same way, but the
color LED can only light over a small part of
RV3’s range, and it gets dim faster.

Project 74

Day Light
Build the circuit, and
turn on the slide
switch (S1). Set the
lever
on
the
adjustable resistor
(RV) so the color
LED (D8) just gets
bright. Now when
you block the light to
the
photoresistor
(RP), the color LED
will turn off. If the
color LED cannot be
turned on or off at
any RV setting, then
change your room
lighting.

Project 76 Dark Light

Project 75 Lower Day Light
This circuit is like the
preceding one, but
can be used in
darker rooms. Build
the circuit, and turn
on the slide switch
(S1). Set the lever
on the adjustable
resistor (RV) so the
color LED (D8) just
gets bright. Now
when you block the
light to the photoresistor (RP), the
color LED will turn
off.

Project 77 Blow Noise
Build the circuit, and turn on the slide switch (S1). Blow into the
microphone (X1), and hear it on the speaker (SP2).

Build the circuit, and turn on the
slide switch (S1). Set the knob on
the 500kW adjustable resistor
(RV3) all the way to the right. If the
room light is bright then the color
LED (D8) should be off. Cover the
photoresistor (RP) or take the
circuit into a dark room, and the
color LED should turn on.

-50-

Project 78

Listen to the
Light Change
The
color
LED actually
contains separate red, green,
and blue lights, with a
microcircuit controlling them.
Each time the LED changes
colors, the voltage across it
changes. Each time the
voltage changes, you hear a
“click” from the speaker.

Project 79
Adjustable Listen to
the Light Change
Turn on the slide switch (S1). Set
the lever on the adjustable resistor
(RV) for different brightness levels
on the color LED (D8). You also
hear a clicking sound from the
speaker (SP2).

The transistor (Q2) amplifies the
LED current, to make the speaker
(SP2) sound louder.

-51-

Turn on the slide switch (S1). The color
LED (D8) changes colors in a repeating
pattern, and you hear a clicking sound
from the speaker (SP2).

Project 80
Bright or Loud?
Turn on the slide switch (S1). Set the
lever on the adjustable resistor (RV) for
different brightness levels on the color
LED (D8). The color LED is bright on a
more limited range of RV settings than
in the preceding project, and the
speaker (SP2) is not nearly as loud.
Now push the press switch (S2); the
LED is dimmer but the sound is louder.
When S2 is off the transistor
(Q2) has little effect, and the
circuit is similar to project
46. With S2 pressed, the
transistor acts as an
amplifier, increasing the
current through the speaker.
The LED current is lower in
this arrangement.

Project 81

LED Keyboard Control
Build the circuit, and turn on the slide
switch (S1). You hear a sound pattern
that is synchronized with the color LED
(D8) flashing. You can press keys on the
keyboard (U26) to change the sound.
The color LED turns off briefly when it
changes colors. Here the color LED
controls the keyboard through the
transistor (Q2), so when the color LED
turns off, the keyboard sound is also
turned off. This produces the sound
effects you hear.

Project 83
Photo LED
Keyboard
Control
Use the project 81 circuit, but replace
the 5.1kW resistor (R3) with the
photoresistor (RP). Wave your hand
over the photoresistor or adjust the
room lighting to vary the amount of
light shining on the photoresistor, and
listen to the sounds. You can also
press keys on the keyboard (U26) to
add more sounds.

Project 84

Project 82
LED
Keyboard
Control (II)
Use the preceding circuit, but
remove the 5.1kW resistor
(R3). Now there is only sound
when you press keys on the
keyboard, and the sounds for
some keys are different.

Adjustable
LED Keyboard
Control
Modify the project 81 circuit to match
this one. Turn on the slide switch (S1)
and move the lever on the adjustable
resistor (RV) to vary the sounds. You
can also press keys on the keyboard
(U26) to add more sounds.

-52-

Project 85 Capacitor Keyboard Control
Build the circuit, and turn both
slide switches (S1). You hear
a sound pattern that is
synchronized with the color
LED (D8) flashing. Move the
lever on the adjustable
resistor (RV) to change the
sound produced. You can also
press keys on the keyboard
(U26) to change the sound.
Adding the capacitor changes
the range of tones produced
by the keyboard.

Project 87

Project 86
Capacitor
Keyboard
Control (II)
Use the preceding circuit, but replace
the 1mF capacitor (C7) with the 0.1mF
capacitor (C2). The sounds are
different now.

Voice & Keyboard Echo
Build the circuit as shown. Place the circuit in
a quiet room. Connect the speaker (SP2)
using the red & black jumper wires, then hold
it away from the microphone (X1). Turn on the
slide switch (S1). Talk into the microphone or
press keys on the keyboard (U26), and listen
the echo on the speaker. Adjust the volume
using the knob on RV3. Adjust the amount of
echo using the lever on RV; move the lever up
for more echo or down for less echo. Try this
at different RV settings, because the effects
are very interesting with both high and low
echo amounts.
Note: You must hold the speaker away from
the microphone or the circuit may self-oscillate
due to feedback. You also need a quiet room,
with low background noise.

-53-

Project 88

LED Voice Keyboard Echo
Build the circuit as shown. Place the circuit in a quiet
room. Connect the speaker (SP2) using the red & black
jumper wires, then hold it away from the microphone.
Turn on the slide switch (S1). Talk into the microphone
or press keys on the keyboard (U26), and listen the
echo on the speaker. Adjust the amount of echo using
the lever on the adjustable resistor (RV); move the
lever up for more echo or down for less echo. Try this
at different RV settings, because the effects are very
interesting with both high and low echo amounts.
The color LED (D8) lights when keys are
pressed but will be dim. It is easier to see
in a dimly lit room.
Note: You must hold the speaker away
from the microphone or the circuit may selfoscillate due to feedback. You also need a
quiet room, with low background noise.

Project 89 Project 90
Photo LED
Photo LED
Keyboard
Keyboard
Echo
Use the preceding circuit, but
replace the microphone (X1) with the
photoresistor (RP). As you are
pressing keys on the keyboard
(U26), vary the amount of light
shining into the photoresistor to
change the sound. Try it using
different settings on the adjustable
resistor (RV).

Use the preceding circuit, but
remove the adjustable resistor (RV)
from the circuit. Press keys on the
keyboard (U26), and vary the light to
the photoresistor (RP) to adjust the
volume. There won’t be any echo
effects now.

Project 91 Audio Dark Light
Build the circuit, and
turn on the slide
switch (S1). Set the
knob on the 500kW
adjustable resistor
(RV3) to the right
until the color LED
(D8) is off. Cover
the photoresistor
(RP) or take the
circuit into a dark
room, and the color
LED should turn on,
and
you
hear
clicking from the
speaker (SP2). The
clicking will not be
very loud.
-54-

Project 92

Oscillator
Build the circuit, and turn the slide switch
(S1). You hear a tone. You can also press
keys on the keyboard (U26) to change the
sound.
This circuit is an oscillator, because it
produces a repetitive electrical signal on its
own. You hear it as sound waves from the
speaker. The signal is produced by a circuit
inside the keyboard module, but may be
controlled using your Snap Circuits®
resistors and capacitors, and the keys on
the keyboard. The keys are actually
connecting different resistors inside the
keyboard, similar to the 5.1kW resistor (R3).

Project 95
Oscillator (IV)
Use the preceding circuit, but replace
the 5.1kW resistor (R3) with the 100W
resistor (R1). The frequency of the
sound is higher now, and you hear
several clicks a second.

Project 96
Oscillator (V)
Use the preceding circuit, but replace
the 470mF capacitor (C5) with the 1mF
capacitor (C7). The frequency of the
sound is much higher now, and you hear
a continuous tone.
-55-

Project 93

Oscillator (II)
Use the preceding circuit, but replace
the 0.1mF capacitor (C2) with the 1mF
capacitor (C7). The frequency (pitch)
of the sound is lower now.

Project 94

Oscillator (III)
Use the preceding circuit, but replace
the 1mF capacitor (C7) with the 470mF
capacitor (C5). The frequency of the
sound is now so low that you just hear
a click every few seconds.

Project 97
Project 98
Oscillator (VI) Left Right Bright Light
Use the preceding circuit, but
replace the 1mF capacitor (C7) with
the 0.1mF capacitor (C2). Do you
hear anything? The circuit is
producing a high frequency tone,
which may be too high for your ears
to hear, especially if you are older.
Now remove the 0.1mF capacitor
from the circuit. This makes the
tone even higher frequency, and
you probably won’t hear anything
now. Dogs have better high
frequency hearing, so maybe your
dog can hear it.

Turn on the slide switch
(S1) and move the
lever on the adjustable
resistor (RV) around.
The color LED (D8) is
bright if the lever is to
the far left or far right,
and dim if the lever is in
the middle.

Project 99

Adjustable Oscillator
Build the circuit, and turn the slide switch
(S1). Turn the knob on the 500kW
adjustable resistor (RV3) to see the range
of sounds that can be produced; there will
only be sound for a small part of RV3’s
range. You can also press keys on the
keyboard (U26) to change the sound.
RV’s 500kW adjustment
range is wide, and the
oscillator circuit inside
the keyboard (U26)
won’t function over RV’s
full range. At some
settings the circuit may
function, but produce too
high of frequency for
your ears to hear.

Project 101
Adjustable
Oscillator
(III)
Use the preceding circuit, but
replace the 1mF capacitor (C7)
with the 470mF capacitor (C5).
You can hear a clicking sound
for a small part of RV3’s
adjustment range.

Project 102
Adjustable
Oscillator
(IV)
Use the preceding circuit, but
remove the 470mF capacitor
(C5) from the circuit. See the
range of sounds that this
circuit can produce.

Project 100
Adjustable
Oscillator
(II)
Use the preceding circuit, but
replace the 0.1mF capacitor
(C2) with the 1mF capacitor
(C7). The frequency (pitch) of
the sound is lower now.

Project 103 Water Detector
Build the circuit, and
initially leave the loose
ends of the red &
black jumper wires
unconnected. Turn on
the slide switch (S1);
nothing happens. Now
place the loose ends
of the red & black
jumper wires into a
cup of water, without
their snaps touching
each other. The color
LED (D8) should be
on now, indicating that
you have detected
water!
-56-

Project 104

Clicker
Build the circuit, and turn the slide switch (S1). The color LED (D8) is
flashing, and you hear a clicking sound.

The color LED turns off briefly when
it changes colors. What you hear in
the speaker is the change in current
as the LED turns on or off.

Project 105

Clicker with Echo

Modify the preceding circuit to be this one, which adds echo effects.
Turn on the slide switch (S1) and push the press switch (S2) to see the
color LED (D8) flashing and hear a clicking sound. When you release
the press switch, the color LED shuts off but you hear echo effects. Use
the lever on the adjustable resistor (RV) to set the echo level.

-57-

Project 106 3V Audio Amplifier
Build the circuit, and turn on the
slide switch (S1). Connect a
music device (not included) to the
audio jack (JA) as shown, and
start music on it. Turn the knob
on the 500kW adjustable resistor
(RV3) to adjust the volume.
The transistor (Q2) amplifies the
current from your music device, to
make the sound louder. The
resistors (R1 & RV3) and
capacitors (C5 & C7) condition
the signal to minimize distortion.

MP3 player

Project 107
Mini Music Player
To demonstrate how much the transistor was
amplifying the sound, connect the speaker
directly to the audio jack, as shown here, and
start music on your music device. If you don’t
hear anything then hold the speaker next to
your ear, or set the volume control on your
music device higher.

MP3 player

Project 108

Voice Echo with Light
Build the circuit as shown, and place it in a quiet room.
Connect the speaker (SP2) using the red & black jumper
wires, then hold it away from the microphone (X1). Turn on
the slide switch (S1). Talk into the microphone, and listen the
echo on the speaker, and see it on the color LED (D8). Adjust
the amount of echo using the lever on the adjustable resistor
(RV); move the lever up for more echo or down for less echo.
Try this at different RV settings. You may need to talk loud
directly into the microphone to make the color LED bright.
Note: You must hold the speaker away from the microphone
or the circuit may self-oscillate due to feedback. You also
need a quiet room, with low background noise.

-58-

Project 109

Color Sound
Normally the color LED changes colors, but here
it doesn’t, why? The U26 keyboard produces a
changing voltage, intended to produce sound on
the speaker. The color LED is designed for use
with a stable voltage (like the batteries); when
used with the changing voltage from the
keyboard, it gets confused and blurs its pattern.
Red is the easiest color for the color LED to
produce, and blue is the hardest. So when the
voltage to it is weak, the more difficult colors get
dim first.
The keyboard produces separate tones for the
blue and green keys, which are played together
at the speaker. The two tones are also control
the color LED. When the tones combine, it is
easier for the color LED to produce green and
blue color.

Project 110
Color Sound (II)

Project 111
Color Sound (III)

Use the preceding circuit, but add the 0.1mF
capacitor (C2) over the keyboard (U26)
using a 1-snap wire, as shown. Press a blue
and a green key at the same time, while
turning the TUNE knob.
Watch the colors on the color
LED (D8), and listen to the
sound.

Use the preceding circuit, but use the 1mF
capacitor (C7) instead of the 0.1mF capacitor
(C2). Press a blue and a green key at the
same time, while turning the TUNE knob.
Watch the colors on the color LED (D8), and
listen to the sound.

-59-

Next, replace the 1mF capacitor (C7) instead
of the 470mF capacitor (C5). Press one of
the green keys and hold it down. Every few
seconds, the color LED flashes and you hear
a click from the speaker.

Build the circuit and turn the slide switch
(S1). Press any key on the keyboard
(U26), but just one key at a time. The
color LED (D8) lights (mostly red), and
you hear a tone from the speaker (SP2).
Now press one blue key and one green
key at the same time, to produce 2
tones on the speaker. Watch the color
LED (D8) closely; you should see more
green and blue color than before. Try
viewing it in a dimly lit room.
Now turn the TUNE knob while pressing
the blue C key and the green C key at
the same time. Slowly turn the knob
across its entire range, and see how the
LED color changes.
The spectrum of LED color here
depends on your batteries. With strong
batteries you will see more green and
blue. With weak batteries you will mostly
see red.

Project 112
Backwards Color
Sound
Use any of the 3 preceding circuits, but reverse the
direction of the color LED (D8). The circuit works the
same, but the sound may not be as loud and the LED
may not be as bright.
Normally the color LED doesn’t work
when you connect it backwards, but in
this circuit it does. The changing
voltage produced by the keyboard
actually goes both ways (positive and
negative), so here the color LED will
work in either direction.

Project 113

White Light
Build the circuit and turn the slide switch (S1). Press any key on the
keyboard (U26), but just one key at a time. The color LED appears
white, and isn’t changing colors like it normally does. If you look closely
at the color LED you can see separate red, green, and blue lights on it,
which combine to produce white. This is best seen in a dark room. You
can also view it with the egg attachment on the color LED, which helps
to blend the LED colors together.
The color LED actually contains separate red, green,
and blue LED controlled by a microcircuit. It is designed
for use with a stable voltage (like the batteries); when
used with the keyboard output (a changing voltage
intended to produce sound on the speaker), it gets
confused and blurs its pattern. The result appears white
because mixing equal amounts of red, green, and blue
light makes white light.

Project 114 Red to White
Use the preceding circuit, but replace the 5.1kW resistor (R3) with
the 500kW adjustable resistor (RV3). Press any key on the keyboard
(U26), but just one key at a time. Slowly turn the knob on RV3 from
right to left across its range while watching the color LED (D8)
closely. Notice how first red gets bright, then green too, then also
blue. This is best seen in a dark room. You can also try it with the
egg attachment on the color LED.
RV3 controls the voltage
to the color LED, through
transistor Q2. When the
voltage is low, the color
LED only produces red,
since that is the easiest
color for it to produce. As
the voltage increases,
green light is added, then
blue.

Project 115

Alarm

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

-60-

Project 116 Super Voice Echo with Light
Build the circuit as shown, and turn on
the slide switch (S1). Talk into the
microphone, and listen the echo on the
speaker, and see it on the color LED
(D8). Set the sound volume using the
knob on the 500kW adjustable resistor
(RV3). Adjust the amount of echo using
the lever on the adjustable resistor
(RV).
Note: There will only be sound if RV3
is set towards the left (most of its range
will have no sound). Also, at the loudest
RV3 setting the circuit may oscillate
and make a whining sound; just set the
RV3 volume a little lower to stop it.

Project 118
Photo Echo
Use the preceding circuit, but replace the press
switch (S2) with the photoresistor (RP), Adjust
the amount of light shining on the photoresistor
to change the sound and light.

Project 119
Loud Press
Photo Echo
Use the circuit from project 117 (with S2) or 118
(with RP), but replace RV3 with a 3-snap wire. The
sound will be louder but the light will be dimmer.
-61-

Project 120

Project 117

Press Echo

Use the preceding circuit, but
replace the microphone (X1)
with the press switch (S2).
Set RV3 to max volume (turn
it to the left). Press S2 to see
light on the color LED (D8),
and hear a clicking sound
from the speaker (SP2).

Knob Echo
Build the circuit as shown,
turn on the slide switch (S1),
and turn the knob on the
500kW adjustable resistor
(RV3). You hear clicking in the
speaker (SP2), and the color
LED (D8) flashes. Adjust the
amount of echo using the
lever on the adjustable
resistor (RV). Try this at
different RV settings.
If you remove the speaker
(SP2) from the circuit then the
color LED (D8) will be a little
brighter, because the echo IC
(U28) isn’t trying to control the
speaker at the same time.

Project 121

Echo Light Headphone
Build the circuit as shown, and connect your
own headphones (not included) to the audio
jack (JA). Turn on the slide switch (S1).
Talk into the microphone, and listen the
echo on your headphones, and see it on
the color LED (D8). Set the 500kW
adjustable resistor (RV3) for most
comfortable sound level (turn to the left for
higher volume, most of RV3’s range will be
very low volume); then adjust the amount
of echo using the lever on the adjustable
resistor (RV). Only the left side of your
headphones will have sound.

WARNING: Headphones performance varies, so use caution. Start with
low volume, then carefully increase to a comfortable level. Permanent
hearing loss may result from long-term exposure to sound at high volumes.

Project 123

Headphones
(not included)

Press Echo Light

Build the circuit as shown, and
turn on the slide switch (S1).
Push the press switch (S2) to
see light on the color LED (D8),
and hear a clicking sound from
the speaker (SP2). Adjust the
amount of echo using the lever
on the adjustable resistor (RV).

Project 122
Echo Light
Headphone Variants
Use the preceding circuit, but
replace the microphone (X1) with
the press switch (S2). Press S2 to
see light on the color LED (D8),
and hear a clicking sound from
your headphones.
Next, replace the press switch with the
photoresistor (RP), Adjust the amount
of light shining on the photoresistor to
change the sound and light.
You can use a stereo speaker (not
included) instead of headphones.
When using it with the microphone
(X1), you may need to lower the
volume to prevent feedback into
the microphone.

Project 124
Photo Echo Light
Use the preceding circuit, but
replace the press switch with the
photoresistor (RP). Adjust the
amount of light shining on the
photoresistor to change the sound
and light. You may need a big
difference in brightness to notice
the effects.
Next, replace the photoresistor with
the microphone (connect the “+”
side to the echo IC (U28)). Talk
loudly directly into the microphone
to flash the light and hear your
voice on the speaker (SP2), but
your voice will be badly distorted.
-62-

Project 125

Another Voice Echo Light
Build the circuit as shown, and turn on the slide switch (S1). Talk into the
microphone (X1) to light the color LED (D8) and hear your voice on the speaker
(SP2). Adjust the amount of echo using the lever on the adjustable resistor
(RV).
Next, replace the microphone with the press switch (S2). Push the press switch
to see light on the color LED, and hear a clicking sound from the speaker.

Project 126

Daylight Voice Echo
Note that there is a 4-snap wire under Q2, partially hidden. Place the circuit in a quiet
room with bright light shining into the photoresistor (RP). Connect the speaker (SP2)
using the red & black jumper wires, then hold it away from the microphone (X1). Turn
on the slide switch (S1). If the speaker makes a whining sound that does not stop, then
you need brighter light on the photoresistor, or the room is too noisy.
Talk into the microphone, and listen the echo on the speaker. Now block the light to the
photoresistor to turn off the circuit; slowly wave your hand over it to turn the echo on and
off. You can adjust the amount of echo using the lever on the adjustable resistor (RV).
The photoresistor controls power to
the echo IC (U28), and acts as an
on/off switch. If there is some light on
it but not bright light, it may only
partially turn on the echo IC, causing
the echo IC to malfunction.
Also, you must hold the speaker
away from the microphone or the
circuit may self-oscillate due to
feedback. You also need a quiet
room, with low background noise.

-63-

Project 127

Dark Voice Echo
The photoresistor controls power to the
echo IC (U28), and acts as an on/off switch.
If the photoresistor is not dark enough, it
may only partially turn on the echo IC,
causing the echo IC to malfunction.
Also, you must hold the speaker away from
the microphone or the circuit may selfoscillate due to feedback. You also need a
quiet room, with low background noise.

Build the circuit as shown, and place it in
a quiet room. Connect the speaker (SP2)
using the red & black jumper wires, then
hold it away from the microphone (X1).
Turn on the slide switch (S1); nothing will
happen unless the room is dark. This
circuit only works if there is no light on the
photoresistor (RP).
Cover the photoresistor, talk into the
microphone, and listen the echo on the
speaker. You can adjust the amount of
echo using the lever on the adjustable
resistor (RV). Shine light on the
photoresistor to shut off the circuit.
If the speaker makes a whining sound that does
not stop, then you need to block light from the
photoresistor better, or the room is too noisy.

Project 128

Dark Echo Light
Modify the preceding circuit to match this
one; it uses the color LED (D8) instead of
the speaker (SP2). Turn on the slide switch
(S1); nothing will happen unless the room is
dark. This circuit only works if there is no
light on the photoresistor (RP).
Cover the photoresistor, talk into the
microphone, and see the light flash. You can
adjust the amount of echo using the lever
on the adjustable resistor (RV). Shine light
on the photoresistor to shut off the circuit.
If the color LED never turns off, then you
need to block light from the photoresistor
better.

Project 129
Dark Echo
Variants

Use either of the preceding two
circuits, but replace the microphone
(X1) with the press switch (S2) or
500kW adjustable resistor (RV3). Press
S2 or turn the knob on RV3 to change
the sound or light.

-64-

Project 130

Day Echo Light
Build the circuit as shown, and
place it where there is bright light
shining into the photoresistor
(RP). Turn on the slide switch
(S1). If the color LED never
turns off, then you need brighter
light on the photoresistor.
Talk into the microphone, and
see the color LED (D8) flash.
Now block the light to the
photoresistor to turn off the
circuit; slowly wave your hand
over it to turn the echo on and off
while talking. You can adjust the
amount of echo using the lever
on the adjustable resistor (RV).

Project 132
Photo Light Timer

-65-

Project 131
Day Echo
Variants
Use the preceding circuit, but replace the
microphone (X1) with the press switch (S2)
or 500kW adjustable resistor (RV3). Press
S2 or turn the knob on RV3 to change the
light.
You can also replace the color LED (D8)
with the speaker (SP2). When used with the
microphone, you must connect the speaker
using the red & black jumper wires and hold
it away from the microphone, and also omit
C7.

Project 133
Adjustable Photo Light Timer

Build the circuit, and turn
on the slide switch (S1). If
there is light on the
photoresistor (RP) then
the color LED (D8) will be
on. Block the light to the
photo-resistor, and the
color LED should slowly
get dimmer and dimmer.

This circuit is similar to the
preceding one, except the color
LED (D8) stays on longer when
you block the light to the
photoresistor (RP). Use the lever
on the adjustable resistor (RV) to
set how long the color LED will
stay bright after the photoresistor
is covered.

The 470mF capacitor (C5)
stores up some electricity,
and releases it when you
block the light.

The resistance of RV
slows down the discharging of the 470mF
capacitor (C5).

Project 134

Tone Stoppers
Build the circuit and turn the slide switch (S1). Press any key on the
keyboard (U26). You hear a tone from the speaker (SP2), though it may
not be very loud.
Now push the press switch (S2) while pressing the same key. The
sound is louder now, because the press switch bypassed the 0.1mF
capacitor.
Capacitors can store electricity in small amounts. This
storage ability allows them to block stable electrical signals
and pass changing ones, making them useful in filtering and
delay circuits. Capacitors with higher values have more
storage capacity, and can pass changing signals more easily,
In this circuit the 0.1mF capacitor blocks most of the keyboard
tone signal. You can hear the difference when you press S2
to bypass the capacitor.

Project 135
Tone Stoppers (II)

Project 136
Tone Stoppers (III)

Use the preceding circuit, but replace
the 0.1mF capacitor (C2) with the
larger 1mF capacitor (C7). Compare
the sound volume to the preceding
circuit.

Use the preceding circuit, but replace
the 1mF capacitor (C7) with the much
larger 470mF capacitor (C5). Compare
the sound volume to the preceding
circuits. How much difference does
pressing S2 make now?

The sound is a little
louder now because
the
larger
1mF
capacitor
passes
more of the tone
than the smaller
0.1mF capacitor did.

The sound is much louder now because
the larger 470mF capacitor passes
much more of the tone than the smaller
1mF capacitor did. Now pressing S2
does not increase the sound, because
C5 is already passing all of it.

Project 137
Tone Stoppers (IV)
Use the circuit from project 135 (with the 1mF capacitor (C7)), but
add the 500kW adjustable resistor (RV3) as shown here. Slowly
turn RV3’s knob to vary the pitch (frequency) of the tone from
lowest to highest possible (there will only be sound for a small
part of RV3’s range). At the same time, press S2 on and off
several times, to see how C7 is changing on the sound.
Next, replace C7 with smaller C2 or larger C5, and compare the
capacitor’s effect as you vary the tone frequency.
C7 will give less change on
high frequency tones than
on low frequency tones; you
should be able to notice the
difference as you vary the
tone using RV3. The smaller
C2 will affect both high and
low tones a lot. The larger
C5 will have little effect on
both high and low tones.

-66-

Project 138 Tone Stoppers (V)
In project 137, there is only sound for
a small part of RV3’s range, which
can be difficult to tune. To help,
modify the circuit to add the
adjustable resistor (RV) in series with
RV3, as shown. Slowly adjust RV
and RV3 to vary the tone from lowest
to highest possible, while pressing
S2 on and off, to see how the
capacitors (C7, or C2 or C5) change
the sound.
You can also replace RV3 with the
photoresistor (RP). Set RV to the left,
and then adjust the tone by varying
the light to RP, while comparing the
effects of the capacitors.

Project 139

Build the circuit with the black
jumper wire connected as
shown, and turn it on.
Nothing happens. Disconnect
the jumper wire and the color
LED (D8)
comes
on,
signalling an alarm.

RV
is
more
sensitive and can
be adjusted from
200W to 50kW,
compared
to
200W to 500kW
for RV3.

Project 140

Alarm Light

Voice Changer with Headphones
This project requires stereo headphones or a stereo speaker (neither
included); connect them to the audio jack (JA). Set the 500kW adjustable
resistor (RV3) to mid-range. Turn on both slide switches (S1), you hear a
beep signaing that you may begin recording. Talk into the microphone until
you hear a beep (signaling that recording time is over), then turn off the left
slide switch to exit recording mode. Push the press switch (S2) to play back
the recording and flash the color LED (D8), and turn the knob on RV3 to
change the playback speed. You can play your recording faster or slower by
changing the setting on RV3.
Adjust the volume to your headphones or stereo speaker using the lever on
the adjustable resistor (RV).
Recording time is 6 seconds at normal speed, but this can be changed
depending on the setting of RV3 when you are making the recording.

Headphones or Stereo Speaker (not included)
-67-

WARNING: Headphones performance varies, so use caution. Start with
low volume, then carefully increase to a comfortable level. Permanent
hearing loss may result from long-term exposure to sound at high volumes.

Project 141

Day Keyboard

Build the circuit (note that there is a 4-snap wire under Q2, partially
hidden) and turn the slide switch (S1). Press keys on the keyboard
(U26). This keyboard only works during the day, so you have to have
light on the photoresistor or there won’t be any sound. If you cover the
photoresistor or place the circuit in a dark room then it won’t work. If the
light is dim then the sound may be abnormal.

Project 142

Night Keyboard

Build the circuit (note that there is a 4-snap wire under Q2, partially
hidden) and turn the slide switch (S1). Press any key on the keyboard
(U26) and set the 500kW adjustable resistor so the sound just shuts off.
Now block the light to the photoresistor (RP) and press some keys to
play tones.

-68-

Project 143

Color Keyboard
Build the circuit and turn the slide switch (S1). Press and hold down any
green key on the keyboard (U26), and see what happens.

Project 144 Color Keyboard (II)
Modify the preceding circuit by
adding the adjustable resistor
(RV) as shown here. Turn the
slide switch (S1). Move the lever
on the adjustable resistor around;
best effects are when it is to the
left. Press keys on the keyboard
(U26) at the same time. You will
see some cool effects.

Project 145

Color Keyboard (III)
Build the circuit and turn the slide switch (S1). Press and hold down any
green key on the keyboard (U26), and see what happens.

Project 146 Color Keyboard (IV)
Modify the preceding circuit by
adding the 100W resistor (R1) and
replacing the 1mF capacitor (C7)
with the 470mF capacitor (C5), as
shown here. Turn the slide switch
(S1) to see some cool effects.
Press any of the blue keys for
more effects. Pressing the green
keys won’t do anything.
-69-

Project 147

Color Keyboard (V)

Turn on the slide switch (S1).
Move the lever on the
adjustable resistor (RV) around
near the left (not the middle or
right). Press any of the blue
keys for more effects. Pressing
the green keys may not do
anything.

Project 148
Color Keyboard
(VI)
Use the preceding circuit, but replace the
1mF capacitor (C7) with the 0.1mF capacitor
(C2). The sound is a little different now, and
the green keys can change it.

Project 149 Adjustable Voice Changer & Light
Set the 500kW adjustable resistor (RV3) to midrange. Turn on both slide switches (S1), you hear
a beep signaling that you may begin recording.
Talk into the microphone until you hear a beep
(signaling that recording time is over), then turn
off the left slide switch to exit recording mode.
Push the press switch (S2) to play back the
recording, and turn the knob on RV3 to change
the playback speed. You can play your recording
faster or slower by changing the setting on RV3.
Move the lever on the adjustable resistor (RV) to
change the brightness of the color LED (LED)
during playback. Most of RV’s range will give little
or no LED brightness.
Recording time is 6 seconds at normal speed, but
this can be changed depending on the setting of
RV3 when you are making the recording.

Project 150
Adjustable
Voice
Changer &
Light (II)
Use the preceding
circuit, but swap the
locations of the speaker
(SP2) and color LED
(D8). Now the color
LED is at full brightness
during playback, and
RV adjusts the sound
volume.

-70-

Project 151

Play Fast

Build the circuit and turn the slide switch (S1). Push the press switch
(S2) and play keys on the keyboard (U26). Play fast, because this
keyboard will only work for a few seconds! Push S2 again to restart the
keyboard and its timer.

Project 152

Red First
The voltage needed to turn on an LED
depends on the light color. Red needs the
least voltage, and blue needs the most.
With S1 at points C & D and S2 off, the
voltage to the color LED is lowest, and may
barely be enough to turn on the red color.
Pressing S2 bypasses the NPN transistor
(Q2), and boosts the LED voltage a little.
Shifting S1 to points A & B increases the
circuit voltage from 3V to 6V, making the
LED work for a greater part of RV’s range.

-71-

Turn on the slide switch (S1). Set the lever on
the adjustable resistor (RV) all the way to the
left. The color LED (D8) should be on, but may
be mostly red. Slowly move the lever on RV to
the right until the LED is completely off. Notice
that the red color stays on the longest.
Now push the press switch (S2) and adjust RV
again, watching the LED colors. Blue and green
color may also appear now, but may go dim
before red does.
Now move S1 from the points marked C & D to
the points marked A & B. Move RV’s lever
around again, watching the LED colors and
brightness. Try pushing S2 again, but it won’t
make as much difference now.

Project 153 Adjustable Timer Tone
Note that there is a 3-snap wire
under Q2, partially hidden. Turn
on both slide switches (S1) and
push the press switch (S2). You
hear a tone, which turns off after
a while. Push S2 again to restart
the keyboard and its timer. Use
the adjustable resistor (RV) to set
how long the timer keeps the
sound on for, it can be set for a
few seconds or very long. You
can change the tone that plays by
pressing keys on the keyboard
(U26).

Project 154
Photo Timer
Tone
Use the preceding circuit, but replace
the 5.1kW resistor (R3) with the
photoresistor (RP). The circuit works
the same way, but you can vary the
pitch of the tone by adjusting the
amount of light on the photoresistor.

Turning off the left slide switch
turns off the tone, but not the keys
or timer.

Project 155

Delay Lamp
Push and release the press switch (S2), then turn on the
slide switch (S1). Nothing happens at first, but after a few
seconds the color LED (D8) turns on. Press S2 to turn off D8
and reset the delay timer.
The adjustable resistor (RV) is used as a fixed resistor, and
moving its lever won’t have any effect.
This circuit works because capacitor C5
can store electricity. When you turn on the
circuit, electricity flows through resistor RV
into C5. When C5 gets full, electricity starts
flowing into transistor Q2, which turns on
the color LED. Pressing S2 empties C5,
and resets the timer. Capacitors C2 and
C7 also store electricity, but only small
amounts; if used in this circuit they would
appear to fill up instantly.

Project 156
Adjustable
Delay Lamp
Use the preceding circuit, but replace
adjustable resistor (RV) with the
500kW adjustable resistor (RV3). Set
the knob on RV3 to different positions,
press S2 to start the timer, and see
how long it takes for the color LED to
turn on. Turning RV3’s knob clockwise
gives longer delay, turning counter
clockwise gives shorter delay.
RV3 controls how fast electricity flows
into capacitor C5. Increasing RV3’s
value makes it take longer to charge
up C5.
-72-

Project 157

Water Alarm
Build the circuit, and initially leave the loose
ends of the red & black jumper wires
unconnected. Turn on the slide switch (S1);
nothing happens. Now place the loose ends
of the red & black jumper wires into a cup of
water, without their snaps touching each
other. You should hear a tone now, indicating
that you have detected water!
Don’t drink any water used here.
You could place this circuit
in your basement, then it will
sound an alarm if your
basement starts to flood
during a storm.

Project 159

Project 158
Continuity
Tester
Use the preceding circuit,
but instead connect the
loose ends of the jumper
wires
to
different
materials in your home. If
you hear sound, then the
material you tested has
low resistance and is a
good
conductor
of
electricity.

High Low Light

The left side of RV is connected to 6V, while
the right side is only connected to 3V; so the
color LED will be brighter when RV’s lever
is to the left. Moving the lever toward the
middle increases the resistance in the
circuit, and the higher voltage left side will
be less affected than the right side.

Turn on both slide switches (S1). Move the lever on
the adjustable resistor (RV) all the way to the left or
right, and watch the brightness of the color LED (D8).
The light should be a little brighter when RV’s lever is
to the left.
Now move RV’s lever toward one side, but not all the
way. There should be a larger difference between the
same positions on the left compared to the right.

-73-

Project 160

Flicker Clicker
Turn on the slide switch
(S1). Move the lever on
the adjustable resistor
(RV) around to make the
color LED (D8) flicker and
make clicking or buzzing
on the speaker (SP2).
Press keys on the
keyboard (U26) for more
fun effects. Try pressing a
blue key and a green key
at the same time, while
moving
RV’s
lever
around.

Project 162
Slow Flicker
Clicker
Use the preceding circuit, but
replace the 1mF capacitor (C7)
with the larger 470mF capacitor
(C5). With RV set to the left,
the LED flashes and the
speaker clicks about once a
second. As you move RV’s
lever toward the right, the time
between
flashes/clicks
increases and can get very
long. Also try holding down one
of the blue keys; best effects
are when RV is set toward the
left.

Project 163

Project 161
Fast Flicker
Clicker
Use the preceding circuit, but replace the
1mF capacitor (C7) with the smaller 0.1mF
capacitor (C2). It works the same way, but
the tone has higher pitch, and the color
LED may appear to be on continuously.
If the speaker is buzzing
and the color LED is on
but not flashing, then the
color LED is probably
flashing so fast that it just
appears as a blur.

Timer Tone
Turn on the slide switch (S1) and
push the press switch (S2). You
should hear a tone; adjust its pitch
using the adjustable resistor (RV).
The tone shuts off after about 10
seconds. Push S2 again to re-start
the keyboard and its timer.
Some settings on RV may not
produce any sound. Press S2 and
set RV to where you hear sound.

-74-

Project 164

Little Battery
Set the knob on the 500kW adjustable resistor (RV3) to the
left. Place the color LED (D8) across the points marked B &
C (“+” to B); the LED lights as the capacitor charges. Next,
place the color LED across points A & B (“+” to A) instead;
now the LED lights as the capacitor discharges. Move the
color LED back to B & C and repeat. Use the knob on RV3
to vary the charge / discharge rate, but keep it close to the
left (otherwise the LED would be too dim to see).
The capacitor is storing energy like a little battery.

Batteries can hold a lot
more electricity than
capacitors
because
batteries store chemical
energy while capacitors
store electrical energy.

Project 166

Project 165
Tiny Battery
Use the preceding circuit, but
replace the 470mF capacitor (C5)
with the smaller 1mF capacitor
(C7). Set RV3 all the way to the
left. Place the color LED across B
& C to charge C7, then across A
& B to discharge it. The LED will
only flash for a moment, because
C7 can’t store much electricity
(C5 holds 470 times more). The
LED is easier to see in a dimly lit
room.

Little Battery Beep
The capacitor is storing
energy like a little battery.
The “beep” you hear is the
voice changer (U27) entering
recording mode, but you
can’t make any recording
with this circuit. Capacitor C5
can’t store enough electricity
to operate the voice changer
circuit, but it can power it long
enough to make a beep.

Set the knob on the 500kW adjustable
resistor (RV3) to mid-range. Place the
470mF capacitor (C5) across the
points marked B & C (“+” to C), then
SWING its “+” side around to point A
(without unsnapping it from point B).
Swing its “+” side between points C &
A several times.
When the capacitor (C5) touches point
C, the color LED (D8) flashes to show
that the batteries charged up the
capacitor. When the capacitor touches
point A, you hear beep from the
speaker (SP2) to show that the audio
circuit discharged the capacitor.
You can change the “beep” sound a
little by turning the knob on RV3.

-75-

Project 167

Capacitors in Series
Turn on the right slide switch (S1). Press
any green key and compare the sound with
the left slide switch on or off.
With the left switch off, the 0.1mF and 1mF
capacitors (C2 & C7) are connected in
series. Turning on the left switch bypasses
the 0.1mF capacitor. Notice that having the
0.1mF included has a big effect on the tone.
Think of capacitors as
storage tanks for electricity.
If you place a small storage
tank in series with a big
one, electricity flows into
both at the same time, but
the small one fills up
quickly and stops the flow.

Project 169
Capacitors in Series (III)
Use the project 167 circuit, but replace the 0.1mF
capacitor (C2) with the much larger 470mF
capacitor (C5). Press any green key and compare
the sound with the left slide switch on or off.
Now the tone is the same whether the left switch
is on of off, because connecting the large 470mF
in series with the small 1mF has little effect on the
total capacitance.
Swap the locations of the 1mF and 470mF
capacitors (C7 & C5). Press any green key and
compare the sound with the left slide switch on or
off (When the switch is off, hold down the key,
because you will only hear a click every few
seconds.) Now turning on the left switch has a big
effect on the circuit, because connecting the small
1mF in series with the large 470mF greatly
increases the total capacitance.

Project 168
Capacitors
in Series (II)
Use the preceding circuit,
but swap the locations of
the 0.1mF and 1mF
capacitors (C2 & C7).
Press any green key and
compare the sound with the
left slide switch on or off.
The tone does not
change nearly as much
as in the preceding
circuit. When capacitors
are connected in series,
the
smaller
value
dominates the circuit.

Project 170 More Capacitors in Series
Turn on the right slide
switch (S1). Press any
green
key
and
compare the sound
when you remove one
or two of the capacitors
(C2, C5, and C7) and
replace them with a 3snap wire. You will only
hear a click every few
seconds if C5 is the
only one in the circuit.

-76-

Project 171

Capacitors in Parallel
Turn on the right slide switch (S1). Press
any green key and compare the sound with
the left slide switch on or off.

Project 173
Capacitors in Parallel (III)
Use the project 171 circuit, but replace the 0.1mF
capacitor (C2) with the much larger 470mF capacitor
(C5). Press any green key and compare the sound
with the left slide switch on or off. (When the switch is
on, hold down the key, because you will only hear a
click every few seconds.)
Turning on the left switch has a big effect on the circuit,
because connecting the large 470mF in parallel with
the small 1mF greatly increases the total capacitance.
Swap the locations of the 1mF and 470mF capacitors
(C7 & C5). Press any green key and compare the
sound with the left slide switch on or off. Now the tone
is the same whether the left switch is on of off,
because connecting the small 1mF in parallel with the
large 470mF has little effect on the total capacitance.
-77-

Project 172
Capacitors in
Parallel (II)

With the left switch on, the 0.1mF and 1mF
capacitors (C2 & C7) are connected in
parallel. Turning off the left switch
disconnects the 0.1mF capacitor. Notice that
having the 0.1mF included has only a small
effect on the tone.

Use the preceding
circuit, but swap the
locations of the 0.1mF
and 1mF capacitors (C2
& C7). Press any green
key and compare the
sound with the left slide
switch on or off.

Think of capacitors as
storage tanks for electricity. If
you place a large storage
tank in parallel with a big one,
electricity flows into both at
the same time, but keeps
flowing until both are full.

The tone changes
much more now than in
the preceding circuit.
When capacitors are
connected in parallel,
the
larger
value
dominates the circuit.

Project 174 More Capacitors in Parallel
Turn on the right
slide switch (S1).
Press any green
key and compare
the sound when
you remove one
or two of the
capacitors (C2,
C5, and C7). You
will only hear a
click every few
seconds if C5 is in
the circuit.

Project 175

Resistors in Series
Inside the keyboard module (U26) is an
oscillator circuit that produces separate
tones for the blue and green keys. The
frequency (pitch) of the tone is set using
an internal resistor-capacitor network,
with each key representing a different
resistor value. The green keys can be
adjusted using the tune knob.
The tone of the green keys can also be
changed using external resistors and
capacitors, which is done in many of the
projects.

Project 176

Turn on the right slide switch
(S1). Set the lever on the
adjustable resistor (RV) to each
side and compare the sound
with the left slide switch on or off.
With the lever up, RV is a 200W
resistor. Turning the left switch
off connects this in series with
the 5.1kW resistor (R3), and
has a small effect on the tone.
With the lever down, RV is a
50kW resistor. Turning the left
switch off connects this in
series with the 5.1kW resistor
(R3), and has a big effect on
the tone.

Resistors in Parallel
Think of resistors as
obstructions to the flow of
electricity. When there is only
one path for electricity and
part of it has a big
obstruction, not much will
flow. When there are several
paths for electricity and one
has a big obstruction, a lot
will flow because most will
flow
through
the
unobstructed path.

Turn on the right slide switch (S1). Set the
lever on the adjustable resistor (RV) to
each side and compare the sound with the
left slide switch on or off. If there is no
sound when the lever is set all the way up,
adjust it down a little until there is sound.
With the lever up, RV is a 200W resistor.
Turning the left switch off connects this in
parallel with the 5.1kW resistor (R3), and
has a big effect on the tone.
With the lever down, RV is a 50kW resistor.
Turning the left switch off connects this in
parallel with the 5.1kW resistor (R3), and
has a small effect on the tone.
Pressing any of the green keys now will
change the tone, by connecting resistors
inside the keyboard in parallel with your
R3-RV resistor network.

-78-

Project 177

These five resistors are all
connected in series, so the
highest value, will have the
most effect.
Swapping the locations of any
parts in the circuit (without
changing the direction of their
“+” side) will not change how
the circuit works. Try it.

Project 178

Lots of Resistors in
Series
Turn on the slide switch (S1). There are five
resistors (R1, R3, RV, RV3, and RP),
connected in series, that are controlling the
current to the color LED (D8). See which
resistor has the most effect on the LED
brightness, by replacing them with a 3-snap
wire or the red/black jumper wires, one at a
time. The resistance of RV and RV3 depends
on their setting, so try them at different
settings. Note that the photoresistor’s (RP’s)
resistance can be very high if there isn’t bright
light shining on it.

Lots of Resistors in
Parallel
These five resistors are all
connected in parallel, so the
smallest one (R1, 100W),
will have the most effect.

-79-

Turn on the right slide switch (S1).
There are five resistors (R1, R3, RV,
RV3, and RP), connected in parallel,
that are controlling the current to the
color LED (D8). See which resistor
has the most effect on the LED
brightness, by removing them one at
a time. The resistance of RV and RV3
depends on their setting, so try them
at different settings.

Project 179

Be a Loud Musician
It’s Raining, It’s Pouring:
A G E A G E
GG E
It’s

G E E

rain-ing, it’s pour-ing, Rain-y days aren’t

F F D D

like to jump, we

bor-ing. We

G F E D

like to splash, Let’s hope it rains till

Jingle Bells
EE E E E E

mor-ning.

E G C D E–

Jin-gle bells, jin-gle bells, Jin-gle all the way,

F F

Some songs have
been modified to
C G F D C–
make them easier
one horse o-pen sleigh.
to play on your
keyboard.

FFFEEEE

Oh what fun it is to ride in a

London Bridge is Falling Down
G A G F
EF G
DE F
Lon-don Bridge is
Let’s play some more songs. Build the circuit shown here (it is similar
to the project 1 circuit, but louder), and turn on the slide switch (S1).

G A

Lon-don Bridge is

fal-ling down,

E F G

Fal-ling down, fal-ling down.

E F G

D– G–

fal-ling down,

E C–

My fair

la-dy.

For best song quality, align the blue and green keys together: Turn the
TUNE knob while pressing the blue C key and the green C key at the
same time. Slowly turn the knob across its entire range, and see how
the sound varies. At most TUNE knob positions you will notice
separate tones from the blue and green keys, but there will be a knob
position where the blue and green tones blend together and seem like
a single musical note - this is the best TUNE setting to play songs with.
The blue and green keys are now aligned together.

If You’re happy and You Know It
C C F F F F F F E F
If your’re hap-py

and you know it,

G–

C C

G G

A–

To play a song, just press the key corresponding with the letter shown.
If there is a “–” after a letter, press the key longer than usual.

If you’re hap-py

Project 180
Be a Loud Musician (II)
Use the preceding circuit and songs, but press both the blue and
green keys for each note, at the same time. Try this with the blue and
green keys aligned (as per project 2), but also try them at different
TUNE knob settings (so the keys are out of alignment.

If your’re hap-py

G G

and you know it,

A A A# A# A# A# D D
A# A# G G

If your’re hap-py

and you know it,

G F

F G

clap your hands.

A# A# A A

and you know it,

A Tisket, A Tasket
EGEFGE G C
A tis-ket a tas-ket,

E C

clap your hands.

A G F F–

And you real-ly want to show it,

D E

F–

clap your hands.

E A G E E

A green and yel-low bas-ket

F FDDFF D D G

I wrote a let-ter to my love and

F E D E C–

on the way I dropped it.
-80-

Project 181

Morse Code

Build the circuit and turn on the right switch (S1). Press
one key in a series of long and short bursts with pauses
in between, and use Morse Code to send secret
messages to your friends.
You can use the difference in pitch between keys to send
messages to different people. For example, sending
Morse Code with the blue C key can mean that the
message is for one friend, using the green C key can
mean it’s for someone else, the green B key can be
someone else. Turn on the left slide switch makes the
pitch of the green keys much different, so can be used to
identify messages for additional friends.

Morse Code: The forerunner of today’s telephone system
was the telegraph, which was widely used in the latter half
of the 19th century. It only had two states - on or off (that is,
transmitting or not transmitting), and could not send the
range of frequencies contained in human voices or music. A
code was developed to send information over long distances
using this system and a sequence of dots and dashes (short
or long transmit bursts). It was named Morse Code after its
inventor. It was also used extensively in the early days of
radio communications, though it isn’t in wide use today. It is
sometimes referred to in Hollywood movies, especially
Westerns. Modern fiber optics communications systems
send data across the country using similar coding systems,
but at much higher speeds. Indian tribes sometimes used
smoke signals to send messages.
-81-

A
B
C
D
E
F
G
H
I
J
K
L
M

._
_...
_._.
_..
.
.._.
__.
....
..
.___
_._
._..
__

MORSE CODE
N
_.
O
___
P
.__.
Q
__._
R
._.
S
...
T
_
U
.._
V
..._
W
.__
X
_.._
Y
_.__
Z
__..

._._._
Period
Comma _ _ . . _ _
Question . . _ _ . .
1
.____
2
..___
3
...__
4
...._
5
.....
6
_....
7
__...
8
___..
9
____.
0
_____

Project 182

Transistor Audio
Amplifier
Build the circuit with the speaker (SP2) connected
using the red & black jumper wires. Set the
adjustable resistor (RV) to mid-range, and turn on
the slide switch (S1). Hold the speaker next to your
ear and blow into the microphone (X1), or talk
directly into it with your mouth close to it.
This circuit amplifies your voice and plays it on the
speaker. It should be easy to hear the blowing, but it
may be difficult to understand your voice, because
there isn’t enough amplification and there will be
some distortion. Also, the sound from the speaker
may not be as loud as hearing your voice directly.

Project 183

Transistor Audio
Amplifier (II)
With headphones it may be
easier to recognize the
difference between the
circuit sound and hearing
your voice directly, than it
had been with the speaker.

Headphones
(not included)

If you have headphones (not included),
then modify the preceding circuit to match
this one, and connect your headphones to
the audio jack (JA). Set the adjustable
resistor (RV) to mid-range, and set the
500kW adjustable resistor (RV3) for most
comfortable sound level (turn to the left for
higher volume, most of RV3’s range will be
very low volume). Turn on the slide switch
(S1). Blow into the microphone (X1), or talk
directly into it with your mouth close to it.
The sound may not be very loud.

WARNING: Headphones performance varies, so use caution. Start with
low volume, then carefully increase to a comfortable level. Permanent
hearing loss may result from long-term exposure to sound at high volumes.

-82-

Project 184
Build the circuit and turn on the switch (S1). Initially set the lever on the
adjustable resistor (RV) to the left, then move it later to vary the range of
sounds that can be produced. Make your parts using either the water
puddles method (A), the drawn parts method (B), or the pencil parts method
(C). Touch the metal in the jumper wires to your parts and listen to the sound.

Make Your Own Parts
Method A (easy): Spread some water on the table into
puddles of different shapes, perhaps like the ones
shown here. Touch the jumper wires to points at the
ends of the puddles. Small, narrow puddles may not
produce any sound.
Method B (challenging): Use a SHARP pencil (No. 2 lead is best) and draw
shapes, such as the ones here. Draw them on a hard, flat surface. Press hard
and fill in several times until you have a thick, even layer of pencil lead. Touch
the jumper wires to points at the ends of the drawings, then move them across
the drawing to vary the sound. You may get better electrical contact if you wet
the metal with a few drops of water. Wash your hands when finished.

Method C (adult supervision and permission required): Use some doublesided pencils if available, or VERY CAREFULLY break a pencil in half. Touch
the jumper wires to the black core of the pencil at both ends.

Long, narrow shapes
have more resistance
than short, wide ones.
The black core of
pencils is graphite,
the same material
used in the resistors.

Next, place the loose ends of the jumper
wires in a cup of water, make sure the
metal parts aren’t touching each other.
The water should change the sound.
The pitch may depend on the amount of
water, so see if adding more water to the
cup changes the sound.
Now add salt to the water and stir to
dissolve it. The sound should have
higher pitch now, since
salt water has less
resistance than plain
water.
Don’t drink any water used
here.

-83-

Project 185
Color Touch Light
Build the circuit. It doesn’t do anything,
and may appear to be missing
something. It is missing something,
and that something is you.
Touch points A & B with your fingers.
The color LED (D8) may be lit. If isn’t,
then you are not making a good
enough electrical connection with the
metal. Try pressing harder on the
snaps, or wet your fingers with water
or saliva. The LED should be on now.
If it isn’t very bright, then try going into
a dimly lit room.

Project 186
Test Your Hearing

Project 187
See the Sound

This project requires a smart phone with an internet connection, so you
can download a free app. Find and download a “function generator” app
that can generate sine and square signals. Visit the Snap Circuits® Sound
product page at http://www.elenco.com/downloads/scs185/ to find a few
suggestions.

This project requires a smart phone with an internet connection, so you
can download a free app. Find and download an “oscilloscope” app that
lets your smart phone act as an oscilloscope. Visit the Snap Circuits®
Sound product page at http://www.elenco.com/downloads/scs185/ to find
a few suggestions.

Set the app for “Sine” function (for a
single tone), start it, and vary the
frequency across the available range.
You can listen to the sound directly on
your smart phone, or use the circuit in
project 60. Set the volume control on
your smart phone (and using RV, if
you are using project 60) so that the
sound is at a comfortable level for
middle frequencies.
See what range of frequency you can
hear. Notice that the sound is loud at
middle frequencies, but low (or no
sound at all) at low or high frequency.
There are two reasons for this:

An oscilloscope is an instrument that engineers use to actually look at
electrical signals. Constant tones are especially interesting to look at,
because they are repetitive and actually look like a wave.
Start the app and talk
into the smart phone’s
microphone, and watch
your voice on the screen.
Try making a single tone
at different frequencies,
or whistling, or snapping
your fingers.

1. Your hearing ability depends on frequency. Most people can hear
frequencies in the range of 20 Hz to 20,000 Hz, but much better in the
middle of this range than at the low or high ends of it. As you get older
you don’t hear higher frequencies as well, so use the same circuit to
see what range of frequency your grandparents can hear.
2. Your speaker’s ability to produce sound depends on frequency, and it
may not perform as well at low or high frequency. Speakers are only
designed to produce sound in the range that we can hear.
Part B: set the frequency on the function generator app to just below what
you can hear, then change the function from “Sine” to “Square” function
(for a tone with lots of overtones). You should be able to hear it now,
because a signal with overtones has some energy at higher frequencies,
which should be within your hearing range.

Next, use the one of the keyboard (U26) circuits such as projects 1 or 2526. Make sound with the keyboard and see what it looks like.
Try an echo circuit such as project 29, and see what an echo looks like.
-84-

Project 188

See the Spectrum

This project requires a smart phone with an internet connection, so you can
download a free app. Find and download a “spectrum analyzer” app that
lets your smart phone view the frequency spectrum of a signal. Visit the
Snap
Circuits®
Sound
product
page
at
http://www.elenco.com/downloads/scs185/ to find a few suggestions.
A spectrum analyzer is an instrument that engineers use to look at the
frequency content of electrical signals, and shows which frequencies have
the most energy. A pure tone will have all its energy at a single frequency,
while a tone with overtones will have the most energy at the main tone,
but also have energy at multiples of the main tone. A complex sound will
have its energy spread across many frequencies.
Spectrum analyzers usually show data as a chart of energy content versus
frequency. Energy is usually shown in dB (decibels), a logarithmic
measurement, so the strongest frequencies have much more energy than
the weak ones shown. There is always a “noise floor” of background noise,
which can make weak signals difficult to observe.
Start the app and talk into the smart phone’s microphone, and watch the
frequency content of your voice on the screen. Try making a single tone
at different frequencies, or whistling.

Next, use the one of the keyboard (U26) circuits such as projects 1, 6, or 25-26.
Make sound with the keyboard and see what its frequency content looks like.

BONUS CIRCUIT FOR SNAP CIRCUITS® LIGHT OWNERS
If you own Snap Circuits® LIGHT (Model SCL-175), then
you may also build this circuit. Do not connect additional
voltage sources from other sets, or you may damage
your parts. Contact Elenco® if you have any questions.

Project #B1
See the Sound
This circuit uses the color organ module (U22) from the SCL-175
set. Build the circuit as shown, turn off the left slide switch (S1),
and turn on the right slide switch. Press keys on the keyboard to
make sounds and change the light on the color organ. Turn on the
left slide switch to add optical control, and wave your hand over
the photoresistor to also change the sound and light. If desired,
add one of the SCL-175 LED attachments on the color organ.
-85-

OTHER SNAP CIRCUITS® PRODUCTS!

For a listing of local toy retailers who carry Snap Circuits® visit www.elenco.com or call us toll-free at 800-533-2441. For Snap Circuits®
upgrade kits, accessories, additional parts, and more information about your parts visit www.snapcircuits.net.

Snap Circuits® Jr.
Model SC-100

Build over 100 projects
Including:

• Flying saucer
• Spin draw

Snap Circuits®
Model SC-300

Build over 300 projects
Including:

• Sound activated switch • AM radio
• Alarm circuit
• Radio announcer

• Lie detector
• Burglar alarm

Snap Circuits® Pro
Model SC-500

Snap Circuits® Extreme
Model SC-750

Build over 500 projects

Build over 750 projects

• Digitally tuned FM radio
• Adjustable light control

• Strobe light
• Transistor AM radio

Including:

• Digital voice recorder
• AC generator

Including:

• Electromagnetism
• Rechargeable battery

Contains over 30 parts

Contains over 60 parts

Contains over 75 parts

Contains over 80 parts

• Photoresistor
• Motor

• Two transistors
• Microphone

• Recording IC
• FM module

• Solar cell
• Electromagnet

Including:

• Music IC
• Space War IC

Snap Rover®
Model SCROV-10

Have FUN building your own RC Snap Rover®
using the colorful Snap Circuits® parts that
come with this kit. There is no soldering
required as all the parts snap together with
ease. Once completed, you will be able to
navigate your surroundings with the easy-touse Snap Rover® remote control.

Contains over 20 projects
and over 30 parts

Including:

• Power amplifier IC
• Variable capacitor

Snap Circuits® Light
Model SCL-175

Build over 175 projects
Including:

Including:

• Transformer
• Analog meter

Snap Circuits® Green
Model SCG-125

Alternative Energy Kit

Build over 125 projects and have loads of fun learning
• Fiber Fun
• Follow the Music
about environmentally-friendly energy and how the
• Dancing Lights
• Audio Infrared Detector electricity in your home works. Includes full-color manual
with over 100 pages and separate educational manual.
Contains over 55 parts
This educational manual will explain all the forms of
Including:
environmentally-friendly energy including: geothermal,
Strobe light, color organ, infrared detector, color hydrogen fuel cells, wind, solar, tidal, hydro, and others.
changing LED, fiber optic cable, and more!
Contains over 40 parts.

Including:

• Vibration switch
• Computer interface

Snaptricity®
Model SCBE-75

Build over 75 projects

Projects relate to electricity in the home and
magnetism and how it is used.

Contains over 40 parts

Including:
Meter, electromagnet, motor, lamps, switches,
fan, compass, and electrodes.

-86-

SCS-185 SOUND Block Layout

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 Service • 150 Carpenter Ave.
Wheeling, IL 60090 U.S.A. Note: A complete parts list is on pages 2 and 3 in this manual.

Base grid (11.0” x 7.7”) overlays many parts

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SCS 185_Manual 185 Manual

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