Elenco Electronics EP-130 User manual

Copyright © 2009 by Elenco®Electronics, Inc. All rights reserved. 753039
No part of this book shall be reproduced by any means; electronic, photocopying, or otherwise without written permission from the publisher.
ELECTRONIC
PLAYGROUNDTM
and LEARNING CENTER
MODEL EP-130
Elenco®Electronics, Inc.
Wheeling, IL, USA
99 Washington Street
Melrose, MA 02176
Phone [phone]
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com

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TABLE OF CONTENTS
Before We Begin Page 4
Installing the Batteries 4
Making Wire Connections 5
Components 5
BuildingYour First Project 9
Troubleshooting 10
Helpful Suggestions 10
I. ENTERTAINMENT CIRCUITS 11
1. Electronic Woodpecker 12
2.The Chirping Bird 13
3. Electronic Cat 14
4. Sonic Fish Caller 15
5. Machine Gun Pulse Oscillator 16
6. Electronic Motorcycle 17
7.Two-tone Patrol Car Siren 18
8. Electronic Siren 19
9. Electronic Metronome 20
10. Electronic Grandfather Clock 21
11. Light-controlled Electronic Harp 22
12. Horror Movie Sound Effects 23
13. Strobe Light 24
14. Rapid LED Display Switching
(persistence of vision test) 25
II. BASIC SEMICONDUCTOR & COMPONENTS CIRCUITS 26
A BIG CHANGE 27
15. Capacitor Discharge/High Voltage Generator 28
16. Capacitors in Series & Parallel 29
17. Resistors in Series & Parallel 30
18. Light Dimmer 31
19.Transistor Switcher 32
20.Transistor Circuit Action 33
21. Sound Amplifier 34
22. Flip-flop Multivibrator with LED Display 35
III. LED DIGITAL DISPLAY CIRCUITS 36
23. Seven-segment LED Digital Display Circuit 37
24. Basic LED Display 38
25.Transistor Control Switching of the LED Display 39
26.Transistor, CDS Cell, and LED Display Circuit 40
IV. A TOUR THROUGH DIGITAL CIRCUITS 41
27. Diode-Transistor Logic AND with LED Display 42
28. DTL OR Circuit with LED Display 43
29. DTL NAND Circuit with LED Display 44
30. DTL Exclusive OR Circuit 45
31.Transistor NOR Circuit with LED Display 46
32.Transistor Flip-Flop Circuit 47
33.Transistor Toggle Flip-Flop 48
V. MORE ADVENTURES WITH DIGITAL CIRCUITS 49
34.Transistor-Transistor Logic Buffer Gate 50
35.TTL Inverter Gate 51
36.TTL AND Gate 52
37.TTL OR Gate 53
38.TTL Exclusive OR Gate 54
39.TTL NOR Gate 55
40.TTL Three-Input AND Gate 56
41.TTL AND Enable Circuit 57
42.TTL OR Enable Circuit 58
43.TTL NAND Enable Circuit 59
44.TTL R-S Flip-Flop 60
45.Toggle Flip-Flop Circuit Made from NAND Gate 61
46.TTL Line Selector 62
47.TTL Data Selector 63
Important: If you encounter any problems with this kit, DO NOT RETURNTO RETAILER. Call toll-free [phone]
or e-mail us at: [e-mail]. Customer Service • 150 Carpenter Ave. • Wheeling, IL 60090 U.S.A.
• Do not short circuit the battery
terminals.
• Never throw batteries in a fire or
attempt to open its outer casing.
•
Use only 1.5V “AA” type, alkaline
batteries (not included).
• Insert batteries with correct polarity.
• Do not mix alkaline, standard (carbon-
zinc), 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.
• Do not mix old and new batteries.
• Remove batteries when they are used
up.
• Batteries are harmful if swallowed, so
keep away from small children.
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.
WARNING:
CHOKING HAZARD - Small parts.
Not for children under 3 years.
Conforms to all applicable U.S. government
requirements.
Batteries:
!

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VI.THE WORLD OF TRANSISTOR-TRANSISTOR LOGIC 64
48.TTL Astable Multivibrator 65
49.TTL Tone Generator 66
50.Winking LEDs 67
51. A One-Shot TTL 68
52.Transistor Timer with TTL 69
53. Buzzin’ LED 70
54. Son of Buzzin’ LED 71
55. Set / Reset Buzzer 1 72
56. Set / Reset Buzzer 2 73
57. Sound Machine 74
58. Big Mouth 75
59. Shot in the Dark 76
VII. APPLICATION CIRCUITS BASED ONTHE OSCILLATOR 77
60.Variable R-C Oscillator 78
61. Oscillator with Turn-off Delay 79
62.Temperature-Sensitive Audio Oscillator 80
63.Two-Transistor, Directly-Connected Oscillator 81
64. Push / Pull Square Wave Oscillator 82
65. Pencil Lead Organ 83
66. LED Strobe Light 84
67. Electronic Organ 85
68. Daylight Early Bird 86
69. Intermittent Alarm Detector 87
VIII. BASIC OPERATIONAL AMPLIFIER CIRCUITS 88
70. Comparator 89
71. Basic Increase in DC Voltage 90
72. Constant-Current Source 91
73. Integrating Circuit 92
74. Schmitt Trigger Circuit 93
75. Non-inverting Two Power Supply Amplifier 94
76. Inverting Two Power Supply Amplifier 95
77. Non-inverting Single Power Supply Amplifier 96
78.Two Power Supply Differential Amplifier 97
79.Tone Mixing Amplifier 98
80. Power Amplifier Using Operational Amplifier 99
81.Voltage Controlled Oscillator Circuit 100
82. Operational Amplifier Buzzer 101
83. Burglar Alarm 102
84. Hand-Operated Sweep Oscillator 103
85. Falling Bomb Squad 104
86. Emergency Siren 105
87. First Aid Siren 106
88. Musical Tempo Generator 107
89. Operational Amplifier Winking LED 108
90. LED Flashing Light 109
91.Two LED Winker 110
92. One Shot Light 111
93. LED Initials 112
94.Wake Up Siren 113
95.Voice Activated LED 114
96. Logic Tester 115
IX. MORE ADVENTURES WITH OPERATIONAL AMPLIFIERS 116
97. Alternating Current Sound 117
98. Light Control Sound Circuit 118
99. Sound Alarm Circuit 119
100. Study Timer 120
101. Kitchen Timer 121
102.
Three-Input AND Gate Using Operational Amplifier 122
103.Voice Level Meter 123
104. Power-on Reset Circuit 124
105. Delayed Timer 125
106. Pulse Frequency Doubler 126
107.White Noise Generator 127
108. DC-DC Converter with Operational Amplifier 128
X. COMMUNICATION CIRCUITS 129
109. Code Practice Oscillator with Tone Control 130
110. Crystal Set Radio (Simple-Diode Radio) 131
111.Two-Transistor Radio 132
112.Wireless Code Transmitter 133
113. AM Radio Station 134
114. Operational Amplifier Radio 135
XI.TESTING AND MEASURING CIRCUITS 136
115. Aural Continuity Tester 137
116. Conductivity Tester 138
117.Transistor Checker 139
118. Sinewave Audio Oscillator 140
119. Low Distortion Sinewave Oscillator 141
120.Twin-T Audio Oscillator 142
121. Pulse Oscillator Tone Generator 143
122. Audio Signal Tracer 144
123. Radio Frequency Signal Tracer 145
124. Square Wave Audio Oscillator 146
125. Sawtooth Wave Oscillator 147
126. Rain Detector 148
127.
Water Level Buzzer with Operational Amplifier 149
128. Metal Detector 150
129.Water Level Alarm 151
130.Three-Step Water Level Indicator 152
INDEX 153
PARTS LIST 155
DEFINITION OF TERMS 156
IDENTIFYING RESISTOR VALUES 159
IDENTIFYING CAPACITOR VALUES 159
METRIC UNITS AND CONVERSIONS 159

Welcome to the exciting world of electronics! The
Elenco®EP-130 Electronic Playground Kit may be
your first experience in electronics. This manual
describes 130 different experiments you can perform
with your kit. We have included everything that you
need for all of the experiments (except the batteries).
As you read this manual and complete the
experiments, you will notice that we’ve organized the
projects and information in a logical sequence. We’ll
have you start with simple circuits and work toward
more complex ones.Take your time and have fun.
You can assemble all of the projects without
soldering because each component is connected to
spring terminals. A wiring sequence is included with
each project, so all you have to do to build a working
project is connect wires between the terminals listed
in the wiring sequence. We have provided plenty of
pre-cut, insulated wire. All of the projects are
powered by low voltage batteries, so there is none of
the danger associated with using standard AC
voltages.
Simple, clearly-written instructions help you operate
and experiment with each project.A diagram called a
schematic is included with later projects. A
schematic is an electronics blueprint that shows how
various components are wired together. Each
component has its own schematic symbol. The
symbols for the various components in your lab kit
are printed next to each component.
You’ll notice that we often refer to a
Volt / Ohm Meter
(VOM) for making measurements. A VOM, or
multimeter, is a device that measures voltage,
current (amperes or amps), and resistance (ohms -
Ω).We will tell you more about these later. If you are
going to understand electronic circuits, it is important
that you learn to measure circuit values - for only
then can you really begin to understand electronic
circuitry.
So, we recommend that you invest in a VOM with a
sensitivity reading of 20,000
ohms-per-volt or more.
Ohms-per-volt is a rating for the sensitivity of the
device (the higher the rating, the more sensitive the
meter).
You don’t have to use a VOM to build the
experiments, but you’ll find it will help you to better
understand how the circuits work. A VOM is a basic
test instrument and it is an excellent investment -
you’ll always want and need one as long as you stay
interested in electricity and electronics.
-4-
BEFORE WE BEGIN
Your kit requires six (6) “AA” batteries. Install the
batteries in the compartment at the back of your kit.
Be sure to install them correctly according to the (+)
and (–) markings inside the compartment. The (+)
end of a battery is the one with the small metal cap.
Note: Whenever you are not using your kit, remove
the batteries. Never leave weak or dead batteries in
your kit - they can leak damaging chemicals, even if
they are “leak-proof” type batteries. This is a good
habit to get into for all battery-operated products.
INSTALLING THE BATTERIES
+
–
–
+
–
+
+
–
–
+
–
+
+
–
–
+
–
+
+
–
–
+
–
+

-5-
The spring terminals and the pre-cut wires supplied
with your lab kit make it a snap to wire together the
various projects. To connect a wire to a spring
terminal, simply bend the spring over to one side and
insert the wire into the opening.
Sometimes you need to connect two or three wires to
a single spring terminal, so be sure the first wire
doesn’t come loose when you add the second and
third wires.The easiest way to do this is to push the
spring on the side opposite side where you
connected the first wire.
Be sure that you only insert the exposed, shiny part
of the wire into the spring terminal. If the plastic
insulation part of the wire is inserted into the
terminal, electrical contact is not made. To remove
the wire from the spring terminals, simply bend each
terminal and pull the wires from it.
After a lot of use, the exposed metal ends of some of
the wires might break off. If this happens, remove
3/8” of insulation from the broken end and twist the
strands together.You can remove the insulation with
a wire-stripper tool or a penknife. Be very careful
doing this, as a penknife is very sharp.
MAKING WIRING CONNECTIONS
Your kit has more that 30 separate components. If
this is your first experience with electronics, you
probably don’t know the difference between a
resistor and a transistor. If so, don’t worry - the
general purpose fo each component will be
explained. The explanations help you understand
what each component does, and you will understand
more about each component as you build the
projects.
There is a parts list near the back of this manual.You
might want to compare the parts in your kit with
those in the list.
Resistors: Why is the water pipe that goes to your
kitchen faucet smaller than the one that comes to
your house from the water company? And why is it
much smaller than the main water line that supplies
water to your entire town? Because you don’t need
so much water. The pipe size limits the water flow to
what you actually need. Electricity works in a similar
manner, except that wires have so little resistance
that they would have to be very, very thin to limit the
COMPONENTS

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flow of electricity. They would be hard to handle and
break easily. But the water flow through a large pipe
could also be limited by filling a section of the pipe
with rocks (a thin screen would keep the rocks from
falling over), which would slow the flow of water but
not stop it. Resistors are like rocks for electricity, they
control how much electric current flows. The
resistance, expressed in ohms (Ω, named after
George Ohm), kilohms (kΩ, 1,000 ohms), or
megohms (MΩ, 1,000,000 ohms) is a measure of
how much a resistor resists the flow of electricity. To
increase the water flow through a pipe you can
increase the water pressure or use less rocks. To
increase the electric current in a circuit you can
increase the voltage or use a lower value resistor
(this will be demonstrated in a moment). The symbol
for the resistor is shown below.
Resistor Color Code: The colored bands on the
resistors are the method for marking the value of
resistance on the part. The first ring represents the
first digit of the resistor’s value. The second ring
represents the second digit of the resistor’s value.
The third ring tells you the power of ten to multiply by
,
(or the number of zeros to add).The final and fourth
ring represents the construction tolerance. Most
resistors have a gold band for a 5% tolerance. This
means the value of the resistor is guaranteed to be
within 5% of the value marked. See color code chart
on page 159.
Control (variable resistor): Many electronic circuits
require a variable resistor, and that is just what the
control is.You can use it as a light dimmer, a volume
control, and in many other circuits where you’d like to
be able to change resistance easily and quickly.
This is a normal resistor with an additional arm
contact that can move along the resistive material
and tap off the desired resistance.
Capacitors: Capacitors can pass alternating current
(AC) signals while blocking direct current (DC)
signals.They can also store electricity or act as filters
to smooth out pulsating signals. Very small
capacitors are usually used in high-frequency
applications such as radios, transmitters, and
oscillators. Very large capacitors normally store
electricity or act as filters.
The
capacitance (electricity storage capacity) of a
capacitor is expressed in a unit called a
farad . The
farad is an extremely large amount of electricity, so
the value for most capacitors is given in millionths-of-
a-farad (microfarads).
Electrolytic - The four largest capacitors are
electrolytics. They are marked with a “–”. You must
connect them into the circuit only one way - the (+)
and (–) wires must always go to the correct
terminals.
Disc - These capacitors have no polarity and can be
connected either way.
Tuning Capacitor: The tuning capacitor is used with
the antenna to select radio frequencies. As you
rotate the knob, you change the capacitance. This
changes the frequency these circuits work best with.
The tuning capacitor lets through only one frequency
and blocks out the rest.
Diodes: There are three diodes in your kit. Diodes
have many uses in electronics, but they have one
simple characteristic - they allow electricity to flow
through them in only one direction. Your kit has one
silicon diode (marked Si) and two germanium diodes
Disc Electrolytic

-7-
(marked Ge); they each have their own uses as we’ll
explain later.
Transistors: Your lab kit has three transistors. The
working part of each transistor is a tiny chip (made of
either germanium or silicon). Each transistor has
three connection points: B (base), C (collector), and
E (emitter). Transistors are used to amplify weak
signals.They are also used as switches to connect or
disconnect other components and as oscillators to
allow signals to flow in pulses.
LEDs (Light Emitting Diodes): LED stands for Light
Emitting Diode. These little parts are special diodes
that give off light when electricity flows through them.
(Current can pass through only in one direction - just
like “regular” diodes).
LED Digital Display: To make the display, seven
LEDs are arranged to form an outline that can show
all the numbers and most of the letters in our
alphabet. An eighth LED is added for the decimal
point.
The LED display is mounted on a little board with
resistors permanently wired to it. (The resistors are
there to help prevent you from burning out the
display with excess current).
Integrated Circuit: As you might already know, after
the transistor was invented in the middle 1940’s, the
next big breakthrough in electronics was the
integrated circuit in the early 1960’s. The great
advantage of ICs (as we call them) is that the
equivalent of hundreds or even thousands of
transistors, diodes, and resistors can be put into a
small package.
There are two types of ICs used in this kit - the quad
two-input NAND and the dual-operational amplifier.
You will learn more about these later.
Our simple ICs will help you learn enough to begin to
understand the basic principles of the more
advanced ICs.
Cadmium Sulfide (CdS) Cell: This is a
semiconductor - that is, it conducts electricity, but
partially resists it. The resistance of this device
changes with the amount of light that shines on it. (It
is similar to your kit’s control - to vary the resistance
of the control, you rotate the knob; to vary the
resistance of the CdS cell, you permit more or less
light to shine on the front of the cell.)
Note: We’ve provided a special light shield to use
with the CdS cell. When you place this over the cell,
it helps block light from the cell.
PNP NPN

-8-
Antenna: The radio antenna is the cylindrical
component with a coil of fine wire wrapped around it.
The dark colored rod is made mostly of powdered
iron. Ferrite cores (rods made from powdered iron
and other oxides) make efficient antennas for almost
all transistor radios.
Transformer: If you wrap two wires from different
circuits around different ends of an iron bar then a
current flowing through the wire from the first circuit
will magnetically create a current in the wire from the
second circuit! If the second coil has twice as many
turns (more magnetic linkage) as the first coil then
the second coil will have twice the voltage but half
the current as the first coil. A device like this is called
a
transformer .
The magnetic field created in an iron bar by an
electric current in the coil around it can be harnessed
if the bar is allowed to rotate - it is a motor. It could
be used to drive the wheels of a car, for example.The
reverse is also true, if a magnet within a coil is
rotating then an electric current is created in the coil
- a generator. These two statements may not seem
important to you at first but they are actually the
foundation of our present society. 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.
Speaker: A speaker converts electrical energy into
sound. It does this by using the energy of an AC
electrical signal to create mechanical vibrations.
These vibrations create variations in air pressure,
called sound waves, which travel across the room.
You “hear” sound when your ears feel these air
pressure variations. You need high current and low
voltage to operate a speaker, so we will always use
the transformer with the speaker. (Remember that a
transformer converts high-voltage/low-current to low-
voltage/high-current).
The earphone is similar to the speaker, except that it
is more sensitive (and moveable). It is an efficient,
lightweight earphone that can be connected without
drawing too much electrical energy from the circuit.
For very weak sounds, the earphone is best; for
stronger sounds, you will use the speaker.
Batteries: The battery holders are designed to hold
six (6) “AA” batteries. Batteries supply the power for all
the experiments in your kit. When connecting wires to
the batteries, be sure you connect only to the terminals
noted.Terminals 119 and 120 provide 3 volts.Terminals
119 and 121 provide 4.5 volts. You need to be aware
that connecting too much voltage (you can get up to 9
volts from these battery connections) can damage
some parts (they can be burned out). So, be sure to
make the right battery connections.
Caution: When you connect wires to the batteries,
you must be sure to use the correct polarity: (+) and
(–) sides of the battery.With some parts and circuits,
components can be permanently damaged if you
reverse the polarity.

-9-
Switch: You know what a switch is - you use it to
connect or disconnect electrical circuits. When you
slide the switch to the correct position, the circuit is
complete, allowing electricity to flow through it. In
another position, the switch causes a break in the
circuit’s path, so that the circuit is not complete and
electricity cannot flow through it. The switch we’re
using is a double-pole, double-throw switch; this
means it can connect one pair of terminals to either
of two other pair of terminals.You will learn how this
works later on.
Key: The Key is a very simple switch - press it and
the circuit allows electricity to flow through it.
Release it and there is a break in the circuit’s path,
so the circuit is not complete.You will use the key in
many circuits, most often in the signaling circuits (to
send Morse code, and so on).
Terminals: You will use the two terminals (13 and 14)
in some projects to make connections to external
devices, such as the earphone, an antenna or earth
ground connection, special sensor circuits, and so on.
Wires: You will use the wires to make connections
between terminals.
The parts and spring terminals are mounted onto a
platform. If you look underneath it you can see how
wires are used to connect the parts and their
terminals.
BUILDINGYOUR FIRST PROJECT
There is a simple wiring sequence listing for each
project.You should connect appropriate length wires
between the terminals listed in each grouping.
Always use the shortest wire that will do the job.
When you come to a new grouping (separated by a
comma), connect the terminals in that group.
Here’s an example:
Project 1 has the following wire sequence listing:
1-29, 2-30, 3-104-106, 4-28-124, 5-41-105, 27-88,
75-87-103-40, 115-42-119, 76-116, 121-122.
You should connect a wire between 1 and 29,
another between 2 and 30, another between 3 and
104, and then another between 104 and 106.So, you
continue until all connections are made.
Caution: In each wiring sequence, we’ve
deliberately left an important power wire connection
as the last connection. It is important that you make
this last connection LAST. With some circuits, if you
complete one part of the electronic circuit before
another, a transistor or another part can be
damaged. So, follow the wiring sequence exactly.

-10-
HELPFUL SUGGESTIONS
Keeping a Notebook
You’re going to find out a lot about electronics as you
play around with this kit. Much of what you discover
about electronics in early projects will be useful in
later projects. We strongly suggest that you keep a
notebook to help you collect and organize all of this
information.
Your notebook doesn’t have to be like the ones you
keep at school.Think of it as your diary - you’ll have
fun looking at it after you finish connecting all 130
projects.
Marking the Wiring Sequence
As you wire up a project (especially the ones with
lots of connections) you might find it helpful to mark
through each terminal number as you connect a wire
to that terminal.Mark lightly with a pencil so that you
will be able to build a circuit many times and still be
able to read all of the wiring sequence.
Collecting Components
It would be a good idea for you to start collecting
different electronic parts and make your own
electronic parts scrap box. You can build circuits
inside or on a convenient chassis, box, or container.
You might turn it in as a Science Fair project at
school and make a major research project out of it.
TROUBLESHOOTING
If you assemble each project according to its wiring
sequence, you should have no problem getting the
projects to work properly. But if you do have a
problem, you can usually find and correct it by using
the following troubleshooting steps. These steps are
similar to those used by electronics technicians who
troubleshoot complex electronic equipment.
1. Are the batteries fresh? If not, they may be too
weak to power the project.
2. Have you assembled the project properly? If
everything else checks out okay, check all the
wiring connections to be sure you have wired all
the terminals correctly.Sometimes it’s a good idea
to have someone else take a look at it too.
3. How about following the schematic diagram and
circuit explanation? As you progress in your
knowledge and understanding of electronics, you
should be able to do some troubleshooting only by
following a schematic; and if you add the circuit
description, you should be able to figure out
problems for yourself.
4. If you have a VOM, try some voltage and current
measurements - very soon you’ll find out just how
handy a VOM can be to an electronics technician!

-11-
I. ENTERTAINMENT CIRCUITS

-12-
Have you ever heard a red-headed woodpecker
chirping? Here is an electronic bird that sounds a
little like a red-headed woodpecker. If you have one
of these birds around your house, it might come to
visit this electronic relative!
This is a fairly simple circuit. Follow the wiring
sequence below and the drawings we’ve provided.
Make all the connections and have some fun with
this project.
The basic circuit we’ve shown here does not have a
switch or key, but you can add one very easily.
Simply replace wire connection 124-28 with
connections 124-137 and 138-28 in order to
connect the key. To use the switch, replace
connection 124-28 with connections 124-131 and
132-28.When you press the key or slide the switch,
the circuit path for the electrical current is complete
and you hear the woodpecker. The key provides a
more convenient control for carrying the kit outside
as you try to attract birds with your bird caller.
Try different combinations of resistance and
capacitance in place of the 1kΩresistor and the
100μF capacitor.To change the 100μF capacitance
to 470μF, disconnect the wire at terminal 116 and
reconnect it to terminal 118.Then, transfer the wire
attached to terminal 115 to terminal 117. Now your
“bird” might sound more like a cricket or a bear!
You can also try the 3V power supply (V is the
abbreviation for volt or volts - the basic unit of
measure of electric energy). Disconnect the wire
from terminal 119 and connect it to terminal 123.
Now the “bird” will sound more like an English
sparrow.
When experimenting with this circuit, you can
change almost anything without causing damage.
However, do not decrease the 47kΩresistor to
below 10kΩor the transistor might be damaged.
EXPERIMENT #1: ELECTRONIC WOODPECKER
Wiring Sequence:
o1-29
o2-30
o3-104-106
o4-28-124
o5-41-105
o27-88
o75-87-103-40
o115-42-119
o76-116
o121-122
Schematic

-13-
Here’s a circuit that imitates more of our feathered
friends - you could say it mocks the mockingbird!
Complete the circuit as shown below and slide the
switch to position A to turn on the power.You won’t
hear any sound from the speaker yet. Press the key
and you’ll hear a chirping sound from the speaker.
Release the key - you’ll still hear the chirping sound,
but then it will slow down and stop.You can see that
when the key is released, the first transistor “Q1” is
cut off from the battery. The second transistor “Q2”
can still produce the chirping sound, until transistor
“Q1” stops controlling it through its base.
Try a different value capacitor in place of the 10μF
and the 100μF capacitors and hear what happens.
These capacitors control the amount of electricity
reaching the transistors through connections to the
transistor bases. Remember to keep notes on your
experimentation.
Notes:
EXPERIMENT #2: THE CHIRPING BIRD
Wiring Sequence:
o1-29
o2-30
o3-106-110
o4-41-131-138
o5-44-109
o40-114-91-75
o42-85
o43-105-86-77
o119-45-115-113-92
o76-137
o78-116
o120-132
Schematic

-14-
Bothered by mice? And you don’t have a
mousetrap?Try this instead - see if the sound of the
electronic feline can keep those pests away.
Follow the wiring sequence and drawing, and start
the experiment with the switch set to B. Press the
key and release it immediately.You’ll hear the “cat’s
meow” from the speaker. Adjust the control knob
while the meow is dying away - what effect does it
have on the circuit’s operation? Set the switch to A
and try again. Now the sound is lower and lasts
longer as if the cat is begging for a dish of milk.
You can experiment with this circuit to produce a
variety of other sounds. But don’t change the value
of the 0.05μF capacitor to more than 10μF or
reduce the value of the 10kΩresistor - otherwise,
the transistor might be damaged.
Notes:
EXPERIMENT #3: ELECTRONIC CAT
Wiring Sequence:
o1-29
o2-30
o3-41-109
o4-72-82-132-114
o5-106-110
o27-40-105
o115-113-42-119
o71-138
o81-28
o116-131
o120-137
Schematic

-15-
Did you know that some marine animals
communicate with each other by sound? You’ve
probably heard that whales and porpoises
communicate by sound, but they’re not the only
ones. Research indicates that some fish are
attracted by certain sounds. This circuit will let you
do some research of your own.
When you make the last connection, you’re actually
turning on the power.You should hear sound pulses
from the speaker. Change the sound by turning the
control. This circuit is a variation of the audio
oscillator circuit. (You’ll learn more about audio
oscillators later on in this manual).
How well does this work in attracting fish? If you
have an aquarium at home or at your school, place
your kit near the aquarium glass and see if fish are
attracted to the sound.
Or, you can actually try it out while fishing. Get
another speaker and attach it to terminals 1 and 2
using long lengths of insulated wire. Carefully wrap
the speaker in a waterproof plastic bag or seal it
inside a jar.Be sure no water can reach the speaker.
Now, lower it into the water.Then, cast a line into the
water and wait for the results.
If you don’t have much luck with this project, try
altering a few parts values for a different pulse
sound. Try a different value for the 0.1μF capacitor
or the 0.05μF capacitor. Be sure to keep notes of
your results - and good fishing! Who knows, you
might find the type of signal that attracts a whale!
Notes:
EXPERIMENT #4: SONIC FISH CALLER
Wiring Sequence:
o1-29
o2-30
o3-93-100-110
o4-120
o5-41-109
o27-94
o28-40-99
o42-119
Schematic

-16-
In this you’ll build a circuit that engineers call a
“pulse oscillator”. It makes sounds like a machine
gun. (Engineers have all kinds of technical words to
describe their circuit and ideas - you might as well
get used to them now and soon you’ll be talking just
like an electronics engineer.)
There are many ways to make oscillators. You will
build several of them in this kit. Later on, you will be
told how they work. For now, we’ll simply tell you
what an oscillator is.
An oscillator is a circuit that turns itself on and off (or
goes from high to low output). A pulse oscillator is
controlled by pulses such as those made by a
capacitor charging and discharging. This oscillator
turns on and off slowly, but some oscillators turn on
and off many thousands of times per second.“Slow”
oscillators are often used to control blinking lights
(like the turn signal in a car or truck). Faster
oscillators are used to produce sounds.“Super” fast
oscillators produce radio frequency signals (RF
signals).These RF signal oscillators turn on and off
millions of times per second.
The number of times an oscillator turns on and off
each second is called the frequency of the oscillator
and is measured in units called hertz (Hz). This
oscillator has a frequency of about 1 to 12Hz. The
frequency of a radio frequency signal oscillator would
be measured in kHz, (kilohertz, meaning a thousand
hertz) or MHz (megahertz, meaning a million hertz).
When you finish wiring, press the key to start the
oscillator. Adjust the control (50kΩvariable resistor)
to change the sound coming from the speaker from
a few pulses per second to a dozen or so per
second. You can also change the frequency of this
oscillator by trying other capacitors in place of the
10μF capacitor. Be sure to observe the (+) and (–)
connections (polarity) on the capacitors marked
with a (+) sign.
Notes:
EXPERIMENT #5: MACHINE GUN PULSE OSCILLATOR
Wiring Sequence:
o1-29
o2-30
o3-110-114
o4-27-138
o5-41-109
o28-82
o40-113-81
o42-119
o121-122
o124-137
Schematic

-17-
Ever try steering a motorcycle (OK, maybe a
bicycle) with just four fingers? That’s dangerous on
a real motorcycle, but it’s a lot of fun in this
electronic version.
To use this project, connect the components
according to the wiring sequence. Then grasp the
exposed metal ends of each of the two long wires
(connected to terminals 110 and 81) between your
thumb and the index finger of each hand. Now vary
the pressure (your “grip”) and listen to the sound
from the speaker. The sound changes as you
change your grip on each wire.
You can also get different sounds by controlling the
amount of light that falls on the CdS cell. With a
strong light on the CdS cell, you can control the
operation entirely by exerting more pressure on the
wires in your hand. Use your hand to make a
shadow over the CdS cell and see what happens.
When you hold the ends of the wires, you make
yourself another part of the circuit - a resistor.
Changing your grip changes the resistance to the
current in the project.With some practice you will be
able to make this circuit sound like a real motorcycle
on the go.You can make it idle as well as race.
You can experiment with different values for the
0.1μF and 0.05μF capacitors, but don’t use values
above 10μF or the transistor might be damaged.
Notes:
EXPERIMENT #6: ELECTRONIC MOTORCYCLE
Wiring Sequence:
o1-29
o2-30
o3-16-105-109
o4-120
o5-41-106
o15-82
o40-110-WIRE
o42-119
o81-WIRE
Schematic
WIRE

-18-
Here is a loud siren that is so much like the real
sirens on some police cars and ambulances, that
you may have to be careful not to confuse your
neighbors. The initial tone is high, but when you
close the key, the tone lowers. You can control the
tone the same way police and ambulance drivers
do.
This is the same type of oscillator circuit used in
many other projects. When you press the key,
another capacitor is added to the circuit to slow
down the oscillator action.
Notes:
EXPERIMENT #7: TWO-TONE PATROL CAR SIREN
Wiring Sequence:
o1-29
o2-30
o3-104-106-110
o4-85-120
o5-41-109
o40-137-105-86
o103-138
o42-119
Schematic

-19-
Here’s another siren - don’t be surprised if this
becomes the most popular circuit in this entire kit.
This circuit sounds even more like a real siren on a
police car! After completing the wiring, press the
key. You’ll hear a tone gradually getting higher.
Release the key, and the tone becomes lower and
then fades out.
Here are some of the modifications you might want
to try:
1. Change the 10μF capacitor to a 100μF or 470μF.
This gives a very long delay for both turn on and
turn off.
2. Change the circuit to eliminate the delays by
temporarily disconnecting the 10μF capacitor.
Simply disconnect one of the wires from terminal
113 or terminal 114. (Sounds dead in
comparison doesn’t it!)
3. Change the 0.02μF capacitor to a 0.01μF and
then to a 0.05μF.
Notes:
EXPERIMENT #8: ELECTRONIC SIREN
Wiring Sequence:
o1-29
o2-30
o3-103-109
o4-119-137
o5-47-110
o46-104-90
o114-48-120
o85-138
o86-89-113
Schematic

-20-
Here’s a circuit you might find useful if you’re
learning to play a musical instrument. This is an
electronic version of the metronome used by music
students everywhere.
Press the key.You’ll hear a sound from the speaker
at fixed intervals. Now, turn the control knob to the
right and you’ll hear the sound “speed up” as the
intervals between sounds shorten.
Try a different resistor in place of the 4.7kΩresistor.
(This resistor is in series with the control. That is,
they are connected end to end so that the current
runs through both components.) Also, try a different
capacitor in place of the 100μF capacitor and see
what effect this has on circuit operation. Remember
to keep track of the results in your notes.
Try connecting the 470μF capacitor to the batteries
to hear the difference a stronger capacitor makes.
Connect terminal 117 to terminal 119 and terminal
118 to terminal 120. You might have to adjust the
control also to maintain the same pulse rate.
Notes:
EXPERIMENT #9: ELECTRONIC METRONOME
Wiring Sequence:
o1-29
o2-30
o3-104-116
o4-28-138
o5-41-103
o27-80
o40-115-79
o42-119
o120-137
Schematic