Elenco Electronics EP-50 User manual

753057
Copyright © 1998 ElencoTM Electronics, Inc.
ELECTRONIC
PLAYGROUNDTM
and LEARNING CENTER
MODEL EP-50
ElencoTM Electronics, Inc.
Wheeling, IL, USA

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TABLE OF CONTENTS
Definition of Terms Page 3
Answers to Quizzes 5
Introduction to Basic Components 6
Experiment #1: The Light Bulb 8
More About Resistors 10
Experiment #2: Brightness Control 11
Experiment #3: Resistors in Series 12
Experiment #4: Parallel Pipes 13
Experiment #4B: Comparison of Parallel Currents 14
Experiment #5: Combined Circuit 16
Experiment #6: Water Detector 17
Introduction to Capacitors 18
Experiment #7: Slow Light Bulb 20
Experiment #8: Small Dominates Large 21
Experiment #9: Large Dominates Small 22
Experiment #10: Make Your Own Battery 23
Test Your Knowledge #1 24
Introduction to Diodes 24
Experiment #11: One - Way Current 25
Experiment #12: One - Way Light Bulbs 26
Introduction to Transistors 27
Experiment #13: The Electronic Switch 28
Experiment #14: The Current Amplifier 29
Experiment #15: The Substitute 30
Experiment #16:
Standard Transistor Biasing Circuit 31
Experiment #17: Very Slow Light Bulb 32
Experiment #18: The Darlington 33
Experiment #19: The Finger Touch Lamp 34
Experiment #20: The Battery Immunizer 35
Experiment #21: The Voltmeter 36
Experiment #22: 1.5 Volt Battery Tester 38
Experiment #23: 9 Volt Battery Tester 39
Experiment #24: The Anti-Capacitor 40
Introduction to Inductors and Transformers 42
Test Your Knowledge #2 43
Experiment #25: The Magnetic Bridge 44
Experiment #26: The Lighthouse 45
Experiment #27: Electronic Sound 46
Experiment #28: The Alarm 48
Experiment #29: Morse Code 49
Experiment #30: Siren 50
Experiment #31: Electronic Rain 51
Experiment #32: The Space Gun 52
Experiment #33: Electronic Noisemaker 53
Experiment #34: Drawing Resistors 54
Experiment #35: Electronic Kazoo 56
Experiment #36: Electronic Keyboard 57
Experiment #37: Fun with Water 58
Experiment #38: Transistor Radio 60
Experiment #39: Radio Announcer 62
Experiment #40: Radio Jammer / Metal Detector 63
Experiment #41: Blinking Lights 64
Experiment #42: Noisy Blinker 65
Experiment #43: One Shot 66
Experiment #44: Alarm With Shut - Off Timer 67
Experiment #45: The Flip - Flop 68
Experiment #46: Finger Touch Lamp With Memory 69
Experiment #47: This OR That 70
Experiment #48: Neither This NOR That 71
Experiment #49: This AND That 72
Experiment #50: Audio NAND, AND 73
Experiment #51: Logic Combination 74
Test Your Knowledge #3 75
Troubleshooting Guide 75
For Further Reading 75

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DEFINITION OF TERMS
(Most of these will be introduced and explained during the experiments).
AC Common abbreviation for
alternating current.
Alternating Current A current that is constantly
changing.
AM Amplitude modulation. The
amplitude of the radio signal is
varied depending on the
information being sent.
Amp Shortened name for ampere.
Ampere (A) The unit of measure for electric
current. Commonly shortened
to amp.
Amplitude Strength or level of something.
Analogy A similarity in some ways.
AND Gate A type of digital circuit which
gives a HIGH output only if all
of its inputs are HIGH.
Antenna Inductors used for sending or
receiving radio signals.
Astable Multivibrator A type of transistor
configuration in which only one
transistor is on at a time.
Atom The smallest particle of a
chemical element, made up of
electrons, protons, etc.
Audio Electrical energy representing
voice or music.
Base The controlling input of an NPN
bipolar junction transistor.
Battery A device which uses a
chemical reaction to create an
electric charge across a
material.
Bias The state of the DC voltages
across a diode or transistor.
Bipolar Junction
Transistor (BJT) A widely used type of transistor.
Bistable Switch A type of transistor
configuration, also known as
the flip-flop.
BJT Common abbreviation for
Bipolar Junction Transistor.
Capacitance The ability to store electric
charge.
Capacitor An electrical component that
can store electrical pressure
(voltage) for periods of time.
Carbon A chemical element used to
make resistors.
Clockwise In the direction in which the
hands of a clock rotate.
Coil When something is wound in a
spiral. In electronics this
describes inductors, which are
coiled wires.
Collector The controlled input of an NPN
bipolar junction transistor.
Color Code A method for marking resistors
using colored bands.
Conductor A material that has low
electrical resistance.
Counter-Clockwise Opposite the direction in which
the hands of a clock rotate.
Current A measure of how fast
electrons are flowing in a wire
or how fast water is flowing in a
pipe.
Darlington A transistor configuration which
has high current gain and input
resistance.
DC Common abbreviation for direct
current.
Decode To recover a message.
Detector A device or circuit which finds
something.
Diaphragm A flexible wall.
Differential Pair A type of transistor
configuration.
Digital Circuit A wide range of circuits in
which all inputs and outputs
have only two states, such as
high/low.
Diode An electronic device that allows
current to flow in only one
direction.
Direct Current A current that is constant and
not changing.
Disc Capacitor A type of capacitor that has low
capacitance and is used mostly
in high frequency circuits.
Electric Field The region of electric attraction
or repulsion around a constant
voltage. This is usually
associated with the dielectric in
a capacitor.
Electricity A flow of electrons between
atoms due to an electrical
charge across the material.
Electrolytic Capacitor A type of capacitor that has
high capacitance and is used
mostly in low frequency
circuits. It has polarity
markings.

Electron A sub-atomic particle that has
an electrical charge.
Electronics The science of electricity and
its applications.
Emitter The output of an NPN bipolar
junction transistor.
Encode To put a message into a format
which is easier to transmit.
Farad, (F) The unit of measure for
capacitance.
Feedback To adjust the input to
something based on what its
output is doing.
Flip-Flop A type of transistor
configuration is which the
output changes every time it
receives an input pulse.
FM Frequency modulation. The
frequency of the radio signal is
varied depending on the
information being sent.
Forward-Biased The state of a diode when
current is flowing through it.
Frequency The rate at which something
repeats.
Friction The rubbing of one object
against another. It generates
heat.
Gallium Arsenide A chemical element that is
used as a semiconductor.
Generator A device which uses steam or
water pressure to move a
magnet near a wire, creating an
electric current in the wire.
Germanium A chemical element that is
used as a semiconductor.
Ground A common term for the 0V or
“–” side of a battery or
generator.
Henry (H) The unit of measure for
Inductance.
Inductance
The ability of a wire to create an
induced voltage when the current
varies, due to magnetic effects.
Inductor A component that opposes
changes in electrical current.
Insulator A material that has high
electrical resistance.
Integrated Circuit A type of circuit in which
transistors, diodes, resistors,
and capacitors are all
constructed on a
semiconductor base.
Kilo- (K) A prefix used in the metric
system. It means a thousand of
something.
LED Common abbreviation for light
emitting diode.
Light Emitting Diode A diode made from gallium
arsenide that has a turn-on
energy so high that light is
generated when current flows
through it.
Magnetic Field The region of magnetic
attraction or repulsion around a
magnet or an AC current. This
is usually associated with an
inductor or transformer.
Magnetism A force of attraction between
certain metals. Electric
currents also have magnetic
properties.
Meg- (M) A prefix used in the metric
system. It means a million of
something.
Micro- (m
m) A prefix used in the metric
system. It means a millionth
(0.000,001) of something.
Microphone A device which converts sound
waves into electrical energy.
Milli- (m) A prefix used in the metric
system. It means a thousandth
(0.001) of something.
Modulation Methods used for encoding
radio signals with information.
Momentum The power of a moving object.
Morse Code A code used to send messages
with long or short transmit
bursts.
NAND Gate A type of digital circuit which
gives a HIGH output if some of
its inputs are LOW.
NOR Gate A type of digital circuit which
gives a HIGH output if none of
its inputs are HIGH.
NOT Gate A type of digital circuit whose
output is opposite its input.
NPN Negative-Positive-Negative, a
type of transistor construction.
Ohm’s Law
The relationship between
voltage, current, and resistance.
Ohm, (W
W) The unit of measure for
resistance.
OR Gate A type of digital circuit which
gives a HIGH output if any of its
inputs are HIGH.
Oscillator A circuit that uses feedback to
generate an AC output.
Parallel When several electrical
components are connected
between the same points in the
circuit.
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Pico- (p) A prefix used in the metric
system. It means a millionth of
a millionth (0.000,000,000,001)
of something.
Pitch The musical term for frequency.
Printed Circuit Board A board used for mounting
electrical components.
Components are connected
using metal traces “printed” on
the board instead of wires.
Receiver The device which is receiving a
message (usually with radio).
Resistance The electrical friction between
an electric current and the
material it is flowing through;
the loss of energy from
electrons as they move
between atoms of the material.
Resistor Components used to control
the flow of electricity in a circuit.
They are made of carbon.
Resistor-Transistor-
Logic (RTL) A type of circuit arrangement
used to construct digital gates.
Reverse-Biased When there is a voltage in the
direction of high-resistance
across a diode.
Saturation The state of a transistor when
the circuit resistances, not the
transistor itself, are limiting
the current.
Schematic A drawing of an electrical circuit
that uses symbols for all the
components.
Semiconductor A material that has more
resistance than conductors but
less than insulators. It is used
to construct diodes, transistors,
and integrated circuits.
Series When electrical components
are connected one after the
other.
Short Circuit When wires from different parts
of a circuit (or different circuits)
connect accidentally.
Silicon The chemical element most
commonly used as a
semiconductor.
Solder A tin-lead metal that becomes a
liquid when heated to above
360 degrees. In addition to
having low resistance like other
metals, solder also provides a
strong mounting that can
withstand shocks.
Speaker A device which converts
electrical energy into sound.
Switch A device to connect (“closed” or
“on”) or disconnect (“open” or
“off”) wires in an electric circuit.
Transformer A device which uses two coils
to change the AC voltage and
current (increasing one while
decreasing the other).
Transient Temporary. Used to describe
DC changes to circuits.
Transistor An electronic device that uses
a small amount of current to
control a large amount of
current.
Transmitter The device which is sending a
message (usually with radio).
Truth Table A table which lists all the
possible combinations of inputs
and outputs for a digital circuit.
Tungsten A highly resistive material used
in light bulbs.
Tuning Capacitor A capacitor whose value is
varied by rotating conductive
plates over a dielectric.
Variable Resistor A resistor with an additional
arm contact that can move
along the resistive material and
tap off the desired resistance.
Voltage A measure of how strong an
electric charge across a
material is.
Voltage Divider A resistor configuration to
create a lower voltage.
Volts (V) The unit of measure for voltage.
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QUIZ ANSWERS
First Quiz: 1. electrons; 2. short; 3. battery; 4. increase; 5. insulators, conductors; 6. decreases, increases; 7. decreases;
8. voltage; 9. alternating, direct; 10. increases, decreases.
Second Quiz: 1. reverse; 2. LEDs; 3. amplifier; 4. integrated; 5. saturated; 6. alternating, direct; 7. decreases, increases;
8. magnetic; 9. increases; 10. twice
Third Quiz: 1. feedback; 2. air, pressure; 3. decreases; 4. radio; 5. inductors; 6. OR; 7. NAND

-6-
INTRODUCTION TO BASIC COMPONENTS
Welcome to the exciting world of Electronics! Before
starting the first experiment, let’s learn about some of the
basic electronic components. Electricity is a flow of sub-
atomic (very, very, very, small) particles, called
electrons. The electrons move from atom to atom when
an electrical charge is applied across the material.
Electronics will be easier to understand if you think of the
flow of electricity through circuits as water flowing
through pipes (this will be referred to as the water pipe
analogy).
Wires: Wires can be thought of as large, smooth pipes
that allow water to pass through easily. Wires are made
of metals, usually copper, that offer very low resistance to
the flow of electricity. When wires from different parts of
a circuit connect accidentally we have a short circuit or
simply a short. You probably know from the movies that
this usually means trouble. You must always make sure
that the metal from different wires never touches except
at springs where the wires are connecting to each other.
The electric current, expressed in amperes (A, named
after Andre Ampere who studied the relationship
between electricity and magnetism) or milliamps (mA,
1/1000 of an ampere), is a measure of how fast electrons
are flowing in a wire just as a water current describes
how fast water is flowing in a pipe.
The Battery: To make water flow through a pipe we need
a pump. To make electricity flow through wires we use a
battery or a generator to create an electrical charge
across the wires. A battery does this by using a chemical
reaction and has the advantage of being simple, small,
and portable. If you move a magnet near a wire then
electricity will flow in the wire. This is done in a generator.
The electric power companies have enormous
generators driven by steam or water pressure to produce
electricity for your home.
The voltage, expressed in volts (V, and named after
Alessandro Volta who invented the battery in 1800), is a
measure of how strong the electric charge from your
battery or generator is, similar to the water pressure.
Your Electronic Playground uses a 9V battery. Notice the
“+” and “–” signs on the battery. These indicate which
direction the battery will “pump” the electricity, similarly to
how a water pump can only pump water in one direction.
The 0V or “–” side of the battery is often referred to as
“ground”. Notice that just to the right of the battery
pictured below is a symbol, the same symbol you see
next to the battery holder. Engineers are not very good
at drawing pictures of their parts, so when engineers
draw pictures of their circuits they use symbols like this to
represent them. It also takes less time to draw and takes
up less space on the page. Note that wires are
represented simply by lines on the page.
The Switch: Since you don’t want to waste water when
you are not using it, you have a faucet or valve to turn the
water on and off. Similarly, you use a switch to turn the
electricity on and off in your circuit. A switch connects
(the “closed” or “on” position) or disconnects (the “open”
or “off” position) the wires in your circuit. As with the
battery, the switch is represented by a symbol, shown
below on the right.
Pipe
Wire
Water
Pump Battery
Symbol for
Battery
(+)
9V
(–)
Valve
Switch
Symbol for Switch

The Resistor: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 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 (W, named after
George Ohm), kilohms (KW, 1000 ohms), or megohms
(MW, 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 on the
right.
Rocks in Pipe Resistor Resistor Symbol
-7-

EXPERIMENT #1: The Light Bulb
First, you need a 9V battery (alkaline is best). Fold out
the the battery holder cutouts and snap the battery into
its clip. Always remove the battery from its clip if you
won’t be using your Playground for a while.
Your Electronic Playground consists of electronic parts
connected to springs and mounted on a cardboard panel.
You will use wires to connect these springs together to
form a circuit. You are provided with several different
lengths of wires, and it is usually best to use the shortest
length of wire that comfortably reaches between two
springs so that your wiring appears less confusing and
easier to check. Notice that each spring has a number
next to it. For each circuit we will tell you the spring
numbers to connect in order to build the circuit. And as
you build each circuit you will slowly learn more and more
about electronics.
Enough talk, let’s start building your first circuit. To
connect a wire to a spring, bend the spring back to one
side with one finger and slip the metal end of the wire into
the spring; let go of the spring and it should clamp the
wire firmly in place. Tug lightly on the wire to make sure
you have a secure connection. And be sure the spring
touches the metal portion of the wire, the colored plastic
insulation doesn’t count. To remove a wire, bend the
spring and pull the wire away. When you have two or
more wires connecting to the same spring, make sure
that one wire does not come loose while you connect the
others. This will be easier if you connect the wires on
different sides of the spring.
12 3
-8-
Now connect the wires for this circuit
according to the list below, which we’ll call
the Wiring Checklist. When you’re
finished your wiring should look like the
diagram shown here:
Wiring Checklist:
o27-to-56
o55-to-45
o44-to-3
o4-to-26
Be sure all your wires are securely in
place and not loose. Also make sure the
metal in the wires is only touching the
spring and wires that it is connected to,
and not to any nearby springs or other
wires.

-9-
Press the switch (next to springs 55 and 56) and the LED
(light emitting diode) lights up, and turns off when you
release the switch. The LED converts electrical energy
into light, like the light bulbs in your home. You can also
think of an LED as being like a simple water meter, since
as the electric current increases in a wire the LED
becomes brighter. It is shown here, with its symbol.
Take a look at the water diagram that follows. It shows
the flow of water from the pump through the faucet, the
small pipe, the water meter, the large pipes, and back to
the pump. Now compare it to the electrical diagram next
to it, called a schematic. Schematics are the “maps” for
electronic circuits and are used by all electronic
designers and technicians on everything from your
Electronic Playground to the most advanced
supercomputers. They show the flow of electricity from
the battery through the switch, the resistor, the LED, the
wires, and back to the battery. They also use the symbols
for the battery, switch, resistor, and LED that we talked
about. Notice how small and simple the schematic looks
compared to the water diagram; that is why we use it.
Now you will see how changing the resistance in the
circuit increases the current through it. Press the switch
again and observe the brightness of the LED. Now
remove the wires from the 10KWresistor (springs 44 and
45) and connect them to the 1KWresistor (springs 40 and
41). Press the switch. The LED is brighter now, do you
understand why? We are using a lower resistance (less
rocks), so there is more electrical current flowing (more
water flows), so the LED is brighter. Now replace the
1KWresistor with the 100KWresistor (springs 51 and 52)
and press the switch again. The LED will be on but will
be very dim (this will be easier to see if you wrap your
hand near the LED to keep the room lights from shining
on it).
Well done! You’ve just built YOUR first electronic circuit!
Water Meter LED Symbol for LED
Water Diagram
On/Off
Valve
Water
Meter
Rocks
Pump
Schematic

Ohm’s Law: You just observed that when you have less
resistance in the circuit, more current flows (making the
LED brighter). The relationship between voltage, current,
and resistance is known as Ohm’s Law (after George
Ohm who discovered it in 1828):
Current =
Resistance: Just 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; it is the loss of energy from electrons as they
move between atoms of the material. Resistors are
made using carbon and can be constructed with different
resistive values, such as the seven parts included in your
Electronic Playground. If a large amount of current is
passed through a resistor then it will become warm due
to the electrical friction. Light bulbs use a small piece of
a highly resistive material called tungsten. Enough
current is passed through this tungsten to heat it until it
glows white hot, producing light. Metal wires have some
electrical resistance, but it is very low (less than 1Wper
foot) and can be ignored in almost all circuits. Materials
such as metals which have low resistance are called
conductors. Materials such as paper, plastic, and air
have extremely high values of resistance and are called
insulators.
Resistor Color Code: You may have seen the colored
bands on the resistors and may be wondering what they
mean. They 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. The
colors below are used to represent the numbers 0
through 9.
Use the color code to check the values of the seven
resistors included in your Electronic Playground. (The
values are marked next to them on the box). They are all
5% tolerance.
The Variable Resistor:We talked about how a switch is
used to turn the electricity on and off just like a valve is
used to turn the water on and off. But there are many
times when you want some water but don’t need all that
the pipe can deliver, so you control the water by adjusting
an opening in the pipe with a faucet. Unfortunately, you
can’t adjust the thickness of an already thin wire. But you
could also control the water flow by forcing the water
through an adjustable length of rocks, as in the rock arm
shown below.
In electronics we use a variable resistor. This is a normal
resistor (50KWin your Playground) with an additional arm
contact that can move along the resistive material and
tap off the desired resistance.
There is a scale printed next to the dial on the variable
resistor which shows the percentage of the total
resistance that is between springs 49 and 50. The
remaining resistance will be between springs 48 and 49.
The resistance between springs 48 and 50 will always be
50KW, the total resistance.
Now let’s demonstrate how this works.
MORE ABOUT RESISTORS
-10-
Example of Color Code
OrangeRed
Violet Gold
27 X 103 = 27,000 W,
with 5% Tolerance
COLOR VALUE
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9
Rock Arm
Variable Resistor
Insulating Base Material
Wiper Contact
Thin Layer of
Resistive
Material
Stationary
Contact
Movable
Arm
Leads
Variable
Resistor Symbol for Variable
Resistor
Voltage
Resistance