Elenco Electronic Component Kit User Manual

BASIC ELECTRONIC COMPONENTS

MODEL ECK-10

Instruction Manual

by Arthur F. Seymour MSEE

It is the intention of this course to teach the fundamental operation of basic
electronic components by comparison to drawings of equivalent mechanical
parts. It must be understood that the mechanical circuits would operate much
slower than their electronic counterparts and one-to-one correlation can never
be achieved. The comparisons will, however, give an insight to each of the
fundamental electronic components used in every electronic product.

Resistors

Capacitors Coils

Semiconductors

Others

Transformers

ELENCO

®

Copyright © 2012, 1994 by Elenco®Electronics, Inc. All rights reserved. Revised 2012 REV-M 753254

No part of this book shall be reproduced by any means; electronic, photocopying, or otherwise without written permission from the publisher.

-1-

RESISTORS

RESISTORS,

What do they do?

The electronic component known as the resistor is
best described as electrical friction. Pretend, for a
moment, that electricity travels through hollow pipes
like water. Assume two pipes are filled with water
and one pipe has very rough walls. It would be easy
to say that it is more difficult to push the water
through the rough-walled pipe than through a pipe
with smooth walls. The pipe with rough walls could
be described as having more resistance to
movement than the smooth one.

Pioneers in the field of electronics thought electricity
was some type of invisible fluid that could flow
through certain materials easily, but had difficulty
flowing through other materials. In a way they were
correct since the movement of electrons through a
material cannot be seen by the human eye, even
with the best microscopes made. There is a
similarity between the movement of electrons in
wires and the movement of water in the pipes. For
example, if the pressure on one end of a water pipe
is increased, the amount of water that will pass
through the pipe will also increase. The pressure on
the other end of the pipe will be indirectly related to
the resistance the pipe has to the flow of water. In
other words, the pressure at the other end of the
pipe will decrease if the resistance of the pipe
increases. Figure 1 shows this relationship
graphically.

Electrons flow through materials when a pressure
(called voltage in electronics) is placed on one end
of the material forcing the electrons to “react” with
each other until the ones on the other end of the
material move out. Some materials hold on to their
electrons more than others making it more difficult
for the electrons to move. These materials have a
higher resistance to the flow of electricity (called
current in electronics) than the ones that allow
electrons to move easily. Therefore, early
experimenters called the materials

insulators

if they

had very high resistance to electon flow and

conductors

if they had very little resistance to
electron flow. Later materials that offered a medium
amount of resistance were classified as

semiconductors

.

When a person designs a circuit in electronics, it is
often necessary to limit the amount of electrons or
current that will move through that circuit each
second. This is similar to the way a faucet limits the
amount of water that will enter a glass each second.
It would be very difficult to fill a glass without
breaking it if the faucet had only two states, wide
open or off. By using the proper value of resistance
in an electronic circuit designers can limit the
pressure placed on a device and thus prevent it from
being damaged or destroyed.

SUMMARY: The resistor is an electronic
component that has electrical friction. This friction
opposes the flow of electrons and thus reduces the
voltage (pressure) placed on other electronic
components by restricting the amount of current that
can pass through it.

Figure 1

Low Resistance

Pipe

High Resistance

Pipe (rough walls)

Low Pressure

High Pressure

Through Same

Size Opening

Water Tank

-2-

RESISTORS

RESISTORS,

How are they made?

There are many different types of resistors used in
electronics. Each type is made from different
materials. Resistors are also made to handle
different amounts of electrical power. Some
resistors may change their value when voltages are
placed across them. These are called voltage
dependent resistors or

nonlinear

resistors. Most
resistors are designed to change their value when
the temperature of the resistor changes. Some
resistors are also made with a control attached that
allows the user to mechanically change the
resistance. These are called variable resistors or
potentiometers. Figure 2 shows physical shapes of
some different types of resistors.

The first commercial resistors made were formed by
wrapping a resistive wire around a non-conducting
rod (see Figure 3). The rod was usually made of
some form of ceramic that had the desired heat
properties since the wires could become quite hot
during use. End caps with leads attached were then
placed over the ends of the rod making contact to
the resistive wire, usually a nickel chromium alloy.

The value of wirewound resistors remain fairly flat
with increasing temperature, but change greatly with
frequency. It is also difficult to precisely control the
value of the resistor during construction so they
must be measured and sorted after they are built.

By grinding carbon into a fine powder and mixing it
with resin, a material can be made with different
resistive values. Conductive leads are placed on
each end of a cylinder of this material and the unit is
then heated or cured in an oven. The body of the
resistor is then painted with an insulating paint to
prevent it from shorting if touched by another
component. The finished resistors are then
measured and sorted by value (Figure 4). If these
resistors are overloaded by a circuit, their resistance
will permanently decrease. It is important that the
power rating of the carbon composition resistor is
not exceeded.

Figure 2

Carbon Film

Variable

Carbon Composition

THE WIREWOUND RESISTOR

Figure 3

THE CARBON COMPOSITION RESISTOR

Ceramic Rod

Wire

End CapProtective Coating

Figure 4

Insulating Paint Carbon & Resin

Mixture

Conductive Wire

-3-

RESISTORS

CARBON FILM RESISTORS

Carbon film resistors are made by depositing a very
thin layer of carbon on a ceramic rod. The resistor
is then protected by a flameproof jacket since this
type of resistor will burn if overloaded sufficiently.
Carbon film resistors produce less electrical noise
than carbon composition and their values are
constant at high frequencies. You can substitute a
carbon film resistor for most carbon composition
resistors if the power ratings are carefully observed.
The construction of carbon film resistors require
temperatures in excess of 1,000

O

C.

Metal oxide resistors are also constructed in a
similar manner as the carbon film resistor with the
exception that the film is made of tin chloride at
temperatures as high as 5,000

O

C. Metal oxide
resistors are covered with epoxy or some similar
plastic coating. These resistors are more costly than
other types and therefore are only used when circuit
constraints make them necessary.

Metal film resistors are also made by depositing a
film of metal (usually nickel alloy) onto a ceramic
rod. These resistors are very stable with
temperature and frequency, but cost more than the
carbon film or carbon composition types. In some
instances, these resistors are cased in a ceramic
tube instead of the usual plastic or epoxy coating.

When a resistor is constructed so its value can be
adjusted, it is called a variable resistor. Figure 6
shows the basic elements present in all variable
resistors. First a resistive material is deposited on a
non-conducting base. Next, stationary contacts are
connected to each end of the resistive material.
Finally, a moving contact or wiper is constructed to
move along the resistive material and tap off the
desired resistance. There are many methods for
constructing variable resistors, but they all contain
these three basic principles.

Figure 5

METAL OXIDE RESISTORS

METAL FILM RESISTORS

THE VARIABLE RESISTOR

Figure 6

Carbon Film

Ceramic Rod Flameproof Jacket

Leads

Movable

Arm

Wiper

Contact

Stationary

Contact

Thin Layer

of Resistive

Material

Non-conductive

Base Material

-4-

RESISTORS

RESISTOR VALUES AND MARKINGS

The unit of measure for resistance is the ohm, which
is represented by the Greek letter Ω. Before
technology improved the process of manufacturing
resistors, they were first made and then sorted. By
sorting the values into groups that represented a 5%
change in value, (resistor values are 10% apart),
certain preferred values became the standard for
the electronics industry. Table 1 shows the standard
values for 5% resistors.

Resistors are marked by using different colored
rings around their body (see Figure 7). 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. The final and fourth ring
represents the tolerance. For example, gold is for
5% resistors and silver for 10% resistors. This
means the value of the resistor is guaranteed to be
within 5% or 10% of the value marked. The colors
in Table 2 are used to represent the numbers from 0
to 9.

Note: If the third ring is gold, you multiply the first
two digits by 0.1 and if it is silver, by 0.01. This
system can identify values from 0.1Ω to as high as
91 x 10

9

, or 91,000,000,000Ω. The amount of power
each resistor can handle is usually proportional to
the size of the resistor. Figure 8 shows the actual
size and power capacity of normal carbon film
resistors, and the symbols used to represent
resistors on schematics.

10 11 12 13 15 16 18 20
22 24 27 30 33 36 39 43
47 51 56 62 68 75 82 91

Table 1

Figure 7

OrangeRed

Violet Gold

27 X 103= 27,000 Ω,

with 5% Tolerance

COLOR VAL UE

Black 0

Brown 1

Red 2

Orange 3

Yellow 4

Green 5

Blue 6

Violet 7

Gray 8

White 9

Table 2

Figure 8

Regular Variable

Resistor Symbols

1/8 Watt

1/4 Watt

1/2 Watt

-5-

RESISTORS

SELF TEST

1. A flow of electrons through a material:
a) Voltage c) Current
b) Resistance d) Conductance

2. The pressure that pushes electrons through a

material:

a) Voltage c) Conduction
b) Current d) Resistance

3. A material that has very high resistance to electron

flow:

a) Conductor c) Resistor
b) Semiconductor d) Insulator

4. A material that allows electrons to flow easily:
a) Conductor c) Resistor
b) Semiconductor d) Insulator

5. A material that produces electrical friction and

restricts the flow of electrons:

a) Conductor c) Resistor
b) Semiconductor d) Insulator

6. A resistor that is made by wrapping a wire around a
ceramic rod:

a) Carbon Film c) Thermistor
b) Carbon Composition d) Wirewound

7. A resistor made by heating powder and resin in an
oven:

a) Carbon Film c) Thermistor
b) Carbon Composition d) Wirewound

8. A resistor made by depositing a very thin layer of
resistive material on a ceramic rod:

a) Carbon Film c) Thermistor
b) Carbon Composition d) Wirewound

9. One of the preferred values for a 5% resistor:

a) 4000Ω c) 77Ω
b) 560Ω d) 395Ω

10. The amount of wattage a resistor can handle is

determined by:

a) Value c) Current
b) Voltage d) Size

THEORY

Circle the letter that best fits the description.

PRACTICE

Open the bag marked “resistors” and fill in the table below.

Color 1 Color 2 Color 3 Color 4 Value Percent Wattage

EXTRA CREDIT

Using a razor blade or sharp knife, scrape away the paint on the body of one resistor and determine the type of
construction used to make it. Try and determine all of the materials used including the metals used to make the
leads.

-6-

CAPACITORS,

What do they do?

Capacitors are components that can store electrical
pressure (Voltage) for long periods of time. When a
capacitor has a difference in voltage (Electrical
Pressure) between its two leads it is said to be
charged. A capacitor is charged by forcing a one
way (DC) current to flow through it for a short period
of time. It can be discharged by letting an opposite
direction current flow out of the capacitor. Consider
for a moment the analogy of a water pipe that has a
rubber diaphragm sealing off each side of the pipe
as shown in Figure 9.

If the pipe had a plunger on one end, as shown in
Figure 9, and the plunger was pushed toward the
diaphragm, the water in the pipe would force the
rubber to stretch out until the force of the rubber
pushing back on the water was equal to the force of
the plunger. You could say the pipe is charged and
ready to push the plunger back. In fact, if the
plunger is released it will move back to its original
position. The pipe will then be discharged or with no
charge on the diaphragm.

Capacitors act the same as the pipe in Figure 9.
When a voltage (Electrical Pressure) is placed on
one lead with respect to the other lead, electrons are
forced to “pile up” on one of the capacitor’s plates
until the voltage pushing back is equal to the voltage
applied. The capacitor is then charged to the
voltage. If the two leads of that capacitor are
shorted, it would have the same effect as letting the
plunger in Figure 9 move freely. The capacitor
would rapidly discharge and the voltage across the
two leads would become zero (No Charge).

What would happen if the plunger in Figure 9 was
wiggled in and out many times each second? The
water in the pipe would be pushed by the diaphragm
then sucked back by the diaphragm. Since the
movement of the water (Current) is back and forth
(Alternating) it is called an Alternating Current or
AC. The capacitor will therefore pass an alternating
current with little resistance. When the push on the
plunger was only toward the diaphragm, the water
on the other end of the diaphragm moved just
enough to charge the pipe (transient current). Just
as the pipe blocked a direct push, a capacitor clocks
direct current (DC). An example of alternating
current is the 60 cycle (60 wiggles each second)
current produced when you plug something into a
wall outlet.

SUMMARY: A capacitor stores electrical energy
when charged by a DC source. It can pass
alternating current (AC), but blocks direct current
(DC) except for a very short charging current, called
transient current.

CAPACITORS

Pipe Filled with Water

Rubber Diaphragm

Sealing Center of Pipe

Plunger

Figure 9

-7-

CAPACITORS,

How are they made?

There are many different types of capacitors used in
electronics. Each type is made from different
materials and with different methods. Capacitors
are also made to handle different amounts of
electrical pressure or voltage. Each capacitor is
marked to show the maximum voltage that it can
withstand without breaking down. All capacitors
contain the same fundamental parts, which consist
of two or more conductive plates separated by a
nonconductive material. The insulating material
between the plates is called the dielectric. The basic
elements necessary to build a capacitor are shown
in Figure 10.

Perhaps the most common form of capacitor is
constructed by tightly winding two foil metal plates
that are separated by sheets of paper or plastic as
shown in Figure 11. By picking the correct insulating
material the value of capacitance can be increased
greatly, but the maximum working voltage is usually
lowered. For this reason, capacitors are normally
identified by the type of material used as the
insulator or dielectric. Consider the water pipe with
the rubber diaphragm in the center of the pipe. The
diaphragm is equivalent to the dielectric in a
capacitor. If the rubber is made very soft, it will
stretch out and hold a large amount of water, but it
will break easily (large capacitance, but low working
voltage). If the rubber is made very stiff, it will not
stretch far, but will be able to withstand higher

pressure (low capacitance, but high working
voltage). By making the pipe larger and keeping the
stiff rubber we can achieve a device that holds a
large amount of water and withstands a high amount
of pressure (high capacitance, high working voltage,
large size). These three types of water pipes are
illustrated in Figure 12. The pipes follow the rule that
the capacity to hold water, (Capacitance) multiplied
by the amount of pressure they can take (Voltage)
determines the size of the pipe. In electronics the
CV product determines the capacitor size.

CAPACITORS

THE METAL FOIL CAPACITOR

Soft Rubber

Figure 12

Stiff Rubber

Stiff Rubber

Larger Size

Large Capacity

Low Pressure

Low Capacity

but can withstand

High Pressure

High Capacity and can withstand High Pressure

Figure 10

Lead 1

Nonconductive Material

Conductive Plate

Lead 2

Figure 11

Lead 1

Paper or Plastic Insulator

Conductive Foil

Lead 2

-8-

DIELECTRIC CONSTANT,

What is it?

The dielectric (rubber diaphragm in the water pipe
analogy) in a capacitor is the material that can
withstand electrical pressure (Voltage) without
appreciable conduction (Current). When a voltage is
applied to a capacitor, energy in the form of an
electric charge is held by the dielectric. In the
rubber diaphragm analogy the rubber would stretch
out and hold the water back. The energy was stored
in the rubber. When the plunger is released the
rubber would release this energy and push the
plunger back toward its original position. If there
was no energy lost in the rubber diaphragm, all the
energy would be recovered and the plunger would
return to its original position. The only perfect
dielectric for a capacitor in which no conduction
occurs and from which all the stored energy may be
recovered is a perfect vacuum. The

DIELECTRIC

CONSTANT

(K) is the ratio by which the
capacitance is increased when another dielectric
replaces a vacuum between two plates. Table 3
shows the Dielectric Constant of various materials.

To make a variable capacitor, one set of stationary
aluminum plates are mounted to a frame with a
small space between each plate. Another set of
plates are mounted to a movable shaft and designed
to fit into the space of the fixed plates without
touching them. The insulator or dielectric in this type
of variable capacitor is air. When the movable plates
are completely inside the fixed plates, the device is
at minimum capacitance. The shape of the plates
can be designed to achieve the proper amount of
capacitance versus rotation for different
applications. An additional screw is added to
squeeze two insulated metal plates together
(Trimmer) and thus set the minimum amount of
capacitance.

CAPACITORS

Air, at normal pressure 1 Mica 7.5

Alcohol, ethyl (grain) 25 Paper, manila 1.5

Beeswax 1.86 Paraffin wax 2.25

Castor Oil 4.67 Porcelain 4.4

Glass flint density 4.5 10 Quartz 2

Glycerine 56 Water, distilled 81

Table 3

THE VARIABLE CAPACITOR

Figure 13

Fram e

Movable

Plates

Shaft

Fixed Plates

Trimmer