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ELT2010 Electro-Assembly 2
Student Manual
This module is an opportunity to build skills in manufacturing circuits using printed circuit boards and a
variety of electrical/electronic components. The module begins with a review of circuits, soldering
technique, multimeter use and new components will be introduced – all of which will be used in the
manufacture of a circuit board.
Safety Review
Working with electricity has distinct hazards associated with it. It takes very little electricity to cause
serious injury or death, so precautions must be taken. Eye protection should always be worn to protect
from possible explosions and flying materials. The dangerous situation is created when the human body
becomes the conductor for electrical current. This electrical charge can cause serious damage to organs
and systems in the body if it passes through the body. Never work with electricity when there is water
present, bare wires or if you are working with unfamiliar equipment.
Circuit Review
Voltage is measured in volts, resistance in ohms and amperage in amps. The symbols for these
properties are V (volts), Ω (ohm), A (amperes). These three electrical properties are at the heart of every
electrical circuit. The best way to measure them is by using a multimeter, but there is a formula for
solving one property when the other two are known. This formula is known as Ohm’s Law: I=V/R.
Watch the videos “Resistance in Circuits parts 1 & 2” as a review
Every simple circuit has three basic parts: a power source, a conductor and a load. The power source
could be a battery, transformer, or wall outlet. Conductors are any of a variety of materials which
conduct electricity and the load is any component which provides resistance or performs work. A basic
circuit has the three basic parts with the addition of a protective device and a control device. In simple
terms, a protective device is a fuse which protects the load devices and conductors in the event too
much current enters the circuit. A control device is simply a switch which opens the circuit to stop the
flow of current (turn it off) and closes it to allow the flow (turn it on).
Series and parallel circuits are arrangements of loads within a circuit. Series circuits are best explained as
old-school Christmas tree lights. In an old string of lights, when one light went out, the circuit was
broken and none of the lights would work. It didn’t matter if it was the first light or the last, the flow of
electrons was disrupted and none would work. In a parallel circuit, the electricity flows uninterrupted
and the loads tap into it and various points. House wiring is done in parallel circuits, with the exception
of circuits with switches in them. Power is taken to a switch, but one of the lines is interrupted when the
switch is open (off). None of the plugs or lights on that circuit that are beyond that switch will have
power until the switch is closed (on), and no other components between the switch and power source
(breaker box) are affected by the switch.
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ELT2010 Electro-Assembly 2
Student Manual
Using a Multimeter
Multimeters are a piece of electronic equipment which allows you to measure voltage, resistance and
amperage, all with one unit.
Watch the video “THE BEST Multimeter Tutorial” as a review.
Soldering
In ELT1010 you completed a course on soldering and you also disassembled
an electronic device. The most important part of being able to solder
properly is properly tinning your soldering iron and keeping it clean. Using
the right solder is also important – you don’t want to use an acidic flux or
you will risk having the acid affect your solder joint over time. You also want
to make sure you are using a lead-free solder because the vapors given off
by melted lead can be hazardous over time. The following videos are a good
reminder of how to solder and desolder properly.
Watch “How and Why to Solder Correctly” and “How to Remove Solder” for review
Every electronic device uses a variety of components. These components may have obvious purposes,
such as a switch or light bulb, but many appear to be tiny, innocuous ‘things’.
Resistors
The most common and easily identified component is the resistor. The simple purpose of resistors is to
provide resistance in a circuit. Resistors can either be the little brown ceramic looking things with
colored stripes, or they could be an element for giving off heat. Resistors can be designed to have a fixed
resistance, or they could be variable. Variable resistors are called rheostats and examples of rheostats
would be dimmer switches which control automobile dashboard lights,
or video game controls. Rheostats control the resistance in a circuit.
Potentiometers are a type of variable resistor which controls voltage in
a circuit. An example of a potentiometer would be the volume control
on audio equipment.
Resistors are identified in different ways. Fixed resistors use a color
code to identify them. Each band represents a numerical value
associated with it and they are read from the end which has a band the
closes to it. These resistors will have either four or five bands – the five
banded resistors are built to be within a higher tolerance than four
banded. What this means is that that with four banded resistors there
will be a greater chance of change in resistance over a given time
period that with five banded resistors. There is a color chart for
identifying resistors in your module.
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ELT2010 Electro-Assembly 2
Student Manual
Measuring individual resistors can be done by reading the color codes and calculating the resistance and
they can also be measured by using a multimeter. In the case of a circuit, the resistance that has been
measured is used in equations to accurately determine the resistance in a circuit. In a series circuit the
total resistance is simply the total of the resistors added together. In a parallel circuit, the total
resistance of the whole circuit is less than the resistance of the lowest resistor because each resistor
provides separate paths for current to flow.
Read Chapter 10 in your textbook and complete the resistor questions in your workbook.
Diodes
A diode is a device which allows electricity to pass only in one direction. In
effect, it operates like a valve. This is an important property when it comes to
converting AC current to DC. A rectifier pack controls the direction of the
current being allowed into a circuit.
Watch the video “MAKE presents – The Diode” and answer the questions in the workbook.
Capacitors
A capacitor allows the storage of electrical charge. It
differs from a battery in that it doesn’t create electricity
chemically, but is just a storage vessel. They come in a
large variety of sizes and measured in farads. A
common use for capacitors is as the power source for
modern camera flashes. Once charged, the capacitor
hold the charge until it is required to be instantaneously
discharged to operate the flash. This also explains why
there is often a delay between pictures when the flash
is used – you are actually waiting for a capacitor to be
recharged from the camera’s batteries.
There are three types of capacitors: variable, fixed nonpolarized, and polarized. The variable capacitors have a
shaft which turns a varied thickness spacer between the
storage plates. The greater the distance between
storage plates, the greater the saved charge. Non
polarized capacitors have a lower capacitance (ability to
stow charge) and don’t have to be installed in a circuit
in a specific way. Polarized capacitors have a positive
and negative terminal indicated on them, and they
MUST be installed in the correct way.
Watch the video “MAKE presents – The Capacitor” and answer the questions in the workbook.
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ELT2010 Electro-Assembly 2
Student Manual
Transistors
The invention of the transistor has allowed for the development of the most complicated electronic
devices. A transistor can be used as switches to control current, as a type of variable resistor to control
current, and as amplifiers to increase current or voltage.
Transistors have three poles – or terminals – and are either NPN or PNP. The middle pole is the base and
the other two are the collector and emitter. The schematic
symbol for an NPN transistor has the arrow pointing out and the
PNP has the arrow pointing in. The different materials used in
making the transistors are what control the current or electronic
conductivity. A transistor is like a faucet – the actual handle
controls the flow (base), the water source provides the flow
(emitter) and the spout is where the water is discharged from
(collector). It is important to ensure transistors of the right type
are installed in the correct orientation.
Watch the video “MAKE presents – The Transistor” and answer the questions in the workbook.
Integrated Circuits
The brains of today’s electronics are integrated
circuits. They are singular devices which are
actually a collection of diodes, resistors,
transistors and other devices built into a single
component unit. Each integrated circuit (IC) is
built to perform specific functions and operate
in specific conditions. Some ICs come with their
own cooling system to help dissipate the heat
generated during circuit function.
Integrated circuits have at least two rows of
mounting pins. One corner of the IC chip will
have a dot above a pin which indicates that as
being pin number one. There will be an
indication on the board schematic as to how
the pins must be oriented.
Watch the video “MAKE presents – The Integrated Circuit” and answer the questions in the workbook.
Inductors
Most inductors are based on a coil of wire which act as a choke or impedance coil which oppose any
change in current flow. They are able to store and release energy in their magnetic field, with makes
them useful as magnets in a variety of applications. Magnetic properties, however, are only present
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ELT2010 Electro-Assembly 2
Student Manual
during the application of energy and they stop when the energy
flow is interrupted. These are called electromagnets because they
only posses this magnetic property when energy is flowing.
The left hand coil rule is used to determine the polarity of
electromagnets. As a coil is held in the left hand with the fingers
pointing in the direction of current flow, the thumb points to the
north pole of the magnet. The coils themselves make a difference in
the inducting properties of the inductor. The size of the wire, the
number of wraps, the diameter of the core, and the space between
wires all have affect the inductance properties.
Watch the video “MAKE presents – The Inductor” and answer the questions in the workbook.
Transducers
Speakers, microphones, and magnetic disk drives are all examples of transducer use. Basically, any time
energy changes from one form to another, it uses a transducer. In the devices mentioned, magnets are
often used to generate energy. In speakers, the energy is applied to a coil around a permanent magnet
to make it move and create sound waves. In some microphones, the movement of the magnet in a coil
creates current, but some microphones utilize carbon, capacitors and crystals instead. Magnetic drives –
like floppy discs and cassette tape players – amplify the signal present on a thin plastic medium and use
the current created to transfer information in a binary code format.
Read chapter 32 in your text and answer the questions in the workbook.
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ELT2010 Electro-Assembly 2
Student Manual
A circuit board is a non-conductive sheet material on which various electronic components are attached
by soldering, and connected to each other by imprinted copper connections. This module examines the
way that circuit boards are made in industrial production facilities, and by hobbyists.
Printed Circuit Boards
The earliest version of printed circuit boards were actually metal frames onto which components were
attached. They were in turn connected to each other by having short pieces of wire soldered to their
connecting points.
The main issue with this old-style form of circuit building was the complexity of wires and the difficulty
involved in controlling the size of the unit, not to mention the difficulty in accessing all of the
components and wires for testing and repair.
The development of printed circuit boards was a
breakthrough in electronics. A thick, non-conducting
material was coated with a thin conductive layer, the
layout of the components was determined and excess
conductive material was removed. The remaining
conductive materials (called traces) did what wires used
to do in early circuit building. Typically, holes were drilled
for the components to be inserted in and they were
soldered from the bottom.
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ELT2010 Electro-Assembly 2
Student Manual
Making printed circuit boards has evolved into a simple process that can be done at home or school. For
the purposes of this module and program, but because of the chemicals involved, the process will be
examined, but not practiced.
Watch the video “Circuit Skills – Circuit Board Etching” and answer the questions in your workbook.
Breadboards
Building temporary circuits is called
breadboarding. The big thing about
breadboarding is that it allows you to
build a temporary version of a circuit
before creating a finished soldered
version. There are different types of
breadboards – the 130 in 1 lab board that
is used in this class is one. The drawback
to this type of board is that, although the
connections are temporary, you are
limited to the components which are
permanently mounted on the board.
Solderless breadboards allow for the
temporary assembly of circuits using as
many different components as you have on hand. It is always a good idea to build a temporary version
of any circuit you are going to build, not only to ensure all of the components function, but to
demonstrate the output, or action, that is expected from the circuit. Breadboarding will allow you to
make changes to the circuit before building the final version.
Watch the video “Intro to Breadboard Electronics” and answer the questions in your workbook.
Building a Circuit
The big activity portion of this course will be actually building a circuit. Your teacher will supply you with
a kit which uses a variety of components and includes a printed circuit board. Before you start soldering
everything together, you should put everything together on a bread board. It is important to determine
how the leads work in your bread board.
Watch the video “Collin’s Lab – The Real Breadboard”.
Do not make any marks in this booklet.