Kitronik Mono amplifier kit Instruction sheet

MONO AMPLIFIER KIT
CREATE YOUR OWN SPEAKER DOCK WITH THIS
TEACHING RESOURCES
SCHEMES OF WORK
DEVELOPING A SPECIFICATION
COMPONENT FACTSHEETS
HOW TO SOLDER GUIDE
Version 3.0

Mono Amplifier Teaching Resources
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Index of Sheets
TEACHING RESOURCES
Index of Sheets
Introduction
Schemes of Work
Answers
The Design Process
The Design Brief
Investigation / Research
Developing a Specification
Which Batteries Should I Use With My MP3 Amplifier?
Mounting the Speaker
Design
Design Review (group task)
Soldering In Ten Steps
Resistor Values
Capacitor Basics
Ceramic Disc Capacitors
Instruction Manual
Evaluation
Packaging Design
ESSENTIAL INFORMATION
Build Instructions
Checking Your Amplifier PCB
Adding an On / Off Switch
Designing the Enclosure
How the Amplifier Works
Online Information

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Introduction
About the project kit
Both the project kit and supporting material have been carefully designed for use in KS3 Design and Technology
lessons. It is designed so that even teachers with a limited knowledge of electronics should have no trouble using it
as a basis from which they can form a scheme of work.
The project kits can be used in two ways:
1. As part of a larger project involving all aspects of a product design, such as designing an enclosure for the
electronics to fit into.
2. On their own as a way of introducing electronics and electronic construction to students over a number of
lessons.
This booklet contains a wealth of material to aid the teacher in either case.
Using the booklet
The first few pages of this booklet contain the information to aid the teacher in planning their lessons and also cover
worksheet answers. The rest of the booklet is designed to be printed out as classroom handouts. In most cases all of
the sheets will not be needed and therefore they don’t contain page numbers, allowing teachers to pick and choose
as they feel fit.
Please feel free to print any pages of this booklet to use as student handouts in conjunction with Kitronik project
kits.
Support and resources
You can also find additional resources at www.kitronik.co.uk. There are component fact sheets, information on
calculating resistor and capacitor values, puzzles and much more.
Kitronik provide a next day response technical assistance service via e-mail. If you have any questions regarding this
kit or even suggestions for improvements, please e-mail us at:
Alternatively, phone us on 0845 8380781.

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Schemes of Work
Two schemes of work are included in this pack; the first is a complete project including the design & manufacture of
an enclosure for the kit (below). The second is a much shorter focused practical task covering just the assembly of
the kit (next page). Equally, feel free to use the material as you see fit to develop your own schemes.
Before starting we would advise that you to build a kit yourself. This will allow you to become familiar with the
project and will provide a unit to demonstrate.
Complete product design project including electronics and enclosure
Hour 1
Introduce the task using ‘The Design Brief’ sheet.
Demonstrate a built unit. Take students through the
design process using ‘The Design Process’ sheet.
Homework: Collect examples of MP3 players & accessories. List the common features of these products
on the ‘Investigation / Research’ sheet.
Hour 2
Develo
p a specification for the project using the ‘Developing a Specification’ sheet.
Resource: Sample of products (amplifiers & MP3 player accessories).
Homework: Using the internet or other search method, find out what is meant by ‘design for
manufacture’. List five reasons why design for manufacture should be considered on any design project.
Hour 3
Read ‘Designing the Enclosure’ sheet. Develop a product design using the ‘Design’ sheet.
Homework: Complete design.
Hour 4
Using cardboard
,
get the students to model their enclosure design. Allow them to make alterations to
their design if the model shows any areas that need changing.
Hour 5
Split the students into groups and get them to perform a group design review using the ‘Design
Review’
sheet.
Hour 6
Using the ‘Soldering in
8
S
teps’ sheet
,
demonstrate and get students to practice
soldering. Start the
‘Resistor Value’ and ‘Ceramic Disc Capacitors’ worksheets.
Homework: Complete any of the remaining resistor / capacitor tasks.
Hou
r 7
Build the electronic kit using the ‘Build Instructions’.
Hour 8
Complete the build of the electronic kit. Check the completed PCB and fault find i
f required using the
‘Checking Your Amplifier PCB’ section and the fault finding flow chart.
Homework: Read ‘How the Amplifier Works’ sheet.
Hour 9
Build the enclosure
.
Homework: Collect some examples of instruction manuals.
Hour 10
Build the enclosure
.
Homework: Read ‘Instruction Manual’ sheet and start developing instructions for the amplifier.
Hour 11
Build the enclosure.
Hour 12
Using the ‘Evaluation’ and ‘Improvement’ sheet, get the students to evaluate their final product and
state where improvements can be made.
AdditionalWork
Package design for those who complete ahead of others.

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Electronics only
Hour 1
Introduction to the kit demonstrating a buil
t unit. Using ‘Soldering in
8
S
teps’ sheet practice soldering.
Hour 2
Build the kit using the ‘Build Instructions’.
Hour 3
Check the completed PCB and fault fi
nd if required using ‘Checking Y
our
A
mplifier PCB’ and fault finding
flow chart.
Answers
Resistor questions
1st Band 2nd Band Multiplier x Value
Brown Black Yellow 100,000 Ω
Green Blue Brown 560 Ω
Brown Grey Yellow 180,000Ω
Orange White Black 39Ω
Value 1st Band 2nd Band Multiplier x
180 Ω Brown Grey Brown
3,900 Ω Orange White Red
47,000 (47K) Ω Yellow Violet Orange
1,000,000 (1M) Ω Brown Black Green
Capacitor ceramic disc values
Printing on capacitor Two digit start Number of zero’s Value in pF
222 22 00 2200pF (2.2nF)
103 10 000 10000pF (10nF)
333 33 000 33000pF (33nF)
473 47 000 47000pF (47nF)

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The Design Process
The design process can be short or long, but will always consist of a number of
steps that are the same on every project. By splitting a project into these
clearly defined steps, it becomes more structured and manageable. The steps
allow clear focus on a specific task before moving to the next phase of the
project. A typical design process is shown on the right.
Design brief
What is the purpose or aim of the project? Why is it required and who is it
for?
Investigation
Research the background of the project. What might the requirements be?
Are there competitors and what are they doing? The more information found
out about the problem at this stage, the better, as it may make a big
difference later in the project.
Specification
This is a complete list of all the requirements that the project must fulfil - no
matter how small. This will allow you to focus on specifics at the design stage
and to evaluate your design. Missing a key point from a specification can
result in a product that does not fulfil its required task.
Design
Develop your ideas and produce a design that meets the requirements listed
in the specification. At this stage it is often normal to prototype some of your
ideas to see which work and which do not.
Build
Build your design based upon the design that you have developed.
Evaluate
Does the product meet all points listed in the specification? If not, return to the design stage and make the required
changes. Does it then meet all of the requirements of the design brief? If not, return to the specification stage and
make improvements to the specification that will allow the product to meet these requirements and repeat from
this point. It is normal to have such iterations in design projects, though you normally aim to keep these to a
minimum.
Improve
Do you feel the product could be improved in any way? These improvements can be added to the design.
Design Brief
Investigation
Specification
Design
Build
Evaluate
Improve

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The Design Brief
A manufacturer of MP3 players has developed a simple audio amplifier
circuit. The circuit has been developed to the point where they have a
working Printed Circuit Board (PCB). Although they are used to the design
of MP3 players, they have not designed an amplifier case before.
The manufacturer would like ideas for an enclosure for the PCB, batteries
and speaker to be mounted in. The manufacturer has asked you to do this
for them. It is important that you make sure the final design meets all of
the requirements that you identify for such a product.
Complete circuit
A fully built circuit is shown below.

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Investigation / Research
Using a number of different search methods, find examples of similar products that are already on the market. Use
additional pages if required.
Name………………………………………………… Class………………………………

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Developing a Specification
Using your research into the target market for the product, identify the key requirements for the product and
explain why each of these is important.
Name……………………………………………………… Class………………………………
Requirement
Reason
Example: The enclosure should have
some holes.
Example: So that the sound can be heard.

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Which Batteries Should I Use With My MP3 Amplifier?
The Amplifier will work off a supply of 2.2 volts to 5.5 volts; however you won’t be able to set the volume as high on
the lower voltages. The higher the voltage, the more batteries you will need and the bulkier the case will have to be
to accommodate them. You might also want to consider how long the amplifier would work for before the batteries
need to be changed. Some options are shown in the table below:
Picture Description Voltage Capacity Estimated
life Max power
Polymer
Lithium Ion
Cell
3.7 V 400 mAh 2 days 0.7 W
Polymer
Lithium Ion
Cell
3.7 V 1000 mAh 5 days 0.7 W
2x AAA 3V 1000 mAh 7 days 0.45W
3x AAA 4.5 V 1000 mAh 4.5 days 1 W
2X AA 3V 1500mAH 10 days 0.45W
3x AA 4.5 V 1500 mAh 6 days 1 W
3x C cell 4.5 V 3000 mAh 13 days 1 W
You will have to decide which of these is most important and select your choice of batteries accordingly:
 Compact case.
 Higher volume.
 Long battery life.
Please note that the estimated battery life has been calculated running the amplifier on standard alkaline batteries
at full power, hence the higher power choices have a shorter battery life. Obviously if you don’t run your MP3 player
at the maximum volume, the batteries will last longer.
Please note that Polymer Lithium Ion cells require a different charger compared to standard rechargeable batteries.

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Mounting the Speaker
To get the best performance from your amplifier, you will need to mount the speaker into an enclosure. If the
speaker is left in open air, as the paper cone moves in and out, the air will move around the edge of the speaker,
giving it poor performance. Try listening to the difference in audio quality with the speaker in the open air, and then
cup your hands around the speaker. It is much better when you stop the air going around the edge of the speaker
and force it to be pushed forward.
This is why it’s so important to mount the speaker. You will have to let the sound out and can design your own
speaker grill, or simply you can use the example shown below.
The speaker grill pattern bellow has been designed for the speaker supplied. The three outer points have been
designed as retaining points for holding the speaker in place.
The grill is printed to size and can be used when developing your enclosure design as well as for a template for
drilling the holes when you are building your enclosure. The recommended drill size is 6mm, except for the three
outer points, which may need to be different depending upon how these are used to secure the speaker.

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Design
Develop your ideas to produce a design that meets the requirements listed in the specification.
Name……………………………………………… Class………………………………

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Design Review (group task)
Split into groups of three or four. Take it in turns to review each person’s design against the requirements of their
specification. Also look to see if you can spot any additional aspects of each design that may cause problems with the
final product. This will allow you to ensure that you have a good design and catch any faults early in the design
process. Note each point that is made and the reason behind it. Decide if you are going to accept or reject the
comment made. Use these points to make improvements to your initial design.
Comment
Reason for comment
Accept or Reject

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Soldering in 8 Steps
Place soldering iron tip on the pad.
Make sure the soldering iron has warmed up. If necessary use a
brass soldering iron cleaner or damp sponge to clean the tip.
Pick up the Soldering Iron in one hand, and the
solder in the other hand.
CLEAN SOLDERING IRON
2
PICKUP IRON AND SOLDER
3
HEAT PAD
4
Place the component into the board, making sure that it goes in the
correct way around, and the part sits closely against the board.
Bend the legs slightly to secure the part. Place the board so you can
access the pads with a soldering iron.
INSERT COMPONENT
1

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Feed a small amount of solder into the joint. The solder
should melt on the pad and flow around the component leg.
Remove the solder, and
then remove the soldering
iron.
Leave the joint to cool for a few seconds, then using a
pair of cutters trim the excess component lead.
APPLY SOLDER
5
STOP SOLDERING
6
TRIM EXCESS
7
REPEAT
8
Repeat this process for each solder joint required.

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Resistor Values
A resistor is a device that opposes the flow of electrical current. The bigger the value of a resistor, the more it
opposes the current flow. The value of a resistor is given in Ω (ohms) and is often referred to as its ‘resistance’.
Identifying resistor values
Band Colour 1st Band 2nd Band Multiplier x Tolerance
Silver  100 10%
Gold  10 5%
Black 0 0 1
Brown 1 1 10 1%
Red 2 2 100 2%
Orange 3 3 1000
Yellow 4 4 10,000
Green 5 5 100,000
Blue 6 6 1,000,000
Violet 7 7
Grey 8 8
White 9 9
Example: Band 1 = Red, Band 2 = Violet, Band 3 = Orange, Band 4 = Gold
The value of this resistor would be:
2 (Red) 7 (Violet) x 1,000 (Orange) = 27 x 1,000
= 27,000 with a 5% tolerance (gold)
= 27KΩ
Resistor identification task
Calculate the resistor values given by the bands shown below. The tolerance band has been ignored.
1st Band 2nd Band Multiplier x Value
Brown Black Yellow
Green Blue Brown
Brown Grey Yellow
Orange White Black
Too many zeros?
Kilo ohms and mega
ohms can be used:
1,000Ω = 1K
1,000K = 1M

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Calculating resistor markings
Calculate what the colour bands would be for the following resistor values.
Value 1st Band 2nd Band Multiplier x
180 Ω
3,900 Ω
47,000 (47K) Ω
1,000,000 (1M) Ω
What does tolerance mean?
Resistors always have a tolerance but what does this mean? It refers to the accuracy to which it has been
manufactured. For example if you were to measure the resistance of a gold tolerance resistor you can guarantee
that the value measured will be within 5% of its stated value. Tolerances are important if the accuracy of a resistors
value is critical to a design’s performance.
Preferred values
There are a number of different ranges of values for resistors. Two of the most popular are the E12 and E24. They
take into account the manufacturing tolerance and are chosen such that there is a minimum overlap between the
upper possible value of the first value in the series and the lowest possible value of the next. Hence there are fewer
values in the 10% tolerance range.
E-12 resistance tolerance (± 10%)
10
12
15
18
22
27
33
39
47
56
68
82
E-24 resistance tolerance (± 5 %)
10
11
12
13
15
16
18
20
22
24
27
30
33
36
39
43
47
51
56
62
68
75
82
91

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Capacitor Basics
What is a capacitor?
A capacitor is a component that can store electrical charge (electricity). In many ways, it
is like a rechargeable battery.
A good way to imagine a capacitor is as a bucket, where the size of the base of the
bucket is equivalent to the capacitance (C) of the capacitor and the height of the bucket
is equal to its voltage rating (V).
The amount that the bucket can hold is equal to the size of its base multiplied by its
height, as shown by the shaded area.
Filling a capacitor with charge
When a capacitor is connected to an item such as a battery, charge will flow from the battery into it. Therefore the
capacitor will begin to fill up. The flow of water in the picture above left is the equivalent of how the electrical
charge will flow in the circuit shown on the right.
The speed at which any given capacitor will fill depends on the resistance (R) through which the charge will have to
flow to get to the capacitor. You can imagine this resistance as the size of the pipe through which the charge has to
flow. The larger the resistance, the smaller the pipe and the longer it will take for the capacitor to fill.
Emptying (discharging) a capacitor
Once a capacitor has been filled with an amount of charge, it will retain this charge until it is
connected to something into which this charge can flow.
The speed at which any given capacitor will lose its charge will, like when charging, depend on
the resistance (R) of the item to which it is connected. The larger the resistance, the smaller the
pipe and the longer it will take for the capacitor to empty.
Maximum working voltage
Capacitors also have a maximum working voltage that should not be exceeded. This will be
printed on the capacitor or can be found in the catalogue the part came from. You can see
that the capacitor on the right is printed with a 10V maximum working voltage.
C
V
R
BATTERY
V
R
BATTERY CAPACITOR
R
C

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Ceramic Disc Capacitors
Values
The value of a capacitor is measured in Farads, though a 1 Farad capacitor
would be very big. Therefore we tend to use milli Farads (mF), micro Farads
(F), nano Farads (nF) and pico Farads (pF). A F is a millionth of a Farad, 1F
= 1000 nF and 1nF = 1000 pF.
The larger electrolytic capacitors tend to have the value printed on the side of
them along with a black band showing the negative lead of the capacitor.
Other capacitors, such as the ceramic disc capacitor shown on the right, use a
code. They are often smaller and may not have enough space to print the
value in full, hence the use of the 3-digit code. The first 2 digits are the first
part of the number and the third digit gives the number of zeros to give its
value in pF.
Example: 104 = 10 + 0000 (4 zero’s) = 100,000 pF (which is also 0.1 F)
Work out what value the four capacitors are in the table below.
Printing on capacitor Two digit start Number of zero’s Value in pF
222
103
333
473
1F
= 1,000mF
1F
= 1,000,000F
1F
= 1,000,000,000nF
1F
= 1,000,000,000,000pF

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Instruction Manual
Your amplifier is going to be supplied with some instructions. Identify four points that must be included in the
instructions and give a reason why.
Point to include
:
Reason:
Point to include
:
Reason:
Point to include
:
Reason:
Point to include
:
Reason: