Kitronik 2121 Quick start guide

PROGRAMMABLE TIMER KIT
CREATE YOUR OWN
UNQUIE
TIMER WITH THIS
TEACHING RESOURCES
SCHEMES OF WORK
DEVELOPING A SPECIFICATION
COMPONENT FACTSHEETS
HOW TO SOLDER GUIDE
Version 2.0

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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
Design
Design Review (group task)
Soldering in Ten Steps
Resistor Values
LEDs & Current Limit Resistors
Why use a PIC micro-controller?
Instruction Manual
Evaluation
Packaging Design
ESSENTIAL INFORMATION
Build Instructions
Build Instructions continued
Checking Your Programmable Timer PCB
Testing the PCB
Fault Finding
Fault Finding continued
Designing the Enclosure
Possible student programming tasks
How the programmable timer works
Online Information

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Introduction
About the project kit
Both the project kit and the supporting material have been carefully designed for use in KS3 Design and Technology
lessons. The project kit has been 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 contains information to aid the teacher in planning their lessons and also covers
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, hence there being no page numbers, teachers can pick and choose as they see 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 timing products that are currently on sale. These may include
clocks, watches, stop watches etc. List the common features that make these suitable for their
intended use.
Hour 2
Develop a specification for the project using the ‘Developing a Specification’ sheet.
Resource: Sample timing products.
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
Split the students into groups and get them to perform a group design review using the ‘Design
Review’ sheet. Start the ‘Resistors’ sheet.
Homework: Complete any of the remaining resistor tasks.
Hour 5
Using the ‘How to solder’ sheet dem
onstrate and get students to practice soldering.
Hour 6
Build the electronic kit using the ‘Build Instructions’.
Hour 7
Complete the build of the electronic kit. Check the completed PCB and fault find if required using
‘Checking Your Timer PCB’ and fault finding flow charts.
Homework: Read ‘How the Timer Works’ sheet.
Hour 8
Programming task 1
–
The basic timer.
Hour 9
Programming task 2
–
The timer with time up warning bleeps.
Hour 10
Using cardboard get the students to model their enclosure design. A
llow them to make alterations
to their design if the model shows any areas that need changing.
Hour 11
Build the enclosure.
Homework: Collect some examples of instruction manuals.
Hour 12
Build the enclosure.
Homework: Read ‘Instructions’ sheet and start developing instructions for the student’s timer
design.
Hour 13
Build the enclosure.
Homework: Complete instructions for the student’s timer design.
Hour 14
Using the ‘Evaluation and Improvement’ sheet, get the students to evaluate their final prod
uct and
state where improvements can be made.


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AdditionalWork
Programming tasks,
 Task 3 - User configurable delay
 Task 4 - Musical
Package design for those who complete ahead of others.
Electronics only
Hour 1
Introduction to the kit demonstrating a
built unit. Using the ‘How to solder’ sheet practice
soldering.
Hour 2
Build the kit using the ‘Build Instructions’.
Hour 3
Check the completed PCB and fault find if required using the ‘Checking Your timer PCB’ and fault
finding flow charts.
Hour 4
Pr
ogramming task 1
–
The basic timer.
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

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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 clock manufacturer has designed a simple timer. The timer will
be very cheap to produce and can be used for applications that do
not require split second accuracy.
The manufacturer can think of a great many applications that the
timer could be used for, such as for timing peoples turns on a
board game.
The manufacturer would like you to research and select a
particular use for the timer. They would then like you to produce a
design that is suitable for that use. The design must meet all the
requirements of the selected target market.
Description of the Timer
Once the timer is started it waits for a period of time and then produces a tone using a sounder. As the timer is
programmable the duration of the timer and how long it sounds for can be adjusted. A push button switch is used to
start the timer.
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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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 Ten Steps
1. Start with the smallest components working up to
the taller components, soldering any interconnecting
wires last.
2. Place the component into the board, making sure
that it goes in the right way around and the part sits
flush against the board.
3. Bend the leads slightly to secure the part.
4. Make sure that the soldering iron has warmed up
and if necessary, use the damp sponge to clean the
tip.
5. Place the soldering iron on the pad.
6. Using your free hand, feed the end of the solder onto
the pad (top picture).
7. Remove the solder, then the soldering iron.
8. Leave the joint to cool for a few seconds.
9. Using a pair of cutters, trim the excess component
lead (middle picture).
10. If you make a mistake heat up the joint with the
soldering iron, whilst the solder is molten, place the
tip of your solder extractor by the solder and push
the button (bottom picture).
Solder joints
Good solder joint Too little solder Too much solder

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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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LEDs & Current Limit Resistors
Before we look at LEDs, we first need to start with diodes. Diodes are used to control the direction of flow of
electricity. In one direction they allow the current to flow through the diode, in the other direction the current is
blocked.
An LED is a special diode. LED stands for Light Emitting Diode. LEDs are like normal diodes,
in that they only allow current to flow in one direction, however when the current is
flowing the LED lights.
The symbol for an LED is the same as the diode but with the addition of two arrows to
show that there is light coming from the diode. As the LED only allows current to flow in
one direction, it's important that we can work out which way the electricity will flow. This
is indicated by a flat edge on the LED.
For an LED to light properly, the amount of current that flows through it needs to be controlled. To do this we use a
current limit resistor. If we didn’t use a current limit resistor the LED would be very bright for a short amount of
time, before being permanently destroyed.
To work out the best resistor value we need to use Ohms Law. This connects the voltage across a device and the
current flowing through it to its resistance.
Ohms Law tells us that the flow of current (I) in a circuit is given by the voltage (V) across the circuit divided by the
resistance (R) of the circuit.
R
V
I=
Like diodes, LEDs drop some voltage across them. For a high brightness white LED this is 3.5 volts.
Suppose this LED is run off a 5V supply there must be a total of 5 volts
dropped across the LED (VLED) and the resistor (VR). As the LED
manufacturer’s datasheet tells us that there is 3.5 volts dropped across
the LED, there must be 1.5 volts dropped across the resistor. (VLED + VR =
3.5 + 1.5 = 5V).
LEDs normally need about 10mA to operate at a good brightness. Since
we know that the voltage across the current limit resistor is 1.5 volts and
we know that the current flowing through it is 0.01 Amps, the resistor can
be calculated.
Using Ohms Law in a slightly rearranged format:
=== 150
01
.
0
5.1
I
V
R
Hence in this circuit we would need a 150Ω current limit resistor.
R
V BATTERY
I LED
V LED
V R

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LEDs Continued
Packages
LEDs are available in many shapes and sizes. The 5mm round LED is the most common. The colour of the plastic lens
is often the same as the actual colour of light emitted – but not always with high brightness LEDs.
Advantages of using LEDs over bulbs
Some of the advantages of using an LED over a traditional bulb are:
Power efficien
cy
LEDs use less power to produce the same amount of light,
which
means that they are
more efficient. This makes them ideal for battery power applications.
Long life
LEDs have a very long life when compared to normal light bulbs.
They also fail by
gradually dimming over time instead of a sharp burn out.
Low temperature
Due to the higher efficiency of LEDs
,
they can run much cooler than a bulb.
Hard to break
LEDs are much more resistant to mechanical shock
,
making them more diffi
cult to break
than a bulb.
Small
LEDs can be made very small. This allows them to be used in many applications
,
which
would not be possible with a bulb.
Fast turn on
LEDs can light up
faster than normal light bulbs, making them i
deal for use in car break
lights.
Disadvantages of using LEDs
Some of the disadvantages of using an LED over a traditional bulb are:
Cost
LEDs currently cost more for the same light output than traditional bulbs.
However, t
his
needs to be balanced against the lower running cost of LEDs due to their greater efficiency.
Drive circuit
To work in the desired manner
,
an LED must be supplied with the correct current. This could
take the form of a series resistor or a regulated power supply.
Directional
LEDs normally produce a light
that is focused in one direction
,
which is not ideal for some
applications.
Typical LED applications
Some applications that use LEDs are:
 Bicycle lights
 Car lights (break and headlights)
 Traffic lights
 Indicator lights on consumer electronics
 Torches
 Backlights on flat screen TVs and displays

Road signs
 Information displays
 Household lights
 Clocks

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Why use a PIC micro-controller?
This timer could be built using two 555 timers instead of the micro-controller. The 555 timer circuit needs lots of
extra components to work and as a result it is bigger. This can be clearly seen if you look at the two circuit diagrams
below. The one on the left is the 555 timer based circuit (19 parts) and the one on the right is the micro-controller
based circuit (11 parts).
There are a number of other advantages of using a micro-controller; some of these are outlined below.
Advantages of using PIC micro-controllers:
 Complex functionality can be produced a very low cost.
 Circuit size (as described above).
 It is very easy to make minor alterations to the function of the product.
o These include changing the length of the delays and the duration of sounds.
o The ability to change the tone of the buzzer and even play musical tunes if so desired.
 Flexibility. The circuit could easily be used for a completely different function by simply re-writing the
software.
Easy to develop and debug. Most software packages allow you to simulate the software while it is being developed
making it much more likely to work when used. It is also possible to break the functionality down into small steps
which is easier to get right then jumping straight to the final design

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Instruction Manual
Your programmable timer 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:

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Evaluation
It is always important to evaluate your design once it is complete. This will ensure that it has met all of the
requirements defined in the specification. In turn, this should ensure that the design fulfils the design brief.
Check that your design meets all of the points listed in your specification.
Show your product to another person (in real life this person should be the kind of person at which the product is
aimed). Get them to identify aspects of the design, which parts they like and aspects that they feel could be
improved.
Good aspects of the design
Areas that c
ould be improved
Improvements
Every product on the market is constantly subject to redesign and improvement. What aspects of your design do you
feel you could improve? List the aspects that could be improved and where possible, draw a sketch showing the
changes that you would make.

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Packaging Design
If your product was to be sold in a high street electrical retailer, what requirements would the packaging have? List
these giving the reason for the requirement.
Requirement
Reason
Develop a packaging design for your product that meets these requirements. Use additional pages if required.