D&T: Electronics and Control Systems
Unit A511: Introduction to designing and making
Name: Luke Farrell
Candidate number:
Centre Number: 16527
Reasons for theme choice
I have chosen security as my theme choice as the crime rates in the UK are increasing, I am making a heat
sensor for people that go out a lot and leave their house vulnerable for burglaries. The heat sensor will be
able to detect if anyone is in the house by detecting the heat they give off naturally. This is a very good
way of detecting people as it is quite hard to cover up. I have also picked the theme security as the crime
rate in Essex and other county's have risen.
Creativity (slide 2)
Theme Choice
• Choose and state the theme for the project.
• Explain why you have chosen it.
• Use a mind map (spider diagram) explore possibilities. Show a range of possible
problems and situations related to the theme.
• For example:
This could be hand
drawn and scanned
into your presentation
•
Choose one to develop for your project – show your choice on the chart
violence
Hard to stop
Investigation of Users’ Needs
My alarm will be used to stop/put off burglars from stealing your
household possessions
what
It could be
used at night
when the
owner is asleep
or out
My alarm will
be used in a
corridor were
the burglar
would walk
through to
detect the
heat given off
by them
The owner of a
household/office
will use this
alarm
how
The owner of the house will put the heat sensor
on a wall next to a entrance into the house or
window which will detect the heat of a person
when entering the room/corridor
So that they owner will feel a
little more secure in their
house, without the need to
worry about their belongings
being stolen or from being
attacked
Heat sensors are used all the time n many different ways. Eg: they are used in
earthquake wreckages to find people by locking on to there heat levels, And
they are also used in the customs looking for illegal immigrants in the back of
cars or lorries.
There are different types of heat sensors This is a table from
(http://www.engineeringtoolbox.com/temperature-sensors-d_448.html)
showing the different types and the different features.
Creativity (slide 4)
Users Needs
• What does the user need to solve the problem you have identified?
• Evidence that there is a need (WHAT):
–
–
•
Evidence of users (WHO):
–
–
•
Annotated pictures
Newspaper clippings describing what happened (most articles will state what happened, who it
happened to and probably where.
Brief survey
People in newspaper clippings
Evidence of the situation (WHERE)
–
Pictures showing where there might be a problem and where the solution you propose might be used.
Circuit with pcb
Creativity (slide 5)
Carry out a brief questionnaire
• Produce 10 questions that will help discover information that will show that people
exist who have the problem you are exploring.
• Get 10 people to answer your questions.
• Ask questions to identify WHAT the problem might be.
• Ask questions to identify WHO might have the problem and might want your
product.
• Ask questions to identify WHEN and WHERE the problem might be.
• Ask questions to identify the nature of the possible solution. (This might help you
draw up your specification.
• Don’t forget to explain why you ask each question – don’t ask pointless questions
that you will not learn anything from.
• Make sure you do a tally of the results and explain what they show
survey
1.How many rooms do you have ?
2.Is your house isolated?
3.Has your house ever been burgled?
4.Have you got many valuables?
5.How many neighbours do you have?
6. How many rooms have valuables
7. Which room would you put the alarm in?
8.How many people live in your house?
9.Do you already own a burglar alarm.
14
15
17
18
15
Yes
yes
no
no
no
Yes
no
no
no
no
Yes
yes
yes yes
yes
0
0
1
2
1
all all
5
10
all
19
no
yes
yes
2
8
16
no
no
yes
1
10
15
14 14
no no
no
no
no
no
yes
yes
yes
2
1
1
9
10
7
questionaire
How many rooms are in your house
Creativity (slide 6)
Product Comparison
• Analysis of products related to the theme.
• Three pictures of products related to the theme. The analysis should show a trend,
such as cost complexity or type of user. (Probably 3 different types of security
device.)
• The table below could be used. (See the next page for some examples)
Product
Name and
picture of
product 1
Name and
picture of
product 2
Name and
picture of
product 2
Cost
Typical user
When / Where
used?
Function
Technology
used
(Input / Output)
Manufacturing
process used
Examples of products for comparison (all alarms of some sort)
Remember these are examples – you need to get your own
Product Description – Personal Attack Alarm (£5.99) - From Amazon
Tiny matchbox sized attack alarm with a useful key ring attachment. Simply pull pin out to activate
alarm. Emits 130 decibel siren Supplied with alkaline battery 5 year no-quibble guarantee. Size: 4.4 x 3.8
x 1.6cm Weight: 20gms .
From Amazon
Product Description – Carbon Monoxide Alarm (£16.66) - From Amazon
Requires 3 X AA Batteries, LCD Display, Approved Test and hush button Alarm memory function, Audio
and visual Alarm, Self test function, Highly accurate carbon monoxide detection, Audibility: 85DB @ 1
metre distance Sound and LED indication Standby: Green LED flashes once every 30 seconds Alarm: Red
LED flashes quickly with alarms sounding every 5 seconds and repeat Low battery indicator: Sounds every
30 seconds when batteries are lower than 3.3v with green LED, Malfunction indicator
Product Description – Cold Alarm for Old People (£27.50) - From Amazon
Keep warm and stay safe with this affordable and effective alert to the dangers of falling temperatures.
Particularly useful for the elderly and less mobile, who are often especially vulnerable and cannot
always detect or respond to getting cold, this Cold Alarm provides early warning of colder conditions in
the home, so you can take simple steps to prevent ill health. The Cold Alarm delivers early warning of
falling temperatures in the form of an easy-to-understand traffic light style LED display, which is backed
up by an audible alarm at the lowest temperatures. Green light flashing every 10 seconds shows that
the temperature is above 18°C : considered normal safe environment;
Amber light flashing indicates that the temperature is between 12°C and 18°C :take action to increase
warmth;
Red light flashing warns of a dangerously low temperature of between 7°C and 12°C : there could be a
risk of hypothermia, need to take action;
Red light flashing and beeping alarm alerts to immediate danger of a temperature below 7°C :
dangerously cold.
sensors/alarms
This is a great little security wireless camera with night
vision using infra red led's. Can see up to 10m. This
camera transits wireless images to its owner up to a
range of 20m.
This security keypad door lock is great to keep you feeling
more secure about not having your shed or house burgled.
With no wires this device becomes far more easy to use And
is very cheap to get
These cctv systems are very useful in keeping an eye
on what happens around your house. It is easy to
setup and use and comes with 4 cameras. Even though
it costs a lot it is very useful.
Creativity (slide 7)
The Design Brief
• Summarise what you have found out so far in terms of there being a definite
situation, a recognised problem and people who have a need for what you could
design to help them.
• Write a clear Design Brief that describes clearly what you are going to design and
make.
• Write down what you need to do next or find out next e.g.
–
–
–
Decide in detail what your circuit is going to need to do to solve the problem.
What circuits and components might be available for you to use.
What software you have available to you, to help you solve the problem and design a solution.
Creativity (slide 8)
Product Analysis
• Analyse in detail 2 products related to your project (probably 2 different types of
burglar alarms, one fairly simple and one a little more complex.)
• Use the table on the next slide to help you organise the information.
A simple system for
the hotel room on
holiday.
A more complex
system for the
home.
Name and picture of product 1
Name and picture of product 2
Yale wirefree Premium Alarm Kit HSA6400
Friedland Response SL5 Wirefree
Telecommunicating Alarm System
Function
A house burglar alarm, once set off will contact you
once it has been set off.
A functional burglar alarm, that contacts up to 3
numbers once set off.
User need
fulfilled
It has a loud alarm and is easy to install.
A loud alarm that protects your house from being
burgled .
Materials used
in construction
abs and screws with copper and solder with the
circuit board.
Abs, screws and copper solder with the circuit board
Durability of
product
It is very durable as it has long life lithium batteries.
It is very durable
Sustainability
(6Rs)
It is recyclable and reusable.
This product is recyclable and reusable
Life cycle
It can be recycled and the components can be
melted down or reused.
It can be recycled and the components can be melted
down to be reused
Energy use
A lithium battery
A lithium battery
Use 10 or 12 point
text in this table
Creativity (slide 9)
Name and picture of product 1
Function
User need
fulfilled
Materials
used in
construction
Durability of
product
Sustainability
(6Rs)
Life cycle
Energy use
Name and picture of product 2
Design (slide 10)
The Specification
• Summarise the information to produce a list of points that describe what your
“product” will need to be like to solve the problem.
• Remember that you are only describing what the circuit will need to do to solve the
problem.
• This list of points is the “specification”
• Function:
–
–
–
–
•
•
•
What it needs to sense – inputs
What it needs to do when whatever is sensed – output
Include any timings if appropriate – delays etc.
Include indicators etc.
Power supply.
Safety features.
Manufacture / construction.
Do specification!
specification
Feature described
Reason for feature
To protect a house from burglars.
So that the owner doesn’t feel the need to worry about any
of their possessions being taken from their house by any
burglars or to be worrying about the threat of attack as the
alarm will detect the person coming into their house and will
turn on a siren which will alert the owner.
To detect heat given off by a burglar.
Because heat sensors are very sensitive and hard to get
around is you will always be giving off heat from your body.
To sense heat that the person gives off.
Because the alarm system I will be making will rely on a heat
sensor to stop the burglar from stealing your stuff.
The output will be a loud siren.
The reason for the loud siren will be because, it can either
wake up the house owner or alert the neighbours or any
passers by, that the house is being burgled.
The power supply will be a battery.
It will be a battery because it will be hard to cut off the power
if the burglar tries to stop the alarm because the battery will
be inside the alarm.
The room will have to be dark.
The reason for the room having to be dark, is mainly because
burglars have a trend to rob people at night, so if the alarm is
turned on at night it will only go on when it is dark and when
the burglar is detected.
There will be a transistor in my circuit
The reason for me using a transistor in my circuit is that they
are cheap and reliable to set the siren off if anyone walks into
the room/corridor without turning the alarm off.
My alarm will be compact
My alarm will be compact so that it will be hard to notice
when the burglar breaks into your house, it will also be cheap
and easy to manufacture.
My alarm will be high up
The reason for this is so that my alarm will be even harder to
notice if you don’t already no it is there and it is also a easy
place to detect heat from, as it will stay colder higher up so
when the burglar breaks in he will be even more easier to
detect.
I will be using circuit wizard
The reason for me using circuit wizard to develop my circuit is
so that, I will be able to design it and see how it works on a
program before I start manufacturing my alarm.
Design (slide 11)
System Diagram
• Show a systems chart to show possible inputs, outputs and processes.
• Show pictures of the components required for each input or output mentioned.
Delay
before
INPUT
Time
delay
between
power on
and input
sensed?
INPUT
List of possible things
that could be sensed +
images of possible
components.
Combine
inputs?
Delay
after
INPUT
PROCESS
More than
one input
that needs
combining
? – e.g.
AND or
OR?
Time delay
after input
sensed?
List of possible ways
that the output can be
controlled.
Delay
before
OUTPUT
Time delay
before the
output is
turned on.
OUTPUT
List of possible
outputs ( include
power indicators
etc.) + images of
possible components
Delete these instructions
from your table.
•
Do not include combining inputs and delays if not appropriate to what you are
designing – although you could use the columns to show that the response is
immediate. (i.e. 0 seconds.)
System diagram
Security alarm ideas , e.g. burglar alarms or
personal safety
Delay
before
INPUT
0
INPUT
Heat
sensors(cold/hot)
Combine
inputs?
Dark
sensor
probes
Delay
after
INPUT
PROCESS
Delay
before
OUTPUT
OUTPUT
10
Transistor/mosfet
0
Siren and flashing
LED
3
transistor
0
Flashing LED and
alarm e.g. siren
Ptm/ptb switch
Dark
sensor
10
Transistor/mosfet
0
siren
Reed switch
Heat
sensor
10
Transistor/mosfet
0
Siren with flashing
LED
Latch switch
Dark
sensor
10
Transistor/mosfet
0
siren
Light
sensors(light/dark)
Ptm
switch
10
Transistor/mosfet
0
Siren
I will also have a flashing LED on my circuit
Design (slides 12 and 13)
Slide 10 – Ideas for the circuit
• Include 3/4 circuits that could solve the problem:
– Picture of each circuit – from internet, hand drawn and scanned in or from circuit wizard.
– Brief description of the circuit saying what does in terms of what it senses and how it
controls its outputs.
– How well it could it solve the problem?
Slide 11 – Development of the chosen circuit
• Choose one circuit and give your reasons for choosing it.
• Build it in circuit wizard
– Show screen shots of the circuit being developed – component values being changed to
fine tune the way it works (especially in terms of timing delays etc.)
– Show annotated screen shots of the circuit being tested to show that it will work and that
it will solve the problem.
• It is important that at least three annotated stages are shown of the circuit
being developed, that the screen shots show it working so that it is clear
that it solves the problem.
3-4 circuits that can solve the problem of burglars
This is a basic heat sensor alarm that is used to detect if there
is a person/burglar in the your house if your asleep/out, it is
useful as heat sensors are very effective to catching out burglar
sneaking around your house, as it is very hard to stop
producing heat from your body as your body is constantly at
average temperature of 37.2, whilst room temperature is 17.5
that is a big difference that the temperature sensor detects
that will set the alarm off. However this alarm doesn't’t have a
big radius for the heat detecting so you will have to get a few
to cover the whole house.
This is a ptm pressure pad/mat burglar alarm, this alarm
detects the pressure created after a a person has trodden onto
the pressure pad/mat which the circuit will detect and activate
the siren which will attempt to startle the burglar, and wake up
the house owner if in. this alarm I hard to not set off as it can
be hidden very easily e.g. under doormats, with this alarm
being hidden there is a very likely chance that the burglar will
step on the ptm switch which will turn on the siren. However
you will need a lot of these alarms near all your
windows/doors if you want to cover the whole house and it is
not spread over a large area so they have a chance of jumping
over your alarm bearing it useless.
Part 2 ¾ circuits to solve the problem of burglars
Design (slide 14)
Development of the PCB
• Show the stages of the development of the finished circuit into the final
PCB
• You must show at least 3 stages of development.
• Each stage must be annotated to describe the changes and the reasons for
them.
• The final PCB must be shown including the off board components and the
connecting wires – it would be a good idea to label this final stage.
• The list of components must be included – images of the components to be
used could get extra marks. (from earlier in the project?)
Figure 1
Figure 2
My circuit
Figure 3
Figure 4
Figure 5
•Figure 1 shows my circuit after has been turned into a pcb with the copper background,
it also shows a error (green line), and 2 blue wires which show that the circuit was
unable to link the components with the copper tracks.
•Figure 2 shows my circuit with the copper background deleted, it also shows a
error(green line) this is show that some components have been able to connect together.
It also shows 2 of the blue wires that means I still haven’t connected the components.
•Figure 3 shows the circuit with the error being corrected by me turning on interactive
routing and moving all the components around to make them all connect together. It
also shows that I have managed to link the two components up with copper tracks (no
blue lines)
•Figure 4 shows my circuit being shrunk in size as I moved all the components closer
together and also decreased the size of the circuit board, which will lower the cost of the
copper needed and make my circuit easier to make.
•Figure 5 shows my circuit being connected to a switch and a 9v battery to give my circuit
a turn on/off switch and a power source, if I have a battery in my circuit it will also be
harder to turn off if a burglar tries to disable the alarm.
This is my circuit as a pcb, it
includes a logic gate which links
both of the inputs up, my logic
gate is a and gate as the room
or corridor the alarm is in will
have to be dark to turn on, and
the heat sensor will detect
when someone has entered
which will power up the
transistor, the transistor will
then boost the power up to
turn on the alarm which will
put off the burglar or alert the
owner.
Circuit components:
• 1 LED
• 1 siren/buzzer
• 1 logic gate (and)
• 1 thermsitor
• 1 dark sensor
• 1 resistor
• 1 9v battery
• 1 potentiometer
Making (slide 15)
Planning for manufacture
• Use the table below to describe how you plan to make your circuit.
• Use the information and pictures of equipment on my website to help you.
Description of Process
Tools/Materials required
Design PCB and create mask
Delete any of the processes
that don’t apply
Cut board to size
Expose Mask and photoPCB to UV
Develop exposed PCB
Etch PCB
Drill holes in solder pads
Add resistors
Add capacitors
Add transistors/thyristors
Add Chip socket
Add off board components
Add chip to socket
You need to add detail to this
column for each process
Tips for success
Planning the manufacture process
Process description
Equipment
requirement
Safety issues
Tips for success
Design PCB and mask
Circuit wizard
None needed
None needed
cut board to size
Band saw
The saw blade is sharp so don't put your
hands near it when its on
Make sure the measurements are
correct before you start cutting
Expose mask and photo PCB to UV light
UV light
Photo PCB
Mask of circuit
The UV light can damage your eyes so
cover your eyes
Expose the mask for 10 minutes
Develop exposed PCB
Development fluid
Use it gently as it could splash on to
your clothing
Wear gloves and goggles to protect your
hands and eyes from damage
Etch PCB
Bubble etch tank
etchant
The etchant is corrosive so take care
when using it and don’t get it on your
hands
Wear gloves and goggles to protect your
hands and eyes, leave the pcb in the
etchant for 1-2 minutes
Drill holes
Drill
Drill press-optional
Don’t put your hands to close to the
drill as it is dangerous
Make sure that you center the drill for
easy hole cutting
Solder resistors
Soldering equipment: soldering iron ,
solder and solder board
Don’t breathe in the gas given off from
the solder, don’t touch the tip of the
soldering iron as it is very hot
Hold the resistor in place and bend the
wires out at the bottom of the resistor,
use little solder
Solder capacitors
Soldering equipment: soldering iron ,
solder and solder board
Don’t breathe in the gas given off from
the solder, don’t touch the tip of the
soldering iron as it is very hot
Hold the capacitor in place, make sure it
is in the right way round and solder
quickly or it will overheat, use little
solder
Adding transistors
Soldering equipment: soldering iron ,
solder and solder board
Don’t breathe in the gas given off from
the solder, don’t touch the tip of the
soldering iron as it is very hot
Put the transistors in correctly, hold it in
place and use a little amount of solder
Add off board components
Soldering equipment: soldering iron ,
solder and solder board
Don’t breathe in the gas given off from
the solder, don’t touch the tip of the
soldering iron as it is very hot
Strip the wire from the ends of the
battery connector so that the wire is
touching the copper, use little amounts
of solder
Making (slide 16 to 18 - approx)
Manufacture of the circuit
• Include photographs to show the stages of the making of your circuit
• Annotate each picture to show what is happening.
• Highlight any problems that were encountered and what you did to solve the
problem or anything that you changed as the circuit was constructed (i.e. what is
different to what you planned. This is an important part of the mark scheme.
• In addition:
–
–
–
•
You must include a clear photo of the whole circuit including the off board components and the
connecting wires.
You must include a clear photo of the top side of the PCB showing the components.
You must include a clear photo of the underside of the PCB showing the soldered joints.
To ensure the marks for problem solving are gained it might be best if the changes
mad and the problems encountered are summarised at the end of this section.
Here I soldered my wires on the
wrong sides of the LED and I had
shrink wrapped it so I had to redo
a different LED.
This is my buzzer with the exposed
wire tinned to make the wire
stronger and easier to solder.
This is me stripping some wire to
expose the individual wires inside
ready to be tinned.
This is some flexible wire cut to a
length of 15cm and is ready to be
stripped.
This is my power switch that will
turn on the circuit.
Evaluation (slide 19)
Testing your circuit
• Show a step by step plan that can be used to test your finished circuit.
Write it as if it were for a person who does not know how it is supposed to
work.
• Tick of each step to show that the circuit works.
Evaluation
• Describe what went well and what did not go so well in the manufacture of
your circuit
– Consider the development of the circuit and the development of the PCB
– Consider the actual building of the circuit
•
•
•
•
Could it have been made differently? – alternatives?
Could it have been made better? – how?
Compare what you did to the steps of your plan
See table on next slide as a suggestion.
Evaluation (slide 20)
Evaluation (continued)
Description of Process
What went well
Problems encountered/changes
made
Design PCB and create
mask
Cut board to size
Expose Mask and
photoPCB to UV
Develop exposed PCB
Etch PCB
Drill holes in solder pads
Add resistors
Add capacitors
Add transistors/thyristors
Add Chip socket
Add off board components
Add chip to socket
Copy the planning table and edit as
required.
Comments only need to be brief.
Action taken to deal with
problem
Evaluation (slide 21)
Improvements
• In addition to describing how the circuit could have been manufactured
better;
• Describe how the circuit could be improved to function better to solve the
problem more effectively.
–
–
–
–
Different inputs
More inputs
Different control of the outputs
Different outputs