D&T: Electronics and Control Systems
Unit A511: Introduction to designing and
making
Name:
Candidate number:
Centre Number: 16527
The theme I have chosen to do is security
The reasoning for me choosing security as my theme is mainly because
when ever I watch the news or read a newspaper I always seem to find one
article about burley in their some where, also another main reason of more
pressing on concern is that just last year the house over the road from
where I live was burgled while they where inside it because they didn’t have
an alarm
Orangeis
the area I
have
chosen to
do
Motion
senor
connected
to a flashing
led which is
connected
to a speaker
Pressure
senor on a
door mat or
a some
windows to
detect
changes in
weight
Buzzer that produces a
load notice when either
input goes off so people
can tell that there's a
shed being robbed
Flashing led to people
can tell it’s your shed
that’s being robbed
Protect sheds
in crowed area
Shed alarm
Surveys
stop them
from dying
In the bath
because the
water is hot
Baby bath
temp alarm
Market research
To be able to tell
if it Is worth
investing in the
area
Marketing
Security
Areas of
crime
Feeling
secure
Heat senor
Goldie
locks
circuit??
Fake
cctv
Alarm which goes of
when temp gets to high
Fake alarm boxes
with LED on them
which flash
Area of crime are
good marketing
areas because
people will more
likely want to
protect
Investigation of user needs
How: this alarm would
work in the dark
because that is when
they will most likely
burgle you and be able
to detect changes in
heat such as when a
burgle comes into a
room
Why: people would want
this because they would
want to protect the things
in there shed with out
having to be out there
guarding it thought out the
day and night
When: People who would usually
want a shed alarm are people
that go on holiday or that they
live in a enclosed area which has
had a lot of burglaries or perhaps
they would set a their shed
alarm when they go to sleep at
night there afraid of being
robbed in the night and not
being able to hear it happening
from their room
Where:
Usually people who
live in a crowed area
or some where in a
isolated area like this
images
Question air
•
1. Do you live in a area with a lot of houses and do you own a shed- why because if you live in a crowed area you might and
you don’t have a shed alarm you might be burgled because you’re a easy target?
•
2.do you live in a area of crime-because my survey has sated that quite a few people have been burgled in the last few
months which would state that there Is a gap in market for these kinds of alarms.
•
3. How valuable is the content of your shed-because the if the person doesn’t own very valuable items In there shed then
the buyer wont see the value of an alarm because they wont mind losing their items because they can properly claim it on
insurance
•
4.Is the police force where you live good
•
5.have there been robberies in your area lately –survey to found out if it’s worth selling in this area?
•
6.would you buy a easy fit alarm-some people don’t like the complicated ones?
•
7. would you buy this product if some one came around and fitted it for you-some people are more likely to buy it if they
don’t have to do any work?
•
8. what would prefer? (Please circle your answer)
A flashing LED with a siren just a flashing LED just a Led just a pressure plate or a pressure plate connected to a flashing LED
and a siren Just a pressure plate and a siren just a pressure pate and led or just a pure sure plate and a flashing led
9. Do you live a secluded area?- from investigation of user needs I an see that secluded areas are more likely to get burled
10. How much would you pay for a alarm? (Please circle your answer)
£10 £30 £50 or £100 or more
Question
YES
NO
1
7
3
2
5
5
3
4 people said quite
valuable things
where being kept in
their shed
6 said not very
valuable things
where being kept in
their shed
4
10
5
3
7
6
10
0
7
10
8
7 said a flashing led
with a siren
9
6
4
10
7 people said up to
£30
3 said more then
the max listed
product
cost
Typical
user/when
where
function
Technology
used (input/
output
Manufacturi
ng process
used
NIKKAI EASY FIT
CAR ALARM
SYSTEM KIT + 2
REMOTE KEYFOBS
29.99
A typical user is
anyone that ones a
car it will most
properly used by
people that either
leave there car in a
car park a lot or
some one that lives
in the city
The function
Of this alarm is to
go off when a
amount of peruse
is applied to the
window or if it is
broken
The technology
used is a
speakers and
some led which
are triggered by
touch
Polostirsine
plastics
Honeywell Pet
Friendly Accenta
Pro Burglar Alarm
System
£151.00
A typical user is
anyone that
wants to
product a large
area of there
house
The function of
this alarm is that if
one of motion
sensors is
triggered then it
will go off flashing
a led and making
noise
The technology
is a motion senor
which is
connected to a
led and a
speaker which
goes of once
triggered and
stays on
ABS plastics
£189.00
A typical user is
properly any one
that lives in a
isolated area
because that alarm
can call the police as
soon as it’s activated
The function of
this alarm is to go
of when one of it’s
motion or heat
sensors are
triggerd this alarm
can only be rest by
a key code which is
The technology
used works on
motion and heat
sensors placed
around a house
and as soon as they
go off they call a
number which is
ABS plastics
Yale wirefree
Premium Alarm Kit
HSA6400
•
Identifying the trend
•
•
In slide 7 I showed you 3 eletrioncal alarm products all from amazon now in all these products their was a clear trend
That trend being that as the alarms got more and more specialised in what job they where doing the cost of buying the
device goes up we can quite clearly see this in slide 7 because the first alarm I shod you only costs around about £30.00,
where as the last one I showed you costs around 189.00 in most stores.
My explanation for this is that alarms that only serve one function are cheaper because they are easy to make where as
alarms that have many functions and product something in more ways then one cost more because they are harder to
manufacture and also to design
•
Examples of products
Product -Motion Sensor Alarm/ Home/ Garage/ Shed/ Extra Remote price- £7.40
This easy to install motion sensor alarm includes 2 remote control key-rings
5m range and wall mount.
The main unit requires 4 x AA batteries (not supplied) or alternatively, a 6V adaptor can be used
The remote units come supplied with 3 x AG13 button cell batteries
This is an ideal burglar deterrent
•
•
•
•
•
Fire angel CO-9D Digital Sealed for Life Carbon Monoxide Alarm Automatic self diagnostic check;7yr sealed for life Lithium battery;Loud
85dB alarm at 1 metre; Large Test & Silence button; Large multi-function digital screen and room thermometer.
7yr sealed for life Lithium battery
Loud 85dB alarm at 1 metre
Large Test & Silence button
Large multi-function digital screen and room thermometer.
•
Friedland Response SL2 Wire free Multi User Keypad Controlled Burglar Alarm System
•
•
•
•
•
Suitable for any home
Secure 868MHz technology
Comprehensive range of accessories
Tamper and jamming detection provides additional security and prevents interference from potential intruders
Energy saving solar siren
Helix mini personal alarm with rip cord
operation, 100db, EACH
function
This alarm’s job is to make a loud noise
when the cord is pulled
User needs fulfilled
People would buy this if they where going
out at night
Martials used in construction
polystyrene
Durability
This alarm is designed to brake as soon as
it is pulled so I don’t think it’s very
durable
Sustainability
This alarms casing would have been made
out of a plastic
lifecycle
The life cycle of this alarm is that I would
break as soon as some ones pulled the
cord
Energy use
Two nine volt batteries
Design brief
•
I am going to design a device that will sense a burglar breaking into a shed
•
The inputs I am thinking for using for this circuit will be a
-pressure mat to sense the burglar if comes any where near the door once the alarm is set
- heat senor because if some how gets past the pressure mat and into the shed we want to be able to detect him before he can
steel anything.
The outputs I plan to use for this circuit are a siren because if your asleep at the top of your house and your shed is at the bottom
of your garden your not likely to hear any one breaking in.
-flashing LED the reason behind a flashing led is because most people in my survey results said that they would feel that a
flashing LED would attract more attention then just a bright red one.
The processes I plan to use to drive my circuit is a mosfet because that process has the largest electrical drive and the biggest gain
out of those choose able giving me more accurate results making my product more efficient getting me better results
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.
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
specification
•
•
•
•
•
•
The purpose of the my product is to be able to detect when some one is trying to breaking into your shed
while you sleep, a reason for this is that people that have a shed and want to keep it safe with out have to
be out there guarding it.
The product would be a alarm which would sound when the burglar enters your shed and then the alarm
would detect the changes in heat and or the pressure detect changes is light when he/she opens the door
once they have been detected a buzzer will sound on a latch and not turn of until the owner rests it.
Reasons for heat sensor- there effective at detecting people because vey one gives of heat so we can see if
thee in a room quite easily
Reason for pressure mats- they have to enter the shed some where so if place presser mats where there
more likely to enter so that way where more likely to find them and stop them bugling into peoples
homes.
Reason for latch- every one other alarm has one, also the reason for having a latch
The device would have to be small enough to be transportable with ease the circuit board would properly
be either in the shape of a rectangle or in the shape of a square Depending on the way we arrange it
Red is
what I
have
chosen to
do
Time delay
after battery
is
switched on
Possible
inputs
Combine
inputs
Delay
after
INPUT
PROCESS
Delay
before
OUTPUT
OUTPUT
Combined
outputs
Zero seconds
Motion
sensor
Pressure
and heat
seniors
Zero
seconds
Transisto
r
Zero
seconds
Buzzersiren
Siren and
LED
3 seconds
Temp
sensors
Heat
senor
and light
senor
3
seconds
Darlingto
n
pair
3
seconds
LED
Siren and
flashing
LED
4
seconds
Pressure
mat
Heat and
dark
senor
4
seconds
Mosfet
4
seconds
Flashing
LED
5
seconds
Dark senor
Humidity
and light
5
seconds
Transisto
r and a
comparat
or
5
seconds
6 seconds
Light
senor
Humidity
and dark
6
seconds
Thyristor
6
seconds
7 seconds
Humidity
senor
Motion
and light
7
seconds
7
seconds
Motion
and dark
8
seconds
8 second
8
seconds
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?
– Choose one circuit and give your reasons for choosing it.
Slide 11 – Development of the chosen circuit
• Build your chosen circuit in circuit wizard
– Show annotated 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.
– Include a video of it working using “Blueberry FlashBack Recorder for top marks.
• It is important that the screen shots and video show it working so that it is
clear that it solves the problem.
The development of my circuit
• This my starting circuit as you can see it
Uses two separate circuits that both require
Separate turning on at different points at
Different times then also do not have a
On/off switch so once there on there stuck on
This was costly and infective because I found
That you do not have to use two separate
Circuits to so hold 2 inputs so I came up with
This
Second stage of development
• For the second stage we
combined the two inputs
into one circuit using a logic
gate so we didn’t have to
build to separate circuits
We also add a Latching
On/off switch so people can
turn the circuit on and off
How ever there were
problems with this circuit
because it required both
inputs to be on at the same
time before it sounded the
alarm which was a problem if
the burglar didn’t trigger both
of them imputes so I came up
With this.
Third stage of development
For this stage of development we switched to or gate in stead of an and gate so that if
one of the inputs is triggered with out
the other the alarm will still sound we
also upgraded to a more powerful driver so
that the inputs would be able to detect more
sensitive changes in there environment and
react quicker to them.
I felt that the circuit was almost complete but
Then look at my spider diagram of security and
What makes people feel safe(slide 2) and I found that the alarm may benefit from a
flashing light of some kind
Fourth stage of development
• For this stage we added a lamp to the
circuit so that once the buzzer was
triggered the lamp would go of alerting
people that this shed is being robbed and
not there's.
But I felt that this was the wrong kind of
lamp because it wasn’t flashing it also
wasn’t bright enough.
Fifth stage of development
• For this circuit we changed the
Lamp for a led so that it would shine
Brighter and so we could choose the
Bulbs colour as well
We also added a A-stable to the
Circuit so that the led flashes on
And of frequently
Adding the a-stable led to some strange problems with the circuit where as soon as I
turned the circuit on the out puts turned on and wouldn’t turn off even when all the
inputs where off. Possibly because of the variable resistors charge
6th stage of development
•
For this stage of development I decided to change the LED from a normal LED to a flashing LED because first of all my
question air results show that more people want flashing led then a normal led because of the fact that in my survey
results most people said that they would prefer a flashing LED then a non flashing LED which was just bright I also removed
the a stable as it was no longer needed and was just making the circuit larger
Slide 21 continued
At first when I tested this circuit I couldn’t under stand why it wasn’t working the problem was that
why I turned my all my inputs of the buzzer and flashing led where still going at first my reaction
was that their was something wrong with the mosfet and that I should change the circuit
7 stage problem inconunterd
When I changed the circuit to combat the problem with what I thought was the mosfet I
simply just took out the mosfet and put in a comparator and a transistor instead because
they have a similar amount electrical drive
At first I was happy with my circuit but when I came to
putting it into a pcb I found that my circuit was to
complex and was also just not routing properly so I went
back and look at the old circuit with the mosfet and I still
couldn’t find what was causing the problem so I asked a
few people who where doing the same circuit as me and I
found that my variable resistor was at the wrong
percentage witch was causing the problem so once ide
fixed that I went back to my old circuit and came up with
this
This is my
final working
circuit
Testing circuit
What's suppose to
happen
Un expected
problems
How to fix
unexpected problems
Turning the circuit on
When you slide the
sptp switch to on if a
green light comes on
then the circuit is
working
If green light is not
coming on then
circuit is broken
In a case such as this
the most likely
problem is that you
have wired up the
green LED wrong
Input one the
thermistor
Once you wave your
hand over the
thermistor if the
buzzer and the
flashing led both turn
on then it’s working
If once you wave
your hand over the
thermistor the
buzzer and the led
don’t go off then
some thing is wrong
in the circuit
In this case it’s going
to be one of two
things, one you wired
it up wrong or two
your variable resistor
has the wrong
percept
Input two the
pressure mat
If you step on the
pressure mat and
insure that the
buzzer has sounded
and that the led is
flashing then you can
be sure it’s working
If nothing happens
when you step on it
then you can be sure
it’s not working
In this case make
sure you have weird
up the pressure mat if
that doesn’t work
then make sure the
pressure mat isn't
damaged
Testing output one
the buzzer
Once you have testes
both inputs you have
to insure the outputs
are working basically
use one of your
inputs and then wait
for the buzzer to
sound
If the buzzer does
not sound then there
is something wrong
with you buzzer
To fix your buzzer you
first have to check if
the wiring is done
properly if so then
insure to see if your
buzzer is damaged
Testing out put two
the led
Once you have testes
both inputs you have
to insure the outputs
are working basically
If this doesn’t
happen then
something is wrong
with your circuit
To fix this problem
you have to first check
the wiring and if the
wiring is fine check
PCB development stage one
This was my circuit when I
first turned it into a PCB
As you can see their a still a
few faults with the circuit
such as the 3 blue lines on
the board
Blue line
PCB development stage 2
In this version of my pcb I decided to
focus on getting rid of the blue lines
in the pcb circuit board in doing this I
had to make the circuit board a bit
larger this is something I should
change later
PCB development stage 3, 4 and 5
In these stages of development I decided
to move the components around on my
circuit board to reduce the size of the
board when it’s made cutting it’s cost
Stage 3
Stage 4
Stage 5
PCB development
the completed
pcb and the bill of
materials
This is my
working pcb
in video form
you have to
double click
the black box
for it to play
Process description
Equipment
required
Safety issues
Tips for success
Design pcb and mask
Circuit wizard
Ensure that you are
not at the computer
for to long with out
taking breaks other
wise it could damage
your eyes
Don’t over
complicate your
circuit
Cur board to size
Band saw
Band saws are sharp ensure that
your hands are away from the saw
when you are using it, Also when
using saw insure that clothing is
away from the saw to avoid it
getting caught
Insure that your are
happy with your
measurements
before you start
cutting
Expose mask and
photo pcb to uv light
Uv light, photo pcb,
mask of your circuit
Cover up uv light or
cover up open skin on
your body when using
it
Expose it for longer
then five minutes
Develop exposed pcb
Development fluid
Wear gloves and
goggles and cover up
skin because liquid is
corrosive
Don’t pour to much
fluid on or you'll melt
the board
Etch pcb
bubble etch tank#
Etching fluid
Don’t spill the fluid on
your skin because it’s
corrosive
Only use the amount
of fluid you need
don’t waste materials
by over using
Drill holes
Drill, Drill press
(optional)
Insure hands are away
from the drill when
using the drill other
wise it will go through
your hands
Make sure your
drilling the correct
area
Tools used in the making of the alarm
•
•
•
•
•
•
Soldering iron
Solider
Solider braid
Felix wire
Masking tape
Craft kinfe
Manufacture of off board components
•
•
Led and thermistors,
For the led I first had to collect red and black wiring and then i tint the ends wires of the flexi wire so it
would attach to the led easier I would then solider the wires to the led you have to be careful with this
though as the wires must go on the right prong of the led red wire goes on the rounded side black on the
flat, A problem I in counted though was that I put the black wire on the round side, this was easily fixed by
desoilding the join and putting it in the correct place.
•
With the thermistor I had to do exactly the same thing as with the Led but I didn’t need to worry about
the positive and negatives wire place meant so I used a grey Flexi wire instead
Manufacture of off board components
•
•
Push button switches, pressure mats sptd toggle switches
For making the pressure mat I first had to collect a set amount of card, I then had to messes a square out onto the card
twice then with the 3rd one we had to message out another square but this time I had to cut out a small whole in the
middle of that square to act as the connecter in the pressure mat
•
With the push button switch I took some Félix wire striped both ends of the wire place tinited the end I was going to solider
the push button to, I then would take the wire but it through the loop whole in the push button switch, and then I wold
bend the end of the wire so it count fall out whilst I solider it in. I then solider the other end of the wire to the board by
putting them in bending the wire and soldering
On board components
•
•
•
Resisters and variable resisters
How I soldered the resisters 1st I would insure the resister was of the correct strength by checking that I had the correct
colour bands on the front of the resister.
When soldering the resister I would put it into the board and bend the wire back so that the resistor was unable to fall out of
the board I would then solider the resistor in place using the soldiering iron I would then cut the resister wires that remaned
after soiling the component into place
What the board
looks like with
all resistors
soldered in
place
Bending
resistor
wires
All resistors
in place
On board components
•
•
Battery snap/chip socket
With the chip socket I had to make sure that I had the correct size chip for the board by counting how many legs the chip
socket had, Once I had the right chip socket I would put it in the board and bend the wires a small bit just so it wouldn’t fall
out unless I jogged it, then when soldering I would take the soldiering iron and run a peace of solider along the joint very
quickly, My reasoning behind this was because the circuit board allows solider to run between the chip socket legs because
otherwise it would make the component very hard to solider in with out connecting the joins and blowing the circuit later
•
With the battery snap Simply tinted the ends of the wire and put them into the board and twisted them round through a
whole for better support and then solider them into place
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.
• Provide a video showing it working so that it is clear that it solves the
problem. Use Blueberry Flashback Recorder).
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