Transcript ge wireless home security system

D&T: Electronics and Control Systems
Unit A511: Introduction to designing and making
Name: Alexander Lewis
Candidate number: 9099
Centre Number: 16527
Theme choice
I have chosen the theme security as today more
than ever crime has been on the rise in my
area and I have seen many statistics on the
news that has shocked me so I am now aware
that there is a need to solve these problems.
Mind mapping of
ways to make
people feel
secure
I have chosen this idea
The Questionnaire asked to 10 people to
find if there is a need for a product.
1. How often do you go on holiday?
I chose this question because statistics show that there are lots of burglaries of hotel rooms and campervans
as they are less secure than homes.
2. Do you stay in hotels or in a campervan when you go away?
I want to find out if people do stay in these vulnerable places
3. Do you worry about the safety of your belongings that you bring with you?
I asked this question because if people are concerned about their belongings then there is a need for a
product to make them feel safe.
4. Do you worry about someone entering your hotel room/campervan?
I chose to ask this question as if there is a problem then I can design a product to prevent this.
5. Have you ever been burgled while your are abroad?
I want to know if people have been affected by this again to see if there is a need for a new product.
6. Would the door being wedged closed make you feel safer?
This is a possible suggestion of a way to prevent the intruder as well as make the person feel safe.
7. If it had an alarm on it would that also help you feel safer?
I asked this question because I want to know if there are features to include on the product.
8. Which of these features would make the product better suited to your needs?
Again, more suggested features
9. Would a power indicator be useful?
Same as above
10. If you choose an alarm do you want it to stay on for a short amount of time?
Same as above
The results
Here are the replies from the questionnaire:
Question 1
Question 2
Question 3
Question 4
Question 5
1 month
4
Yes , mostly
4
Yes
7
Yes
10
Yes
3 months
2
Yes, sometimes
3
No
3
No
0
No
6 months
3
Not really
1
1 year
1
Never
2
Question 6
Yes
No
Question 7
9
1
Question 8
Question 9
8
On-Off switch 10
Yes
7
Yes
No
2
Loud Alarm
No
3
No
Led
8
Sensitive switch 8
6
Question 10
Yes
10
4
4
6
Analysis
From these results and evidence I have gathered I can conclude that there is a need to design a product
that will protect people when they are aboard/in a hotel/in a campervan. This is because my
questionnaire shows that people go on holiday fairly often and that when they do the don’t feel secure.
Also, the questionnaire suggests possible features of the product.
Identifying a need
This news article
suggests that
door locks are
unsecure on
their own and a
product to help
protect rooms is
needed.
73% of burglaries occur
through front door!*
*=FBI and NPS
60% of burglaries occur while
a home is occupied!*
Many hotels are
being broken
into including a
big LA hotel.
Market Research
Product
Cost
Typical user
When / Where
used?
Function
Technology used
(Input / Output)
Manufacturing
process used
£2.49
Students and
people who
travel to leave
behind a
dorm/room
door
To stop the
door opening
and sound an
alarm if tried
On off switch to
activate
Micro switch to
sound
Alarm
Injection
moulding
£3.35
People who
have baths and
will be out of
the room when
they are filling it
To alert
homeowner
when the
height of the
bath reaches a
critical level.
Float switch,
Alarm
To alert the
owner when
something in
the room
moves or the
key code is
entered
incorrectly.
Keypad, Alarm
system, two
image sensors
and two reed
switch sensors
for doors
Alarm door stop
from Amazon
Bath water height
Alarm from Amazon
Yale burglar alarm
system from Amazon
£99.99
Home owners
who are
concerned
about burglary.
Injection
moulding
Injection
moulding
Trend in products
From my research I can conclude that the more
sophisticated and the more features a product
the higher its price and the better quality the
product is. This is because the more expensive
products are more sophisticated and they
have more expensive components and are
made of higher quality materials, e.g. ABS
plastic for the case.
Design Brief
From the evidence I have collected and
suggestions from the questionnaire I am
going to design a device that will sense
when a burglar tries to enter the room and
will alert the person inside.
Specification
My proposed product will protect the house and belongings inside. It will do this because there
has been a steep rise in the number of burglaries of all buildings.
My proposed product should trigger an alarm when someone tries to enter the room and stops
them from doing so because that’s what most people wanted in my questionnaire.
My product will sense the door opening. It will do this because 70% of burglaries happen
through a door.
My product will have an output of an alarm as it was a popular choice in my questionnaire.
My product will be powered by a PP3 9v battery as it is a safe voltage, portable and was also
popular in my questionnaire.
My product will have an on/off switch to easily turn the product on and off. It will also have an
green LED to indicate when it is on. It will have these two features because they are popular
in my questionnaire and other successful products on the market have them.
My product will be designed and manufactured using CAD such as Circuit Wizard 2 and a Denford
PCB milling machine and software. I will use these because they make designing easier and
quicker.
My product will be tested on Circuit Wizard 2 because I will know that the product works before
manufacturing.
Detailed product analysis
Product 1
Door alarm
A simple
door alarm
for travel and
for home.
Product 2
Home security system with two door alarm sensors
with wireless relays back to keypad and alarm
system.
A more complex system and therefore a higher
price.
Detailed product analysis
Product 1
Product 2
To alert people around the door
that it has been triggered.
To provide a warning when a house
is being burgled.
People who travel and want extra
safety or home owners.
Better off home owners who want to
protect their home.
Cheaper plastics, circuit
components and PCB
ABS, circuit components and PCB.
Also contains wireless transmitters.
Low
High quality and durability.
Less environmentally friendly as
More environmentally friendly and
less has been spent on production. sustainable as more has been spent.
Manufacturing of product. Use of
Manufacturing of product. Use of
product. Disposal of product.
product. Disposal of product.
System design
Imput 1
Combine?
Imput 2
Process 1
Light sensor
NAND?
PIR motion
sensor
Dark sensor
AND?
PIR motion
sensor
Output 1
Output 2 ?
Monostab Mosfet
le
LED
Motor
Switch
Astable
Transistor
Buzzer
/siren
LED
NOR?
Temperatur
e sensor
Transistor
Astable
Motor
Buzzer/siren
Temperature
sensor
OR?
Dark sensor
Thyristor
Monostable
Solenoid
Solenoid
Switch
XOR?
Sound
sensor
Mosfet
Darlington
pair
Flashing
LED
Flashing LED
Light sensor
Darlingto
n pair
Thyristor
Sound sensor
Process 2
Exploring circuit ideas
This circuit shows a switch activating a thyristor which
powers a bulb. However this circuit does not have and alarm
nor a LED to show activation so I will need to modify this.
This circuit is much better than previous as it does
have and alarm and it latches on but there is an Light
Dependent Resistor as well which I don’t need to
have.
PTB (Reset) 9V
R3
R2
Test R4
BZ 1
D1
Copper
Contacts
D2
PTB_ 1
R1
Thyristor
0V
This circuit has most of the features I need. It does
have a buzzer/siren and could be used for my circuit
but it has some extra features such as a test switch and
it also have a latch which I wont need. However this is
closest to the circuit that is needed to be designed.
Developing a circuit
My first stage of development. I have created a
basic alarm system with no latch. As the switch is
pressed the buzzer sounds.
The second stage. I have now added and Power
indicator. This is because 7 out of 10 people in my
questionnaire wanted one.
This next stage I added a LED to increase user ability as
now deaf people know when the device has been
triggered. It is also a popular option in the
questionnaire.
The 4th stage of development has a Darlington pair to improve
the gain of the circuit making it more sensitive. I have also
replace the LED with a flashing version and modified the
circuit so that the siren and LED will pulse. This is because a
pulsing light and noise attracts attention better.
This is the final stage. The circuit now latches on and it has a reset
switch which also doubles up as a test button.
This is a video of the final circuit
working. First I test that nothing
happens when it is turned off then I
turn it on and the power indicator
lights up. I test the reset as it can be
used to test the circuit. Finally, I
activate the circuit and then reset
the latch and turn it off. By using
the test procedure I know my
circuit solves the need I set out in
my design brief and that it works
fully.
Bill of materials
Name
Cost
Quantity
150 Resistor
1
1K Resistor
2
PCB
1
2N5060 Thyristor
1
390 Resistor
1
9V Battery
1
BFY51 NPN Transistor
1
Siren
1
Flashing LED (red)
1
Green LED
1
SPST switch
3
Total:
Total
PCB development
Using the CAD program, Circuit Wizard 2, I converted the
final circuit diagram into the printed circuit board format.
The video shows how.
Now I delete the copper fill so it is easier to
shrink the circuit.
I attach off board components
and then I test the circuit using
the same testing procedure as
earlier.
PCB Development
I continue to shrink the board so less materials are used in the physical manufacturing. Finally, I test it.
The equipment
Profile cutter used to
trip PCB board to
correct size.
Heat gun used to melt the shink
wrap around the wire and the
component it is attached to, this
prevents short circuiting.
UV light expose box
used to develop PCB
design onto a blank
copper board.
Wire cutter can be used to cut the
length of wires down to the correct
size.
Bubble etch tank. This
is used to dissolve the
copper not covered by
the photo resist
created from the UV
light. Contains ferric
chloride and is very
corrosive so gloves and
goggles must be worn.
Wire strippers which
remove the plastic
coating around wires
so that they can be
soldered to the PCB.
Solder, comes in two varieties both
lead and lead free. The solder is
heated with a soldering iron and is
melted around a joint and then
allows current to flow through it.
Soldering iron and board with
clamp. The iron is used to heat the
solder around the joint and the
board and clamp hold the PCB still.
PCB drilling ng machine is used to
drill holes in the pads of the PCB
after etching so wires can pass
through.
Manufacture
I start manufacture by assembling the required components. Once
that is done I heat the soldering iron and start to solder on the
resistors, checking that they are in the correct place and are the
correct value by referring to my circuit.
Before every solder joint I first place the component into the
correct position and bend the legs slightly outwards so it doesn’t
fall out. Next I dap the iron tip onto the wet sponge to clean it of
solder then leave it to heat up again. Then I hold the iron like a
pencil and heat the joint and finally push solder into the join area
and the solder will melt over the pad.
To finish the component I cut the extra legs with
wire cutters.
My first problem was when I accidently soldered the
wrong value resistor in place. If I hadn't of checked
then the circuit may not have worked and there
could be significant damage to the circuit.
All of the resistors correctly in
place.
Next I solder on the thyristor and transistor. This was my next problem I encountered.
When soldering the thyristor on two solder joints joined together.
This could cause a short circuit and may permanently damage the board.
So I removed it by running a hot soldering iron between the joint.
After that I started to tin wires for the off-board components. This is done by stripping the wires then running
solder down the exposed copper so that it is easier to solder the wires later.
The first component I solder to the wires is the flashing red LED. I make sure the right colour wire is on the
correct leg. The shorter leg on the flat side of the LED is negative.
To finish the LED I shrink wrap the connections to prevent possible short circuiting.
I repeat and finish the green power indicator LED.
The next off board component I will solder is the push to make switch. This will act as my reset switch for the
thyristor latch. I first tinned more wires in the same way as earlier and then soldered them onto the switch by
pushing the wire through the inside first as it will be easier to solder.
I trim the wires and then I shrink wrap it.
I also repeat the same process for the STSP switch.
The finished off-board components.
When I solder the micro-switch I accidently solder the wrong terminal which would reverse the circuits
function If I hadn't of checked it first.
I finally solder it on and complete the circuit. Then I test it.
Description of Process
What went well
(What did you do to avoid errors)
Problems encountered or changes
made
Action taken to deal with problem
Design PCB and create
mask
Manually moved components to
use less track and save
resources
The circuit didn’t work first time
I checked the connections and
the program had deleted one so
I replaced it and it worked.
Expose Mask and
photoPCB to UV
Exposing it
None
None
Develop exposed PCB
Developing it
None
None
Etch PCB
Etching the PCB
None
None
Cut board to size
Cut correctly
None
None
Drill holes in solder pads
Positioning of the drill
For the thyristor the holes were to
small
I enlarged them with a bigger
drill bit.
Add resistors
Most of the soldering
One solder joint flowed over two
pads
Used the soldering iron to
separate them by running it in
between the pads.
Add capacitors
Soldering
None
None
Add transistors/thyristors
Soldering
None
None
Shrink wrap connections
between off board
components and board
Shrink-wrapping
I held the heat gun near the
component for too long so the wire
began to melt
Add off board components Sensible length of wire used
Used the heat gun for a shorter
time
I soldered the wire to the wrong end
De-soldered the wire and
of the micro-switch so it reversed the correctly soldered it on top the
function of the circuit.
other terminal.