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

Security Baby bath temp alarm

Shed alarmProtect sheds in crowed area

stop them from dyingIn the bath because the water is hot

Heat senor

Alarm which goes of when temp gets to high

Buzzer that produces a load notice when either input goes off so people can tell that there's a shed being robbed

Pressure senor on a door mat or a some windows to detect changes in weight

Feeling secure

Fake cctv

Fake alarm boxes with LED on them which flash

Marketing Surveys

Areas of crime

Orangeis the area I have chosen to do

Area of crime are good marketing areas because people will more likely want to protect

Market research To be able to tell if it Is worth investing in the area

Flashing led to people can tell it’s your shed that’s being robbed

Motion senor connected to a flashing led which is connected to a speaker

Goldie locks circuit??

Investigation of user needs

Where: Usually people who live in a crowed area or some where in a

isolated area like this images

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

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

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

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 burled10. 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

Manufacturing 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 functionOf 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

Yale wirefree Premium Alarm Kit HSA6400

£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 used in the key pad

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 restated

ABS plastics

• 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.

Creativity (slide 9)

Name and picture of product 1 Name and picture of product 2

Function

User need fulfilled

Materials used in construction

Durability of product

Sustainability (6Rs)

Life cycle

Energy use

Use 10 or 12 point text in this table

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

Time delay after battery isswitched on

Possible inputs

Combineinputs

Delay after INPUT

PROCESS Delay before OUTPUT

OUTPUT Combined outputs

Zero seconds Motion sensor

Pressure and heat seniors

Zero seconds

Transistor

Zero seconds

Buzzer-siren

Siren and LED

3 seconds Tempsensors

Heat senor and light senor

3 seconds

Darlington pair

3 seconds

LED Siren and flashing LED

4 seconds

Pressure mat

Heat and dark senor

4 seconds

Mosfet 4 seconds

Flashing LED

5seconds

Dark senor Humidity and light

5 seconds

Transistor and a comparator

5 seconds

6 seconds Lightsenor

Humidity and dark

6 seconds

Thyristor 6 seconds

7 seconds Humidity senor

Motion and light

7 seconds

7 seconds

8seconds

Motion and dark

8 seconds

8 second

Red is what I have chosen to do

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 onThis 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 withThis

Second stage of development• For the second stage wecombined the two inputs into one circuit using a logic gate so we didn’t have to build to separate circuitsWe 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 developmentFor 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 outthe 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 thecircuit so that once the buzzer was triggered the lamp would go of alertingpeople 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 alsowasn’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 theBulbs 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 use one of your inputs and then wait for the Led to start flashing red

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 that you haven't damaged your led when soiling it in place

PCB development stage one

This was my circuit when I first turned it into a PCBAs 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

Solider chip sockets Soldering ironLogic gates, mosfet

Insure that your hands are far away from the soldering iron when using it because you could burn your self otherwise

Solider resistors Soldering ironresistors

Insure that your hands are far away from the soldering iron when using it because you could burn your self otherwise

Bend the resistors in place so that they fit through the holes once their through the hold bend them a bit so they cant fall out.Make sure it’s the right band resistors

Solider inputs Soldering ironThermistor, pressure mat

Insure that your hands are far away from the soldering iron when using it because you could burn your self otherwise

Make sure their soldiered in the correct place

Solider outputs Soldering ironFlashing ledBuzzer

Insure that your hands are far away from the soldering iron when using it because you could burn your self otherwise

Make sure their soldiered in the correct place

Solider of board components

Soldering ironBattery snapOn switch

Insure that your hands are far away from the soldering iron when using it because you could burn your self otherwise

Make sure their soldiered in the correct place

Shrink wrap connections between of board components and wires

Heat gunHeat shrink tubing

Don’t shoot your self with the heat gun

Add chip to sockets

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

Bending resistor wires

All resistors in place

What the board looks like with all resistors soldered 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

Action taken to deal with problem

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.

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