D&T: Electronics and Control Systems

Unit A511: Introduction to Designing

Name: Connor Brookfield

Candidate number:

Centre Number: 16527

SECURITY

BY Connor Brookfield

Creativity

I have chosen security because there is a need for a rape alarm as 1-in-5 women collage age or older get raped.

Investigation of users needs

• To solve the problem of rape or reduce the risk of rape they user needs a rape alarm.

This girl could feel safer if she had a rape alarm or if it had a street light to make it brighter

If she had a rape alarm someone would be alerted.

These are all articlesFrom the internet and news papers

Survey and Reasons For Questions1) Are you a:man, woman, young girl?- I want to find out gender as a woman or young girl will

be typical user. 2) 2) If you’re a man or woman do you have a daughter?-If daughter goes out parents might

buy her one so she is safer. 3) If you’re a woman do you and/or daughter go out at night?- Might not use product if they

don’t go out at night.4) Do you feel safe going out at night?- If they don’t feel safe then they will be more likely to buy

the product.5) Are you aware of the danger of going out at night?- If they are not aware of danger but got told

they might buy one.6) Would you feel safe going out at night if you had a attack/rape alarm?-If they had one they

could feel safer knowing they have a rape/attack alarm.7) how much would you be willing to pay: under£10,£10,£10+(circle answer0?-Might not want to

pay much so find out who much they willing to pay so decide what materials to use. 8) Would you go for a new cheaper brand or more expensive trusted brand?- Might not buy it as

from new brand. 9) What would you prefer:

Press a button? A sensor that detects when someone comes within a metre for more than 30 seconds?-To see how complex they want it to be.

• • 10) if you wouldn’t buy it for yourself would you buy it or recommend it for/to someone?-

They might buy one for someone else or get one and recommend it.

YES NO1) man-3

woman-5 young girl-2

2) 4 63) 7 34) 5 55) 4 66) 8 27) Under£10-3

£10-5 £10+-2

8) 7-new brand 3-trusted brand

9) 9 press button 1-sensor

10) Buy for self-8 recommend-2

Summary of the questionaire

• From the answers on my questionnaire I come to the conclusion that I should make a rape alarm because 7/10 people said they go out at night and out of that 7, 5 people said they don’t feel safe.

• Also I can conclude that I need to put a push button switch in it as 9/10 people said they want to push a button.• Next to enthuses the point of there is a gap in the market for a rape alarm because 7/10 people said they would buy a new

brand rather than go with a trusted brand which shows they want a new product.• I can also extract from the questionaire result that 50% of the 10 asked would pay around£10 for the product.• Finally when asked do you know the dangers of going out at night? 6/10 people said they were not aware.

Picture of filled out questionarie

Creativity

product cost Typical user when/where

used

function Technology used (input/ output)

Manufacturing process

used

140 decibel mini personal attack alarm.

£6.39 When someone is alone in dark or going out in dark.

Press a button and siren goes off.

Push to make switch and then a buzzer sounds.

Injection mould and PCB working then assembly.

Remote car alarm.

£22.39 Someone who owns a car.

When the motion sensor picks up movement in or around car led flashes.

Motion sensor and then led flashes.

PCB soldered then plastic case injection moulded then assembly.

Honeywell pet friendly acenta £151.00

Someone who owns a house.

Alarm goes of when sensor picks up movement.

Movement sensor and then when senses movement an alarm goes off

Injection mould for plastic casing then PCB working then assembly

Trend: the trend is that as the price goes up the more inputs & outputs it has or more features.

Creativity

• I am going to make a rape alarm as there is a problem of girls being raped and no one can hear until the woman tells someone.

• In my circuit I will need a siren or something that makes a loud sound.• I could use a circuit similar to a burglar alarm, however it will be simpler as a burglar alarm uses

movement sensors where as I will use a button(push to make switch).• I have chosen to make a rape alarm because while researching i found numerous newspaper articles about

women or girls getting raped; one of these articles is shown earlier in the presentation.

Design Brief

Product analysis

MINI PERSONAL ATTACK RAPE PANIC ALARM 91dB LOUD KEYRING SIZE

SWT 120DB Keyring Personal Attack / Rape Alarm

Function To prevent/deter rapist or attackers.

To deter someone from attacking or raping you.

User need fulfilled Yes it makes a loud noise when triggerd.(90db siren)

The users needs are fulfilled as makes a loud noise when triggerd.(120db)

Materials used in construction

Pcb&Components, injection mould casing.

Pvc casing and the pcb and components.

Durability of product The product is fairly durable as it has a hard plastic case.

The case will make it durable as its plastic.

sustainability The product is sustainable because it can be reused by replacing the battery.

The product is not sustainable because it cannot be recycled.

Energy use 9 volt battery. 9 Volt battery.

Life cycle Life cycle is: brought, used, no longer needed, thrown away

Life cycle: bought,used, not needed anymorer, thown in the bin

Design

SpecificationThe purpose of the proposed product is to make someone feel safe in the dark. This is because people can get

raped or attacked in the dark.The product should make a loud noise when the button is pressed, because peole want help if they get raped.The product will sense the pressure when the button is pushed because a push button switch will be the trigger

for the circuit.The output will be need to make a loud noise( a siren for example) beacause if someone gets raped it is

normally a sucluded area so they will need to alert people far away.The power supply will be a 9volt battery as its easy to replace and portable.The circuit will run on 9volts because you need at least 9volts to power a siren.My product will not have an on/off switch because it will always be on standby .It will have a power indicator because it will alaways be on standby so a power indicator will save the user

testing it.The circuit will be designed on circuit wizard because its a good programme to design circuits on.Manufacturing: it will be designed on circuit wizard converted to a PCB then cut using Computer Edging Process

and finally components are solderd in.I will test it on circuit wizard and oncer its made this is because i then have proof it works

Systems diagram

Input Process and Logic Output

Movement sensor Thyristor Buzzer

Push to Break Transistor Siren

Push to Make Mosfet Led

Dark sensor/ light sensor And/Nand Flashing Led

noise monitor Or/Nor

Nor invertor

I have given alternate input, process, logic gates and outputs but have highlighted the components I will use in my circuit.

Circuit design 1

• When the switch(sw1) is closed and the push to make switch is pressed the circuit is triggerd and makes a shrill note to try scare of the attacker.

• Also the thyristor acts as a latching switch so the circuit will stay on until it is reset or turned off.

BZ 1

R 2

R 1 R 4

Thy r ist o r

9V

0V

R 3

L ED

P TMPTB

SW 1

Personal attack alarm

Block diagram

Inputthe input is the PTM which will be you pressing the button.

ProcessThe process will be the thyristor latching on and driving the circuit.

OutputThe output will be the buzzer producing the shrill note.

Circuit design2

• When the PTM switch is pressed the transistor drives the circuit and the buzzer produces a loud noise.

• The LED is the power indicator so you know if its working or not.

Block diagram

Input The input is the PTM switch which is you pressing the button.

Process The transistor is then activated and drives the power to the buzzer.

OutputThe output is the buzzer making a loud noise.

Circuit design 3

• When it is turned on the two monostables make a wailing sound. This is because they are on 2 different frequencys.

• The speaker then amplifies the sound of the wailing this could scare away the attacker.

Block diagram

Input The input is the person turning on the circuit.

ProcessThe process is the two monotstables making a wailing sound because of the 2 different frequencys.

Output The output is the speaker amplifying the waling sound.

Circuit design 4 • The inputs are PTM switch and PTB switch Ihave put both in because this could represent a button trigger or a pull cord trigger to the circuit.

• I put the output as a buzzer because they produce a noise which could scare away an attacker.

Block diagram

Input The input is a push to make switch and push to break.

ProcessThe process is a nor gate to combine the 2 inputs and a transistor.

OutputThe output is a buzzer because they produce a loud sound.

My chosen circuit

• I am going to use circuit 2 because it simply and easy to make in school. I have not used circuit 3 because it could be mistaken for a police car and i could of used circuits 1 and 4 as they would fulfill the purpose aswell.

Developmentof circuit

• 1)

2)

Developing circuit 2

This is my final circuit, I have chosen to turn into a PCB.

Video of working circuit(click)

First stage of conversion to pcb• This is when I first converted it to a pcb. The green wires mean it is only 89%

routed. So i decided to move the compionents around to see if it would fully route, although before i did anyhing i turned on automatic rounting which stops the tracks become diagonal.

• I deleted the copper fill because if not the etching process I will use will be unsucessful.

Second stage• I have now re arranged the components so that they are routed correctly

and so it will function properly. Now it works properly i will move the so i can make the circuit smaller and neater by doing this i will be saving money as i will need a smaller PCB and i will use less resources.

Third stageThis is the view of the circuit now i have made it neater and made it smaller as you

can see i have not used half of the pcb.

Fourth stage• Now I have re-routed the circuit I have added

the off board components to test if it will work in reality.

What my circuit doesThe toggle switch is to turn it on and off, then you use the red(ptm) or gray(ptb) button switch to trigger the circuit, it will stay on until reset by turning it off with the toggle switch.

Annotated final pcb designPush to make swith

Toggle switch

Push to break switch

Or gate

buzzer

9 volt battery

2N5060 thryistor

10k resistor

1k resistor

Development of the PCB

Test plan for pcb design

Feature Expected result Actual result Does it solve the problem

Siren make loud noise?

Siren will sound Siren sounds Yes

Press the Ptm switch

The circuit is triggered

The circuit triggers Yes

Press the PTB switch

The circuit will trigger

The circuit is triggered

Yes

Thyristor Stay on until circuit is reset

Stays on until the circuit is reset

Yes

Turn on circuit Circuit should be ready to use

Circuit is ready to use

Yes

Reset Wont reset until circuit is turned off

Didn’t reset until circuit turned off

Yes

Video of pcb working(click)

Bill of materials

Planning the manufacture processDescription of Process Tools/Materials required Tips for success

Design PCB and create mask Circuit wizard Make sure you use right size tracks.

Cut board to size Band saw Check your pads, tracks, holes and measurements are the right size before cutting.

Expose Mask and photoPCB to UV -PhotoPCB -UV light- Mask of my circuit

Make sure that you don’t expose the pcb for to little or to long time.

Develop exposed PCB

Etch PCB

Drill holes in solder pads Drill Poke small hole in middle for accurasy

Add resistors Soldering iron The resistor itselfsolder

The soldering iron will be hot so don’t burn yourself.

Add transistors/thyristors Soldering iron The thryristor itselfsolder

The soldering iron will be hot so don’t burn yourself.

Add Chip socket Soldering iron The chip socket itselfsolder

The soldering iron will be hot so don’t burn yourself.

Add off board components Soldering iron The battery, siren, switches itselfsolder

The soldering iron will be hot so don’t burn yourself.

Add chip to socket Soldering iron The chip itselfsolder

The soldering iron will be hot so don’t burn yourself.Also earth yourself before you touch the chip so you don’t blow it.

Tools• Soldering iron – A heat source used for soldering , its electrically powered. Also it has a copper tip for efficient heat transfer.

Components – these are sometimes very complex but can be really simple aswell. They can be a switch which can trigger the circuit.(EG) Push button switch triggering a siren to go off.

Copper braid- the copper braid was helpful because it was easy to clean up some of the solder around the joints . Also it was helpful because on my chip socket i soldered over two joints.`Heat gun- to shrink wrap the components on my circuit.

Problems encountered while in maufacture.

• One of my problems was that I had soldered my chip socket in the wrong way-it was easily fixed though as I just put the logic chip in”upside down” as such.(picture below)

• Also I soldered in the wrong resistor so I used a copper braid to clean some of the solder away so I could take it out of my circuit.(picture below)

Problems encountered while in manufacture continued

• In addition I also put in a push to make switch where there was meant to be a push to break switch. This is because i picked up the wrong

Final working circuit working video.

EvaluationDescription of Process What went well Problems

encountered/changes madeAction taken to deal with

problem

Add resistors I soldered the right value resistor into the write place.

I soldered one resistor in that was the wrong value

I removed it and put the write one in.

Add switches I used put the switch in the write place.

I put a push to make where there is meant to be a push to break

Removed the PTM and put in the PTB

Add thyristors I soldered it in the write place.

none

Add Chip socket I didn’t double join any pins that were meant to be double joined.

I put the chip socket in upside down

I had to place the chip in the socket upside down to.

Add off board components I used a siren and wired it up correctly, E.g got the positive and negative write.

none

Add chip to socket I put it in fine and earthed myself to make sure i didnt “blow” it.

Because i had placed the chip socket in upside down i had to put it in upside down.

Evaluation(narrative)

• In my coursework I produced a personal attack alarm which I successfully manufactered and it works. However I did encounter many problem in the making of the circuit itself and the powerpoint. Firstly I found it difficult to found it difficult to find evidence that there was a need for the product. Following this I also found it diffcult to find pictures of a place where someone could be attacked.

• Next my second problem that I encountered was that I had to develop a circuit and I used an or gate but it wouldn’t have worked in reality because I had used to push to make switches so one could have been a push button representation but I didn’t know what the other coukd be so I changed it to a push to break switch which was representing a pull chord.

• That was the only problems I had with the powerpoint I next ncounterted problems while making the circuit.

• In addition to the powerpoint problems I had problems while in manfucature of the circuit.• The first problem was that I soldered in my chip socket upside down which isn’t a major problem

because you can solve it easily- just put the chip in upside down aswell.• Secondly i think i could have improved my circuit by making my soldering neater. So to help this i used

the copper braid to remove some of the solder aweay from the joints. By doing this it makes the joint smaller and also makes it look neater than what it was like before.

• Also i think i could have improved the quality of my circuit if i had taken my time in the manufacture process because i rushed it at point and didn’t check that what i was doing; for example i soldered in the wrong resistor and that was due to me not checking.