d&t: electronics and control systems unit a511: introduction to designing and making

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:

• Choose one to develop for your project – show your choice on the chart

This could be hand drawn and scanned into your presentation

violence Hard to stop

USERS NEEDS

WHEN

WHO WHY

WHERE

Investigation of Users’ Needs

It could be used at night when the owner is asleep or out

what

My alarm will be used to stop/put off burglars from stealing your household possessions

My alarm will be used in a corridor were the burglar would walk through to detect the heat given off by them

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

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

The owner of a household/office will use this alarm

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.

http://www.engineeringtoolbox.com/temperature-sensors-d_448.html


Users Needs• What does the user need to solve the problem you have identified?• Evidence that there is a need (WHAT):

– Annotated pictures– Newspaper clippings describing what happened (most articles will state what happened, who it

happened to and probably where.

• Evidence of users (WHO):– 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


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

survey1.How many rooms do you have ? 14 15 17 18 15 19 16 15 14 142.Is your house isolated? Yes yes no no no no no no no no3.Has your house ever been burgled? Yes no no no no yes no no no no4.Have you got many valuables? Yes yes yes yes yes yes yes yes yes yes5.How many neighbours do you have? 0 0 1 2 1 2 1 2 1 1

6. How many rooms have valuables all all 5 10 all 8 10 9 10 77. Which room would you put the alarm in?8.How many people live in your house?9.Do you already own a burglar alarm.

questionaireHow many rooms are in your house


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 CostTypical user

When / Where used?

FunctionTechnology

used(Input / Output)

Manufacturing process used

Name and picture of product 1



Product Description – Personal Attack Alarm (£5.99) - From AmazonTiny 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 AmazonRequires 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 AmazonKeep 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.

Examples of products for comparison (all alarms of some sort)Remember these are examples – you need to get your own

sensors/alarmsThis 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.


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.


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.


Friedland Response SL5 Wirefree Telecommunicating Alarm System

Name and picture of product 2Yale wirefree Premium Alarm Kit HSA6400

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


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

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!

specificationFeature 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.

• 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.)

Delay before INPUT

INPUTCombine inputs?

Delay after

INPUT PROCESSDelay before

OUTPUT OUTPUT

Time delay between power on and input sensed?

Delete these instructions from your table.

List of possible things that could be sensed + images of possible components.

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.

Time delay before the output is turned on.

List of possible outputs ( include power indicators etc.) + images of possible components

System diagram

Delay before INPUT

INPUTCombine inputs?

Delay after

INPUTPROCESS

Delay before

OUTPUTOUTPUT

0 Heat sensors(cold/hot)

Dark sensor

10 Transistor/mosfet 0 Siren and flashing LED

probes 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

Security alarm ideas , e.g. burglar alarms or personal safety

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?)

My circuit 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.

Figure 1 Figure 2 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.

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 Tips for successDesign 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

Delete any of the processes that don’t apply

You need to add detail to this column for each process

http://admartin.net/

Process description Equipmentrequirement

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 lightPhoto PCBMask 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 tanketchant

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

Planning the manufacture process

Drill holes DrillDrill 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


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


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


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 my power switch that will turn on the circuit.

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.

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 (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.


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

d&t: electronics and control systems unit a511: introduction to designing and making

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