ELECTRONICS: Security By Victoria Kerr 10SCandidate number:

Why did I choose security as my theme?

• I chose security as my theme for this task because it is has many different aspects. The different aspects vary from a big and expensive as a bank security system to as cheap and simple as a rape alarm.

Analysis

CostThe majority of people do not have a lot of money to spend and do not want to spend it all on the product, so it must be cheap. It also has to out run its rivals . It must be cheap to make as well. Otherwise we will not be able to sell it cheaply.

SafetyIt will not run on mains but on battery so you cannot get an electric shock from using mains near water, because of this it would make sense to also make it portable. It will have a water proof case so it is safe with a battery.

Tools/equipmentI will be using a soldiering iron, a clipboard, a PCB circuit board and the necessary components.

TimeIt must be able to be made quickly, and so it cannot be too complicated.

MaterialsIt will be made with a PCB circuit board with some components and some solider, it will have a clear water tight case made from a smart plastic.

ResearchI have done a lot of research into other products and I have found that most of them have more than one output, and so I must also have 2 outputs. One example is a product had 2 LEDs.

SIMPLE ANALYSIS OF WHAT I NEED TO CONSIDER.

Products

Security

BathroomRape

Fire

Burglary

Cold

Bath Temp

A product to measure the temperature of water and projects this information to you.

Good to stop people form getting minor burns, but some people may think it is not worth it.

Bath height

A product to alert you when your bath water is at the right height.

This is good because it means you do not waste water, you can do other things while waiting for your bath to be ready. Bad because not all people leave there bathroom when having a bath.

A product to alert you when your house is on fire.

A product to alert you when your food is burning.

This is good because it means you don’t have to stand around to make sure your food will not burn. If you are a good cook you would know when the food is ready.

This is good because you can save your life.There is a lot of completion in the field of fire alarms.

A product to wake up an person who has gotten too cold.

Good because it means you save a life. But you may not hear it.

A product to tell you when your house gets too cold.

Good because you can then turn up the heat, its bad because many people may think it is a waste of money.

A product to scare of any burglaries.

Good because it make the user feel safe but there is a lot of completion in this field.

A product to alert the police if you get burglaries happen.

Good because it help the police to know when you are burgled and makes you feel safe but it has already happened.

A product to alert people around you that you are in need.

Good because it makes the user feel safe but people may not come and help.

BASIC USERS NEEDS MIND MAP

This product is designed for teenagers and above. This design is not recommend for anyone under the age of 13 as they will find the device inaccurate, because they have more sensitive skin than people above that age and so they could still burn themselves even with the product in use. This device is going to be best used by a person who has regular baths for long periods of time.

This device is a temperature sensor. When you place it in the water it will show a coloured LED (light emitting diode). Red for too hot, green for good or warm and blue for too cold. This is not a toy and should not be used as one, this should be keep out of the reach of small children as they might choke on small parts. This is so people do not burn themselves when they run a bath.

This will be used in the bathroom, you could take to a friends house or on holiday, and use it there if you feel the need to arise. It was designed small so it can be easily used in travel and other times.

What and Why?

Who?

Where and When?

MORE DETAILED USER NEEDS TEXT

• In this survey I have questioned 10 people to see if they have ever burnt themselves getting into a bath that is to hot. I found that 60% have burned themselves when getting into a bath that is too hot.

ConclusionI do in fact have a need for my product and so I should continue into designing and making it into a marketable circuit.

Reason for asking the questions.

• Do you take regular bath?• I asked this because then I know if the product would be used regularly or only on occasion. • Have you ever burnt your self when getting into a bath?• This is to find out if the people I am asking these questions are looking at this from the point of view of

someone who has ( I have already established that people do burn themselves in baths)• Would you buy one if it was on the market?• This is to find out if I make this product whether or not it would sell.• Would you prefer 4 LEDs to 3?• This is to help me decide whether I will have 3 or 4 LEDs in the final product.• Would you like the product to be small and compact (portable)?• This is also to discover if I will need to design it to be portable.• Would you like a power indicator?• This is to find out whether I will need to put one in the final design.• Do you want one?• This is to find out if they would just want one or if they would actually buy one.• Would you pay £5.00 For it?• This is to help me determine the amount of money I should be spending on the product.• Do you want a buzzer if it gets too hot?• This is to help me know whether or not I need to put one in the design.• Do you want it to have a on/off switch?• This is help me decide if I put one in the final product.

This tells me that most people want this design and would prefer 3 LEDs to 4, they also would prefer it to be portable.

Question Yes No

Do you take regular bath? XXXXXXX XXXHave you ever burnt your self when getting into a bath? XXXXXXXX XX

Would you buy one if it was on the market? XXXXXX XXXX

Would you prefer 4 LEDs to 3? XXX XXXXXXXWould you like the product to be small and compact (portable)? XXXXXXXX XX

Would you like a power indicator? XXX XXXXXXX

Do you want one? XXXXXXXX XX

Would you pay £5.00 For it? XXXXX XXXXX

Do you want a buzzer if it gets too hot? XX XXXXXXXX

Do you want it to have a on/off switch? XXXXXXXXX X

Conclusion • In the survey on the slide before this one, I have asked 10 people if they own a

bath and if they do then I ask if they will answer some questions for me. I found out that 80% want a small and compact device, as opposed to the 20% who would want it larger when I asked them why this was they all said it was so they would not drop it and break it. I also found out that 70% have a regular bath so I know it would be used. To do this survey I gave one sheet (which looked like the one below) to my father to take to work, there he placed it on a desk and asked his co-workers to tally it. I then gave a different sheet back asking people why they made these decisions.

EVIDENCE OF MY RESEARCH HAVING TAKEN PLACE.

Product ComparisonProduct Cost

Typical userWhen / Where

used?Function Technology used

(Input / Output)Manufacturing process used

£4.80Used in a private

room/bedroom to protect it

Stop an intruder from entering a

roomPressure pad +

SirenInjection

moulding+ PCB

£49.00Use when in

distress from an attacker or

something else

To bring help to you

Push the button and the alarm is

triggered and automatically

attempts to call up to 3

telephone numbers of

family or friends, or emergency numbers

Injection moulding +PCB

£369.95 Use to protect your precious

itemsTo protect your precious things

Keypad + Open Case

injection moulding+PCB

3 Modes Home Security Alarm with Wedge (Black)

Yale Distress Alarm

Phoenix Titan Fire Safe Large

3 modes design.Can make a 120 decibel alarm sound for alerting.When it is placed behind the door, it will prevent the intruders from entering by the wedge.Easy and convenient to use.Package Details Weight144.45 g Size21.5*12*4 cmCopied from www.focalprice.com

A modern, compact high security electronic fire-resistant safe for residential and business use. Integral security alarm for unauthorized entry. 1-hour fire protection for paper, CDs and DVDs. Fitted alarm.. Cover for up to £2,000 cash and up to £20,000 jewellery/valuables. Ready for fixing. Fixing bolts, instructions and warranty supplied. Specifications:External W x D x H: 460 x 480 x 530mm. Internal W x D x H: 323 x 300 x 393mm. Supplied with fixings. Weight: 75kg.Copied from www.screwfix.comThe Yale distress alarm provides comfort and security to elderly or vulnerable people who are, nevertheless, independent and living alone.When the panic button is pushed the alarm is triggered and automatically makes repeated attempts to connect to up to 3 telephone numbers of family or friends, or emergency numbers. Once contact is established a 2-way conversation is possible.The unit can be operated from a remote fob worn as a pendant that is functional up to 50m.The Yale distress alarm is easy to install and is mains powered. An optional back-up battery is available (not supplied). Copied from direct.tesco.com

The Trend....The trend is that the more expensive the product is the better it is quality. This means that the £4.80 alarm is not as good as the £49.00 one which is not as good as the £369.95 one. As you have noticed the best one is the £369.95 one, this one might also be the one which has sold the lest of because it is too expensive from most people to buy, but some people will got all out for there security....

I have chosen to do a bath temperature alarm because I often have a bath and step into the bath and I burn my legs and feet, I have also found that many other people do as well, so I have decided to make this design to stop this happening again. My design may have 3 LEDs, one green for ‘just right’, one blue for ‘too cold’, and one red for ‘too hot’, however it may have 5 colours. I am considering designing a round shape to make it more interesting but it may be a rectangle shape to be traditional. I do not know yet but in the slides to come I will have made up my mind.

Design Brief

Product one (related to my design)

• Bath Level and Temperature Alert Alarm• This professional Bath Level and Temperature

thermometer can be used in the bathroom where extra care is required. This fantastic little gadget shows the water temperature with high/low alert feature. The Bath Level and Temperature Alert Alarm also includes a water overflow alarm system.

• Features of the Bath Level and Temperature Alert Alarm

• The Bath Level and Temperature Alert Alarm has the following features:

• Digital temperature display;• Alarms if water temperature outside pre-set level;• Temperature range: - 50°C ~ 120°C / -58°F ~248°F;• Water level alert;• Real time clock with count down timer;• Uses 2 x AAA size batteries (not included);• Measures 8 x 10 x 3.5 cm – weight is 95 grams.• FROM www.healthandcare.co.uk

Product Two (related to my

design)

• Grant Water Bath Thermostatic/Ambient JB AQUA 26 26L 5ºC - 98ºC MAX. 220-240V 50HZ A.C. prd0296

• The heater mat and sensor in JB Aqua units are bonded to the underside of the tank, optimising working space and temperature uniformity, and are supplied with clear polycarbonate, gabled lids to minimise evaporation and energy loss and a polycarbonate base tray to promote heat convection and optimise temperature uniformity. Stainless steel tanks in outer cases of painted zinc-treated steel. The thermostat dial is graduated in 2°C divisions from 20° to 90°C with a removable setting knob to allow recalibration. With adjustable over temperature cut-out to protect against control failure and a fixed thermal cut-out which guards against accidental dry running or failure of both control systems. An alarm light illuminates if the cut-out operates. Stability at 37°C (DIN 58966) ±1.0°C.

• FROM: betterequipped.co.uk/

Function To warn you when the water is to high and/or to hot

To warn you when the water too high and/or to hot

User need fulfilled

“Very good, I thought it was expense for what it is, but very good all the same” (taken from quotes people said.)

“ Perfect, it ticked all the right boxes! I use it to make sure my kids do not run the bath too high, Brilliant for the price!!” (taken from quotes people said.)

Materials used in construction

polycarbonateStainless steel zinc-treated steelPCBComponents

White Plastic Clear PlasticPCBComponents

Durability of product

Very Durable Okay Durability

Sustainability (6Rs)

Very sustainably the materials can be reused Very sustainably the materials can be reused

Life cycle After it has left the factory it moves over to the shops, from there it moves the destination, after its full use it moves to the recycling factory and is taken down it is basic components and sold off again. However the metal components move the a metal recycling factory to be melted down, the remain parts get throw in land fill sights.

After it has left the factory it moves over to the shops, from there it moves the destination, after its full use it moves to the recycling factory and is taken down it is basic components and sold off again. The remain parts get throw in land fill sights.

Energy use Uses main power Uses 2 x AAA size batteries

Grant Water Bath Thermostatic/Ambient

Bath Temperature and Water Level Alert Alarm

Specification Point Feature Reason for feature

Purpose of the product? To stop people from burning themselves when getting into a bath

It is what it is designed to do.

What will the inputs be? The input will be a temperature sense

Because otherwise it will not be able to sense the temperature and so not do its job

What will the product need to sense?

The temperature of a bath of water

Because otherwise the product would not be doing what it was designed to do

What will the output need to be?

It will be 3 LEDs Because that is what the rivals are doing and so I need to have it too, also 70% want 3 LEDs

What will the power supply be? Batteries So that it is portable, 80% of the people I asked wanted it that way

Will it have a on/off switch? Yes Yes so that it does not waste the battery power

Will it have a power indicator? Yes So that people know when the battery needs changing

Input Process Output

Heat Op amp

Mosfet

Transistor

Sound

Light

BuzzerLoudspeakerSiren

LED flashingLED bi colourLED tri colourLED (normal)Bulb

= My Choice

I HAVE CHOSEN TO DO THESE INPUTS AND OUTPUTS FROM LOOKING AT OTHER DESIGNS

Light

Monostable

Thyristor

Circuit 1

• As temperature increases, the LED will light at a certain degree of heat, which can be set by adjustment of variable resistor.

• Good points It can be adapted by resistor• Bad points It is only one LED

(N TC )

VR 1

R 2

R 1

LED

9V

0V

SW 1

TH 1

B C 10 8

Circuit 2

• As temperature increases, at a certain degree of heat the LED will light.

• Good pointsIt is for certain temp • Bad points It is only one LED

SW 1

(N TC)

VR 1

R 2

R 19V

0V

LED

TIP 12 1

TH 1

Circuit 3

• When the temperature increases to a certain level, a motor will switch on with represents the pump.

• Good points It is for a certain temperatureBad points It is for a fire alarm not

a water temperature

0V

9V

R 1

R 2O P -AM P

R 3T IP 12 1

RLA - 1D 1

VR 1

TH 1

12V

0V

(N TC )

SW 1

Circuit 4

• When the device is put in water the LEDs will light up showing the temperature of the bath, when the last on lights up the buzzer also sounds.

• Good points It has a lot of poetical and it is simple.• Bad points It need a lot of work

My Choice

• I have chosen to do the 4th circuit. My reason behind this is because it looked the best out of the four. It had a simple design and an easy layout. I could easily see where I was going to change it and how it would make it better. It was also the best working out of the four, I created all four in a software programme called circuit wizard and it worked the best with the least adjustment.

Circuit modifying

It is now correctly labelled, before it had a green light when it was too hot but that was deceptive because we think that when we see the colour green it is ok to for example walk across the road. now it has a blue LED for cold.

It has now 2 LEDs so it is more like my specification. This means that it now has a red and a blue LED but it does not tell you when you have the right temperature

Circuit modifying It now has 3 LEDs which are all correctly labelled. This is good because it now tell you when it is the right temperature for you to go into. Also onto this design I had a power indicator but only 30% wanted one and as that is the minority group it does not get one, it would also be a waste of money because one of the lights with go on as soon as it is turned on.

It now has a push to make switch to turn it on and off, before it was constantly on until the battery was removed or it ran out of charge which is very wasteful. This is good because 90% of the people who I asked said they wanted to have one in the final product.

Video of working circuitYou may need to press the back arrow to make the video work.

Unfortunately the video can only be seen in slide show form

Here is me turning my circuit into a PCBThis is the first version, it works right but it could be much better.

I need to get rid of the blue line, it makes it more neat.

The circuit components could be more organised and they could be more in line.I will make it smaller,

the people I asked in the questionnaire 80% asked for it to be small and compact, this is not either.

PCBThis is a nice circuit but it is no where near finished, you can see this by looking at the positioning of the circuits, the 2 chips are not placed in the same way.

Also you can see the LEDs, for my design they have to be as close as possible.

Here is me fixing the broken PCBThis does not work because of the placement of 3 things, 1 is the resistor this is because it is in the way of a good connection, also it does not quite reach were it needs to be.

The 2nd reason is because the switch connection is not right, they are not fully connected cutting of the supply of current.

And finally because the red LED is so close to the resistor it cannot connect properly.

PCBThis is good but it can be better, if I change the temperature for the green light and move it around a little more I can have a nice circular shape and have most of the components ordered.

The LEDs could be closer and the chips could be more in line.

The resistors could be more organised

Here is the final working circuit (picture)

I have changed the variable resistor so that now it is set at 30˚-45˚ for the green light which is better because the average bath temperature is 38˚-40˚

As you can see the LEDs are very close.

You will be able to see the chips are both facing the same way.

You will also notice the resistors are mostly all in the same place.

Here is the final working circuit You may need to press the back arrow to make the video work.

Unfortunately the video can only be seen in slide show form

Process Description Equipment Safety Issues Tips for success

Design PCB and mask Circuit wizard Programme None Have a plan of what you want it to do in front of you or in your head so you don't forget.

Cut board to side Band saw Saw blades are very sharp, don’t place hands near it when you turn it on

Ensure the measurements are correct before you cut it

Expose mask and PhotoPCB to UV light

UV light, PhotoPCB, Mask of my circuit.

Ensure UV light is covered because it can damage your eyes

Expose for 10 minutes

Develop exposed PCB Development fluid, protective clothing

It could splash on clothing or on skin so wear protective clothing and if it does splash on skin wash with water immediately

Wear protective clothing and goggles

Etch PCB Etch tank, Etchant, protective clothing

Etching fluid is corrosive so don’t touch it

Wear protective clothing, leave it in etching fluid for 1-2 minutes for best coverage

Drill Holes Drill , PCB, goggles Don’t put hands near drill, bits can fly off PCB so wear goggles to protect your eyes.

Ensure the PCB is in place, wear protective goggles and do not put your hands near the drill or drill bit when it is turned on.

Solder components (On-Board and Off-Board)

Solder, soldering iron, solder board, components, red and black wires, masking tape ( so you can make sure the LED wires do not touch each other)

Soldering equipment gets very hot, so be very careful.

Ensure all components are the right way round and in there correct places. For resistors make sure they are the correct values, do not solider off the pads or tracks, when solider on components do it as fast and effectively as possible so you don't over heat your components. Make sure the LED wires do not touch each other For off board components make sure the wires are long enough and that they are the right colours (for easy identification)

Planning the manufacture process

Beginning of manufacture.

Circuit board, no component soldered on yet. No off board components done either.

I started by doing the off board components, this consisted of soldering wires to the LEDs, the push button switch and the thermistor

I then shrink fitted the off board components, this is to keep them water tight and to hold them together. This means that it is harder to break them, this makes them more durable.

Here are the finished off board components, as you can see the thermistor has a much longer wire then the LEDs and the push button switch, this is so when it goes into the water the rest of the circuit does not get wet.

Finishing of manufacture

I started to solider the resistors, These were the easiest to solider and so I thought I should do them first.

I then soldered in the chip socket, but I did not put in the chip as could damage it in soldering in the other components.

I then soldered on the last of the on board components and started on the off board components.

I then finished the circuit and ensured all the components were soldered on correctly.

I then went to test it and found it did not work, this was due to the variable resistors not being set correctly, I also realised that I should put in a higher resistance so I could get more range, it was now I changed the 390Ώ to a 1kΏ.

This was the circuit board before I cleaned it up, and after I had made the changes, for the clean circuit see the next page.

Pictures of finished circuit

The tape is to hold them together so you can see the colour easier.

Video of working circuitClick to beginThe green light is not very bright

Mistakes

I put in 3 390Ώ resistors, in fact we discovered that I actually need 3 1kΏ resistors.Before picture the left; After picture the right.

I heated the wire inside the line and snapped it off, this was my fault and was caused by being to rough with the equipment.Before picture left; After picture right.

EvaluationWhat is it meant to do Did it do it

Nothing when battery put in Yes

When button pressed one of 3 LEDs turn on

Yes

When temperature changes so does the colour on LED

Yes

When button released LED goes off

Yes

Not turn on when battery not in

Yes

EvaluationDescription of Process What went well Problems encountered/changes

madeAction taken to deal with problem

Solider together off board components

Soldered all together, all shrink wrapped

Was too rough with switch, Pull wire off

Unsoldered wire from switch, replaced wire. Was more careful the second time round.

Add resistors All resistors soldered correct way round

I did not have a large enough resistance value.

Put in 1kΏ resistor instead of a 390Ώ resistor

Add variable resistors Soldered in correct way round, did not split apart.

It took a long time to set it to a particular setting, also was too low a resistance.

Took the time to set it correctly and changed the resistor the next highest.

Add chip socket Soldered in well, did not break leg of socket.

Soldered in backwards. No major problem, just had to put chip in backwards as well.

Add off board components All soldered on correctly, did not pull wires.

None None

Add chip to socket Touched earth before putting in chip, and put it in backwards to fit the mistake when I put the socket in.

I had difficulty finding the correct chip as the chip I thought I needed was not the chip I actually needed.

Tried and tested many chips until correct working chip was found.