1. D&T: Electronics and Control Systems Unit A511: Introduction to designing and making Name: Alexander Lewis Candidate number: 9099 Centre Number: 16527

2. 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.

3. I have chosen this idea Mind mapping of ways to make people feel secure

4. 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

5. The results Here are the replies from the questionnaire: Question 1Question 2Question 3Question 4Question 5 1 month 4Yes, mostly 4Yes 7Yes 10Yes 4 3 months 2Yes, sometimes 3No 3No 0No 6 6 months 3Not really 1 1 year 1Never 2 Question 6Question 7Question 8Question 9Question 10 Yes 9Yes 8On-Off switch 10Yes 7Yes 4 No 1No 2Loud Alarm 10No 3No 6 Led 8 Sensitive switch 8

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.

7. Many hotels are being broken into including a big LA hotel. Identifying a need 60% of burglaries occur while a home is occupied!* 73% of burglaries occur through front door!* *=FBI and NPS This news article suggests that door locks are unsecure on their own and a product to help protect rooms is needed.

8. Market Research ProductCost 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 Bath water height Alarm from Amazon £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 Injection moulding Yale burglar alarm system from Amazon £99.99 Home owners who are concerned about burglary. 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 Injection moulding Alarm door stop from Amazon

9. 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.

10. 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.

11. 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.

12. 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.

13. Detailed product analysis To alert people around the door that it has been triggered. People who travel and want extra safety or home owners. Cheaper plastics, circuit components and PCB Manufacturing of product. Use of product. Disposal of product. Less environmentally friendly as less has been spent on production. To provide a warning when a house is being burgled. Better off home owners who want to protect their home. ABS, circuit components and PCB. Also contains wireless transmitters. LowHigh quality and durability. More environmentally friendly and sustainable as more has been spent. Product 1 Product 2

14. System design Imput 1Combine?Imput 2Process 1Process 2Output 1Output 2 ? Light sensorNAND?PIR motion sensor Monostab le MosfetLEDMotor Dark sensorAND?SwitchAstableTransistorBuzzer /siren LED PIR motion sensor NOR?Temperatur e sensor TransistorAstableMotorBuzzer/siren Temperature sensor OR?Dark sensorThyristorMonostableSolenoid SwitchXOR?Sound sensor MosfetDarlington pair Flashing LED Sound sensorLight sensorDarlingto n pair Thyristor

15. 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. 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.

16. 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 4 th 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. 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. Developing a circuit

17. 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.

18. Bill of materials NameCostQuantityTotal 150 Resistor1 1K Resistor2 PCB1 2N5060 Thyristor1 390 Resistor1 9V Battery1 BFY51 NPN Transistor1 Siren1 Flashing LED (red)1 Green LED1 SPST switch3 Total:

19. 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.

20. PCB Development I continue to shrink the board so less materials are used in the physical manufacturing. Finally, I test it.

21. The equipment Profile cutter used to trip PCB board to correct size. UV light expose box used to develop PCB design onto a blank copper board. 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. Heat gun used to melt the shink wrap around the wire and the component it is attached to, this prevents short circuiting. Wire cutter can be used to cut the length of wires down to the correct size. 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.

23. 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. All of the resistors correctly in place. 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.

24. 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.

25. 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.

26. 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.

27. 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 Develop exposed PCB Developing it None Etch PCB Etching the PCB None Cut board to size Cut correctly None Drill holes in solder pads Positioning of the drillFor 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 Add transistors/thyristors Soldering 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 Used the heat gun for a shorter time Add off board components Sensible length of wire usedI soldered the wire to the wrong end of the micro-switch so it reversed the function of the circuit. De-soldered the wire and correctly soldered it on top the other terminal.