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I am an AS student that is finding my coureswork a bit hard to plan and if possible could you give me some help on how to plan a fire alarm with both smoke and heat detectors and audible and visual warning
I would start with the sensors since the switch and alarm should be easier to construct. The heat sensor is available from shops that deal in alarms. They look like a power transistor. An alternative would be a thermister although more fragile. The smoke sensor will be a little more difficult. I think I would get a commercial smoke detector (about $10) and use the ion exchanger (is that what they are called?) from it. The ones I have seen are silver metal - about 40 mm in diameter - and have a series of metal fins surrounding it. Good Luck!
Matt - You are probably correct. Whatever the thing is, I agree that smoke causes an interruption between the metal "wings" that surround the central chamber and the chamber itself. Perhaps, as the student starts experimenting with the sensors to determine the switching logic required, he will keep us informed.
well for the smoke detector...i have an idea...
how about using a tube and a ir led at one end and a ir detector like a phototransistor on the other end of the tube
remove part of the tube from the middle of it, or drill some holes enought to make the smoke able to come in. so when the smoke comes you get the ir interuped.
it is not such a good idea, but it might work.