A project suggestion for a student

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BrendanP

Senior Member
I was listening to a ABC radio here in Australia last week, they had a segment on about the difficulty children have waking up to the sound of a smoke detector going off in the night.

A researcher is doing a study on the problem, a large percentage of kids wont wake to a alarm in the hall way if their bedroom door is closed. They sleep too heavily.
One possible soloution would be smoke detectors that are RF linked so that if one unit is triggered it TXes to all the units in the house and they all trigger. (A commerical set up would have a learning ability and duplex comms).

Using simplex comms and a non-learning MCU I was thinking this would be a good student project to picaxe as a demonstration of the concept. Smoke detectors are cheap to buy as are the 433mghz TXers.


It would be a fairly simple hack I would of thought.
 
hippy

hippy

Ex-Staff (retired)
I think it's a good exercise and project but not sure of the practicalities in real life.

The slave would have to be near always on to be ready to receive the alarm signal as quickly as possible and that's going to eat up batteries. To use mains power would mean having to use fire-resistant cable and in that case one may as well instead use the same cable to extend the alarm siren into the room where people are sleeping.

One novel aspect of such a wireless system is that it wouldn't be a problem if neighbours were on the same frequency, in fact that has advantages in itself - Although a design which didn't relay an alarm on and on would be needed or the whole town 'lights up' when someone sneaks off to the wrong place for a cigarette.
 
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Dippy

Moderator
Nice project for student but , obv, they're already available - at a price.

Well, having all the neighbours alarms being triggered would be a real hoot , especially when you left your toast in too long.

Battery life needn't be a big problem. Good design would duty-cycle the receiver to minimise average power - just like radio door-bells. The transmitter just needs to transmit for a few duty cycle periods to be sure. Not beyond the wit of man as long as we don't use the cheapest RF modules from Ebay, which, of course, the student will :)

Moving it from school-student project to commercial? Well, that would be an expensive day out as you'd have to get all those accreditations like Kitemarks and all the international ones. So, unless you're keen I'd leave that until you've perfected it and have a big wallet.

I'd like someone to take on a smoke analyser project so my toast does NOT set off a smoke detector!
 
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