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Intruder alarm circuit.

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Joined: Mon Jul 25, 2011 11:37 am
Location: Willington, Co Durham.

Intruder alarm circuit.

Post by malcscott » Wed Nov 20, 2013 5:24 pm

I need a circuit for a simple intruder alarm for an old persons front door entry. Eg - a pir sensor wired to a buzzer. Any ideas?? Malc :aab

Posts: 721
Joined: Fri Jul 29, 2011 10:16 pm
Location: Coningsby, Lincolnshire

Re: Intruder alarm circuit.

Post by Lloyd » Wed Nov 20, 2013 7:27 pm

I got some cheap Micromark 'easywire' 3 wire PIR sensors off ebay, and rigged them up to a 1 transistor circuit driving a relay, which was then connected to a much more complex burglar alarm system that I borrowed the design of from 'Everyday practical electronics'. I think I ran it all off a 9V regulator.

If I can find my circuit scribbles I'll draw it up neatly and put it here.


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Joined: Sat Feb 09, 2013 6:08 pm
Location: due South of Selby, near the Pepperpots, house smells of two stroke.

Re: Intruder alarm circuit.

Post by Wolfie » Wed Nov 20, 2013 7:38 pm

you can buy those PIR beams for shop doorways etc, they are ded cheep.... from ebay, when the beam is broken they say "Bing Bong!"
They use Batteries of course and how long they last could be an issue
Or these.. Hallway Alarm

I use those little wireless doorbells for our garden gate and garage door, simply wired a door contact across the button and arranged that the magnet swiped across the contact rather than holding it closed in any position, the receiver can travel anywhere in the house.. The batteries in the receiver last well over a year and only one transmitter so far has needed a battery (twice) in about 6 years!

Wireless Doorbell

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