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5 Zone Alarm System

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oldtimer

New Member
have you tried holding a magnet near a reed switch to keep it closed while you open the door or window? I haven't but it would be interesting to find out.
 

Nigel Goodwin

Super Moderator
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oldtimer said:
have you tried holding a magnet near a reed switch to keep it closed while you open the door or window? I haven't but it would be interesting to find out.
You need to know exactly where the reed is hidden, and also which way round the existing magnet is - or you've got a 50% change of setting the alarm off when you apply your magnet!.
 

oldtimer

New Member
Yes I know that Nigel but it is fairly easy to find the switch since it has its own magnet and the polarity can be found without operating the reed, I prefer to use plate to plate contacts not because of reed problem,I just thought of that, but because they're cheap and reliable. I was born in Sheffield and hiked around Derbyshire in my youth,durint war tha nose.
 

densimitre

New Member
Hi
I need detect a bell fault in a PIC alarm based project....

the circuit is a common npn transistor with collector pull to 12 volts and a diode to protect tehm from inverse emf coming from relay or bell....

thank you
 

neilz90

New Member
could anyone tell me how to compensate for only 3 zones. I've got it drawn but I haven't filed in any of the values.
 
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