"Mr Sandman" wrote in message
news:WcSdnQ1Etp-cdZnVnZ2dnUVZ8qSnnZ2d@plusnet...
Hi all,

its been a while since I played with electronics, so could do with some
advice.

I have 2 magnetic door locks, keypad operated to control access into my
house. I also have a mains power smoke alarm system.

what I want to do is use a relay operated by the smoke alarm when sounding
to turn off the mag locks to allow people to leave with out having to get
their fobs out.

system was working fine with one mag lock, but now I have two I have a
problem. the smoke alarm when operating shorts out 2 wires going to the
one maglocks power supply. the electricians has simply connected those
wires to to the same connections in the new power supply. the problem is
now that if someone opens the back door with a fob, the front door also
unlocks! and vice versa. I was thinking about using diodes to try to get
round this problem. I'm not sure if I have explained the set up very
well..so ask away if you have any questions!

Two pole relay.