"Andy Cap" wrote in message
...
On Tue, 15 Apr 2008 19:48:39 +0100, "Mr Sandman"
wrote:


Hi Andy. thanks for the useful response! Its just 12 Volts DC, so I can
dig
a couple of diodes out of an old PCB somewhere I'm sure. Where do you
suggest I put them? one on each of the wires to the power supplies? I'm
sure I can have a play, cant do any harm. I suppose there must be some
electron transfer in some direction across the sensing terminals, I just
need to find out which is positive I imagine?

cheers!

Steve

12v is ideal. Just put diode into one of the wires arriving at the lock.

Repeat for the other lock, same wire with diode in the same direction,
(ring
nearest lock for example).

If locks fail to work, reverse the diodes.

Andy

Thanks Andy.

Just to clarify then...or try to! I have two sets of terminals one on each
powersupply, these are called P and B. The keypad shorts P & B together to
switch the power on to the mag locks. So i have a wire coming from the
keypad to both terminals. Both power suppys are set up the same. Then i
have two wires coming from the smoke alarm activated relay. these two wires
go short curuit when the alarm sounds. if i conect these two wires to one
of the power supplys P&B terminals, it all works as planed, ie the door
unlocks, but the electrition has put a wire from the terminals on that power
supplys P&B terminals to the new power supplys P&B terminals. this causes
both power supplys to cut power to the maglocks when the smoke alarm sounds,
but also when one keypad operates it also causes the other doors maglock to
yurn off. So where do i put the diodes so that the smoke alarm relay
operates both power supplys P&B terminals, but dosent allow one power
supplys keypad to short the other keypads power supply P&B?

Hehe

Steve