On Tue, 15 Apr 2008 18:38:04 +0100, "Mr Sandman"
wrote:

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.

You should have an emergency exit switch on the wall by the door which
de-energises the lock when pressed. To have a final exit door which
requires either a carried device to open from the inside or a smoke
alarm to function is not terribly bright.