"Owain" wrote in message
news:3omdnW6B8-62v5jVnZ2dnUVZ8qfinZ2d@plusnet...
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.

What happens if the power supply fails?

If they're on an exit route then locks should have a mechanical release,
or be fail-safe ie release autoimatically when the power is off (ie
magnetic locks, rather than magnetic lock releases)

Owain

----- Original Message -----
From: "Owain"
Newsgroups: uk.do-i-y
Sent: Tuesday, April 15, 2008 10:38 PM
Subject: Electronics advice pls.


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.

What happens if the power supply fails?

If they're on an exit route then locks should have a mechanical release,
or be fail-safe ie release autoimatically when the power is off (ie
magnetic locks, rather than magnetic lock releases)

Owain


if the supply fails, the locks release because they no longer have any
power.


Steve