In article ,
Lee Nowell writes:
Hi All,

We have a burglar alarm with a couple of spare "zones".
Unfortunately, when we had our fire alarms fitted (mains powered and
all interlinked), I didn't think about integrating them with the
burglar alarm so we will be notified if the fire alarm goes off whilst
we are out of the house.

I was wondering, if I put a relay in, would I be able to connect the 2
together such that the burglar alarm treats it like any other zone in
the house.

My logic (which may well be flawed!) is as follows....
- connect the 240v interconnect from one of the smoke alarms to one
side of the relay (I have assumed that the interconnect goes "live"
when the fire alarm goes off - is this true or is it a switch?)
- connect the 12v alarm wire to the other side such that the relay
opens the switch when it gets 240v the other side (i.e. breaks the
alarm feed and sets the alarm off).

I'm sure it is not really this easy ..... and would greatly appreciate
any help you folks can give me.

Some interlinked alarms have a relay module which can be connected
into the interlink, but these aren't cheap. If there's one available
for your model, you could link it to one of the alarm zones.

Mine are the other way around. The smoke detectors run off the
burglar alarm. They are standard 9V battery ones, but an alarm
interface unit same size and shape as a PP3 battery fits in them,
which steps down the 12V alarm supply, and signals back to the
alarm panel if they go off. (It detects this by the increased
current draw of the smoke alarm siren.) Unfortunately, I haven't
seen these available recently - they probably don't conform to
current regs anymore.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]