Edward wrote:

"scada" wrote in message
.net...

"JSW" wrote in message
...
Hi
I want to be able to connect smoke alarms to my existing house alarm. At
my
local alarm shop they sell a small pcb which replaces the 9v PP3 battery
and
allows the smoke alarm to be connected to the main alarm. This pcb
probably
has a voltage regulator on it (12v to 9v) and some sort of current
sensing
to trigger the main alarm when the smoke alarm sounds.
What I want is to be able to make this pcb myself as the shop wanted to
much
for it and a want a few of them, does anybody know a circuit for such a
thing?

Cheers
John



These factory smoke alarms are tested for Heat, Smoke, and whatever
adverse
conditions occur during a fire! Do you realy want to take that chance that
you may get it all right!!!! Buying a proven unit gives peace of mind!



You should also check that your insurance is still valid if you "modify"
your alarm system.

It's a good idea: But suppose it misoperates, perhaps due to some
voltage glitch in the powers supply? Could a 'non standard'
modification that caused a 'false alarm' to the company
monitoring your home alarm system then cost you for a 'false
call-out'.
On other hand if your house is of average size and you are NOT
connected to an alarm monitoring company you can probably hear
your individual smoke alarms if they go off anywhere in the
house? We can.
Here; for rented accommodation there are some requirements that
the alarm be a) AC powered; so kids don't steal the batteries for
their 'toys' and b) With more than one habitable floor, alarms be
linked between floors.
Personally I would keep your systems separate with the possible
exception of an intermediate relay.
Relays are very good at physically/electrically separating
different systems.
Then if a smoke alarm works to activate the home alarm system,
fine. If it doesn't you still got your smoke alarm/s standing
alone, not depending on anything else to power them or give the
alert! Change smoke alarm batteries yearly. Also most smoke
alarms will give a 'beep' indication if battery goes low.
If any gas operated appliances (vented or not) also use a CO
(Carbon Monoxide) detector. Could be cheapest life insurance you
buy!
Last year, near here, someone had a night time fire in their AC
main fuse panel. ALL POWER went off; no lights no AC operated
smoke alarms, nothing. They were lucky to get out!