"NSM" wrote in message news:jDJCd.44550$Y72.1684@edtnps91...

"DaveC" wrote in message
al.net...
| I've got several remote alarm sensors triggered by 120vac relays. When
power
| fails, the alarm calls the right folks.
|
| Problem is that even the small power glitches get these guys out of bed.
Not
| a good thing.
|
| How can I delay the de-energizing of these relays? 5 minutes without
power
is
| OK. Will a series diode and shunt cap do the trick? If so, what size
cap?
If
| not, what're my options?

The normal method is a relay with a hydraulic delay. This means you don't
need a no fail power supply. However these days, if you have backup power,
there are solid state equivalents.

For your method you would need a large cap run off say, 12 VDC - maybe
1000
uF and up.

N



Just put a delay circuit in between the relay contacts and whatever
(assuming low voltage) signal the control to the alarm panel. A 555 IC
driving a small low voltage relay should do the trick.