multiple alarms to one set of buzzers - need circuit

[RaymondR]

You could probably use an SCR rather than a relay if you wanted to go all solid state.

I'd put a couple of limiting resistors on those alarm inputs as well, you are creating a short to ground when you trigger the alarm silence push button.

[Wotname]

Originally Posted by RaymondR

.....

I'd put a couple of limiting resistors on those alarm inputs as well, you are creating a short to ground when you trigger the alarm silence push button.

Err...where is the short to ground?

[RaymondR]

Originally Posted by Wotname

Err...where is the short to ground?

Probably not a problem with the relay since it goes through the relay coil, depends upon the allowable sink of the alarm signals, could be if you wanted to exploit the latching capability of an SCR.

[s/v Jedi]

Originally Posted by RaymondR

Probably not a problem with the relay since it goes through the relay coil, depends upon the allowable sink of the alarm signals, could be if you wanted to exploit the latching capability of an SCR.

No, there is no short to ground. A coil of a relay is a load, not a short.

[RaymondR]

Depend, if you've got a source capable of 30 mA max and a coil resistance which will allow 40 mA to pass it's a short.

[goboatingnow]

Originally Posted by RaymondR

Depend, if you've got a source capable of 30 mA max and a coil resistance which will allow 40 mA to pass it's a short.

It’s still not a short

[Wotname]

Originally Posted by RaymondR

Probably not a problem with the relay since it goes through the relay coil, depends upon the allowable sink of the alarm signals, could be if you wanted to exploit the latching capability of an SCR.

Or one could say "there is no short, one was wrong in thinking there was a short"...