quick psu question

[Mf1999]

hi all,

i am wanting to connect an additional bell box and sound bomb to my system which is already near full capacity, now i know i will need an additional external 12v psu which i will purchase however i realise for the sound bomb (just neg and pos trigger) i will need some kind of relay to connect on the negative trigger cable and wire to the bell output on the panel, now the question i have is what kind of relay is the correct one to purchase for this task? or is there any alternatives to a relay such as using a different trigger method or wiring off the sab module of the new additional bell box?

any advice is much appreciated

 

thanks in advance

[sixwheeledbeast]

I've never fitted soundbombs, theyre pants.

Trigger may take the load depends on the panel.

Relays should be transistorised.

Maybe using a compatible SCB box would save the hassle with the PSU and commoning neg's.

Have you checked your "capacity", I assume you have standby and alarm current values to calculate your battery standby time?

 

[Mf1999]

thanks for the reply,

 

yeah i realise sound bombs aren't the best but i just want to use it up so it's just not sitting there, and yes i do have a spare bell box which i could use.

as i have purchased the psu would it be possible to connect the sab module directly to the psu except for the tamper and bell/strobe trigger which obviously need connecting to the panel.

 

and i haven't done proper tests but from working out from the devices it's about 950ma if everything is going off and every detector is triggered and keypads in use and i believe my panel has a 1250ma psu i think not 100% on that it's old and could do with upgrading anyway.

 

thanks again

[sixwheeledbeast]

Standby current is equally important for battery duration this should be calculated from your battery size with tolerance for ageing.

In alarm current I would want to keep a decent margin lower than maximum load as a bit of tolerance.

You also have to consider how much current the panel uses to charge it's own battery after a power outage and power itself.

All PSU's in the system need to be at the same potential so they will need a wire between them as I mentioned above.