boe power question

firealarmfreak

can someone post me a simple diagram or explain on how to use a dpdt relay to create battery backup for my boe and alarms? Basicly--im making a fire alarm control panel--and i have the boe powerd by 9 volts dc and the audible alarms on 18 volts dc.

I have wired it so when the power goes out--the dpdt relay turns on the trouble led, but i want the trouble led to come on, and it also to switch to battery (2 9 volts for alarms) and (1 9 volt for boe).

I think i can just connect the relay so when the relay has power--the battery circuit is disconnected meaning power is drawn only from the ac-dc adapters--but when the relay is off--power is only drawn from the battery circuit.

thanks

chris.

Post Edited (firealarmfreak) : 10/19/2008 7:06:16 PM GMT

Franklin

I think you are on the right track with the relay but before you get too far hook up two 9v batteries to the alarms and see how long they will run.

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- Stephen

firealarmfreak

ya but how do i connect it so it works how i described? I know what should happen--but im confused on how to connect it. explain? diagram possible?