Hi guys,
I am trying to make a latching relay with a dpdt relay switch and one main power source that when turned off will trigger the relay to pull from a secondary source to light a led until a reset switch is pressed signifying that power in the main is turned back on. My problem is that I don't know where to place the second power source. Any simple diagram would be very helpful.
Thanks

-Griff

 

A diagram showing what you have in mind would be even more helpful.
So when main power goes down it triggers the latching relay to go to backup, and then you push a switch to go back to main source again? Then use a n.c. contact powered by mains, which passes the backup power source to the latching relays "switch-to-backup" coil.