New to relays, please help

Here's one way to make it work..Get a normal 5 pin bosche style 30A relay from an auto store or something. Pin 85: Tie this pin into the first circuit that has power. Pin 86: Run this to ground. Pin 30: Run this to fused 12v assuming you want the second circuit to have 12 volts when the first turns off. Pin 87: Don't connect to anything Pin 87a: Connect to the 12v side of the second circuit you want to power up. Not sure how good you are with relays so here's a quick explanation of how it works..When circuit 1 is ON the relay is energized (pins 85/86 is the coil) and pins 30 and 87 on the relay are common. (ie second circuit is DEAD). Now turn the first circuit off and the coil of the relay shuts down making 30 and 87a common. (ie: second circuit gets 12v and turns ON). Good luck hope that helps. Mike