Fire siren project, relay help needed. September 18, 2011, 12:46:05 PM I'm a vol. emt and fire fighter, I have two identical sirens that I've been running paralell to each other with a dual throw toggle switch, I need to redo these. I dont have room for the dual throw switches, theyre too bulky. so I thought I'd try relays. what I had in mind was, in the first pic. if they make such a thing, using a dual throw relay. i'm not sure if this will work.relay design.jpg (56.4 KB) In the second set up, running two relays, one after the other, using the coil side of the relays in a bridged set up. power wire into relay 1 pos, thenfrom relay 1 neg. to relay 2 pos. then from relay 2 neg. back to the battery.relay design 2.jpg (45.7 KB) in the third, I'm illistrating the idea of using one sirent to trigger the relay to start the other siren. relay design4.jpg (31.6 KB)what do you guys think would be the easiest, what relays would you reccomend?