Topic: Electronics Advice needed

[rbtconsultants]

I would like to use a 12v relay to turn off the turn signal beeper when the brake light is on. I am stealing this idea from someone else, but he did it with a circut board.

I don't know a lot about electronics, but I know enough electrical to figure out how to wire a relay to accomplish this. I figure I will just use an SPDT relay. I will connect the brake light wire as the active juice, and connect the turn signal beeper to the poles such that the turn signal beeper will only get juice when the brake light is not getting juice. Seems simple enough.

However, what I don't know is if I need a diode on the circuit to prevent some sort of inductive voltage from going back to the brake light wiring/switches when the brake light turns off and the magnetic field in the relay coil collapses. I have read enough things on automotive applications of relays to confuse me completely.

I wanted to do this simple and just get a 12v automotive SPDT relay and connect a socket with leads that are connected to the brake light  and beeper wires wires without dealing with diodes and soldering.

Anybody understand what the hell I'm talking about enough to advise me?

Thanks much,

Bob

[razor02097]

take a deep breath man... first off the diode is usually put on a relay as protection to the relay coil but many new automotive relays you buy have that built in.  you are on the right track with your thinking.

[Alan F.]

That's a pretty good idea RBT.  Here's the info you're looking for: http://forums.sohc4.net/index.php?topic=54637.0

Diodes are pretty cheap, using a relay socket and adding a diode will be cheap insurance.  BTW the diode is used to protect the switch contacts that energise the relay coil, a very important issue when you're using your brake switches...

Cheers and thanks again for the original idea.  Everybody else just tosses out the beeper or unplugs it.  I use a loud flasher relay and a bright indicator light.