PeachParts Mercedes-Benz Forum - View Single Post - Dual amp power on-off

jay_bob · #4 04-09-2013, 09:40 PM

Sorry for the technical jargon, I'm a controls engineer and I forget not everyone knows the language.

The number of poles is the number of independent circuits that can be switched by the relay. Normally there are from one to 4 circuits in the relays used in the automotive world. Most are single or double pole.

The "throw" refers to the possible state of the contacts. All relays are at least single throw, which means the contact blocks power from flowing when the coil is off and passes power when the coil is on. Some relays are double throw, which means that the relay contacts have 3 points, a common, a normally open, and a normally closed. Power passes from the common to normally closed if the coil is off, and from the common to normally open if the coil is on.

What you want to do is use the 12 V signal from the car stereo to turn on a relay coil and then use the relay contacts to switch the turn-on signal to the amplifier. If you have a double pole relay then you can use one relay to turn on both amplifiers. If you have only single pole relays, you will need two relays.

There are many different ratings but for your application you only need a relay with contacts rated at least 1 Amp. And you want the coil to be 12 Volts DC. Radio Shack might still have something suitable.