Amplifier audio switch

JayJay · Post by **JayJay** » Fri Mar 30, 2012 11:53 am

Right, I tried to use the CarPC line in to allow an MP3 player to output audio to the amp (routed via the CarPC) but that doesn't work.

So I decided to make a little switch that has two audio inputs and one output with a little DPDT rocker switch so I can flick between them.

I then decided to take it a step further and have a relay detect when an MP3 player/phone etc was plugged in and switch the circuits so I don't need to have a switch fitted, just makes it neater.

This is the relay:

Just realised I've got it the wrong way round, I want the AUX to be the closed (switch on AUX input) but forget that for now.

And this would be the circuit including the relay:

Pretty basic, just a relay switching between two audio inputs. Ground is shared.

But my problem is the switching! I'm sure I can't use the audio signal to do it as it's not a steady signal (not to mention it won't be loud enough). Can anyone think of how I can get a 12V signal to the relay when a cable is plugged in to AUX?

Cheers,
Jay

Post by **Vtecmec** » Fri Mar 30, 2012 12:55 pm

Can you place a relay detecting the -ve from the aux when plugged in and outputting a live signal as a result?

JayJay · Post by **JayJay** » Fri Mar 30, 2012 1:29 pm

Well the audio signals aren't really +ve / -ve DC (just referring to them that way to make it easier to describe it), they're AC with each lead directing to left/right. So it won't be a steady signal and they'll be much lower than 12V so I can't use them to switch the relay, unless I can split one and ramp it up to 12V DC.