When you add up the shipping and handling buying parts from Digi-Key or Mouser, and the time, it is better (IMO) to buy something that works and adapt it, rather then re-invent the wheel.
All you have to do short out the input lines and that will mute the sound.
If you add a resistor, you can attenuate so it doesn't go dead silent.
On a 10k input I would try a 250 ohm load and see how much that drops the sound.
The device I gave you a link to will do two lines.
Add another one to do the four.
It even has a 12 volt trigger and I bet it doesn't
"pop" when switching either.
Here is a device to look at:
What exactly are you trying to do?
Do you want to "bleed" the GPS voice commands over the normal audio?
I would just switch the inputs (FET) and give the GPS priority.
that's really going to be the easiest way to accomplish what you want to do. $100 for a complete setup is really quite good.. of course it ruins the diy stuff, but i really don't think you could come in that low diying a solution..
Originally Posted by heavymetals
those units are a little tricky to setup to switch at the right times-- i did a niles amp in a conference room once with an identical feature(they wanted the background music to play through unless there was a conference call/video meeting)--but once they are setup, they don't need to be touched again..
What did you end up doing?
Originally Posted by Champak
I haven't done it yet because there are a few other things I have to do to the car, but I'm going to follow your suggestions and get one of those devices instead of building one.