Any electrical engineers or electrical gurus?

Well I have an ASE in electrical but thats with cars but here goes a shot. Do you want it to cut the music off and just play your voice or do you want it to just play your voice over the music?

If you want it to cut the music off and play your voice when u push the button find the circuit that powers music signal to speakers and make it so that when u push the button it opens the circuit for the music and closes the circuit for the microphone.

If you want it to lower the music and play ur voice louder (if the volume is controlled by a variably resistor) you can add in a certain ohm resister to the music signal and leave the microphone signal at w/e the volume is set at and that should work.

Like i said my specialty is in the automotive field but electrical is electrical. If you have any questions that I could help at all just let me know.

I can ask my brother tomorrow when I see him, working at National Semiconductor. If he can't figure it out we're in trouble.

I assume you want to do this for parties or something? If you are playing from a cd player, you will need something to interrupt the signal and either a powered mic or some kind of amplifier to run out of the mic to bypass the cd player input.

Do you want to mute the music and speak, or have the music volume turn down but still play in the back ground? What kind of receiver are you using?

You're going to need to amplify the signal of that mic somehow. A microphone takes the sound waves you speak into it, directs them into a diaphragm, and creates an output signal. Do you know what kind of mic you have? If its a condenser mic, then you will need to have an external power source on at all times to induce voltage across the capacitor in the mic.

Honestly, its probably easier and cheaper to pick up a cheap mixer for 40 bones at Radio Shack.

Say you wired the ipod up and used the switch to open the circuit from the ipod and close the circuit to the mic. You'd still want a pre-amp in between the mic and the receiver to regulate the signal from the mic, otherwise you're going to run into issues. The ipod has a "pre-amp" that controls EQ and volume from the wheel, but the mic has no such device that I know of. If you can't control the gain of the amplifier powering the mic, you run the risk of it sounding like garbage.

Furthermore, because the signal from the ipod is so small, you may have the volume cranked way up on the receiver to power it. So when you turn the mic on, with no way to regulate the signal coming from the mic, you could blow the ears off anyone listening with tons of that squealing / distortion type stuff. A cheap mixer will provide you with pre-amps and volume control of each signal coming into the mixer, plus it will allow you to fade the music and mic volume into each other.

Adam