[antz]

Hey everyone,
Off skiing shortly, and had a crazy idea, and don't know if i can make it possible!
Here we go...

Does anyone know if it is possible, to have 2 inputs into headphones,
1 being music from an mp3 player
the other being the sound coming from a push-talk radio.
Simple so far?
My aim would be that, if there is an incoming call on the radio, that it mutes the sound from the MP3 player, so I can hear it clearly.
Just like, in a car fitted with mobile phone equipment, so when there is an incoming call, the radio is muted and the telephone can be heard clearly.

Hope someone can shed some light into this!

Antz

 

[Garbz]

if you can figure out a circuit which knows then the PTT signal comes on, and can trigger a small reed relay or similar such device, and then switch off when the PTT signal stops, then i don't see why not.

 

[Sal]

I was thinking along the lines of a noise gate type circuit but the configuration you need has one signal acting as the trigger to attenuate the other signal. It's actually called 'ducking' in the recording biz.

The circuit is not all that simple and requires a chip called a compander. If you search for noise gates and compressor circuits, that will probably get you in the ballpark.

You may have better luck adapting a commercial product than building something within a DIY amp. You refer to hands free phone systems that duck the car's stereo, and I think that might be a good solution to start with.