Race Track Headsets - 2 Radios / 1 Speaker

[rescue161]

Last year, I bought three Radio Shack race track headsets so three of us could talk to each other and listen to the attached scanner. These headsets are suppose to only be used in pairs and are wired into the scanner for the intercom to work. I made a box so we could hook all three headsets together and still listen to my scanner and talk to each other. The scanner worked great, but the audio amp in the scanner couldn't support three headsets while we tried to talk to each other. The volume was extremely low and when we turned it up, it just squealed and became distorted. After that race, I put them back in the box with all intentions of selling them.

Today, I thought about rewiring them so they could all talk wirelessly via what ever radio service I chose, GMRS, MURS, Nextel Direct Talk, etc. My question is, what type of circuit do I need to build/add to allow the scanner audio to use the same speakers in the head phones as the radio at the same time.

I'm going to just use a standard 1/8" plug for the scanner input/output (two on each headset) so each listener can use their own scanner or use a straight cable and plug into another users headset to listen to their scanner.

I'll probably use a screw-in type connector for the two-way radio connection as I don't want it to easily become unplugged.

Does anyone have any suggestions on what type of circuit I should use?

Thanks,
Scott