Help, I have an idea for an intercom system for me and my partner when we ride the motorcycle, but I don't know where to go to get the plans or help designing the plans.
If I start with two cell phone earpieces with the mini RCA jacks, how hard would it be to make a holder for a AAbattery ,a pot and two jacks that pipe micA to speakerB and micB to speakerA. Freshman electronic was 30 years ago and I just don't remember how to wire it, or find it

Here is someone who thought it was a good idea 30 years ago:
Nady Systems PMC Motorcycle Series (http://www.nady.com/pmc_motorcycle_pg.html)
Nady Systems HTCS-3 Motorcycle (http://www.nady.com/htcs3_motorcycle_pg.html)

Stratmando, I have seen those products. I have the money to build something, but not to spend $175 for those type of units. I was looking to use earpieces I already have, $20 in parts, and my soldergun.

Sorry, I don't run into many people who actually want to build their own anymore.
You could use 2 small amps, or a stereo amp.

I assume you want this wired.

The 1.5 volt batter is probably way too small. You might do with a supply spliiter and a 9V battery

You have to determine the type of mic and the Z of the headphone.

You should have an easy to disconnect system.

If you take a simple mic amp volume control speaker x 2

You will likely end up with a couple of problems:

Volume should depend on ambient noise.
The system should be built into the helmet.
Frequency response should be limited to the voice region.

Manufacturer's data sheets should have enough info to build something.

Se if any of these help:

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