One of the most frequent question asked to me is about how to use a FRS or CB together with a Bluetooth enabled headset.

Well - It's not that different from connecting a cellphone - if you had a suitable dongle.
I have therefor started a small project - How to make a BT dongle for CB or FRS radios.

Looking on the net for a suitable module a found the KC Wirefree KC-5290 to be a suitable candidate.

It needs very few external components - not that expensive in small quantities - and not least - it could be loaded with a kcAudioGateway firmware.    This AudioGateway is in fact weary important - as it has to be reconiced the same way a cellphone will be for the Bluetooth headsets.

Please contribute by making questions or ideas to this project in the Forum : The-BT-for-FRS-and-CB-project

Lets have a look at the ground isolation parts needed.
The FRS/CB on the right side.
In this setup - I'm concentrating on my Midland G7 FRS, witch I find to be one of the better ones out there.
The G7 uses a combi. mic./PTT therefor the CD1 optocoupler. (Upper)

(Lower) is for where you have a separate PTT button!

This setup will make a total galvanic isolation between the Bluetooth electronics and the G7.

This is needed to be sure the will be no electronic noise into the Bluetooth electronics when th G7 is charged.

In the next image I have included the Push 2 talk, and two light emitting diodes.

D2 will light up when the FRS radio is power up, and the D1 wil light when the FRS is in TALK mode. (The PTT button is pressed)

On the LSP output from the FRS - we need to make the ballast to something near 33Ohm, so a resistor in parallel to the small transformer will be needed. The transformer is a small  1:1 with a resistance in about 1K.

The next thing to work on is how to make sure we have the right levels and impedances on the FRS and BT side of the unit.

More of this in a few days ...

regards
STeinar