We’ve got 2 rigs in the car, a 70cm/UHF-CB combo and a 2m. A green light on the rig goes on to show it is receiving, however if you were not quick enough to see it, then you go “which one was it?” (WOWIT).

So, using a latch relay and a couple of resistors, I made a circuit that gets toggled using the MUSIC MUTE outputs from the rigs. This feature is typically only available on commercial rigs. The remote indicator is built-in into an home lamp in-line switch casing and can easily be mounted on the dash. The indicator has a green (UHF) and red (VHF) indicators. The in-line switch is used to turn off the LEDs for night driving, the circuit still detects rig activities and, if required, the LEDs can be turned on to find out which rig last received a signal. If the 2 rigs receive at the same time, the last radio to squelch out will toggle the relay in its favour.

Total cost of the project was $2.64 for the relay, all other components were sourced from junk box, previous projects, and as usual, council clean-up.

The below circuit assumes both rigs and the circuit share the same 12v and gnd. Select resistors to suit the relay and LEDs. The relay I used is a 5v relay with very low current drain.

Watch video of device in operation