Recording to a Camera

Hello, new guy here (introduced myself in the introduction section.)

I own a crappy race car I race with my buddies in the 24 hours of Lemons series. We currently use a very inexpensive BTECH MURS radios.

We have one mounted in the car, with a roof mounted antenna and one in the pits with an extended antenna. It’s a basic set up that has served us very well.

In the car we connect the radio via a NASCAR style (3 Pin) wiring harness.

(This one specifically)

The routing looks like this….


We also run a small camera in the car, which livestreams to YouTube from the car. It has a 3.5mm microphone input.

What I’m trying to accomplish is to build a small circuit to plug in-line with the radio harness. I’d like to capture ambient audio with a small microphone and have that feed through the circuit to the camera. I’d also like to have the circuit switchover to record the race audio when radio traffic, either incoming or outgoing, is detected.

A device like this already exists, but it is $264. I’m hoping this can be built cheaper. (I’m cheap, which should be obvious by my communications set up.) But I am handy with a soldering iron, and do have a basic understanding of electronics. (Very basic.)

I’m hoping someone here has some advice and can steer me in the correct direction.

Thanks in advance for the help and advice.

looks like it’s on sale for $199.00 I would buy it as I doubt you’ll build it cheaper.

Thanks for the info. With the IMSA style connectors I need it’s actually more expensive. But you may be right, the parts to make it work may be equally expensive.

Seems to me like it’s really nothing more than a low power relay. But I’m just not sure, was hoping someone here had experience and could steer me in the correct direction.

It’s just splitters, I doubt it even has components above resistors and a few trimmers maybe. It could have active preamps and then passive splits to the outputs or two preamps and the no split, but I agree that it’s really the cost of the socketry and the box, plus labour and a profit margin. All it is doing is splitting the headphone feed I think? Does it do anything else? In that case you just need to isolate the camera feed so that’s probably a single resistor 10k as a starting figure, then an attenuator to drop the level, and the link to the camera or transmitter with a similar network so incoming and outgoing audio are at the same level. Me, I could build it, but why when it’s not a bad price it seems?