How to control 12v power rail on 3 position switch for FPV system.

Hi

Although a sparks by trade when it comes to electronics I'm pretty much useless. I can solder and understand the basics but need help with this.

The problem is that I have a radio controlled boat which I have fitted with 3 FPV camera's all identical and all 12volt. They are on there own power supply (which is regulated at 12v) so no interference from motors etc and they all work fine independently of each other i.e. when there is only 1 camera plugged in to a 3 port FPV switcher, although when you plug further camera's in the interference starts but it will switch between them and the picture is viewable on each channel. The switcher itself is controlled by a 3 position switch on the remote radio controlled handset and switches only the signal to the transmitter in the boat, i.e. all 3 cameras share the common power rail all of the time. Now I'm going to make and fit an LC filter which may resolve the interference issue as that in itself is simple enough but I would also like to be able to literally turn each camera on / off from the handset as it occurred to me that this will drastically reduce the power consumption of the 3 camera system therefore prolonging the battery life as I only need the camera that is in use at any particular moment in time to be powered up as it were. It would also resolve the interference issue from another angle if the LC filters don't prove to be effective.

Therein lies the problem. Can anyone come up with a suitable product or circuit (I'm confidant I can make it without problems so long as its fairly simple) to do this operating off the same 3 position switch on the rc handset? So instead (or as well as) switching the TX signal between camera outputs I'm switching the 12v supply independently to each camera.

One of the problems is that I am not certain what the signal inputs will be for the 3 position switch from the handset and have no equipment available to measure this. Any help would be very welcome.

Thanks, Chris.