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2015/10/29 Controlling 5 and 12V swtiching with SmartFPV RCCCv2 Video Switching Board
π 2015-10-29 00:00 in Electronics, Rc
The RCCCv2 board is an awesome little board, but unfortunately its switched output are not very usable as general purpose power swtiching. One is strobes, so it goes on and off no matter one, and the other one could switch any load, except that the GND line is switched, not the 5V line. As a result, if I plug my cameras into 5V, thir ground goes to the OSD board, the OSD board is connect to the autopilot and the serial communication grounds the circuit via the autopilot, which means my cameras would turn on regardless of whether their GND connection to the RCCC board is floating, or switched.
It's really too bad that the RCCCv2 will not switch the 5V line instead of the GND line.

My other issue was that I wanted to switch both 5V for the cameras and 12V for the VTX, so the best plan was to switch 2 volt lines with a dual relay. Doing this with the RCCC board was again a bit tricky because it would only switch a ground line that would go floating otherwise, so I had to use a pullup to 5V.

If I had to do this again, while I was not able to find any small RC controlled dual throw relays (the only one I found was huge and 3 times the size and weight), the Pololu 2803 RC Switch with Medium Low-Side MOSFET works for small loads, but if you need relays (and in my case I do because I needed a high side switch, and the mosfet was low side), the next best option is a Pololu 2804 RC Switch with relay. Sadly, the relay on it is big, but I can unsolder it and put a smaller one. I recommend the Pololu switches just because they're very configurable (you can change the setpoint, as well as change the direction they'll turn on/off for).
That said, for more than twice the money, a smaller and less configurable one is the PicoSwitch Radio Controlled Relay.

But anyway, I did have this small dual throw relay already, so I made it work with the RCCCv2 board to switch 5 and 12V.

Relay board testing:

Flipping the lights with my RC contoller

Breadboard testing:

Now trying the whole things with my plane electronics, and checking current draw:

My little dual latching relay board is quite small, it replaces 2 bigger relays:

Initial design:

Better design where the relay is not energized when 5 and 12V power are switched on:

And here is the end result board, showing how it's wired with the RCCCv2 board:

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