Right part: The output.

Bottom part: The logic. We will be using window comparators, for efficiency. Right now using an arduino to drive some relays to do a proof of concept.

To increase efficiency, there’s going to be one LED for the whole board ( lit = OK, not lit = not OK) that will turn itself off when the USB cable is inserted, by seeing if anything is connected to the data line. (If it doesn’t turn off because the USB device is charge only, we’ll live with it, maybe add a toggle switch).