As some of you might already know I have been working on a little project that is supposed to make my radios a bit safer.
Recently I had a little problem with my 9XR-PRO power switch. As you know the 9x/9XR-PRO power switch switches 2 independent circuits. One is the power to the mainboard, and the other is the power to the RF module, as well as a detection circuit that will let the processor know if the power switch is ON or OFF.
So on my radio one side of the switch was/is switching ON and OFF before the other. That means the radio thinks it is OFF while it is still ON. That is not good. Then it hit me that a bad connection on the power switch while flying a model would be a disaster as once the CPU thinking it is time to sleep, it doesn't recover even if the switch connects again. Mike, kinda fixed that on the pro firmware, but I think the others still don't have it? The pro seems to be working better even if sometimes I still see "Shutting Down" when I turn the radio ON. But is doesn't hang anymore.
So, after all that, I have been working on some circuit that keeps the radio ON even if the power switch fails completely. At the same time I am also trying to improve the reverse polarity protection.
I have something already working for the 9x radio with stock board.
I also have something working for the skyboard and Ar9x boards. Actually I etched a new power switch board and installed it on my 9x with skyboard, and it is working.
But I have a question or two about the 9xtreme board.
Does the 9xtreme have some reverse polarity protection at all?? I know we have to ( or should) solder a diode to the switch board. But apart from that, is there any other protection circuitry on the board? A diode, a mosfet?
Also, I see that most (if not all the boards) use a schottky diode as reverse polarity protection. I remember suggesting this a few years ago, even before the sky board, and I have been told at the time that it wasn't a good idea because the voltage reading would not be accurate.

Now all boards use it. So we could have probably avoided many of us destroying their 9x radios
Is there a good reason for using a diode instead of a mosfet as reverse polarity protection, apart from the price of course?
A mosfet offers practically no voltage drop when it is conducting, if it is completely turned ON. So, the voltage reading would be more accurate. Talking to some people, I have learnt that many prefer the mosfet approach, hence my question.
Thank you for your answers
João ( the person that is an absolute ignorant in electronics according to at least one person ).