On Wed, Aug 30, 2023 at 10:09 PM, Paul - AI7JR wrote:
I'm curious about what you propose, but that link doesn't show anything. :-(
Damn. I'm on my phone right now and about to get on a flight so this will have to do -
* Change value of D108 to 5V
* Disconnect Anode of D108 from ground, instead connect to the base of an NPN transistor
* Connect NPN emitter to ground, connect collector to PWM_5V
* Add a resistor from NPN base to emitter (value tbd, likely 1k)
* Add a resistor in series from PWM_5V to to microcontroller (also value tbd, likely 1k or less)
* Repeat for 3V3 rail
Now, whenever the 5V rail exceeds 5.6 volts (zener voltage + NPN Vbe), the NPN turns on, pulling PWM_5V low until the fault clears.
