I'm designing a circuit that needs a 'backpower protection circuit', similar to what the Raspberry Pi HATs use. This is meant to block voltage from the secondary board when the primary board is supplying voltage:
I've prototyped this in CircuitLab using other jellybean parts, and put some oscillating power supplies in place so I can see how it behaves:
However, even when simulating the circuit, I don't see it supplying the max(v1,v2) that I'd expect to R4, which is my simulated load.
Assuming the circuit is correct, how would I measure that the correct voltage is being sourced or sinked to the right side of the circuit? How could I show which "direction" it is coming from? (such as by an LED)