Can anyone see why this simple CMOS Schmitt does not simulate reliably please?
For CircuitMaker users, here's the circuit:
I don't even get an error message. But the input signal, which should be several cycles of a triangular wave, just stops abruptly. Yet, if I replace the generator with a direct connection to either 0V or 5V, I get the correct simulated output (0V or 5V respectively).
It seems the value of R1 is critical. When I lowered that to 519k, the circuit simulated correctly. At 520k it failed!
Any insight as to the underlying cause please?