Simulation not working

I think one problem is likely your resistor value on the LED is too high. As it stands at 9V it will only put about 1ma through the LED and LEDs typically need 10 to 20 ma to light, About a 1K resistor should get you to 10ma.

That said I still can’t get simulation to work even in debug mode with transient selected (you need to start Fritzing with the -d flag to enable debug mode then select the transient mode (greyed out here because debug isn’t active)

in order to get transient mode. Success, the problem isn’t the cap but rather the pot. Its spice model must be incorrect. Replacing it with the one from core parts makes this all work this sketch (run in transient mode under debug) blinks the LED as expected. Note I also reduced the resistor to 1K I don’t know whether 5k6 would work differently (the led may not get enough current to light I expect.)

knightrider-newcap.fzz (40.7 KB)

Peter