Hello,
I've been simulating a circuit of the 'classic' astable multivibrator and analysing the results. This is the old-fashioned two-transistor design where each device (both NPNs) alternately turns off/on the other. I'm sure you know the type of thing. Anyway, the collector voltage of Q2 goes negative to almost the extent of the supply rail! Is this a Spice anomaly or would a real world circuit do the same? I don't see how it's possible for a circuit to generate sub-ground voltage levels. Isn't that theoretically impossible? The clock rate is 400Hz and Vcc is 5V.
-Jeff.