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Why SPICE and other simulation systems don't work.

Take any small signal NPN transistor.


  1. Predict the voltage expected on the (open circuit) COLLECTOR via a SPICE model of the circuit in any AC Circuit simulator you care to use. Do this 1st before you measure.
  2. Take an oscilloscope or standard electronic multimeter (typically 10M ohm plus input resistance) and measure voltage between COLLECTOR (floating) and ground.

Explain your result.

Clue - you cannot break the laws of Physics, even though it appears that's what's happening here :-) - but you do need to KNOW them.

The result you will get is: -0.35V. (NEGITIVE!)

If you use a metal transistor you can open the case and _SEE_ what happens. The reverse-biased junction produces light, and it causes the other junction to produce electricity(all those junctions are silicon solar cells, after all!).

I doubt if your spice models accounted for this. But even if it does, "Simulations are doomed to succeed."


file: /Techref/spicegotcha.htm, 1KB, , updated: 2017/8/2 16:57, local time: 2024/7/23 04:33,

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