Two transistor simulation totally wrong (ID 10-T issue?)

I am very new to Circuit Lab (like about 24 hours). I like what I see, but I can't trust it. I must be doing something very wrong. I'm looking for the sharp eyes that can tell me the magic.

The first circuit I did was a simple common emitter amplifier. The base bias resistances that centered the quiescent current in the middle of the load line were very far off from what I found on the bench. Well, I can tweak designs. No biggie.

So, I put in a more "interesting" circuit, one from a link I'd recently found and built up on a breadboard; Link.

The Curve Tracer curcuit was a fun build, but it wouldn't run at all on the Time Domain Simulation.

So, just as a sanity check, I stripped out everything except the sawtooth generator, and that wouldn't run either. 2 transistors, 2 capacitors and 4 resistors. what have I done?

I told the simulator to go from 0 to 400m by 100u. I got Bigger:

Whereas my oscilloscope says (Note, T1 Collector is yellow, T2 Collector is Purple) Bigger:

How can we resolve this horrible difference? 8mV is not even close to 8V!

Does CircuitLab have a problem figuring out that what looks like a straight path to ground through a saturated transistor might be different if the base is at a different voltage? I’m not getting a lot of confidence in the software but I hate to ask for a refund. Please tell me there is a setting that makes this simulator work right!

I really like the drawing and printing, but I can’t seem to trust the simulator. I’m looking forward to the textbook!

by wdbarker3
April 07, 2020

Thank you for showing us a great puzzler! Did you solve it?

I put a suggestion with some explanation in this simulation Kickstarter1

Briefly, one change to get things going: Unbalance the circuit by forcing T1 OFF at simulation start.

by EF82
July 02, 2020

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