Timeline for LTSpice: What breaks KCL in .op but not in .tran simulation?
Current License: CC BY-SA 3.0
16 events
| when toggle format | what | by | license | comment | |
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| Feb 25, 2018 at 7:07 | history | tweeted | twitter.com/StackElectronix/status/967657374478675971 | ||
| Feb 25, 2018 at 1:15 | history | edited | Sredni Vashtar | CC BY-SA 3.0 |
added 196 characters in body
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| Feb 25, 2018 at 1:01 | history | edited | Sredni Vashtar | CC BY-SA 3.0 |
Gave a more descriptive title, fixed some grammar.
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| Feb 25, 2018 at 0:19 | answer | added | jonk | timeline score: 10 | |
| Feb 24, 2018 at 23:06 | comment | added | jonk | Okay. Found the problem. +1 to you. I'll write up the answer below. | |
| Feb 24, 2018 at 22:28 | comment | added | jonk | I think there is something seriously wrong with the 2N2905A BJT model. Try the 2N2907 and the 2N3906. They seem just fine. | |
| Feb 24, 2018 at 22:22 | comment | added | jonk | @τεκ Agreed. Deleted my comment. | |
| Feb 24, 2018 at 22:21 | comment | added | τεκ | @jonk looked it up, fourth terminal would be substrate. PNP substrate shouldn't be ground. Not the cause of this issue, though. | |
| Feb 24, 2018 at 22:08 | comment | added | τεκ | Hmm. Changing the model to 2n2907 the results are sane, but with 2n4403 the problem also occurs. | |
| Feb 24, 2018 at 22:06 | comment | added | Sredni Vashtar | @G36 the model is one of the default models offered by LTSpice. But - doh!, I thought I had selected a 2N2955 - 15 amps power transistor, while this is a tiny 2N2905, a 600 mA small signal transistor. So, maybe the fact that in a real circuiti it would have been vaporized has something to do with the error. It still begs the question: why .op is getting it so wrong, while .tran is getting it right? | |
| Feb 24, 2018 at 21:57 | comment | added | G36 | There must be something wrong with the transistor model you have used or with LTspice. Because when I place a small resistor (Rs = 1m ohms) in series with the emitter the LTspice shows I(Rs) = 2.37518A. But Ie is still equal to -4.70351A. Strange. | |
| Feb 24, 2018 at 21:52 | comment | added | Sredni Vashtar | How did it get there??? Anyhow, I removed it, saved the netlist, run it again: same results. | |
| Feb 24, 2018 at 21:48 | comment | added | τεκ |
You have an extra 0 there: Q1 out B E *0* 2N2905A
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| Feb 24, 2018 at 21:43 | history | edited | Sredni Vashtar | CC BY-SA 3.0 |
Added netlist, as per request
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| Feb 24, 2018 at 21:36 | history | edited | Sredni Vashtar | CC BY-SA 3.0 |
Added netlist, as per request
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| Feb 24, 2018 at 21:31 | history | asked | Sredni Vashtar | CC BY-SA 3.0 |