Free SPICE simulator..

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Simetrix Intro

I have looked at about 6 or 7 of the "freeware" versions of Spice and this may be the best for simple amplifier design. It seems to be able to read models from other Spice programs which is really nice. If the circuit limits prove large enough this maybe the one to use for the serious DIYer. It also seems to be the one of the easiest to use with lots of examples. If there is enough interest I may provide some circuit files and or parts libraries. Any feedback from experienced users of the freeware Intro version?

http://www.newburytech.co.uk/Pages/download.html


H.H.
 
I have been using simetrix v4.0 and v4.1 for about a year now and found the same problem as Geoff. Bode plots for various amplifiers indicate insufficient phase margin. I am struggling with this for over 3 months now , and I have still no solution, or explanation. Could it be that ''AC analysis is for small signals only'' is the cause of this "problem"?
Nevertheless I think it is a very good piece of software.
I used a very old MicroCap v3 for DOS more than three years and tried and abandoned EWB's MultiSim.
 
SIMetrix Intro

Is you discrepency with phase margin with Spice in general, SIMetrix Intro in particular. I am also interested in which other Spice programs you have tried. Have you tried running the same bench mark circuit on different simulation programs and had different phase results. Thanks for your feedback and I am very impressed with my limited experience with SIMetrix Intro and the GUI is very friendly in comparison with some others.

H.H.
 
H.H.

I tried most, if not all, of the free simulation programs about 2 years ago before settling on SIMetrix Intro. I cannot remember any phase margin errors with the other programs, but my memory is not what it used to be. Anyway, at that time, I had less knowledge of Spice and stability criteria so may have missed a problem had it existed.

I have not found any discrepancies when using op-amp models, only with discrete circuits. Discussions with Rod Elliott, who also uses SIMetrix Intro, have revealed that he has experienced the same problem.

If anyone can offer suggestions as to the possible cause, I would be glad to hear them. Or, better still, if someone has access to two simulator programs, including SIMetrix, could they please run an open-loop Bode plot using a simple circuit (say the ESP 3A) and compare the results.

I have been meaning to write to Newbury Tech on this matter for some time now, but I will hold fire pending any feedback in this thread.

Geoff
 
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