Circuit Simulators

Greg · Post by **Greg** » 30 Jul 2009, 02:48

I couldn't find much on them ...

Who uses 'em ?
What do you use ?
What are the choices ?
Are there any good freeware or budget choices ?

HydrozeenElectronics · Post by **HydrozeenElectronics** » 30 Jul 2009, 04:42

I would be interested in a good shareware version as well.

lcv · Post by **lcv** » 30 Jul 2009, 09:30

Hi,
I've used (and still using) a lot LTspice http://www.linear.com/designtools/software/ to check a number of quantitative data about a given circuit such as frequency res., biasing, gains, shape of clipped waveforms etc. before actually build anything.
I applied this mainly to dist./fuzz, but also compressors.
Example: I have entered in LTspice a modified Shredmaster schematics (my favourite pedal) I built and I've been using since five years. Then, I recently build a modified version of the Tube Driver that relly did not cut through, so I used extensively simulation to adjust the pre and post clipping (tubes) stage signal frequency shaping to match the "reference" Shredmaster behaviour. I was amazed about how similar the two pedals sounded similar once I adjusted that parameters.

A word of warning: the models available do have limitations (that add up to mine... )e.g.
1) I failed simulating Ge biasing and leakages thermal behaviours (I've never achieved a reliable simulation of simple Ge FF !)
2) I could not find suitable models for simulating properly starving plate tubes circuits . Grid current vs, Anode voltage dependency for low anode voltage value is usually not or wrongly taken into accout by the availble models.

One last thing: LTspice can be fed by .wav files, so you can virtually "ear" the circuit characteristic in simulation.
I've never got the time to explore this possibility which IMO has limited practical value anyway

Best Regards,
lcv

JiM · Post by **JiM** » 30 Jul 2009, 19:44

After searching for some time a simple-to-use, open-source, circuit simulator compatible with Linux, i eventually settled for LTSpice too, using wine emulator.
I would prefer a genuine Free Software out of a proprietary freeware, but anyway it works fine. The .wav input/output feature is great, but it takes a long time to simulate a suitable amount of signal time. There is a shitload of Linear Technology opamps models (hey, they give it for promotional purpose !) but you can add any other Spice model by hand.

There is also Qucs : http://qucs.sourceforge.net/ including some HF and digital stuff.
And of course all the command-line-based variations of the original Berkeley Spice ... Most CAD software can export compatible netlists.

DrNomis · Post by **DrNomis** » 12 Oct 2010, 13:55

Greg_G,

At one point I had Circuitmaker 2000 installed on my computer,but i ended up not trusting the results of it because it sometimes gave very strange results,even though I was getting it to simulate an electronically correct circuit....