Simulation software, specifically for eq/filter circuits?

[DavidS]

Looking for a software package, hopefully a good free or open source package, that can handle filter simulation. And general electronics simulation, I suppose, that would be nice. I'm aware of the Duncanamps tonestack calculator, but I'd like something more flexible, that allowed me to create my own schematic and see a response curve out of it.

I know how to use a scientific graphing calculator, but I'd really like something optimised for what I'm trying to do.

Failing that, where do I look for the formulas and equasions for filter circuitry? SHould I just google, or does someone know a keen place to find this info?

Thanks!

[davebungo]

You should probably try to get a copy of the PSpice student edition.  It's not very easy to find but it should be out there somewhere.  Sorry, I can't provide a link.  ORCAD may be able to help though...  There are probably other similar packagaes out there also, but I do find PSpice to be great for the sort of thing you are after.

I probably have the original zip file myself somewhere but it's on my Laptop and I use a MAC for internet stuff.  PM me if you are really struggling or if you can't find an alternative.

[markusw]

You might want to give LTSpice/SWCadIII a try http://ltspice.linear.com/software/swcadiii.exe

It's free and there's also a cool yahoo user group. There you can find even sims for Vactrols.

Markus

[puretube]

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en010007

http://focus.ti.com/lit/an/sbfa001a/sbfa001a.pdf
http://focus.ti.com/docs/toolsw/folders/print/filterpro.html

http://www.circuitsage.com/filter.html