Interesting free symbolic simulation S/W: SapWin

[andy_c]

I'm not sure if anybody's seen this yet, but there's an interesting bit of free software available called SapWin that does simulations of linear circuits and gives their transfer function in symbolic form. I've attached a zip file containing a couple of SapWin circuit files. These are simulations of a closed-box loudspeaker system with a single driver, similar to the SPICE simulations in the article on Dr. Leach's site. These files give the transfer function from the input voltage to the output volume velocity. One includes the effects of voice coil inductance and the other does not.

There seems to be a few quirks with the software, but nothing that can't be worked around. For example, in both of these files, both the numerator and denominator of the transfer function have a zero at the origin, yet it fails to cancel these out. No biggie though, as it's easily seen by inspection. In the attached simulation files, Y1 and Y2 are both equal to the BL product. I could not specify "Bl" for the value of the CCVS, as it required me to enter something beginning with "Y". Also, M_MS is written as L_MS, as the software requires that inductor reference designators begin with "L". For the transformer, "n1" is equal to 1/S_D.

I thought this thing was pretty cool, and may be something that someone might want to try out.

Edit: Oops, forgot the link. It is available here

[Ron E]

Interesting, I downloaded it and looked at a file. This could have some academic applications. So that source arrangement you have there is a gyrator?