I would highly recommend you to download the LTspice, it is free and easy to use.
It takes you a few minutes to draw and simulate.
Thanks
imo! So it does seem to work. I see you simulated removing the diodes and now I remember I added them to raise the voltage of the switching points.
I am still using Win XP Pro SP3 so I downloaded LTSpice IV, version 4.23l. I do not know if files created with later versions would be compatible but may be you can post the file for this circuit and I can try to open it.
I will have to do some learning now. Thanks for the tip.
E.T.A.: I opened one of the example files. I see they use the extension .asc which in my system is already taken by PGP keys but I guess that's not a major problem. I'll have to work around it.
Here's a tip for graphics: this type of graphics are much better compressed with PNG than with JPG. The graphic is crisper and the file much smaller in size. JPG is really only appropriate for photos and similar graphics.