Sorry about the delayed response!
The schematic was generated using the program Capture from the free PSPICE 9.1 student version. The package can be downloaded from various places on the web. It is a bit cumbersome (parts selection is awkward) but with a little practise, it is OK.
In order to produce images such as that posted, I select the entire schematic within Capture, “copy”, then paste into some other drawing program such as Freehand or Powerpoint and finally write out a .gif file.
Jim