The Junk Box Switcher power supply

I built a PCB for a simple switching power supply, originally designed by Keith Payea of the SRS.  It uses an LM393, a P-channel power MOSFET, and darn little else. Since its frequency varies based on load (and nearly everything else imaginable), you can use junk-box parts and build it for cheap.  Here is the schematic (PostScript).  See September 1995 in the article index.