Hi Doug, Snip > P.S. I'm still looking for a transformer design program, so if you > of one, or a source for blocks of ferrite, please tell me! Have a look at Msims Website. They have a cool demo program for all sorts of inductors and xformers. Itīs called "The magnetic library". You do NOT need MSim to use this program. Coiler greets from germany, Reinhard