Kristion: "Besides, I've seen a neat system running a flyback at 100Hz and getting 10cm (!!!) sparks out of the poor thing. Definitely not resonant, just lots of energy dumped to the core FAST.. The energy magnetically stored in the core is the source for the secondary voltage.. Like in induction coil, huh? Ideas and corrections welcome, Kristian." How about some more details. Sounds interesting.... Ed Phillips