At 12:32 PM 1/20/2011, Vitaliy wrote: >I was going to suggest adding a rectifier and a cap, and we actually tried >it at the same time as we were playing with the coils, but it adds cost an= d >costs time -- the students don't have too much of either. Also, the diode >eats some of the energy, which means they would need to pump more current >and have bigger coils. I'd say, not worth it. :) Don't add a diode, use two LEDs wired back-to-back. That assumes a=20 duty cycle of close to 50%. dwayne --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .