>..couldn't you just clamp the upper voltage with a simple shunt >regulator, to make your input range more sensible - doesn't seem like >you'd be wasting much power, and there are plenty of SM regs for <50V >input applications. As in a bit like motor cycles used to do to limit the alternator output voltage so they did not need to put in a regulator - just a big hefty zener diode on a heatsink. I had been thinking along the same lines - might mean those peddling will ease off a bit. If you could also blink a led when this happens then they will know they are producing excess output energy that is going to waste - or is this a fitness machine? BTW I believe that this is effectively the method used to regulate the output voltage of the Bayliss windup radio's and flashlights. There is some sort of beefy transistor across the output of the generator, and when the voltage gets too high an electronic circuit turns on the transistor and loads the output of the generator so the voltage drops sufficiently. Ugh! -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.