I‚Äôm no expert on this subject but my old mate Tom Foster in Bordeaux is. A car alternator looks good at first thought; robust, good power output and easily got from a breaker‚Äôs yard, but in practice the machine‚Äôs design rpm is far too high. At 4000-12000 rpm useful power band, you would need a gear train for a wind or leg powered generator. The ideal rpm, [ or ‚Äėcadence‚Äô, if you want to talk the talk ], for a trusty average hairy Scottish-type leg is around 70 rpm. A typical 3-blade prop producing 500 watts in average wind-speeds would be about 9 feet diameter and run at around 400 rpm. There is a tip-speed ratio restraint on well-designed props; a factor allowing a broad power band and low stalling risks scenario. The tip speed of this prop is nearly 130 mph [Mach 0.18 ] at 400 rpm and it does not take much imagination to realise what will be the resulting noise levels of a tip running at the speed of sound! So again, a gearbox is necessary if using a car alternator. For the DIY man, finding any sort of gearing which is within cost bounds & weight limits, yet efficient
is a daunting task. Direct drive is the best option with perhaps a simple belt and pulley arrangement with a VR of 3 or 4 being tolerable for a man powered device.
Ken, your 24-pole permanent magnet generator, modified from a washing machine looks ideal. This should start pumping out volts at very low speeds. As you are rewinding it, you can arrange the generator to produce 3 [ or 6 or even 12!] phase. This will give a flatter rectified wave that 1√ė.
If your project is to be wind powered, a good starting site is Hugh Piggot-Smith‚Äôs Homepage:http://www.scoraigwind.com
[Hugh is a Scot BTW]
Loads of stuff on prop design, tip-speed ratios, high wind mill shutdown, generator stator winding, carving your own props etc..