On Thu, Jun 23, 2011 at 10:31 PM, RussellMc wrote: > > I would not have considered a stepper motor. > > PM steppers work well as low power alternators. > They have many more poles than a typical small BLDCM do higher output > per rev (danger ...). > > They are however usually very coggy (high saliency) which makes them > harder to start in very low energy input situations. > In some cases that matters, often it doesn't. > > Lack of brushes is nice. > Any BLDCM will work for many values of work. > > > > Russell > -- > I've been expending a little mental energy on permanent magnet alternators for "a while now". Obvious problem is no inherent method of regulation, i.e= .. output entirely dependent on shaft speed and load. Commonly found on motorcycles. Typical regulator circuit is (functionally, at least) a massive zener diode clamping at battery float charge voltage. O= K ish for most engine based applications (lots of power to spare), not acceptable for small, low-power, high efficiency applications. Seems there would be a useful crossover from solar PV panel tech here. Adding some variation of the Maximum Power Point controller could improve efficiency markedly and allow useful generation over a much broader range of wind conditions. -Denny --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .