"Greg Mayman" bravely wrote to "Roy J. Tellason" (02
Sep 03  08:39:00)
 --- on the heady topic of "VEHICLE LED'S"

 GM> Even with a capacitor input filter, the impedance of the usual
 GM> cycle dynamo is too high to charge the cap to the peak voltage,
 GM> as you can do with a mains supply to offset the diode drops.

The impedance is pretty low, in fact I've thought about adding an AC
capacitor across the lamp to increase the power factor and thus extend
the power band somewhat. It's kind of like a resonant circuit where the
capacitor supplies power when the generator goes through zero thus
keeping the filament more fully lit on average by increasing the voltage
across the lamp somewhat. Or more simply by cancelling the series
inductive reactance as seen by the lamp. I haven't taken any measurement
of the dynamo's windings yet but it should be less than about 10
milliHenry. Otherwise there wouldn't be enough voltage getting to the
lamp. So the capacitor would be about 700uF at 60Hz. Ah, I might have
one around to try it out...


 GM> The best form of regulation would be a shunt regulator to bleed
 GM> off some of the current when the voltage got too high for the
 GM> bulb. Unfortunately this would increase the load on the dynamo.

Not on the dynamo... ME!!!   Mr. Motive Source!!!
Nobody is shunting any of *my* energy to ground on my bike!!!


 Mike
 ****

... I worked hard to attach the electrodes to it.
--- Blue Wave/DOS v2.30