Re: That Lowe's flashlight, again

pm wrote:


Has anyone tried running the head of the Lowe's light off a dynamo?

I know I would need a bridge rectifier at least, but I'm wondering
whether it reaches full brightness, or would run too hot at speed.

A bridge rectifier and a switching regulator to lower the voltage to 3 volts or so, and keep it constant. If the output of the dynamo is 6 volts, the rectified voltage is 6 * 1.414.

I think that's the reason there are so few LED dynamo headlights. The cost and inefficiency of the rectification and the regulation makes it unattractive. Also, the LEDs use a lot of current and generate a lot of heat and require steel or aluminum housings to act as a heat sink. Also, 3 watts isn't enough for the high-power Cree LEDs. A filament bulb is perfect for dynamos as it runs off AC just fine with no waste in doing rectification.
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