If you want a bright light on the front of your bike and don't want the hassle of recharging batteries or heaven forbid having to buy new ones, then check this out.
Some expense is required, but no more than the cost of a decent halogen head light.
Also there is some manufacturing involved, but if your still keen, this system works.
The specs are
-No Batteries!! Energy Storage is two supercapacitors 100F, 2.7volt in series, giving 50F at 5.4volts.
-It takes a few minutes to charge but the light will work at full brightness as soon as you start pedaling.
-It has a 15min run time before it starts to dim (when you stop at the lights and the generator is not running) .
The 1Watt LED requires 3.5volts, using the right resistors this time can vary between 4 to 30 mins.
The LED can draw up to 350mA, but my setup drew 160mA, still bright enough to dazzle drivers.
-The generator can run the light and maintain the charge. I used a Stepper Motor from an old dotmatrix printer, it can generate 500mA when shorted on a multimeter.
-Another advantage is the capacitors have no memory problems and are self regulating (meaning they cannot be over charged).