I have a 12v friction drive genny: http://www.streetlowrider.com/shop/p715/dynamo-generator-12v-6w/product_info.htm
and I modified my headlamp: http://www.bicycledesigner.com/bike-...or-chrome.html
to use LEDs I found on Amazon: http://www.amazon.com/Super-Bright-V.../dp/B0066AYRSY
The Genny has 2 poles, labeled H & T. H is a full 12 volts and stands for headlight. T is 6v and is for the tail light. It's an ac generator, so you will have to run a ground wire to the frame to get voltage out of it, as you can't use the H & T leads together, it won't work that way. To convert AC to DC, I got a part from Radio Shack called a Full Wave Bridge Rectifier: http://www.radioshack.com/product/in...lickid=prod_cs
, it has 4 poles labeled +, -, and the other 2 poles are ~ for the AC leads. Wire the H pole on the genny to one of the ~ leads and run the other ~ to ground on the genny and it will convert the power output to DC current.
If you use the LEDs, make sure to use the supplied resistors that come with them or the LEDS will burn out in minutes, they are only 3.3 volts and any more will snuff them. Mine came with 2 sets of resistors, 100 ohms & 470 ohms, the 100's are for dropping 5 volts to 3v, the 470's drop 12v to 3v. They are SUPER bright, when I drive at night there is no problem whatsoever seeing the road.
There is a thread here: http://motorbicycling.com/showthread.php?t=32246
where some enterprising soul gave us all step by step instructions on how to use the white wire, and he used "smoothing capacitors" to smooth out the voltage pulses. I didn't, because I have a 12v battery so the caps weren't needed, but if you intend to use either a friction genny or the infamous "White wire" and NO BATTERY, I do recommend using capacitors.
Something else I learned, find a piece of 5/8" heater hose tubing (an inch long will do) and glue it to the roller of the genny(I used black RTV silicon gasket compound commonly found in auto repair stores), this will slow down the genny's RPMs and help it last longer (or else it will wear down the brass bushing out), not to mention save the tire from excessive wear.
Hope this helps.