Touch a magnet to the bolt and the LED will flash. If you add a capacitor+resistor, the flash slows down and the light gently fades out.

the generator only works on one pole of the magnet. You can attach to the non-working pole then pull the magnet apart fast, the generator flashes here too.

Now the generator can capture all approaching/departing electricity from each pole. If the generator nears one pole, departs it for the other, then depart that one, we generate 4x the electricity

PDF instructions to build a bike light generator and light out of recycled parts.