May 9, 2008

USB bike charger

Before the era of solar chargers, people could charge their phones via their bike dynamo. Phones back then charged at a maximum of 500mA, which is close to the 400mA a regular bike dynamo generates.

Nowadays phones require lots more power. A video of this board can be found here.

What you’ll need:

  • 50x100mm board
  • 4 diodes 1n5817 (in order of preference: 1n581[7,8,9] or 1n400[1,2])
  • large capacitor: 10-35v, 750-1000uf
  • small capacitor: 10-35v, 10-24uf
  • 7805 (don’t get the small 100mA)

What you need to know:

  • Always connect the short pin of a capacitor to ground
  • The ring side of the diode is the side we get our positive
  • The pinout of the 7805 is as follows, hold the text towards you; first is positive input, second is ground and the last is positive output

Position on board


Connecting wires


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