I wanted to be able to charge my cell phone, MP3 player, and other USB devices while not having plug-in power available. This hand-crank generator, originally designed by Ben Heck, ended up working the best.
I'm taking a trip to China soon, and last summer we spent a week without power due to downed trees all over the state. Let's just say it was a rough week. So I wanted to find a way to charge my USB stuff without using those battery packs. Originally I was thinking of making an Altoids can AA battery charger, until I stumbled upon Ben Heck's video on YouTube.
First - RESEARCH. I needed to look up the pin specifications of a USB cord and find a USB extension cord. I needed the female end as well as the male end for testing.
Second - I hit up Walmart and Harbor Freight for cheap hand-crank flashlights. I ended up getting 3 different lights. I got a Gordon crank light ($8), a Gordon LED Dynamo flashlight ($8 for a 2-pack), and an Energizer hand-crank flashlight ($10).
NOTES. Record your findings in your Maker's Notebook. (Shameless plug!)
USB Pins - A quick Google search and you can find all this info, but basically on a regular USB-A cable you need the red and black wires.
Next was a trip to YouTube and to RadioShack. Ben Heck from Element14.com has a video on this exact project.
At RadioShack you will need to pick up a 10-ohm resistor as well as a 5V zener diode.
I found that the small hand-crank LED light from Harbor Freight worked the best due to the fact that it was the only one with a rectifier. Solder your resistor and diode as seen in the picture (borrowed from Ben's YouTube channel).
SIDE NOTE - You can actually remove all of the other components (3.6v battery, misc. resistors) from the PCB. You only need the rectifier.