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Here in Russia people sell stuff on the commuter trains. So I once bought this really cheap hand cranked flashlight for 100 rubles (~$3 US). It worked just fine. I had to take it apart. Inside there were two 3 volts batteries in series, meaning that the dynamo inside the unit generated about 6 vdc. I immediately soldered a usb cable and made this into a hand crank charger for my Android phone.

Here are some pictures of flashlight being taken apart and a USB connector being soldered to it. To figure out polarity and how to propperly connect the usb line I read this page: http://pinouts.ru/Slots/USB_pinout.shtml

I then tested the unit and took this video:

What a great idea! <br>I'll have to try this when I come across a hand crank flashlight...<br>спасибо
Do check the voltage, though. Good luck!
Yeah, my thoughts exactly. You don't want more than a 5V output, which is the ubiquitous USB output voltage. I'd hate for you to damage your phone, or other expensive product.<br> <a><br> http://www.hardwarebook.info/Universal_Serial_Bus_%28USB%29</a><br> <br> You'll need a voltage regulator. Try googling it or even searching instructables. I think I've seen some floating around the site.<br> <br> Try hooking up a meter to the output and crank as fast as you can and see what the readout is. If it never gets higher than 5V then you'll probably be safe without the regulator.<br> <br> <br>

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Bio: I'm a Linux enthusiast, avid diy-er. I work for a company that manufactures "smart" invertors (an Uninterruptable Power Supply for the entire house). I ... More »
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