Charge your mp3 player and light your way anywhere anytime!
This DIY gadget makes a highly satisfying project and is extremely useful for long road trips, mp3 players with tired batteries, plain neatness, and impressing your friends.
The idea is very simple: use a crank charge headlamp and re-route some of the power from the light to a USB port for charging USB devices. We rely on the battery to soak up the voltage peaks so that while you're cranking, it should be around 5v.
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Step 1: Materials
Materials and tools you will need:
-Hand crank headlamp: http://www.leevalley.com/en/garden/page.aspx?cat=2,40731,58277&p=58277
-Female USB port single or double (you can get them out of old computers)
-Soldering iron & solder
This project is "do at your own risk". In other words, I'm not responsible if you fry or damage something in the process. Yada yada yada now let's get on with it.
Step 2: Construction / destruction
All right, time for the screwdrivers. Clear off your desk and put on some good music.
Unscrew the dynamo cover, remove it and take a good close inspection.
Cut out a square in the side of the dynamo case the size of your USB port. You can heat up your knife blade which might make it more tidy and or easier. Press the USB port into the socket you made for it and put a little glue in if necessary to keep it in place.
Step 3: Wiring
Solder two short wires onto the USB power pins, the two outermost pins (other than the mounting legs). Looking at the open side of the USB port with the pins down, the far left pin is POSITIVE and the far right pin is NEGATIVE.
Now solder the other end of your USB port power wires to the headlamp power cord jack. Put the USB positive to the red one on the jack and the USB negative to the black. Be SURE to get the polarity correct.
Step 4: Finish!
Now double check that everything is wired correctly and screw the cover back on. Get an mp3 player, plug it in and CRANK!