Instructables
Picture of USB Rechargeable LED flash light
Photo 922.jpg
In this instructable I show you how to make your own LED flashlight that can be recharged simply by plugging it into the USB port of your computer. I know that you could find something similar from a store, but all of the ones that I found had only a few LEDs so I made my own with eight LEDs.
 
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Step 1: The tools and parts required

The tools include:

1 hobby knife 2 handsaw
3 soldering iron 4 screw driver
5 scissors 6 wire cutters
7 pliers 8 pen
9 drill and drill bits

parts include

1 Stripboard or circuit board 2 8x LEDs
3. on/off switch 4 3x ni-cd button cells
5 1x 36 ohm or 8x 120 ohm resistor 6 plastic and aluminum sheet
7 electric wirier and steel wirier 8 tape
9 solder
10 USB flash drive (I recommend one without a sliding mechanism)

Step 2: Dissisembly

This step is quite easy. Simply use a flat head screwdriver to open the flash drive. The one I started with was broken so I cut the circuit bored off to save some space and to reveal the positive and negative lines, then I used a volt meter to check the polarity of the usb I suggest that you use a pen to mark the positive and negative, if you have done so then you have completed this step.

If you are doing this with working flash drive and you want to keep the memory function, then you have to add an additional circuit. Start by soldering a wire to the ground or negative wire of the flash drive then cut the positive wire and put a three point toggle switch (as seen on the last image) in place of the positive input of the usb will connect to the middle point of the switch and the two far sides of the switch will connect to the positive end of the flash drive and the positive input of the circuit on the fourth step.Finally put some tape on the flash so it doesn't short out.

http://www.artistic-license-inc.com/b2b/pics/Sealed_Sub_Miniature_Toggle_Switch.jpg
alexander.m (author) 5 years ago
the batteries the I have the most experience with are Ni based and if these are any thing like NiMh then these need a system to turn off the power when full, this device will take to much room. and as for the flash drive I thought that it it would be the perfect case because pretty much every one with a computer has some old flash drive with 512 mb or less laying around. and if you don't find any, electronic stores often sell 64 mb for a dollar.
NiCad batteries are more tolerant to a trickle overcharge than the newer NiMH chemistry.  But they can still be damaged by overcharge at too rapid a rate, which I suspect USB could deliver to the button cells.
raykholo5 years ago
goldmine elec has some cheap polyacene batteries that u can use...
http://www.goldmine-elec-products.com/prodinfo.asp?number=G13133
also cheap and they seem worthwile. however, it might involve a voltage regulator to charge, so i would advise u to be careful as to not damage them, and maybe to dump the flash drive case altogether (there are other ways to get a usb plug)