This is my first Instructable and my entry for the USB contest. It is exactly as the title states. This instructable shows how to modify an Solar LED flashlight to take power from USB (and to charge it when it is dark, and the solar panel obviously does not work.)
I know there are other instructables about USB flashlights. I got the idea reading this one when I saw how similar the circuits were. This is the only solar and USB one I know of though. I do not want anyone thinking I copied this idea.
DISCLAIMER: I AM NOT RESPONSIBLE IF YOU FRY YOUR LED LIGHTS, YOUR USB PORT, SET YOURSELF ON FIRE OR KILL YOURSELF (SOMEHOW). WHAT YOU O WITH THIS INFO IS NOT MY FAULT. YOU HAVE BEEN WARNED.
Step 1: Materials
For this instructable you will need:
- One solar LED flashlight (these are widely available for about $1 on ebay. This is where mine came from)
- Male A USB cable (these can be cut from almost and USB cable)
-two resistors (1/4 watt), my LED light's battery was rated at 3.6v, so a 3 K ohm and a 4k ohm would probably be ideal. I could not find these so I substituted. My resistors only gave me 3 volts, and now my LEDs are dim when USB charged
-misc.: wire, solder, soldering iron, pliers, wire cutters, side cutters, dremel (optional), shrink wrap (optional, but recommended), and other hand tools may come in handy
Step 2: Take It Apart
Use pliers to bend the little ware that holds the key chain ring on, and just pry apart at the seams. It's that easy.
Step 3: Electronics...
This is the hard part. The pictures explain it best, but you basically build a voltage diver and hide the resistors in the few places where they fit. You can put the resistors any where so long as they are connected properly.
Note: shrink wrap will prevent shorts and is recommended
Step 4: Case Work
I just got rid of the things in 1 (as in the first yellow square) and cut on the red lines, bent it till it broke on the green line. This made room for my USB cable to fit. You may have to do things differently is your USB cable is different.
Step 5: Snap Together
Holding everything in place line up your usb with your hole. It should snap back together. If not you will have to re align your inside stuff. When done you can reattach the key chain ring. with string or wire and solder.
Step 6: Testing and Improvments
Plug this in to a computer (or for the first time a USB wall charger that you can spare in case you shorted something) for a few minutes and it should be charged up a bit. I should work.
-do not push the botton when it is plugged in. The LEDs will probably fry.
-there is no mechanism to prevent overcharge. Do not leave this plugged in unattended for more than a few minutes. If it is hot unplug it. If it creates fire unplug it and put out the fire.
- use the right resistors (so it is not dim)
-replace the battery with some super-caps
Hope you enjoyed this instructable