A hand-cranked flashlight never needs batteries.
The disadvantage of a flashlight that uses batteries is that the batteries can fail over time while the flashlight is not being used. You can make a hand-cranked flashlight that will illuminate a LED for light at every turn. No batteries are needed, although you will have to buy a white LED from a hobby store or laser supply shop. A stepper motor from an old computer printer must also be acquired–this can be gotten from the used bin of a computer store or at a yard sale. Some experience in using a soldering iron is also needed.
1. Put a sheet of newspaper on a table. Place the computer printer on the newspaper. Remove the screws from the sides, top and bottom of the computer printer with the Phillips screwdriver. Pull the case off the computer printer.
2. Locate the circular-shaped stepper motor that is attached to the circuit board next the ink toner compartment. Remove the screws from around the stepper motor with the Phillips screwdriver.
3. Snip off the wires connected to the stepper motor with the wire cutters. Pull the stepper motor out of the computer printer. Dispose of the computer printer properly.
4. Place the stepper motor on its side on the newspaper. Heat up the soldering iron for five minutes.
5. Hold the white LED in one hand with the two pins that are attached to the base pointing to the right. Hold the soldering iron in the other hand.
6. Rotate the stepper motor until the large slot in the side is facing up.
7. Place the end of one of the two pins attached to the base of the white LED against one of the two metal contacts on the circuit board inside of the large slot.
8. Solder the end of the pin to the metal contact. Let the solder cool for a minute.
9. Place the end of the other pin attached to the base of the white LED against the other metal contact on the circuit board inside of the large slot.
10. Solder the end of the pin to the metal contact. Let the solder cool for a minute.
11. Straighten the pins so that the white LED is not drooping.
12. Pick up the stepper motor in one hand with the white LED facing away from you.
13. Spin the small knurled knob on the stepper motor either clockwise or counterclockwise with the fingers of the other hand to illuminate the white LED. Your hand-cranked flashlight is ready to be used whenever you need light.