'Popular Science' recently published a tutorial for building a homemade flashlight that is powered by recycled batteries. If you've been looking for a clever way to use up all of your old batteries, this fun project is an excellent way to put them to good use.
The DIY project is called the 'Joule Thief' and it consists of a small LED flashlight that is powered by dead batteries. The device works by using up the remaining bits of voltage from dead AA batteries and turning them into a transformer. This conversion process in turn creates a magnetic field. The voltage is then cut and the magnetic field is transferred to the LED light in the form of a strong current. The entire process ultimately allows the LED light to illuminate.
While there is some soldering involved in making this homemade flashlight, the entire process is quick and easy enough to be done at home.