Give your used batteries a second life with this Joule Thief Flashlight!
It works with dead batteries that won’t power your devices anymore.
Note: this will drain the batteries "down to the last drop", which is not good for recyclable batteries.
Be green and enjoy DIY…
Step 1: Parts
10mm white LED.
Batteries holders for AA and/or AAA.
AA or AAA used batteries.
Hot glue gun.
Step 2: Build It
a. Replace the original light bulb with the LED (refer to photos).
b. Solder the batteries holders in parallel (this will allow to use the flashlight with only 1 or more batteries).
c. Build the toroid inductor by winding two wires around the toroid (refer to photos).
d. Solder and assemble the other parts as shown in the circuit diagram.