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A joule thief takes a low DC voltage and boosts it up to a higher voltage. You can even take a battery that other devices will consider to be drained and get a bit more of the energy out of it. You won’t get much current from it, but you can get enough to power a 3 volt LED with a battery that’s drained to less than a volt. That’s why it’s referred to as a joule thief. It’s almost like stealing energy from a dead battery. By the way, some people call it a zombie circuit for this same reason.

If you’re new to building electronics, this is a good circuit for practice. The one I made for this Instructable looks ugly, but it still works. The schematic that I’m following is a basic one that I got from Wikipedia. ( It uses 4 components plus a battery. You can see some schematic reference pictures in step 10 of this Instructable.


- Wire Cutters
- Breadboard
- Soldering Iron
- Helping Hands

- Toroid Core
- Perfboard
- 1k Ohm Resistor
- 2N2222 Transistor
- 3/8” Ring Magnets
- Thumb Tacks

- 22 Gauge Solid Wire
- 22 Gauge Stranded Wire
- Epoxy
- Solder Flux
- Lead-Free Solder
- Lead-Based Solder”

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