Make a Joule Thief

Windell Oskay of Evil Mad Scientist Laboratories joins me to show you how to make to squeeze the life out of your dead batteries by making a simple circuit called the Joule Thief!

More info:

27 thoughts on “Make a Joule Thief

  1. Dan Coulson

    Hate it when people bend transistor leads so close to the case.
    You should always leave at least 1/8″ of lead straight. Bending them too
    close to the case makes the metal leads very weak.

  2. Pete Frise

    Hello thank you so much for sharing, I never though I could make one, I had
    a TV the I did not really use and I took it apart and got me the parts and
    copied the way you did it. I made one and it works, thank you so much.
    I feel smarter

  3. Richard Johnson

    The values of Joule Thief is
    Q1=e.g 2n2222 2n3904 (Do not use 90xx transistors because the gain of the
    transistor is high and will drive over the Joule Thief and will not work.
    R1=350-5000 ohms
    D1= LED [Vfwd=3v]
    Vceo=30v p-p

  4. M USTI

    Even though this video is posted 7 years ago there are people still showing
    this technology like they found something new. Well let me tell you what..
    Sony had this technology back in 1980’s and they build WM-GX series Walkman
    played cassettes had dual band FM radio and also WM-GX650 and higher models
    had a headphone with remote control digital display on it. Guess what? All
    driven by a single AA size not 1.5 Volt but 1.2 volt rechargeable battery.
    Yes back in 80’s they accomplished a 1.2 Volt rechargeable battery not
    just run LED light but run a motor in Walkman to play cassettes and power
    the radio with it. 

    1. Richard Johnson

      +tiffany martin Secondary winding works better than bifilar center tapped
      winding.I changed the transistor to TIP31 power transistor and works very

    2. tiffany martin

      The Toroid boosts power up to a useable voltage that the LED can be lit
      with! The transistor is like a valve and it will only open when the current
      is strong enough, so “juice” flows through the toroid until the transistor
      opens. RimstarOrg has a great video explaining how this works, OH and Jeri
      Ellsworth has a Amamzing video, explaining it too!!!!

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