Whiteboard: Joule Thief


The “Joule Thief” is an LED flashlight that is designed to be run from a half-dead battery. Using a simplistic DC-DC boost converter, it turns the steady c. 1V supply into an oscillating supply sufficient to operate the LED (which requires c. 3V) in enough bright flashes per second that your eye doesn’t perceive the flicker. So, don’t throw away that dead AA just yet…

I haven’t made one just yet, but a CFL in my house just stopped working so I should have all the parts on hand.

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