My Joule Thief





Introduction: My Joule Thief

A Joule thief: (1) is a device that will suck and all of the juice from your "dead" batteries (2) To make it possible for an LED with a voltage requirement of higher than 1.5 volts to run off of a single 1.5 volt battery! For example, run a white LED from a single AA battery! or im my case run 2, 4volt Leds off a battery measuring 1.2 volts on a voltmeter!!!!
I made using 1ups instructable. I just added a switch and put the project in an old Chocolate tin (Altoids tin).

if your wondering what the coil is/ what it dose. Its a hand wound Toroid. I got 15 Toroid Beads out of my old dead x box.
This circuit works by switching current back and forth 40hrtz (40,000 time per second) the Coil builds up a charge from the >1.5volt battery once it build to 4-8 volts it switches the power to the Leds, they light up and then the current is switched back to the Coil and the Cycle repeats faster than you eye can see.
great use: writing with light



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    Here's a Joule Thief with 10 LEDs on a 9v battery:


    nice, just t note, I've read the switching speed is closer to 40KHz then 40Hz

    40 Hz you could HEAR!!! It would sound like a fat guy humming...

    Does more turns equal higher efficiency?

    Picture 22.jpg

    I think that toroid looks scary...but it might lower efficiency. Don't waste turns.

    Awesome job! I still have no idea why they're called Joule Thiefs, but awesome job. All of 1ups Instructables rule! And this one is cool too. Where did you get the circle thing? I forgot what it was called.

    its a hand wound toroid. i took apart my old (already dead) xbox and found 15 Toroid Beads. you just wrap 2 wires around the bead 8-20 times. and its call a Joule thief cause a Joule is a measurement of energy. so your trying to suck all the juice out of the battery. Basically why throw a battery away when you can put in in a Diy flash light. (more info now in the description)


    Why a blue and a white LED? Any special reason? What would the difference be between an 8 turn toroid vs. a 20 turn toroid? Would it have a capacit(atoring?)(ending?)(orizing?) effect? So would more windings smooth out the pulse like a cap? My understanding of the way the oscillating works is...50%. (crud. 15 toroid cores - that's more than I've gathered in the last 2 years...boohoo)