Reverse Joule Thief





Introduction: Reverse Joule Thief

Reverse Joule Thief - no cost by salvaging old PC parts 2012
This is the reverse joule thief I found on YouTube. Supposedly it works better. I wrote this tutorial because I wanted to find a freeway to build the circuit

Step 1: Materials

One old PC power supply, any will do fine.

Step 2: Disassemble

Okay. Now you want to get the power supply out of the PC box by unscrewing four screws that hold the PC Power supply in place.

Step 3: Disassemble

Now that you've got the power supply out of the PC, find the side with the four screws and unscrew them.
Then open the two pieces carefully.

Step 4: Disassemble

Let's began by extracting the toroid bead from the power supply with a soldering iron. Afterwards take off a few copper wires and leave 2 on in order for the Reverse Joule Thief to work.

Step 5: Disassemble

Looking through the circuit board to find the resistor,1K, using the soldering iron again we will extract the resistor,1K, for our Reverse Joule Thief.

Step 6: Disassemble

Again we look through the circuit board to find a transistor, no matter which one,  and use the soldering iron to get it out of the circuit board.

Step 7: Assembly

Now it is time to use the schematic I found on YouTube to build the circuit.
After you are finished, you will have the Reverse Joule Thief circuit ready to use with a 1.5v AA battery free of cost.



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    Hi there!

    I wants to know what is reverse joule thief is? Can anyone explain this to me ?

    Hi there!

    I wants to know what is reverse joule thief is? Can anyone explain this to me ?

    Hi there!

    I wants to know what is reverse joule thief is? Can anyone explain this to me ?

    Hi there!

    I wants to know what is reverse joule thief is? Can anyone explain this to me ?

    you can also use the ac line filter in a psu it is 2 coils of wire side by side see photo below they look somthing like this you can also use these Axial leaded inuctors


    The schematic shown seems very close or exactly the same as other "Joule Thief" schematics I've seen that use a toroid.

    But the 170 uH inductors shown puzzle me a little. Are you taking these and winding a second winding over these smaller inductors to get a transformer similar to the toroid transformer in your schematic?

    The "Joule Thiefs" I've been working with use an inductor like these but have no other windings anywhere. Also no transistor or resistor is used either. Instead, a modern four legged IC is used and no toroid with windings is necessary.
    Further details are not far away. They can be found at:

    no remove the toroid and put the inductors side by side wired the same way as the coils and they will transfer magnetic feilds

    i have now tested this way of makeing the jt yes it does use less current but to add the led is half the brightness of the normal way to wire it

    Thank you for updating me about your testing
    correct me if I'm wrong but this means that the light should work longer for a longer period of time even though it is less bright?

    it does but when you need this light to see that drop in brightness is not wonted longer battery or not but if we add another winding to the unit for led only and do not put one on the first part of the circuit this can also use less current but up the brightness