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.