“The Thief joules “is a small circuit that can” light “, for example, a sufficiently powerful LED from just one low-voltage galvanic cell.
The Joule Thief takes a low DC voltage and boosts it to a higher voltage. We will not get a lot of current from it, but we can get enough to power a 3-volt LED from a battery that is discharged to less than one volt.
Tools and materials: -Nippers; -Breadboard; -Soldering iron; -Third hand ; -Ferrite toroid cores; -Resistor 1 kOhm; -2H2222 transistor; -LED; -Circular magnets-rings;
Step one: toroidal inductor
First you need to make a toroidal inductor. Using 2 wires, the master winds them around the core. The project uses 22 AWG (0.32 mm²) wires, but they can be thinner. The master makes 13 turns. It is better to use wires of different colors.
Having wound the wires, he covers the toroid with epoxy.
Step two: installing the inductor on the board
After the resin has cured, strips the wires and solders to the circuit board. Only two wires means four ends. During installation, they must be arranged according to the scheme.
Step three: resistor
Next, you need to install a 1 kOhm resistor. Connects G1 of a toroidal inductor to any leg of the resistor.
The other end of the resistor must be connected to R2.
Another wire is soldered to point R2. + Batteries will be connected to it.
Step four: transistor
The assembly uses a 2N2222 transistor, but you can use a 2N3904, BC547B, 2SC2500, BC337, 2N2222, 2N4401 or other NPN transistor instead. It should be placed with the flat side of the toroid.
Solder R1 of a toroidal inductor with a transistor collector. We connect G2 to the base of the transistor.
Step five: LED
The LED he was using was taken from a different board. The emitter of the transistor connects to the negative terminal of the LED (cathode). Since the LED leads were short, he soldered the track with solder.
A black wire is also soldered to this one.
The positive lead of the LED should be connected to the same wire as R1.
It is also necessary to pass the wire for G2 without soldering to it. To do this, use a jumper on the other side of the circuit board.
Step six: connecting terminal
This step is not required for the circuit to work, but it will provide a convenient way to connect to different batteries. Putting a disk magnet on each of the power wires, solder a pushpin to each of them.
Step Seven: Testing
Now everything is ready and you can test the device.
First, he connects a slightly discharged battery. As you can see from the photo the LED is on.
Then a strongly discharged battery is used. The voltage on the batteries is 0.7 V. Ka is visible when connected through the “joule thief” the LED is on.
The inductor may hum a little during operation, this is normal in this circuit.