Introduction: Led With a Single AA Battery Aka Joule Thief
In this instructable you will able to make a simple led hack which can power a led with single a AA 1.5v battery. A LED need at least 2.4 v or more voltage. This circuit will boost the voltage up to drive a single led. But it will consume more current than a led need due to conversion of the voltage.
Step 1: The Parts You'll Need to Build This Project.
1.a LED (I have used a bright white led)
2. A NPN transistor any low power will suffice I used BC 548B because it's easily available and I use this transistor all the time
3. A 1kilo ohms resistor.
4. A toroidal core (I salvaged it from a old CFL.
5. Some thin single strand Copper wires (salvaged from cat5 cable.)
6. AA battery.
7. Breadboard. Or perfboard (if you want to make it permanent).
8. Soldering iron ( again if you want to use the perfboard then you'll need this).
Making the toroidal coil.
This is the main thing that you have to make yourself. It's fairly easy to do. Pick two single strand wires from cat5 cable. Or you can use any thin wires. But make sure you use to different colored wire. Hold the two wires and wind in the toroidal core. 8-10 turn will do the job. And look carefully the wires don't overlap. Then cut the excess wires.
Step 3: Put Everything on the Breadboard According to the Schematic
First place the transistor on the breadboard the transistor pin mentioned on the schematic. Then connect the led. Then the coil and the resistor. If you connect the coil wrong way it may not work. Check the schematic. power the circuit with a AA battery if everything's okay Led will glow. Thanks.