# The simple Joule Thief

Contents

The Joule Thief is such an easy and simple device, but what it does is amazing. It can use a battery that is not usable in any other electronic device and give it life again. It can even take a battery that wonât even power a basic LED by itself when it is brand new (1.5 volt AA) and amplify the power so that it can.

This âJoule Thiefâ circuit, using a battery that wonât work in any other device, can power a blue or white LED for approximately 8 days straight before it stops working. It could probably power a red LED for at least 10-12 days. You could also use it to power a microcontroller (such as an AVR or PIC MCU).

This is an entry in the LED Contest with Elemental LED and the Hurricane Lasers contest, so if you like it, vote!

## Step 1: Why is it called a Joule Thief?

The reason the Joule Thief is called what it is is because of what it does. (That sentence was confusing) (:

Basically, what the Joule Thief does is it âstealsâ every last Joule of energy from your batteries. The explanation of what a joule isÂ can be found on the Wikipedia page here.Â The quickest explanation I can think of is that a Joule is a form of energy that, in the way we use it, can be used to power electrical devices. I wonât go into any more detail here because it gets very complicated.

## Step 2: Parts list

To make this âJoule Thiefâ, you will need:

1x 470uH inductor (looks like a fat resistor)
1x 2.2K resistor
2x 1K resistor
2x basic NPN transistor (2N3904, 2N2222, 2N4401, etc.)
1x 1000pf (same thing as 1nf or 0.001uf) ceramic capacitor
1x AA battery + holder (or any other 1.5 volt battery)
As many LEDs as your heart desires.[/box]

## Step 3: Make it on a breadboard!

It is super simple to make on a breadboard because it has such a low parts count. Look at the schematic to figure it out.

## Step 4: Make it permanent!

I have included the .sch and .brd files for making your own PCB. You can send the .brd file to the OSHPark websiteÂ here, and they will make 3 copies of the board for \$2.30 with free shipping. Not even kidding, itâs that cheap.

For more detail:Â The simple Joule Thief