I have not seen a subject devoted to Joule Thief. I think it has its place here, what do you say?
Basically what is Joule Thief?
The Joule Thief is a small electric circuit which allows, from a low DC voltage (example: 1V), to power a device that operates on a higher voltage (example: 3V).
My knowledge in Electronics / Electricity is rather average so if someone has a more technical definition of Joule Thief I am a taker.
Here is the diagram of a simple Joule Thief:
- A batteries (even a battery that looks dead to you)
- A resistance from + or - 1Kohms
- A NPN transistor
- A LED which operates on a voltage of more than 1.5V
- And an Ferrite torus wind with 2 wires. (ten turns)
To better understand here is a video:
http://www.youtube.com/watch?v=gTAqGKt64WM
If I create this subject it is mainly to share our experiences on this circuit between Econologist.
- Have you ever tried to make one? Success? Failure?
- Why did you build one? History to try or for experimentation?
- Are you going further than this simple Joule Thief? Power other device than an LED? With bigger voltages?
- Etc. ..
My experience:
I'm just starting out, I made a Joule Thief from the Diagram (see above), in place of a 2N3904 transistor I put a BC549B and replace the LED with a block of 3 LEDs operating on a voltage of 3,6V.
My battery is of type Alkaline AAA LR03 of 1,5V but not new, it has a voltage of 1,1V.
I did a duration test, it's been 4 hours that the LEDs are on, the brightness has dropped a bit for the moment and the Voltage across the battery is 0,46V.
to be continued... Then I will test with a new battery.
On the net you will find all kinds of experience on the Joule Thief.
Ferrule Joule Thief without Tore, Power from sources other than batteries and even what is called Super Joule Thief which uses High Voltage to power larger bulbs ...