Joule-Thief LED torch

Hi,
Today I have started building this joule-thief LED torch , but got stuck on the toroid section. I dont know how to wind it. The secondary should be on on top of the primary or both are wound on opposite sides? I got a core from an old SMPS.

http://www.geocities.com/lemagicien_2000/elecpage/ledtorch/ledtorch.html

How rf is generated on a toroid? What is the difference between a toroid and a normal inductor?

**broken link removed**

Short how-to video

**broken link removed**

PDF version

I've made several from these, and they work great, very simple to follow instructions.

The toroid is super easy, and doesn't even need to be done neatly. I haven't attempted one of those super small ones though, I have 1/2 inch cores. Suggest you do at least one on the larger core, just to see how simple.

Ya. That video shows the toroid winding clearly. From there I got the link of talking electronics - where some neat circuits are presented with good description.
http://www.talkingelectronics.com/projects/LEDTorchCircuits/LEDTorchCircuits-P1.html

Now I'm thinking what a hell are the old current eating incandescent lamps!

Hi from a noob P

Thanks for that link
I have a box full of dead batteries and I thought since awhile to used them until they are really dead ... until now I only found that circuit but no explanations on what happen with the transformer, I was scratching my head to understand ... now I might understand

rahulan999 said:

Ya. That video shows the toroid winding clearly. From there I got the link of talking electronics - where some neat circuits are presented with good description.
http://www.talkingelectronics.com/projects/LEDTorchCircuits/LEDTorchCircuits-P1.html

Now I'm thinking what a hell are the old current eating incandescent lamps!

Click to expand...