For people that likes to build electronic circuits, there are many
interesting circuits (audio, microprocessors and more ) on http://www.artic-instruments.com

regards
John

The Wikipedia article on Joule Thief is erroneous, incomplete and in a constant state of flux because of many well-meaning but misguided individuals who try unsuccessfully to explain what it is and how it works. One example is the recurring use of the term transformer. This in an incorrect term for the coil. The JT coil has the primary winding that is the only winding needed for operation. The feedback winding is there just to keep the transistor switching, and can be eliminated by replacing it with another transistor. There are a number of so-called “Joule Thiefs” found on the net that use a two transistor circuit having a coil with a single winding. The true Joule Thief has only a single transistor. As for the Wikipedia article, my best advice is to avoid it. If you try to understand it now, then come back later when you think you have learned enough about a JT, you may be disappointed to find that the article is even worse than it was the first time you read it.

Thanks for the Joule Thief blog. It always amazes me how this simple circuit has become so popular. I’ve written a blog with comments about your project.

http://rustybolt.info/wordpress/?p=350

Thanks