Joule Thief

Posted on Feb 4, 2014

Brian and I did spot and eliminate a little problem. I believe it was probably caused by me using an old version of CadSoft`s Eagle, and then (later) a newer version. Therefore I have checked the Eagle project files in the current version (6. 4), and re-made the zip file (linked at the bottom of the page). I think the circuit boards made by oshpark

Joule Thief
Click here to download the full size of the above Circuit.

look very smart and professional, Brian has kindly shared some images and there is a discussion about the project here. This is the first project where I`ve used the "toner transfer" technique to make a printed circuit board. There are plenty of other web-pages which give excellent descriptions of how to do it, so I won`t replicate that. I wanted to make this circuit as small as possible, so I`ve not followed some of the circuit-maker`s conventions. There`s a surface-mount component on the same side as the other components, only the battery holder is on the "correct" side. Here`s the schematic, it works as a voltage converter to draw just 20mA from a 1. 5V cell to light that white LED. The term `Joule Thief` is used because the circuit will work from a cell which would otherwise be considered spent. I found that if the batteries in my Gamecube Wavebird controller stopped working, the same "spent" batteries will quite happily run this torch for a couple of weeks. Continuously.

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