Yet another Joule Thief

I like these circuits somehow, and build new ones regularily.

Also I have 3 component kits on offer already, a new one coming up soon, with a moderate to high grade of difficulty.

This time, you have to open small old potcore transformer cans, unwind them, and rewind again. The ferrite is also kind of brittle, and it is required to use a cutter knife to remove the wire from the prongs. But it is possible.

I made two webpages so far (where you also get links for the component kits)

this is for the transformerless variant.

And this page is a work in progress, it will include instructions how to rewind the transformer cores soon. A classical joule thief circuit can be built 1:1, including 1K resistor.

But I include PNPs and NPNs in the component kit, as well adjustable resistors too, and diodes as well small capacitors.

0.1uF electrolytics are very appropiate! They dont draw enough energy to destroy the transistor, but still can charge up to 50 volts, and at that voltage, will produce a small spark!

The transformerless circuit only gives 30 volts from two batteries, where the one with transformer core gives 56 volts from one battery!

This seems to be the limit of the transistor, and the capacitor too. The coils circuit also has small capacitors, which get some of the voltage backcoupled, so 30 volts is the limit.

Some photos too in the attachment, I have hundreds of these old potcores here, and can get more. They are really very old, so the ferrite is kind of brittle! Or maybe it always was that way?

Last not least, here are some older joule thief circuits I have built some years ago:




Blog entry information

Last update

More entries in General

More entries from takao21203

Share this entry