Regulated Joule thief, how?
March 3, 2012
Many of you have seen or read about a Joule thief, and for the rest of you: http://en.wikipedia.org/wiki/Joule_thief. They come in a great varieties, google easily finds them. One thing that I like about the Joule thief is that it is so forgiving about the applied transformer, the circuit simply adapts to that ever you throw after it. No need for calculations or anything.
Anyway, I'm searching a Joule thief circuit that is a little more advanced than just driving a white LED, I'm searching a regulated power supply. Still able to run on a half depleted AA cell, but providing 5V regulated output, a few mA's will be fine. But I do not just want to clamp the output with a zener, that would be total waste of energy.
So what I'm looking for could be a Joule thief circuit with some sort of feedback where the oscillation is dependent on the output voltage.