A Joule Thief is a simple step-up converter with which you can drive a 3.6V LED with a 1.5V battery even if it is spending the last drops of its life. It merely consists of a transistor, a transformer and a resistor.
The circuit is very forgiving especially concerning the number of coils of the transformer. But I was wondering if there is a way to precicely calculate the voltage produced. It would be nice to use an old 1.5V battery to power a microcontroller. I read people reporting that zeners would interfere with the oscillating behaviour of the circuit.
Does anyone have deeper knowledge of these kind of circuits? And would it be possible to create a stable 5 volts to power a microcontroller?
update The discussion here is the closest I could find and the request is very similar to mine.