Now on-topic.
In these last days I've been thinking about many ways to save and produce electric energy. Almost none of the ideas resulted, but there is one that has worked wonderfully and that's what I've been talking about, it's called "Joule Thief".
According to wikipedia, joule thief is a term used to describe a self-oscillator energy booster, simple and low cost.
The peculiarity of this small circuit is to use almost all the energy of a battery cell, even after reaching that point that supposedly the battery is exhausted.
This is a possible electrical schematic, although there are many variations
And at the pictures of construction
For the coil, I used a metal core taken from a computer, the number of turns and the thickness of the wire was random.
Now the usefulness of this depends on our imagination, maybe light an LED with a single 1.5V cell, even use an old battery to recharge a Ni-Cd battery...
Good Joule Thief's :P
