The Joule Thief first appeared in the mass media in November, 1999, in an article from EPE (Everyday Practical Electronics) and published by Z. Kaparnic, but the expression “joule thief” was coined in 2002 by Clive Mitchell.
The Joule Thief is a simple electronic circuit, which consists in a transistor NPN, a resistor 100 to 1000 Ohms, a ferrite torus and a led. It enables one to use almost all of the energy contained in a battery or an accumulator. Traditional batteries are said to be “dead” when their voltage is down to 0,9V, but the Joule Thief manages to keep the battery functioning until the battery tension is down to 0,7V. To do so, the device raises the battery voltage fictitiously above the minimum voltage needed for the functioning of the battery.
The Joule Thief is useful to avoid battery wastage and when using devices consuming little energy, such as LEDs.
