Joules thief and how to run a LED on a depleted battery

A "joules thief" can power a LED from an almost depleted battery. A joules thief squeezes the last remaining energy out an almost empty battery, even if only 0.3 Volts is left. The schematics diagram is at the end of the video. I got the parts from an old cassette-recorder but it shouldn't cost more than 1$ if you buy the parts in an electronics shop. The parts needed are:
1x LED, any color you like
1x NPN transistor
1x 1kOhm resistor (brown / black / red coding)
1x ferrite toroid (round)
1x copper electrical wire
1x almost depleted battery

Explanation from the Wikipedia site:
"Joule thief" is a nickname for a minimalist self-oscillating voltage booster that is small, low-cost, and easy-to-build; typically used for driving light loads. It can use nearly all of the energy in a single-cell electric battery, even far below the voltage where other circuits consider the battery fully discharged (or "dead"). Hence the name suggests the notion that the circuit is stealing energy or "Joules" from the source. The term is a pun on the expression "jewel thief", one who steals jewelry or gemstones.

The circuit uses the self-oscillating properties of the blocking oscillator, to form an unregulated voltage boost converter. As with all power conversion technology, no energy is actually created by the circuit. Instead, the output voltage is increased at the expense of higher current draw on the input. As a result, the amount of power entering the circuit is the same as the amount leaving, minus the losses in the conversion process.

For more information, take a look at the Wiki yourself:
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