PR4401 LED Driver

Elektor September 2007 comes with a board containing an LED booster circuit which you can try out for yourself. Although tiny, the board contains a complete high-efficiency 500 kHz voltage converter which will light an LED even from an almost flat battery. All that remains for you to do is connect a single 1.5-V battery (dry cell) to one side of the board and a white LED to the other side.