Electronic – LEDs driver circuit


I was wondering what is the role of this type of circuit connected to LEDs.
I found it in a LED torch supplied by 2xAA batteries.
Is it an oscillator? Is it only an energy trick? What are the advantages of driving a LED with high frequencies?

(LEDs emit white light, BJT transistor NPN is 8122 or equivalent NTE108, the value of inductor is 10u about).

Thanks for replies


simulate this circuit – Schematic created using CircuitLab

Best Answer

This circuit is a variant of so called "Joule Thief" which is a variant of "Blocking oscillator". The main use of it is to increase the battery voltage output, which is needed when the battery is considered to be "dead" by regular means.