As featured in Trail-Friendly Radio in the February 2009 edition of WorldRadio on-line magazine, the Joule Thief is a handy LED-based device that can be used to illuminate your field operating position while getting the most out of AA and AAA batteries that have been pronounced "dead" by other electronic devices - such as digital cameras.
A hay-wired version of the Thief shows the simplicity of construction and the handful of parts needed to put it together.
(For a larger view, click on the photograph.)
The drawing below shows the Manhattan-style layout used to build the KI6SN Trail-Friendly Joule Thief.
(For a larger view, click on the drawing.)
Click here to see a Bre Pettis You Tube video showing how the circuit is assembled, including detailed instructions on how to wind the toroidal inductor.