Mount the joule thief on a D-size-battery holder, and it makes a handy flashlight, one that gives your old batteries new life. This article originally appeared in the July 2015 issue of Popular ...

You may have heard that LED flashlights using AA lithium batteries run hotter and die sooner. Is there any truth to this? The short answer: There could be an issue ...

home theater, smartphones, photography, and more. Panasonic has unveiled an LED flashlight that can be powered by nearly any battery you’ve got on hand during an emergency. The Any Battery Light ...