Almost all inexpensive commercial LED flashlights use a 4.5V power supply—three AA or AAA batteries—because white LEDs require 3.3 to 3.5V to fully turn on. Thus ...

High efficiency white LEDs have advanced to the point where they can replace glow bulbs and other light sources not only as indicators, but also for illumination. While many of the claims made about ...

Those portable shake-to-charge devices seem like a good idea, especially for the battery challenged, but how well does this sort of thing really work? Engineer Dave Johnson took this flashlight to the ...

The capacitors are 22 microF. “Dyn” is a dynamo. The part to the left of the dotted line is a perfectly standard LED flashlight circuit. The right is the 'squeeze to charge/power lights' addition. And ...