LED flashlights or "LED torches" (as they are called in Britain) are hand-held flashlights that use light emitting diodes (LEDs) as opposed to the older technology of incandescent light bulbs.
In 1992, bright blue LEDs made from GaN were invented by Shuji Nakamura in Japan. White LEDs were then made based on the technology used in blue LEDs.
LEDs have a high light to power effiency, up to 40LM/W. They are much more durable than conventional lightbulbs. The expected lifetime for LEDs is up to 100,000 hours. These advantages have made the LED flashlight popular. The voltage to drive a LED is 3.0V to 3.6V. So a step up circuit should be used in LED Flashlight using 1 or 2 1.5V dry battery.
Further reading Edit
A flashlight (usually called a torch outside North America) is a hand-held electric-powered light source. Usually the light source is a small incandescent lightbulb or light-emitting diode (LED). Typical flashlight designs consist of the light source mounted in a parabolic or other shaped reflector, a transparent lens to protect the light source from damage and debris, a power source (typically electric batteries), and an electric power switch.
While most flashlights are hand-held, there are head or helmet-mounted flashlights designed for miners and campers and battery-powered lights for bicycles. Some flashlights are powered by hand-cranked dynamos or electromagnetic induction or are recharged by solar power.
The name flashlight is used mainly in the United States and Canada. In other English-speaking countries, the more common term is torch or electric torch.
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