How Light Emitting Diods aka LED work? | |
What is LED? LED is a small light source, which does not get hot as regular light bulbs do, nor does it burn out. LED uses electric current to function, not volts and is not affected by the heat, cold or vibration and they do not flicker like some lights may. They do not need too much current, in fact if less current flows through, they will last longer – up tens thousands of years. It is in fact essential that too much current does not flow through an LED, as it may get damaged as a result. Therefore a current limiting resistor must be applied.
At first, LED lights were used only in various machines and gadgets – they were the blinking lights in computers, ovens, the numbers in the digital clocks etc, and they only came in red and amber. Now, various other colours have been added to the list and the LEDs are used more and more elsewhere – also in traditional lights like night lights, flashlights, exit signs etc.
Another advantage concerning LED is that it is not made of breakable glass and can also be used under water.
Comment by: Big Ed
2007-01-25 04:12 | Voltage is critical....supply 3v to a red 1.5v LED and POOF!
Heat kills LED's many have high tolerances -20c to +85C. Higher power starts and multi watt LED's have built in heat sinks. drive a LED beyond rated amps and excess is generated as heat, not light.
But how do they work? Early experiments in Silicon wafers and dies produced heat as a product of the NPN or PNP junctions. Heat is INFRARED light! As experimenters worked with various doping elements they found this stimulated electrons and produced photons as they changed states.
These photons were varied by materials like gallium arsnide and other exotic compounds, Doped or pure all varies frequency and levels.
LED's now cover the spectrum and also produce light in a single frequency by stimulated emissions...a LASER! Red, Green and now BLUE!
LED's are in every device with lighted keys, buttons or even you phone, watch etc.
The highest light output LED"s exceed 500 lumens at 10-30watts and 8-12VDC. for single emitters. Multi emitters and combo untis mounted on heat sinks cannot be viewed directly they are so bright.
Search gool or Wikipedia for details.
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