Light emitting diode or better known as LEDs (LED), are electronic components that can produce light when an electric current flowing through it.

LED is described with the following symbol

 LED symbol
At the beginning LED is only made in red, but now the colors of yellow, green, blue, and orange are also available on the market. There is also an infrared LED, which produces infrared light.

the colors of led
LED generally has a dome-shaped packaging material made ​​of plastic, with a protruding edge or rim at the bottom of the dome. There are two wire terminals on the bottom, which is cathode and anode. Usually the cathode wire is shorter than the anode wire, see the picture below

anode cathode led
LED requires about 20 mA current to emit light with maximum brightness, although as small as 5 mA current can still produce visible light. An average voltage drop the LED is 1.5 V, thus the supply voltage is 2 V can turn most of LED with maximum brightness. With levels higher voltages, LEDs can be damaged and caught fire when a given forward voltage exceeds 2 V.


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  1. LED's also work on 3v and there are also other method to detect the Anode and cathode point of the LED's given in my blog http://techpeeks.blogspot.com/

  2. @ Sagar: Thank's 4 visit.
    I think 3 VDC is too much for supply voltage of LEDs, it will reduce a life time. For these case, put resistor in series with LED.
    Next I'll post about it.

  3. @Caang:Thank's for your reply on my blog.


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