Know about LEDs

 Light emitting diodes or LEDs produce light when electrons combine with holes in the semiconductor, releasing energy as photon. First ones to be produced were infrared and red LEDs. Other colour and white LEDs were invented later. Initial LEDs were of low power and later high power ones were invented. 7 segment LED displays will be familiar to most of you. Now there are LED TVs and large displays. OLED has an organic compound which produces light and is used in televisions. Three colour LEDs are RGB LEDs which have four leads instead of the two in usual LEDs. The longest of the leads is the common one. In usual LEDs, longer lead is positive. There are also blinking LEDs. Surface mount type of LEDs are used in LED lights which are fast replacing incandescent lights and fluorescent lights. LEDs work on low voltage DC and need a driver unit in LED bulbs, which are usually a small switch mode power supply, which can cause radio frequency interference in amateur radio bands, especially the low quality ones.



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