Source: PRO AV Magazine
Publication date: January 1, 2006
By Tim Kridel
Despite being about the size of your pinkie's fingernail, light-emitting diodes (LEDs) aren't far behind transistors in terms of ubiquity. Over the past few decades, they've found a home in everything from TV remote controls to Jumbotrons. Chances are if you haven't encountered LEDs in an AV installation, you will soon.
All diodes — including LEDs — have an anode (positive) terminal at one end and a cathode (negative) terminal at the other, but they allow current to flow in only one direction. (In an LED, the anode and cathode are the two wires poking out the bottom.) Diodes are unbalanced in the sense that they don't have equal amounts of negatively and positively charged particles. The more extra electrons that are floating around, looking for a home, the more conductive the diode is. A byproduct of their movement is light — a phenomenon LEDs leverage.
Here's how the process works: Multiple electrons orbit around an atom, and the ones with more energy orbit farther away. When an electron jumps to a closer orbit, energy is released as photons, which are a rudimentary form of light. As the homeless electrons move across a diode, they change orbits, producing light. However, sometimes that light isn't visible — as is the case with the infrared produced by the LEDs poking out of the end of your TV's remote control, for example.
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