How To Use Light Emitting Diodes
Ron Heath
Version 1.0
Copywrite 2012
All Rights Reserved
Introduction
This book is intended to be both too simple and too complex. The reader
who is in a hurry may skip over the parts that are too far one way or
the other, however, I have found useful nuggets of knowledge while
reading the most simple things, as well as things that seemed to be too
complex to be actually useful.
Commercially available light emitting diodes started out as fairly dim
lights that had a size of around 0.2 inch diameter and a length of
around 0.34 inches. These were used as indicator lights for electronic
devices. In fact, this is the most common place that you will see them
today.
The first color was red, but green
and yellow soon followed. Infra-red LEDs soon became available also.
The infra-red LEDs are used in the remote control for TVs, and for the
small flag sensors that are in most anything that moves.
All different shapes of LEDs have become available. Some of these have
been installed onto printed circuit boards with plastic light pipes
that direct the light to the front panel.
Ultra-violet,
or black light LEDs are now available. These are used in black light
flashlights. Black light flashlights are used in law enforcement for
viewing powders that glow in black light.
Blue LEDs are rather recent, but they are also commonly available now.