A Guide to Choosing LED’s

What is an LED?
The word LED means ‘light-emitting diode’ and refers to a special type of diode that glows when electricity is passed through it. LED’s can be made from a range of materials – a common semi-conducting material used is called gallium arsenide phosphide.

How do LED’s work?
As with all diodes, LED’s only allow current to pass in one direction. The cathode is normally indicated by a flat side on the casing and the anode is normally indicated by a slightly longer leg (see image below).

LED Light-Output Range & Power Requirements:
LED’s can be supplied in a range of light outputs and individual colours including white, red, green and blue. They can also be supplied in formats that switch between two or more colours known as bi-colour and tri-colour LEDS.

The light output of an LED is measured in nanometer’s (nm*) and they can be manufactured to emit light output as follows (see chart below**):