Only a few years ago, the choice of LEDs was limited to IR, red, yellow, and green (yellowish-green). The LED manufacturers have been busy extending the spectrum, and filling in the gaps. The latest generation of organic LEDs (OLEDs) has added some dazzling new colors to the spectrum. This circuit uses a set of 13 differently colored LEDs to generate a full color spectrum.

WHAT IS LED
LED stands for Light Emitting Diode. LED's are now found on almost evry electronic device including MP3 players, DVD players, TV's, clock radios and computers. LED's have been popular for decades, however today they are cheaper, brighter and come in more colors than ever before. While the incandescent light bulb has been the light of choice for at least 100 years, many believe the LED will soon replace it. Here is how LED light bulbs work
WHAT IS A DIOD LEDs (light-emitting diode) are based on the semiconductor diode. When the diode is forward biased (switched on), electrons are able to recombine with holes and energy is released in the form of light. This effect is called electroluminescence and the color of the light is determined by the energy gap of the semiconductor. The LED is usually small in area (less than 1 mm2) with integrated optical components to shape its radiation pattern and assist in reflection.