The color of the generated light depends on the nature of the materials from which the LED is built, more specifically the width of the forbidden zone between the valence band and the conduction band. This also led to one with a long wavelength pass a lower voltage than one with a short wavelength, such as red and blue 3.6 V 1.5 V. Because the voltage on a little rise led to a greater power, the color just move to a shorter wavelength, a blue LED at low power will seem more green and a red LED is (briefly) yellow with so many current piece that he goes.

Instead of a lamp may also be a modern LED (light emitting diode = light-emitting diode) are used. LEDs are cheaper than incandescent lamps and have a longer life, they give significantly less light also colored (red, green, yellow, orange, blue).

The fire power of red LEDs is 1.6 V. Between a red LED and a 4.5 V battery must be a link be put resistance. We assume that by the 15mA LED must walk. (you can choose the LED current, but may not be over 30mA)

Gallium-aluminiumarsenide (AlGaAs) - red infrared
Galliumarseenfosfide (Gaasp) - red orange yellow (amber)
Galliumnitride (GaN) - green
Gallium (GaP) - green
Zinc selenide (ZnSe) - blue
Silicon carbide (SiC) - blue
Indiumgalliumnitride (DISCUSS) - blue or ultraviolet
Diamond (C) - ultraviolet

Blue LED
The development of the blue LED has been a long time coming. Blue (and white) LEDs based on semiconductor galliumnitride were invented by Shuji Nakamura. Only in the 90s, there are affordable models with a reasonable brightness on the market. Meanwhile (2006), the little blue LED below the green. With the availability of the blue LED, full RGB color mixing possible.

White LED
White LEDs were originally created by using a UV-LED fluorescent layer (phosphorus) to highlight. Meanwhile, there are also variations that directly emit white light. But tricolor LEDs or RGB white LEDs can emit light.

Infrared LED
(Almost all remote controls for electronic devices send their command using IR LEDs. This can be a relatively high processing power. Infrared Leds are also widely used as integrated opto channel coupling agents (Eng. optocoupler), safety components with the sending side and the receiving side optical firmly attached but electrically insulated themselves properly. IR LEDs can also be used as relief aid for analog and digital video cameras with night record "since the CCD sensor also sensitive to the wavelength of an IR LED.

Tip: This feature can also be used to verify that a remote control still work to do by an electronic viewfinder of video or still camera, the light show. An IR LED is also IR half-light of burning IR LED received. One can measure the signal with an oscilloscope.

Two and three colors
There are also two color LEDs. These are normal LED housings which two LEDs are integrated with a different color, usually red and green, have. Two Color Leds, two or three feet, in the first case, the polarity of the voltage to be turned to the color of the LED light that radiates to change. With three legs, each color mixing of red and green made by the flow through the two separate control LEDs (send). Then there are LEDs with more than two colors on the market, including full-color RGB LED. The red, green and (mostly) two blue LEDs, the full color spectrum covered. They are applied in other large and illuminated displays and some furniture design.