Here at Instructables we love LEDs. They sip power, fit pretty much anywhere, are easy to wire up, and light up our projects with their many brilliant colors. Learning how to light one up is a valuable skill and can be quite addictive. So it’s about time we take a moment to think about these little bits of awesomeness and how they work.
This article is one in a series of Instructables articles about DIY technology. The full list can be seen here.
Photo by Q-Branch from LED Throwies
This article is one in a series of Instructables articles about DIY technology. The full list can be seen here.
Photo by Q-Branch from LED Throwies
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Signing UpStep 1: Making light
LED is short for light-emitting diode and as such LEDs work like many other diodes. They are semiconductors that are made more conductive by adding impurities to material. For LEDs, these semiconductors are often gallium arsenide (GaAs), gallium phosphide (GaP), or gallium arsenide phosphide (GaAsP). These semiconductors are used to make wafers as thins as .5 microns or even less. Since one micron is one thousandth of a millimeter, thats pretty tiny.
When electricity is run through these wafers, we get light. With the current, electrons around the atoms get bumped to higher orbitals. As these electrons fall back down into lower orbitals they give off energy in the form of light. The bigger the energy drop the higher the frequency of light that will be given off. In other words, this determines the color of the light. A small drop and the light will be infra-red. A bigger drop will be in the visible spectrum and along with that the color of the light can also be controlled.
With these energy drops determining the color of the light the big question is how to make white light? After all, white light isn't one color, but the combination of many colors. One way would be to use an RGB LED and mix the red, green, and red colors to make white, but this requires some control of the different LEDs. The other method is to apply layers of phosphor on top of an LED, commonly blue, that shifts the wavelength of the light passing through it. It's not too different from how a fluorescent light works and is how many high-intensity white LEDs are made.
Photo by barney_1 from LED matrix using shift registers
When electricity is run through these wafers, we get light. With the current, electrons around the atoms get bumped to higher orbitals. As these electrons fall back down into lower orbitals they give off energy in the form of light. The bigger the energy drop the higher the frequency of light that will be given off. In other words, this determines the color of the light. A small drop and the light will be infra-red. A bigger drop will be in the visible spectrum and along with that the color of the light can also be controlled.
With these energy drops determining the color of the light the big question is how to make white light? After all, white light isn't one color, but the combination of many colors. One way would be to use an RGB LED and mix the red, green, and red colors to make white, but this requires some control of the different LEDs. The other method is to apply layers of phosphor on top of an LED, commonly blue, that shifts the wavelength of the light passing through it. It's not too different from how a fluorescent light works and is how many high-intensity white LEDs are made.
Photo by barney_1 from LED matrix using shift registers
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as for the be nice policy: it wasn intended bad or something, just wondered if it wasnt finished or something