Instructables
Picture of LEDs (Article)
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
 
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Step 1: Making light

Picture of 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
wbo861 month ago

http://www.trait-tech.com/search.aspx?strkey=LED

Hope it's have useful help to you.

dudes3 months ago

so I have a white led, 5 mm, that I am running at 4.04 volts, which is normal. but it says it has a max current of 20 mA, I ran it at 1.4 A or 1400 mA, 70 times what it claims to max at. what is going on here? I'm confused, I thought these were less than .1 watt bulbs, but I put 5.6 watts through them just fine. help.

orvis2 years ago
A wonderfully informative article! There is a small correction to make though: In step one, you same an RGB LED uses "red, green, and red" to make light, wheras it should be "red, green, and blue." Really not a big deal and I think we're all smart enough to figure it out anyways. :)
Electro Kid3 years ago
This is great!!!!!!!!!
godofal3 years ago
so, what is the instructable really?
It's not an intstructable. It's intended to be an article.
well, since the title fix its alot more clear :)

as for the be nice policy: it wasn intended bad or something, just wondered if it wasnt finished or something
Vinsu3 years ago
Lots of anger in the air... I don't know about you guys but I think knowing how stuff works is equally important as making stuff work.
If you folks would look you would see a link in orange "Photo by Q-Branch from LED Throwies" Click on that and it will bring you to what you say nobody is telling you. I know, there is know excuse for them making so small!!!
jensenr30 Vinsu3 years ago
I agree with you Vinsu. so much for the "be nice" policy...
That was constructive criticism
Ghost Wolf3 years ago
let me know when you make your own led.