1.) Where can I buy 'em? I kind of like to play around with some.
2.) Has anyone tried using L. E. D. s to make a flatscreen TV? Since the blue L. E. D.'s been developed, I would think that someone would attempt this. (No, I’m not going to. I’ve got better things to spend my time on than trying to build one of those things.)
You can get them at RadioShack. Though I’m sure another Doper will reccomend a site or catalogue with cheaper and better ones.
I first read about blue LED’s in Popular Science. Flat screen displays are in the works. There are some problems with size and fitting red, blue, and green LED’s into small ‘cells’. The military has already expressed interest in LED screens-less weight, space, and power than CRT, much more durable than LCD.
There's also a few projects attempting to make white LED's that are large enough to replace standard light bulbs.There are cycle lights available that produce very near white light from leds, actually they are a very faint blue.
Forget Radio Shack – try a company that manufactures them, like Gilway Technical Lemp. There are also a number of web sites devoted to LEDs.
The newer Blue LEDs are more powerful and use less energy than the older ones – can’t recall the formulas right now. But they’ve come a long way. There are nice Green, Yellow, and Orange ones around now, too, in addition to the red ones of long standing. By combining elements, they’ve ,ade passable white LEDs.
There’s an interesting article about using LEDs for lighting in this week’s Economist at http://www.economist.com/science/displayStory.cfm?story_id=1365100.
Apparently, producing consistently white light from LEDs isn’t as simply as just turning on a red, blue and green one all at the same time:
So I’m guessing that building your own flatscreen with LEDs would be tricky, although this whole area seems to be receiving a lot of active research.
There’s a sort of LED TV screen in the basement of Sander’s theater at Harvard University.
Cite, ya tease? And link to some of the sites that offer blue L.E.D.s, please, as I’m getting oodles of useless stuff when I try to google it. (Not totally useless, but nothing that says, “Buy Blue L.E.D.s here cheap!”)
Here is one of many companies that make full-color LED displays. They are mostly used for large outdoor displays, like those at sporting events. In some areas of Tokyo you can see these big displays on every street corner, displaying commercials and ads. I don’t know how they solve the color drift problem mentioned above - perhaps they have some feedback mechanism, or maybe they need routine calibration.
I haven’t seen smaller LED screens (i.e. smaller than wall-sized). I guess it’s difficult to make the pixel size small. Plasma displays and LCDs are used for indoor use.
The Discovery Store has cartloads of these things at the register. The light was an intense, almost blinding blue.
Look out!
PS: White LED’s aren’t white, and they aren’t a combination. They are actually BLUE, with a Yellow Phosphor that emits White light.
Phil
PS: Check out www.arcflashlight.com for, in many flash-a-holics opinion the Ultimate Keychain light.
I suggest going to www.digikey.com. My lab ordered a couple of “super ultra blue” LED’s to spice up a current supply we were building and they worked quite well. The part number is 67-1683-ND. They’re panel mount, so they might be awkward shapes for you, but if you just want to play around with them, they should do nicely.
And I just happen to be an undergrad at Harvard. The LED screen that was mentioned is in Loker Commons (essentially the undergraduate common area). It is more like the news ticker by times square than an LED TV, so it is probably not what you had in mind.
I remember LedTronics (http://www.ledtronics.com) from when I was working at Kodak in 1992 and the first blue LED’s appeared from them. We were looking for a way to get a flashlight for use in darkrooms that would generate a consistent light throughout the life of the batteries.
Anyway, they have a spiffy site with a bunch of different kinds of lights.
My favorite electronics supply is always www.newark.com
They have blue leds for $0.66 each. They list a five dollar surcharge for orders under $25, but IME it’s always either waived or forgotten.