The above file as of 5/11/2008 before removal of most notes on items noted in 2002 or before then.
High efficiency LEDs (among ones currently in production) remain heavily only slightly to somewhat more efficient than better incandescent lamps with exception of some recent stellar ones, but here is the explanation why they can be so much more efficient than incandescent in some applications such as traffic lights. (updated slightly 7/22/2008)
My LED FAQ! This covers many of the questions people ask me. Please read this before e-mailing me. New file 7/4/2001, updated significantly 11/11/2008.
Overview of the different LED types - the different colors, brightnesses, and a bit of the basic chemistry and electrical and other properties of each of these. (Updated 6/26/2002)
"LEDs 101" or "LEDs For Dummies" - how to make them work, why to use a dropping resistor instead of a 2.4 or whatever volt regulator. (Don't laugh until you see what I have seen in sci.electronics.basics!) (Opened to the public 7/16/99, but still under construction with an update on 5/1/2003.)
The truth of pulsing LEDs to make them appear brighter. The nonlinearity that sometimes makes this work is in LEDs and not in human vision. This usually does not work when feeding 20 mA or more of average current through an ultrabright LED. (new document 12/1/99, updated slightly 6/19/2001)
My page on more unusual LEDs, such as pink and purple (not violet or UV) ones, multicolor flashing ones and ones powerful enough to require heatsinking. (new document 7/11/2002, updated 8/20/2002)
UV from the right kind of blue LED! Other blue LEDs and blue light sources will get some blacklight effects since many non-blue fluorescent substances fluoresce from some visible light as well as UV. But 450 nM broadband blue GaN LEDs can be made to produce some UV! UPDATED 10/1/2006 - links to spectral results of a hack on a historic obsolete kind of blue LED, the first commercially successful type of high brightness blue LED!
My Yellow SiC LED Page - I managed to get my hands on one of those rare LEDs! (NEW FILE 12/13/2000, updated 6/22/2008)
How much you need of red, green and blue LEDs to make white of various color temperatures. Only certain LED types are covered here. You need more red and especially notably much less blue than many would think! (New file 7/4/2001, updated 1/2/2008)
My Blue LED Shootout - to show advantages and disadvantages of popular and less-popular wavelengths of blue LEDs. (updated slightly 9/24/2000)
My page on Organic LEDs, Polymer LEDs and the like. New and still under construction with slow progress, some on 7/16/2003 - I am mainly following the usual semiconductor kind of LEDs more than stuff sometimes known as "DC electroluminescence".
My Nightlight File. Link from here to there added 1/16/2004 due to recently adding there its first LED nightlight.
Direct entry to this worldwide-significant site has changed in early 2002 - http://ledmuseum.home.att.net/ledleft.htm
NOTABLE - for quite a while Craig Johnson has maintained a "news" page at http://ledmuseum.home.att.net/whatsnew.htm
That one consists of his news largely from within the past 30 days from now, including updates of all sizes from really notable to very minor.
And note that Craig does lots of updating and more updating and more frequently than I do. He has more time to test LEDs and to type web material than I do so you should check this site out. There will always be something you can find there and not in my site, probably even nowhere else in the entire World Wide Web!
Updates continue almost daily with no sign of stopping. Most recent noted significant update 8/1/2008 for an LED, 10/11/2008 for what I noticed as a significant update on an LED flashlight, 9/28/2008 for what I noticed as a significant update on an LED product other than a flashlight, 9/15/2008 for a laser product, 10/10/2008 for a non-LED flashlight, and 9/27/2008 for updating links from his site to other sites.
UPDATE 4/14/2006 - Now added: Spectra of many LEDs, LED flashlights and other LED products, and other light sources especially neon glow lamps. In March 2006 Craig Johnson got hold of a spectrometer (he has had another working for a while in the past), and has published many spectral power distribution curves of LEDs, LED flashlights and a few other LED products as well as several non-LED lamps/products. To get these, look among the first dozen or so of the bazillions of links to other pages in that site, in the left frame of http://ledmuseum.home.att.net/ledleft.htm!
UPDATE 2/19/2007 - Craig Johnson has restored use of his battery runtime analysis apparatus and his "Pro Metric" beam analyzer!
http://www.lightemittingdiodes.org, a site with lots of theoretical info on light emitting diodes, much of it quite technical.
Paul Mathew's LED FAQ - new location.
New location for updated or proposed-update location:
http://www2.whidbey.net/opto/LEDFAQ/The%20LED%20FAQ%20Pages.html
The High Brightness LED Page at Compound Semiconductor.
A list of manufacturers of LED and LED products at the Lighting Research Center at the Rensselaer Polytechnic Institute.
The home page of Renssalaer's Lighting research Center - includes links to LED stuff.
An article in EE Times on the history and progress and the efficiency of white LEDs and high power LEDs.
The "OddOne's" LED and white LED / oddball-LED-applications forum!
Their Main Website in Japan.
The website of their main USA office.
NOTE - current upgraded grade LEDs are best-obtained from Nichia sales offices. They do handle small orders. The ones from surplus outfits are often previous grade (dimmer but still very impressive) even if you confirm the same part numbers. (Nichia is known to improve their LEDs without changing their part numbers.) Or, they may vary strangely in beam width.
They now have UV LEDs, and violet and blue laser diodes.
Toyoda Gosei is another maker of ultrabright blue, blue-green, and green gallium nitride LEDs. This way to a top-level page for their LEDs.
Straight to the web site of Cree, another maker of bright gallium nitride LEDs. But it looks like they stopped making lamps and now just make the dice / chips.
The LED top page of Agilent, spun off by Hewlett Packard.
Lumileds, a joint venture of Agilent and Philips Lighting.
The home page for Lumileds' Luxeon series of high power LEDs. 1-1.2 watt ones are in production now and 5 watt ones are available in some colors with white supposedly becoming available sometime in November 2002 and other colors becoming available soon.
Toshiba. Hit the "Products List" selector and select optoelectronics.
Uniroyal Optoelectronics, another maker of LED chips, InGaAlP and InGaN including 400 nm deep violet.
Uniroyal is in bankruptcy and is selling their assets according to a Novenber 3 2003 article in this Compound Semiconductor page.
AXT, another maker of InGaN chips.
Oriol, a new player in the GaN LED game.
Ledtronics, a maker of LED products such as indicator lamps and LED screw-in light bulbs.
ETG Technology, a source of LED lamps and cluster lamps and 1.2 watt blue, green, white and other LED lamps with Cree XB900 dice. Already known to have supplied samples of LED lamps with Cree "XB290" series dice.
Straight to the web site of Opto Technology, a maker of miniaturized LED cluster lamps in heat-sinkable TO-66 packages and the like. They also do custom jobs.
Lamina Ceramics makes high power LED arrays - for example, ones 1.06 by 1.25 inches (26.67 by 31.75 mm) that can take over 100 watts - these obviously require major heatsinking! Please consider the thermal resistance data to determine temperature rise of the LED junctions (dice or chips) above the temperature of the heatsinkable surface of the array package, and please consider light output as a function of junction temperature (which is in the datasheet). Same for Lumileds and probably many other heatsinkable high power LEDs - the light output is specified with the junctions at 25 degrees C.
Gentex, who makes things such as map lights built into rearview mirrors.
Craig Johnson's list of suppliers, manufacturers, etc. Includes LED products such as brake lights, marine cabin lights and flashlights as well as just LEDs.
Written by Don Klipstein.
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