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[Articles Home]  [Add Article]  

Who Really Invented the LED?

from Pete, AC7ZL on September 28, 2016
View comments about this article!

Who Really Invented the LED?

Introduction

"...And the wizard extended his hand toward the crystal which sat upon the table before him. He imparted it with mystical energy which caused it to glow. Its rich light painted the astonished faces assembled around the table, casting deep shadows which danced on the walls behind them..." Sounds like an outtake from a fantasy movie, or some kind of elf-on-a-magical-quest novel, right?

This is no fantasy at all. If you fabricate a crystal with the right materials, and energize it with an electric current, you can get all kinds of materials to glow, in pretty much any color you please. Sealed in a transparent plastic package with terminals through which the electric current can be applied, we now call such a device a "light emitting diode," or "LED."

I remember the first LED I saw, sometime in the early to mid 1970s. It was tiny, about an eighth of an inch in diameter. It came with an electronic kit that a friend of mine had received for his birthday. I marveled at how such a pure red light could be generated with such little electricity and without the production of any heat. To me, it was magical. Around this time marked the first common appearance of LEDs, arranged into segments, in the displays of calculators and digital clocks. My first digital wrist watch was a black plastic Texas Instruments watch with a red LED display. You had to push a button on the side to light the display and show the time. Now that was high-tech. I couldn't have been happier if I had been given the ignition keys to an Apollo rocket.


Figure 1: An early Texas Instruments LED watch (From: Pinterest)

Nowadays, LEDs are so fully ingrained in everyday life that people take them for granted. They're dirt-cheap and available in every conceivable hue, not to mention infrared and ultra-violet colors. In recent years they've graduated from simple indicators or display devices to high-power applications like automotive tail lamps, stop lights, football game score boards, and general-purpose replacements for incandescent and fluorescent bulbs in lighting fixtures.

To whom can we give credit for this modern technology? Who invented the LED and when was it invented? The answer depends upon who you ask and how one defines the term "invented." I've reached my own conclusions, which I'll share in a moment, but let's look back through time at some possible contenders for the title.

Who Really Invented the LED?

In 1968 Monsanto Corporation became the first company to mass produce discrete LEDs and LED numerical displays. The sheer numbers in which these devices were fabricated helped drive the cost from several hundred dollars per unit to mere pennies apiece, thereby transforming an expensive laboratory curiosity into a practical component for integration into consumer goods. This achievement was essential for getting LEDs into the hands of the general public, though I wouldn't really credit Monsanto with their invention.

Nick Holonyak, Jr., working as a consulting scientist at General Electric, proposed the use of gallium arsenide and gallium phosphide as the materials from which to fabricate an LED crystal. Despite the fact that "experts" around him dismissed his ideas as ridiculous, Holonyak forged ahead, fabricated, and then demonstrated a practical visible-light LED in 1962. Many have called Holonyak the "father" of the LED, but is such credit conclusive? Was this truly the first time that a semi-conducting diode had emitted light?


Nick Holonyak, Jr. (Wiki, Public Domain)


Kurt Lehovec (Wiki, Public Domain)

Apparently not. Ten years earlier, in 1952, Kurt Lehovec led a research team that experimented with and patented a silicon-carbide-based LED. Surely, then, he and his colleagues must have "invented" the LED. But wait, not so fast....

In the 1920's, a self-taught genius by the name of Oleg Losev applied electrical currents to chunks of carborundum. He observed luminous emissions and set out to study the phenomenon. In 1927, the Russian periodical Telegrafiya i Telefoniya bez Provodov published one of Losev's papers entitled, "Luminous Carborundum Detector and Detection with Crystals." In this paper, Losev documented light emission from carborundum (silicon carbide) detector crystals, quantified the polarity and threshold for the electric current required to stimulate the emission, and even quantified the spectral qualities of the emitted light. He correctly understood that the emitted light was "cold" in nature, resulting not from an arc or incandescence, but directly from the semi- conducting action of the crystals. In later papers, he went on to propose advanced applications for such a device, including an "optical relay" for telecommunication use.


Oleg Losev (Wiki, Public Domain)


Henry Round (Wiki, Public Domain)

Losev's work was certainly brilliant and groundbreaking, but did he invent the LED? Was he the first person to observe an LED in operation? The ultimate answer may lie in a brief article submitted by Henry J. Round to the periodical Electrical World. Round wrote the following:

To the Editors of Electrical World:

Sirs:

During an investigation of the unsymmetrical passage of current through a contact of carborundum and other substances a curious phenomenon was noted. On applying a potential of 10 volts between two points on a crystal of carborundum, the crystal gave out a yellowish light. Only one or two specimens could be found which gave a bright glow on such a low voltage, but with 110 volts a large number could be found to glow. In some crystals only edges gave the light and others gave instead of a yellow light green, orange, or blue. In all cases tested the glow appears to come from the negative pole, a bright blue-green spark appearing at the positive pole. In a single crystal, if contact is made near the center with the negative pole, and the positive pole is put in contact with any other place, only one section of the crystal will glow and that same section wherever the positive pole is placed.

There seems to be some connection between the above effect and the EMF produced by a junction of carborundum and another conductor when heated by a direct or alternating current; but the connection may be only secondary as an obvious explanation of the EMF is a thermoelectric one. The writer would be glad of references to any published account of an investigation of this or any allied phenomenon.

Round's letter was published in 1907, twenty years before Losev's work. I've seen no earlier documentation describing the effect, so Henry J. Round may have been the first to publish an account of light-emitting behavior in a chunk of carborundum--even if he didn't quite understand what it was that he was seeing. But does that make him the inventor of the LED?

Before I answer with my own opinion, let's discuss what would motivate someone like Round to apply an electric current to a carborundum crystal in the first place.

Early Radio Detectors

Radio receiver operation involves the process of "detection," the conversion of captured radio frequency energy into currents suitable for driving a sounding device like a set of headphones. Early 20th-century radio receivers made use of what now seems a strange and exotic array of instruments, like the Branley coherer, the Marconi magnetic detector (sometimes known as a "Maggie"), and Reginald Fessenden's electrolytic detector.

In 1874, two decades before the term "radio" was commonplace, Karl Ferdinand Braun discovered that point contacts between certain materials could exhibit semi-conducting properties. That is to say, such contacts exhibited a preference for the flow of electric current in one direction versus the other. This behavior can be exploited in simple radio circuits to strip the carrier from a received signal and recover the audio information encoded on it.

Jagadish Chandra Bose made subsequent use of this phenomenon in the construction of instruments he used to generate and study the properties of microwave radiation. This occurred in the late 1800's.


Karl Braun (Wiki, Public Domain)


Jagadish Bose (Wiki, Public Domain)

In 1906, Greenleaf Whittier Pickard developed and patented a silicon-based radio detector. The invention was based in part on Braun's work. From a modern frame of reference, we would now refer to such a device as a point-contact diode.

Pickard's detector manifested Braun's point contact as a slender but springy piece of wire, dubbed a "cat's whisker". The whisker probed the surface of a silicon crystal, forming a semi-conducting junction where the two materials met. Pickard is said to have tested some 30,000 other combinations of crystal and whisker materials. This resulted in additional useful designs like the Perikon (zincite/bornite) and pyrite detectors.

The trouble with many of these devices was their inherent fragility and instability. The electrolytic detector, for example, consisted of on open cup or capsule filled with sulfuric or nitric acid—nasty stuff, and hardly suitable for portable equipment. Cat whisker-type detectors like those based on galena or silicon worked well, but required considerable fussing to obtain proper operation, and then they could be knocked out of adjustment with little more than a hard stare. In a shipboard environment, where the floor and furniture are in constant motion, this was problematic. In addition strong signals, like those produced by a nearby transmitting antenna, could electrically damage the junction, requiring the whisker to be readjusted to a new "sensitive" spot.

The Carborundum Detector

Carborundum, also known by the chemical name silicon carbide, is rare in its natural form (a mineral called moissanite). In 1884, while trying to develop a process to create synthetic diamonds in an electric furnace, chemist Edward Acheson instead discovered a cost-effective way to produce synthetic carborundum. Carborundum's extreme hardness (second only diamonds) made it an ideal industrial abrasive. Acheson was granted a patent for his process in 1893, and carborundum has been produced for commercial use ever since.


A carborundum crystal (From author's collection)

Enter now General H. H. C. Dunwoody, retired Signal Officer of the U.S. Army and employee of the Deforest Radio Telephone Company. In December of 1906, he patented a radio detector based upon carborundum. This new detector offered wireless operators some important benefits.

Carborundum was by this time a cheap and plentiful material from which to fashion a detector. It was found to perform best, not by probing with a delicate cat's whisker, but through the application of a steel contact point under comparatively high pressure. This meant that once the device was properly adjusted, it had the tendency to maintain that adjustment even in the face of mechanical shock or vibration. And, unlike many other mineral-based detectors, the carborundum detector was not damaged by exposure to the kinds of high-power signals found in shipboard or coastal stations where transmitting and receiving antennas were located in close proximity.


G.W. Pickard (Wiki, Public Domain)


General H.H.C. Dunwoody (Wiki, Public Domain)

For the Deforest company, carborundum held an additional attraction. At that time, wireless communication technology was still in its infancy. Fierce competition provided the engine for endless litigation between companies seeking to make a name and maintain a competitive edge. Dunwoody's invention gave the Deforest company an alternative to the electrolytic detector they were using, and essentially disemboweled legal action taken against them for having employed the latter in their wireless stations without proper license.

For all its merit, there was one drawback to the use of carborundum that is perhaps best explained through analogy. If water flowing through a pipe can be thought of as representative of the flow of electricity through a wire, then a crystal detector like Pickard's or Dunwoody's can be thought of as a one-way check valve. In the case of the valve, a spring forces a poppet into a valve seat and seals it. If pressure is applied in the forward direction, the poppet is lifted off its seat and water can flow through. If the flow should reverse, the spring closes the valve again and flow is terminated.


The forward transfer function for carborundum (From Bucher, 1920)

It stands to reason that a certain minimum forward pressure must be applied to open the valve and keep it open. Because of the action of the spring, water pressure below this value will fail to open the valve, even though applied in the correct direction.

The same holds true for crystal detectors. A certain minimum pressure (voltage) must be applied to achieve meaningful flow (current). The relative stiffness of the "valve springs" in differing crystal detector chemistry accounts for the variation in observed sensitivity from one to another.

Since early radio circuitry could offer no amplification, the only way a detector would function is if the feeble signals captured on the antenna were sufficiently strong to force the detector "spring" to an open position. It follows, then, that the most sensitive (and therefore desirable) crystal materials were those that required the smallest voltages to operate.

The problem with carborundum is that it has, in valve parlance, a very stiff spring. That is to say, a comparatively high voltage must be applied in the forward direction in order to get the detector to turn on. In a crystal radio setting, this means that only the most powerful signals are capable of driving the detector, rendering a carborundum-based radio set essentially deaf to weak signals.

To combat this deficiency, an ingenious method was devised wherein a battery is used to provide a bias voltage. The bias battery wired to provide a fixed voltage (pressure) sufficient to almost—but not quite—push the detector to its on state. Any radio signal now superimposed on this bias, even an incredibly weak one, would be sufficient to drive the detector to its fully on state. The inherently insensitive carborundum detector was thereby made to function as though it were a much more sensitive crystal.


Biasing the carborundum detector in a radio receiver (From Packer and Haugh, 1922)

The genesis of the LED, then, was the search for an improved crystal detector for use in early radio sets. The application of a battery voltage to a carborundum crystal was part of a strategy to improve the radio sensitivity of the material. Now in the case of certain crystalline materials like carborundum, light emission is a natural consequence of electric current acting on the boundaries between crystals and between crystals and the detector probe. It can thus be argued that LEDs were not so much invented as they were discovered.

Undeniably, credit is due Henry J. Round for recognizing the novelty of crystal- generated light, to document it, and to try to quantify the electrical conditions necessary to produce the effect. However, I think it naïve to presume that he was the first to observe it.

To begin with, Round was employed by the Marconi Company at the time. He must have had colleagues and coworkers, and it is possible that one of these individuals brought the effect to Round's attention after having stumbled upon it himself.

Not only that, the art of radio has a longstanding tradition of amateur experimentation. Amateur radio operators and equipment builders, now referred to as "ham" operators, have been around for nearly as long as the science of radio communication itself. Published plans for homebuilt radio gear can be found as far back as 1901. Through the first decade of the 1900's hundreds if not thousands of amateur radio stations were set up. Undoubtedly, some of these operators had experimented with carborundum detectors at their stations. Since bias batteries were essential for effective carborundum detector operation, it is a virtual certainty that at least one of these operators would have noticed twinkles of light emanating from their detector.

Reproducing the Past

Academic discussions of carborundum detectors are well and good, but the big difference between legend and history is that the latter can be independently verified. The claim that a chunk of common industrial abrasive can be induced to produce cold light from an electric current is both intriguing and worthy of confirmation. That is exactly what I set out to do.

First came the matter of obtaining carborundum. In this age of the Internet, an on-line search will reveal numerous sources. Raw carborundum crystals are actually quite beautiful, and chunks of the material are sold as mineral specimens to collectors. In my case, Tucson, Arizona's annual International Gem and Mineral Show provided a grand opportunity to purchase some handsome samples of carborundum crystals for a just a few dollars. From one of these samples, I snapped off a small shard or flake, about the size of a large grain of rice.

Next, I located a spent .22 rifle cartridge. Using my soldering iron as a source of heat, I filled the brass with molten solder. This was to act as my crystal mount.

Finally, using a pair of tweezers, I picked up the carborundum shard and inserted one end of it into the pool of molten solder. I removed the heat. When the solder solidified, the crystal was permanently mounted.

To apply an electric current to the crystal, I snapped the spent cartridge into the jaws of an alligator clip test lead, which was subsequently connected to the positive terminal of a variable DC power supply. A second test lead, connected to the negative terminal of the supply, was fitted with a steel sewing needle. The point of the needle would allow me to probe the surface of the carborundum shard with some degree of precision. I adjusted the current limit on the power supply to something on the order of 50 mA.

The crystal shard was tiny and any light emitted was not likely to be dramatic, so I set up the apparatus just described on the stage of a stereo microscope. In the eyepiece of the microscope, the little flake of carborundum became a tabletop with visible fissures, seams, and stepped surface. My sewing needle probe became a baseball bat.

I set the power supply to about 12 volts, touched the crystal with the point of the needle and immediately witnessed the production of blue-yellow light. The stories were true!

Sometimes light appeared only at the point of the needle. Sometimes fissures or craters in the surface of the sample would flicker. Sometimes the boundaries between adjacent crystals would illuminate.

I also witnessed a variety of colors—yellows, blues, greens, golden hues, and red. In a room devoid of direct sunlight or overly aggressive lighting, the glowing features of the crystal were often bright enough to be visible to the naked eye.

I experimented with different voltages and with reversed polarity. Each change produced slightly different effects but nearly all produced some kind of light emission. Thirty volts was capable of producing an impressive amount of light, though it sometimes also caused local heating and destructive incandescence. Surprise: you can burn out a carborundum detector just like any other LED!

I fitted my microscope with an eyepiece-to-DSLR adapter for my camera. I was able to collect several minutes of interesting video documentation of all that I've just described. I've created a Youtube video entitled: Light Emitting Diodes... in 1907? where you can see actual footage of raw carborundum LEDs in operation.

Conclusion

So where does this leave us? We know that carborundum was used in the construction of certain radio detectors as far back as 1906. We know that in order to render the carborundum sufficiently sensitive for radio receiver use, it was necessary to apply a bias in the form of an external battery current. We know that Round documented the emission of light from an electrically-stimulated carborundum crystal in 1907, and I was able to easily reproduce and verify the effect myself, using a random piece of carborundum crystal and a DC power supply on my bench top.

We know that originally the production of light in the carborundum detector was not an intended or engineered effect, but rather the outcome of previously unrecognized natural processes. The production of light from a semi-conducting junction was therefore discovered, as opposed to invented.

Finally, we know that during the early 1900's, there were many individuals experimenting with detector crystals and detector biasing schemes, most of whom were probably amateurs.

So if the LED wasn't invented, then who should get credit for discovering it? At the risk of sounding anti-climactic, I have to admit that we'll never know for sure. But as a licensed amateur radio operator myself, I like to believe that the first twinkle of LED light witnessed by the human eye was generated and observed by one of my brothers—some forever-to-remain-unknown ham radio operator.

Demonstration Video

Light Emitting Diodes... in 1907?

https://www.youtube.com/watch?v=ZC-e0Ev02sk

Interesting Patent Disclosures

Patent Number: 492,767 Production of artificial crystalline carbonaceous materials -- E. G. Acheson

Patent Number: 706,744 Current-actuated wave-responsive device -- Reginald A Fessenden

Patent Number: 755,840 Detector for flectrical disturbances -- Jagadis Chunder Bose

Patent Number: 796,800 Receiver for use in wireless telegraphy -- Edouard Branly

Patent Number: 836,531 Means for receiving intelligence communicated by electric waves -- Greenleaf Whittier Pickard

Patent Number: 837,616 Wireless telegraph system -- H. H. C. Dunwoody

Patent Number: 884986 Wireless telegraphy -- Guglielmo Marconi

References Materials

Bucher, Elmer E. The Wireless Experimenters Manual, copyright 1920, Wireless Press Inc., New York

Lee, Bartholomew. " How Dunwoody’s Chunk of ‘Coal’ Saved both de Forest and Marconi" AWA Review, 2009, Volume 22, pp. 1-10

Packer, A.H. and Haugh, R.R. Radio for the Amateur, copyright 1922, Goodheart-Wilcox Company, Chicago

Zheludev, Nikolay "The life and times of the LED — a 100-year history" Nature Photonics, April 2007, Volume 1, pp.189-192

H. P. Friedrichs (AC7ZL) Homepage:
www.hpfriedrichs.com

Member Comments:
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Who Really Invented the LED?  
by ZS1ZC on September 28, 2016 Mail this to a friend!
Too many people think that the history of technology is just a dry technical narrative of simple events like patent submissions and journal articles. But when you read articles like this that put names and faces to that history, everything changes and it's not as simple as we'd like to believe.

Then there are the interpersonal battles, the drama and sometimes outright theatre that accompanied some developments, as encountered in the stories of Edison, Tesla, Armstrong and others. All definitely worth telling again and again.
 
RE: Who Really Invented the LED?  
by N8FVJ on September 28, 2016 Mail this to a friend!
Nice article. I knew a Russian at least seen a similar process in the early 20th century. But, unaware of earlier work.
 
Who Really Invented the LED?  
by K9JCS on September 28, 2016 Mail this to a friend!
As Artie Johnson used to say on Laugh In, "Verrry Interesting."

Thanks for taking the time to put this informative article together and sharing it with us. Great combination of two of my favorite subjects, history and electronics.

73
Jim
K9JCS
 
Who Really Invented the LED?  
by KC2QYM on September 28, 2016 Mail this to a friend!
One of most interesting and edifying articles I've read here. Thanks for sharing this great piece with us! Nicely balanced technical writing style.
 
RE: Who Really Invented the LED?  
by KE7FD on September 28, 2016 Mail this to a friend!
Imposters! Everyone knows Al Gore invented L.E.D.s.

Nice detailed write-up. Thanks!

Glen - KE7FD
 
Who Really Invented the LED?  
by KC4ZGK on September 28, 2016 Mail this to a friend!
Nice write up, thanks for your time.
 
Who reduced the LED to practical Application?  
by K6BRN on September 28, 2016 Mail this to a friend!
From your article, it seems clear that Nick Holonyak, Jr. reduced the concept of and LED to a practical and producible product with broad application. So I vote for him.

The first LEDs I experimented with were in about 1972, purchased from Radio Shack and used in a front panel to some electronics I was building with a friend, as a very young man. Their relatively dim red glow was fascinating - no heat, potentially unlimited life, used hardly any power... WOW! Now most of the lights in my home are LED. Took a while to get this far.

Then tiny monochrome LCDs began to show up around 1977 and later displaced LEDs as indicators in low power electronics - like watches.

Bravo to Nick Holonyak, Jr. and all innovators like him!

Brian - K6BRN
 
Who Really Invented the LED?  
by AF7EC on September 28, 2016 Mail this to a friend!
Thank you for your article! Lots of great information and pictures. And THIS is what I call an 'article', not a forum posting disguised as an article. ;-)
 
RE: Who Really Invented the LED?  
by KB3WGE on September 28, 2016 Mail this to a friend!
Neat article,I used to own a watch like that a long time ago,73's ALL KB3WGE a.k.a. Jimi.
 
RE: Who Really Invented the LED?  
by AI4WC on September 28, 2016 Mail this to a friend!
Enjoyable article! Sort of like a college physics lab report, complete with video. Thank you for your research and time!
 
Who Really Invented the LED?  
by WB4M on September 28, 2016 Mail this to a friend!
I thought it was Mr. Zeppelin
 
Who Really Invented the LED?  
by K6OFG on September 28, 2016 Mail this to a friend!
Thank you for this very interesting and informative article. Loved it.
Steve.
 
RE: Who Really Invented the LED?  
by N4OI on September 28, 2016 Mail this to a friend!
I believe you could count on one or two hands the key divine inspirations, upon which the whole of technical innovation has thrived. I particularly remember one of my first electronics classes. The instructor walked among us holding a single, red LED and battery in the palm of his hand. He moved slowly, spoke softly, and treated it as if it were a delicate baby bird.

In a few short months, I was building digital clocks using those ubiquitous seven-segment red displays. Of course, office productivity screeched to a halt as everyone who passed by my desk stopped and stared intently, mesmerized, waiting for the seconds to cascade to minutes...

Good times....

73 ES GOD BLESS DE KEN N4OI
 
RE: Who Really Invented the LED?  
by K6AER on September 28, 2016 Mail this to a friend!
The first large scale use of LED's was by HP in the late 60's. Up to them they ware a lab anomaly.
 
RE: Who Really Invented the LED?  
by KJ4DGE on September 29, 2016 Mail this to a friend!
Very good and well written article. Thank you for the research and clarifications. Other than giving credit where credit is do, Its not so much that as it got invented in the first place. I am sure many inventions get lost to history either through ignorance or ridicule.

I toyed in the early 80's with the idea of making (an did) a light beam communications device based on a Forrest Mim's schematic. Of course no one else had a receiver I knew of who I could talk to :) Still a few years later Heathkit came out with the first personal Laser kit for hobbyists and I played around with that, same idea but different visible light. We very much today take for granted all the things that have pushed from the past into the future. Heck I still like the idea of building crystal radios. Must be whats left of the kid in me.

Kudos again on a great piece.
 
RE: Who Really Invented the LED?  
by SWMAN on September 29, 2016 Mail this to a friend!
Nice article. I have always been fascinated by LEDs especially nowadays with so many styles and types. It's amazing how they have gotten so popular. Especially how bright some of them are with just one single LED. Just about everything for home lighting is on the shelves at all of the stores. It's almost hard to find a CFL in the stores let alone regular incandescent bulbs. Almost everything is LED.
 
RE: Who Really Invented the LED?  
by KA4KOE on September 29, 2016 Mail this to a friend!
Bravo, bravo kind sir!!

This video is exquisitely put together. The accompaniment piece is familiar yet I cannot put the piece and composer to it.

It is familiar because I used it along with several other tunes to learn to play my theremin.

Excelsior!

Fleep
 
RE: Who Really Invented the LED?  
by ONAIR on September 29, 2016 Mail this to a friend!
Great article! LEDs seem to be the the future of lighting, but now it seems that some health concerns are being raised. It appears that higher powered LEDs could contribute to medical issues, and some municipalities are becoming very cautious about installing them in street lighting applications. We'll just have to wait and see how things pan out.
 
Who Really Invented the LED?  
by AH7I on September 29, 2016 Mail this to a friend!
Nice bit of history. Thanks.
73, -Bob ah7i
 
RE: Who Really Invented the LED?  
by W9WQA on September 29, 2016 Mail this to a friend!
i originally put off reading this, thinking it would be boring. once started i realized i may read it again, and i am anxious to alert a technical friend/ham to check it out. very interesting indeed!
 
Who Really Invented the LED?  
by K0JEG on October 1, 2016 Mail this to a friend!
Consider using a better camera or uploading at a more modern resolution than 240 lines! Just because you were recreating a historical test doesn't mean you should use a historical capture source.
 
Who Really Invented the LED?  
by KE4KTO on October 2, 2016 Mail this to a friend!
The article was a nice try but unfortunately, it is fraught with errors. The facts are that Carborundum which is Silicon Carbide is not second to a diamond in hardness. corundum is second to a diamond in hardness. Rubies and sapphires are corundum, which is Aluminum Oxide. Carborundum is silicon Carbide which very rarely occurs in nature. Silicon Carbide is also known as Moissanite. Carborundum and Moissanite are both trade names.
 
RE: Who Really Invented the LED?  
by SWMAN on October 2, 2016 Mail this to a friend!
Wow ! Pickey, pickey, pickey, some people are never happy. I feel sorry for your wives.
 
Who Really Invented the LED?  
by AB9NZ on October 3, 2016 Mail this to a friend!
Beautiful article. Thanks for sharing your wonderful effort.
 
Who Really Invented the LED?  
by N3QE on October 3, 2016 Mail this to a friend!
Noise Emitting Diode (NED)

When connected across a 1000 volt supply it makes a loud noise (once). The NED was discovered by Igor Pravaganda whom you'll recall worked many years trying to filter AC with electrolytics. He'll always be remembered as the father of the confetti generator.
 
RE: Who Really Invented the LED?  
by KA4KOE on October 3, 2016 Mail this to a friend!
SWMAN

I agree! If you complain, then the obvious remedy is to produce an "error-free" article. I doubt, however, that subsequent efforts will be forthcoming.


Fleep
 
RE: Who Really Invented the LED?  
by KG4YMC on October 3, 2016 Mail this to a friend!
great article and well written. thanks for sharing. as spock would say " fascinating. I remember when red led watches came out . I was processing color film and had to remember to take the watch off if got to close to loading film in processor , even the light from it could fog the film . also the were hard to see in daylight . remember when thru the lens slr cameras had them for metering. was bog deal. early lcd watches were expansive. will we discover that ancient cvilizations had this going a long time ago ?
 
RE: Who Really Invented the LED?  
by KA3AUD on October 3, 2016 Mail this to a friend!
Nice job.
 
RE: Who Really Invented the LED?  
by K8QV on October 3, 2016 Mail this to a friend!
Very well done interesting article. So I guess the LED isn't alien technology from the Roswell crash after all. ;)
 
RE: Who Really Invented the LED?  
by WB6RXG on October 3, 2016 Mail this to a friend!
I went to work for Intel in 1977. They had recently acquired a watch company named Microma which used an LCD for the display. Intel employees could buy the watch at a substantial discount.

Intel/Microma had produced a commercial to sell the watchon TV. The commercial was about two Ninja warriors having a sword fight when one of the Ninjas asks the other what the time was. The Ninja had to put down his sword to push the button on his LED watch at which point the first Ninja used that moment to his advantage and "dispatched" the Ninja with the LED watch. Pretty funny at the time and I would bet that the LED watch was the one from Texas Instruments.

I remember being fascinated with LEDs in the early 70's. I also remember that they weren't very bright and were impossible to see in the sunlight or a really brightly lit room.

Stuart WB6RXG
 
Who Really Invented the LED?  
by NA5XX on October 6, 2016 Mail this to a friend!
It was Tesla. People ust don't want to give him credit.
 
RE: Who Really Invented the LED?  
by NT4TS on October 9, 2016 Mail this to a friend!
So now we know, best one yet
Laing NT4TS
 
Who Really Invented the LED?  
by N7MSD on October 9, 2016 Mail this to a friend!
Pete, THANK YOU for that wonderful article! Also thanks for the video (which I had to watch without sound on this work computer). And I had one of those LED watches (my dad got it for me)--had we known what it would be worth today, we never would have tossed it when it died!

I'm also wondering: is the difference between glows, and whether a face glows, more due to impurities/doping, or crystal alignment?

Finally, I never in a million years would have guessed Monsanto made the first commercial LED--MIND BLOWN!
 
Who Really Invented the LED?  
by N7MSD on October 9, 2016 Mail this to a friend!
Pete, THANK YOU for that wonderful article! Also thanks for the video (which I had to watch without sound on this work computer). And I had one of those LED watches (my dad got it for me)--had we known what it would be worth today, we never would have tossed it when it died!

I'm also wondering: is the difference between glows, and whether a face glows, more due to impurities/doping, or crystal alignment?

Finally, I never in a million years would have guessed Monsanto made the first commercial LED--MIND BLOWN!
 
Who Really Invented the LED?  
by N7MSD on October 9, 2016 Mail this to a friend!
Pete, THANK YOU for that wonderful article! Also thanks for the video (which I had to watch without sound on this work computer). And I had one of those LED watches (my dad got it for me)--had we known what it would be worth today, we never would have tossed it when it died!

I'm also wondering: is the difference between glows, and whether a face glows, more due to impurities/doping, or crystal alignment?

Finally, I never in a million years would have guessed Monsanto made the first commercial LED--MIND BLOWN!
 
Who Really Invented the LED?  
by K7TTI on October 11, 2016 Mail this to a friend!
What a great history lesson. Very thorough and informative. Thank you.
 
Who Really Invented the LED?  
by AA9KK on October 13, 2016 Mail this to a friend!
Rudolph The Red-Nosed Reindeer should also receive some credit for this!
 
RE: Who Really Invented the LED?  
by K0UA on October 18, 2016 Mail this to a friend!
Great article, I really enjoyed it. Thank you.

James
 
RE: Who Really Invented the LED?  
by G3YWX on October 19, 2016 Mail this to a friend!
I think you are absolutely right. I find this story fascinating. H J Round who first noticed the effect was a really excellent engineer and rather forgotten today. I wrote an article on my website (https://www.electronics-notes.com/articles/history/pioneers/captain-h-j-round.php) and had a historian call me up and try to get in touch with a relation of his who had previously contacted me. All of this brings these stories to life and makes them very real. I certainly enjoy reading and writing about technology history and in particular that of radio and electronics.
 
Who Really Invented the LED?  
by KF5VUD on October 19, 2016 Mail this to a friend!
Really fascinating stuff, and I especially enjoyed your YouTube video.

Do you have any idea what causes the differences in light color? Different localized crystal structure, perhaps?
 
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