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Electric lighting


Tesla Maps Our Electrical Future - Science & Invention - April, 1930:


“I predict that very shortly the old-fashioned incandescent lamp, having a filament heated to brightness by the passage of electric current through it, will entirely disappear.”


In March 1885 Tesla applied his first patents US334,823 - Commutator for Dynamo Electric Machines - January 26, 1886 (Filed May 18, 1885), US335,786 - Electric Arc Lamp - February 9, 1886 (Filed May 18, 1885) and US335,787 - Electric Arc Lamp - February 9, 1886. These patents were for an improvement in the arc lamp. He used an electromagnet to feed carbons to the arc at a uniform rate to produce a steadier light. Later he applied for patents on arc-lamps regulators and he registered his 'Tesla Arc Light Co' with an aim of implementing his inventions in the field of polyphase alternating currents. Looking for a new high-tech venture, Peck and Brown decided to back Tesla in 1886 and in April 1887, backed by a number of financiers and technicians, Tesla establishes Tesla Electric Company.


In the newly erected laboratory Tesla constructed and demonstrated his first polyphase induction motors and generators. But success was not easily achieved, as his ideas to promote (AC) alternating current was difficult to finance, and by other hand his investors weren't really interested in the development of the AC technology because its future application still was unkown and they were interested just about Tesla's Electric Arc Lamp. His design was a success, but all the money went to the investors. Tesla was soon looking for another opportunity.


Presentation of the Edison Medal to Nikola Tesla: Minutes of the annual meeting of the American Institute of Electrical Engineers, held at the Engineering Societies building - New York City - May 18, 1917:


I realized I would not have produced anything without the scientific training I got, and it is a question whether my surmise as to my possible accomplishment was correct. In Edison's works I passed nearly a year of the most strenuous labor, and then certain capitalists approached me with the project to form my own company. I went into the proposition, and developed the arc light. To show you how prejudiced people were against the alternating-current, as the President has indicated, when I told these friends of mine that I had a great invention relating to alternating-current transmission, they said: —No, we want the arc lamp. We do not care for this alternating-current.— Finally I perfected my lighting system and the city adopted it. Then I succeeded in organizing another company, in April, 1886, and a laboratory was put up, where I rapidly developed these motors, and eventually the Westinghouse people approached us, and an arrangement was made for their introduction. You know what has happened since then. The invention has swept the world.


Early arc lamps produced a brilliant blue-white light, good for street lighting but not for the home, and they emitted noxious fumes. Home lighting was by gas. Street arc lighting used series circuits. Edison introduced the parallel circuit, and designed his lamp for such a circuit. Edison introduced the big scale production and sale of electric power itself on the model of gas lighting, a major industry at the time. He wanted to be first in the business and announced to the press that he had an operable bulb before he actually had a bulb that worked. When Tesla's a.c. system was established, it was grafted on to Edison's, greatly extending its range and efficiency. But, essentially, it was still Edison's parallel circuit, high consumption, incandescent lighting system.



In the list of the Nikola Tesla's many inventions may be found a variety of novel electric lamps, all of which were designed to operate in conjunction with specially designed high frequency power supply units. Some of these lamps were the forerunners of our present day fluorescent tubes. In fact, not long ago a small Californian company announced the development of a high frequency electronically powered fluorescent bulb, dubbed the E-Lamp, which bears a striking resemblance to a bulb that Tesla designed and built nearly one hundred years ago. The principal upon which they both work is identical. Another type of lamp was essentially the same as the slender neon filled tubes that are now commonly bent into the shapes of letters and used in storefront advertising. A third type of electric lamp that Tesla designed, known as the incandescent carbon button lamp, was capable of producing light at high levels of efficiency. A variation on the design of this lamp is embodied in the popular Plasma Globe novelty item. Another lamp that he patented in 1891 under the name "Electric Incandescent Lamp" has recently been adopted by the United States Armed Forces as part of a portable high intensity lighting system. The lamp itself consists of a spark gap enclosed within a small gas filled glass bulb.


Tesla patented both his spark-gap oscillator and his Tesla coil specifically as power sources for a new lighting system that used currents of high frequency and high potential. Lest you get the impression that a lone genius named Tesla invented this new form of lighting out of the blue, you should know that others before him had used high frequencies to stimulate light, and others, like Sir William Crookes, had done the same with high potentials, but Tesla was the first on record to put the two together.

In Jules Verne's 1872 novel A Journey to the Center of the Earth, the narrator tells of a brilliant portable battery lamp used by the underground explorers. The device was powered by a Ruhmkorf coil; a high voltage buzzer-type induction coil (step-up transformer) popular among early electrical experimenters. The Ruhmkorf coil stimulated a lamp (type unspecified but probably a gas tube), which produced the light of an artificial day. The lamp had such a low current draw that the battery lasted throughout the subterranean adventure. Verne evidently was drawing, at least in part, on experimental knowledge of his day for what he calls this ingenious application of electricity to practical purposes.


Tesla's study of high voltage, high frequency alternating currents lead to the development of a large variety of vacuum tubes, some of which had medical applications.



This photograph represents a collection of a few wireless lamps such as he proposes to use in lighting insulated dwellings all over the world from central wireless plants. The two lamps at elther corner at the bottom are illuminated, owning to the fact that a high frequency oscilator was in operation some distance away when this photograph was beeing taken. These tubes were filled with varous gases for experimental research work in determining which was more efficient.


Using the principle of electrical resonance he found that it is possible to eliminate one of the two conductors normally used to carry current from the power supply to the electrical load. He created a light bulb specifically designed to be used in this manner, called the carbon button lamp It was generally based upon the dual-terminal tubes developed by William Crooks. He also developed a single-wire electric motor that could be operated in much the same manner. This involves attaching a metal plate to one of the high-voltage power supply terminals in place of one of the connecting wires. The electrical capacitance at the load, the refractory button or a second metal plate in the case of the motor, serves to complete the circuit through electrostatic induction. [The Inventions, Researches and Writings of Nikola Tesla]



US454,622 - System of Electric Lighting - June 23, 1891

The effect Tesla had discovered with this apparatus, was that at around 20 kHz and 20,000v, such a current applied to a bulb, would cause it to light up not in the ordinary fashion Edison pioneered, but rather as a plasma bulb. Today we call such devices florescent lights, and this is the origin of this technology. As was customary, Tesla was ahead of his time, and it is only comparatively recently this technology has found popularity. While the word ‘Tesla coil’ does not directly feature in the patents, the few turn primary and many turn secondary is unmistakable. If there is a central theme to Tesla’s high frequency researches in the 1890s, it is most certainly his beloved Tesla coil, and this is where it first appears, powering florescent lights. In Figure 3 on the left we see the type of equipment Tesla used in his lab to make his transformers. On the right a blow up illustration from Tesla’s 1896 ozone production U.S. Patent 568,177.



US514,170 - Incandescent electric light - February 6, 1894


The carbon button lamp is a single-electrode incandescent lamp invented by Nikola Tesla as one of a few improved lighting sources with regards to Thomas Edison's Incandescent light bulb. A carbon button lamp contains a small carbon sphere positioned in the center of an evacuated glass bulb. This type of lamp must be driven by high-frequency alternating current (a Tesla Coil, or other source of high voltage, high frequency current, such as a driver for a plasma globe), and depends on an electric arc or perhaps a vacuum arc to produce high current around the carbon electrode. The carbon electrode is then heated to incandescence by collisions by ions which constitute the electric current bombarding the carbon button. Because carbon isn't the best conductor, this causes the button to heat and release electrons into the bulb's vacuum (the technical name for this is "thermionic emission," or the "Edison effect"). These electrons, in turn, excite the remaining air molecules and cause them to create visible light. Supposedly, the bulb should shine 10 times brighter than an incandescent bulb (Note that the excitation of the air molecules, not the incandescence of the button, is actually the main source of light from the bulb, similar to how fluorescent lamps work). Tesla later discovered that versions of it could also be used in wireless, trans-Atlantic telegraphy, and to investigate what we now call X-rays as powerful sources of ionizing radiation. In fact, he even used the lamp (or something similar to it) to take x-ray photographs, 8 years before Wilhelm Rotgen discovered them.


He demonstrated several single-pole lamps which were connected to the secondary, describing the famous brush-discharge tube and expressing the opinion that it might find application in telegraphy. He noted that HF current readily passes through slightly rarefied gas and suggested that this might be used for driving motors and lamps at considerable distance from the source, the high-frequency resonant transformer being an important component of such a system.


His most "sensitive device" according to his descriptions, could be considered as a forerunner of the three-electrode tubes which could be used to amplify and rectify the signals. He designed different bulbs to investigate this phenomena, and it was many years before the invention of the "Audion" (or also known as triode) in 1906 by Lee de Forest.


Tesla took an evacuated incandescent type lamp globe, suspended within it at dead center a conductive element, stimulated that element with high voltage currents from an induction coil, and thus created a beam-like emanation, a brush discharge that was so eerily sensitive to disturbances in its environs that it seemed to be endowed with an intelligent life of its own. The device works best if there is no lead-in wire. In the bulb shown, every measure has been taken to construct it so it is free from its own electrical influence. The bulb could be stimulated inductively by applying energy to metal foil wrapped around its neck. Thus excited, an intense phosphorescence then spreads at first over the globe, but soon gives place to a white misty light, observes Tesla. The glow then resolves into a directional brush or beam that will spin around the central element. So responsive is it to any electrostatic or magnetic changes in its vicinity that the approach of an observer at a few paces from the bulb will cause the brush to fly to the opposite side. A small, inch-wide permanent magnet will affect it visibly at a distance of two meters, slowing down or accelerating the rotation according to how it is held relatively to the brush.


Tesla never patented the rotating brush or used it in any practical application, but he believed it could have practical applications. He saw one use in radio where the device could conceivably be adapted to being a most sensitive detector of disturbances in the medium. The rotating brush appears to be a precursor of the plasma globe toys now in fashion; these are sometimes called Tesla globes. Tesla's new lighting was famous in its time. Tesla, the promoter, saw to it. He conducted demonstrations at lectures before the electric industry associations, before large audiences in rented halls, and before select groups of influential New Yorkers in his Manhattan lab.


His articles about the new lighting were published in the popular scientific press and it was reported in the newspapers. Still, it did not catch on with the powers-that-be who no doubt saw in it Tesla's perennial pile-of scrap problem. But, I wonder, would the whole electric distribution system have to be scrapped to implement the efficiencies of Tesla lighting? Conceivably, the new lighting could be run off of local oscillators at the consumer end, the old power distribution system remaining intact. This is still a possibility, as it has been for about one hundred years.


Tesla's three-electrode tubes are described in the following articles and lectures:


Pioneer Radio Engineer Gives Views On Power - New York Herald Tribune - September 11, 1932


"The chief object of employing very short waves is to provide an increased number of channels required to satisfy the ever-growing demand for wireless appliances. But this is only because the transmitting and receiving apparatus, as generally employed, is ill-conceived and not well adapted for selection. The transmitter generates several systems of waves, all of which, except one, are useless. As a consequence, only an infinitesimal amount of energy reaches the receiver and dependence is placed on extreme amplification, which can be easily affected by the use of the so-called three-electrode tubes. This invention has been credited to others, but as a matter of fact, it was brought out by me in 1892, the principle being described and illustrated in my lecture before the Franklin Institute and National Electric Light Association (Experiments with Alternate Currents of High Potential and High Frequency). In my original device I put around the incandescent filament a conducting member, which I called a "sieve." This device is connected to a wire leading outside of the bulb and serves to modify the stream of particles projected from the filament according to the charge imparted to it. In this manner a new kind of detector, rectifier and amplifier was provided. Many forms of tubes on this principle were constructed by me and various interesting effects obtained by their means shown to visitors in my laboratory from 1893 to 1899, when I undertook the erection of an experimental world-system wireless plant at Colorado Springs".


A sieve can be observed around the incandescent filament.
A sieve can be observed around the incandescent filament.


The True Wireless by Nikola Tesla - Electrical Experimenter - May 1919


"My confidence that a signal could be easily flashed around the globe was strengthened thru the discovery of the "rotating brush," a wonderful phenomenon which I have fully described in my address before the Institution of Electrical Engineers, London, in 1892 (Experiments with Alternate Currents of High Potential and High Frequency), and which is illustrated in Fig. 9. This is undoubtedly the most delicate wireless detector known, but for a long time it was hard to produce and to maintain in the sensitive state. These difficulties do not exist now and I am looking to valuable applications of this device, particularly in connection with the high-speed photographic method, which I suggested, in wireless, as well as in wire, transmission."



The true wireless - Electrical Experimenter, May 1919


Possibly the most important advances during the following three or four years were my system of concatenated tuned circuits and methods of regulation, now universally adopted. The intimate bearing of these inventions on the development of the wireless art will appear from Fig. 10, which illustrates an arrangement described in my U.S. Patent No. 568,178 of September 22, 1896, and corresponding dispositions of wireless apparatus. The captions of the individual diagrams are thought sufficiently explicit to dispense with further comment. I will merely remark that in this early record, in addition to indicating how any number of resonant circuits may be linked and regulated, I have shown the advantage of the proper timing of primary impulses and use of harmonics. In a farcical wireless suit in London, some engineers, reckless of their reputation, have claimed that my circuits were not at all attuned; in fact they asserted that I had looked upon resonance as a sort of wild and untamable beast!



In February, 1892, Tesla gave a lecture to the Institution of Electrical Engineers, in which he described the carbon button lamp in detail. He also described several variants of the lamp, one of which uses a ruby drop in place of the carbon button. Some enthusiasts have argued that this is an early ruby laser.


Experiments with Alternate Currents of High Potential and High Frequency - by Nikola Tesla - A lecture delivered before the IEE, London, February 1892:


"A different arrangement used in some of the bulbs constructed is illustrated in Fig. 23. In this instance a non-conductor m is mounted in a piece of common arc light carbon so as to project some small distance above the latter. The carbon piece is connected to the leading-in wire passing through a glass stem, which is wrapped with several layers of mica. An aluminium tube a is employed as usual for screening. It is so arranged that it reaches very nearly as high as the carbon and only the non-conductor m projects a little above it. The bombardment goes at first against the upper surface of carbon, the lower parts being protected by the aluminium tube. As soon, however, as the non-conductor m is heated it is rendered good conducting, and then it becomes the centre of the bombardment, being most exposed to the same".


This lamp was so constructed so as to place a piece of matter such as carbon, or a diamond or a ruby, in the center, and bombard this “button” with electrical energy that would bounce off the button onto the inside of the globe and bounce back onto the button. If this were a ruby, and Tesla specifically worked with rubies, then is exactly how a ruby laser is created. Tesla refers in Inventions, Researches and Writings of Nikola Tesla to a “pencil-thin” line of light that was created with this device. Tesla probablly not only invented a primitive ruby laser in 1893, but he also demonstrated it and published it’s results. The problem with the device was that it was set up so as to “vaporize,” or destroy, the button, so that the laser effects were probably short-lived.




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