1.
Light-emitting diode
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A light-emitting diode is a two-lead semiconductor light source. It is a p–n junction diode, which emits light when activated, when a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light is determined by the band gap of the semiconductor. LEDs are typically small and integrated optical components may be used to shape the radiation pattern, appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared light. Infrared LEDs are still used as transmitting elements in remote-control circuits. The first visible-light LEDs were also of low intensity and limited to red, modern LEDs are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness. Early LEDs were often used as indicator lamps for electronic devices and they were soon packaged into numeric readouts in the form of seven-segment displays and were commonly seen in digital clocks. Recent developments in LEDs permit them to be used in environmental, LEDs have allowed new displays and sensors to be developed, while their high switching rates are also used in advanced communications technology. LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. Light-emitting diodes are now used in applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes, as of 2017, LED lights home room lighting are as cheap or cheaper than compact fluorescent lamp sources of comparable output. They are also more energy efficient and, arguably, have fewer environmental concerns linked to their disposal. Electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide, russian inventor Oleg Losev reported creation of the first LED in 1927. His research was distributed in Soviet, German and British scientific journals, rubin Braunstein of the Radio Corporation of America reported on infrared emission from gallium arsenide and other semiconductor alloys in 1955. Braunstein observed infrared emission generated by simple diode structures using gallium antimonide, GaAs, indium phosphide, in 1957, Braunstein further demonstrated that the rudimentary devices could be used for non-radio communication across a short distance. As noted by Kroemer Braunstein …had set up a simple optical communications link, the emitted light was detected by a PbS diode some distance away. This signal was fed into an amplifier and played back by a loudspeaker. Intercepting the beam stopped the music and we had a great deal of fun playing with this setup. This setup presaged the use of LEDs for optical communication applications, by October 1961, they had demonstrated efficient light emission and signal coupling between a GaAs p-n junction light emitter and an electrically-isolated semiconductor photodetector
2.
Decimal
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This article aims to be an accessible introduction. For the mathematical definition, see Decimal representation, the decimal numeral system has ten as its base, which, in decimal, is written 10, as is the base in every positional numeral system. It is the base most widely used by modern civilizations. Decimal fractions have terminating decimal representations and other fractions have repeating decimal representations, Decimal notation is the writing of numbers in a base-ten numeral system. Examples are Brahmi numerals, Greek numerals, Hebrew numerals, Roman numerals, Roman numerals have symbols for the decimal powers and secondary symbols for half these values. Brahmi numerals have symbols for the nine numbers 1–9, the nine decades 10–90, plus a symbol for 100, Chinese numerals have symbols for 1–9, and additional symbols for powers of ten, which in modern usage reach 1072. Positional decimal systems include a zero and use symbols for the ten values to represent any number, positional notation uses positions for each power of ten, units, tens, hundreds, thousands, etc. The position of each digit within a number denotes the multiplier multiplied with that position has a value ten times that of the position to its right. There were at least two independent sources of positional decimal systems in ancient civilization, the Chinese counting rod system. Ten is the number which is the count of fingers and thumbs on both hands, the English word digit as well as its translation in many languages is also the anatomical term for fingers and toes. In English, decimal means tenth, decimate means reduce by a tenth, however, the symbols used in different areas are not identical, for instance, Western Arabic numerals differ from the forms used by other Arab cultures. A decimal fraction is a fraction the denominator of which is a power of ten. g, Decimal fractions 8/10, 1489/100, 24/100000, and 58900/10000 are expressed in decimal notation as 0.8,14.89,0.00024,5.8900 respectively. In English-speaking, some Latin American and many Asian countries, a period or raised period is used as the separator, in many other countries, particularly in Europe. The integer part, or integral part of a number is the part to the left of the decimal separator. The part from the separator to the right is the fractional part. It is usual for a number that consists only of a fractional part to have a leading zero in its notation. Any rational number with a denominator whose only prime factors are 2 and/or 5 may be expressed as a decimal fraction and has a finite decimal expansion. 1/2 =0.5 1/20 =0.05 1/5 =0.2 1/50 =0.02 1/4 =0.25 1/40 =0.025 1/25 =0.04 1/8 =0.125 1/125 =0.008 1/10 =0
3.
Digital clock
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A digital clock is a type of clock that displays the time digitally, as opposed to an analog clock, where the time is indicated by the positions of rotating hands. Digital clocks are often associated with electronic drives, but the description refers only to the display. The biggest digital clock is the Lichtzelt Pegel on the television tower Rheinturm Düsseldorf, the first digital pocket watch was the invention of Austrian engineer Josef Pallweber who created his jump-hour mechanism in 1883. Instead of a dial, the jump-hour featured two windows in an enamel dial, through which the hours and minutes are visible on rotating discs. By 1885 Pallweber mechanism was already on the market in pocket watches by Cortébert and IWC, arguably contributing to the subsequent rise, the principles of Pallweber jump-hour movement had appeared in wristwatches by the 1920s and are still used today. While the original inventor didnt have a brand at the time. Plato clocks used an idea but a different layout. These spring-wound pieces consisted of a cylinder with a column inside, affixed to which were small digital cards with numbers printed on them. The Plato clocks were introduced at the St. Louis World Fair in 1904, eugene Fitch of New York patented the clock design in 1903. 13 years earlier Josef Pallweber had patented the same invention using digital cards in Germany, the German factory Aktiengesellschaft für Uhrenfabrikation Lenzkirch made such digital clocks in 1893 and 1894. The earliest patent for an alarm clock was registered by D. E Protzmann and others on October 23,1956. Protzmann and his associates also patented another digital clock in 1970, two side-plates held digital numerals between them, while an electric motor and cam gear outside controlled movement. In 1970, the first digital wristwatch with an LED display was mass-produced, called the Pulsar, and produced by the Hamilton Watch Company, this watch was hinted at two years prior when the same company created a prototype digital watch for Kubricks 2001, A Space Odyssey. Throughout the 1970s, despite the initial hefty cost of digital watches, over the years, many different types of digital alarm clocks have been developed. In Soviet Russia, the 7-segment digital clocks were known as Elektronika 7, Digital clocks typically use the 50 or 60 hertz oscillation of AC power or a 32,768 hertz crystal oscillator as in a quartz clock to keep time. Most digital clocks display the hour of the day in 24-hour format, in the United States and a few other countries, emulations of analog-style faces often use an LCD screen, and these are also sometimes described as digital. To represent the time, most digital clocks use a seven-segment LED, VFD and they generally also include other elements to indicate whether the time is AM or PM, whether or not an alarm is set, and so on. Digital clocks that run on electricity and have no battery must be reset every time the power is cut off or if they are moved
4.
Arabic numerals
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In this numeral system, a sequence of digits such as 975 is read as a single number, using the position of the digit in the sequence to interpret its value. The symbol for zero is the key to the effectiveness of the system, the system was adopted by Arab mathematicians in Baghdad and passed on to the Arabs farther west. There is some evidence to suggest that the numerals in their current form developed from Arabic letters in the Maghreb, the current form of the numerals developed in North Africa, distinct in form from the Indian and eastern Arabic numerals. The use of Arabic numerals spread around the world through European trade, books, the term Arabic numerals is ambiguous. It most commonly refers to the widely used in Europe. Arabic numerals is also the name for the entire family of related numerals of Arabic. It may also be intended to mean the numerals used by Arabs and it would be more appropriate to refer to the Arabic numeral system, where the value of a digit in a number depends on its position. The decimal Hindu–Arabic numeral system was developed in India by AD700, the development was gradual, spanning several centuries, but the decisive step was probably provided by Brahmaguptas formulation of zero as a number in AD628. The system was revolutionary by including zero in positional notation, thereby limiting the number of digits to ten. It is considered an important milestone in the development of mathematics, one may distinguish between this positional system, which is identical throughout the family, and the precise glyphs used to write the numerals, which varied regionally. The glyphs most commonly used in conjunction with the Latin script since early modern times are 0123456789. The first universally accepted inscription containing the use of the 0 glyph in India is first recorded in the 9th century, in an inscription at Gwalior in Central India dated to 870. Numerous Indian documents on copper plates exist, with the symbol for zero in them, dated back as far as the 6th century AD. Inscriptions in Indonesia and Cambodia dating to AD683 have also been found and their work was principally responsible for the diffusion of the Indian system of numeration in the Middle East and the West. In the 10th century, Middle-Eastern mathematicians extended the decimal system to include fractions. The decimal point notation was introduced by Sind ibn Ali, who wrote the earliest treatise on Arabic numerals. Ghubar numerals themselves are probably of Roman origin, some popular myths have argued that the original forms of these symbols indicated their numeric value through the number of angles they contained, but no evidence exists of any such origin. In 825 Al-Khwārizmī wrote a treatise in Arabic, On the Calculation with Hindu Numerals, Algoritmi, the translators rendition of the authors name, gave rise to the word algorithm
5.
Hexagon
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In geometry, a hexagon is a six sided polygon or 6-gon. The total of the angles of any hexagon is 720°. A regular hexagon has Schläfli symbol and can also be constructed as an equilateral triangle, t. A regular hexagon is defined as a hexagon that is both equilateral and equiangular and it is bicentric, meaning that it is both cyclic and tangential. The common length of the sides equals the radius of the circumscribed circle, all internal angles are 120 degrees. A regular hexagon has 6 rotational symmetries and 6 reflection symmetries, the longest diagonals of a regular hexagon, connecting diametrically opposite vertices, are twice the length of one side. Like squares and equilateral triangles, regular hexagons fit together without any gaps to tile the plane, the cells of a beehive honeycomb are hexagonal for this reason and because the shape makes efficient use of space and building materials. The Voronoi diagram of a triangular lattice is the honeycomb tessellation of hexagons. It is not usually considered a triambus, although it is equilateral, the maximal diameter, D is twice the maximal radius or circumradius, R, which equals the side length, t. The minimal diameter or the diameter of the circle, d, is twice the minimal radius or inradius. If a regular hexagon has successive vertices A, B, C, D, E, F, the regular hexagon has Dih6 symmetry, order 12. There are 3 dihedral subgroups, Dih3, Dih2, and Dih1, and 4 cyclic subgroups, Z6, Z3, Z2 and these symmetries express 9 distinct symmetries of a regular hexagon. John Conway labels these by a letter and group order, r12 is full symmetry, and a1 is no symmetry. These two forms are duals of each other and have half the order of the regular hexagon. The i4 forms are regular hexagons flattened or stretched along one symmetry direction and it can be seen as an elongated rhombus, while d2 and p2 can be seen as horizontally and vertically elongated kites. G2 hexagons, with sides parallel are also called hexagonal parallelogons. Each subgroup symmetry allows one or more degrees of freedom for irregular forms, only the g6 subgroup has no degrees of freedom but can seen as directed edges. Hexagons of symmetry g2, i4, and r12, as parallelogons can tessellate the Euclidean plane by translation, other hexagon shapes can tile the plane with different orientations
6.
Adding machine
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An adding machine was a class of mechanical calculator, usually specialized for bookkeeping calculations. In the United States, the earliest adding machines were built to read in dollars. Adding machines were ubiquitous office equipment until they were phased out in favor of calculators in the 1970s, the older adding machines were rarely seen in American office settings by the year 2000. However, they did not gain widespread use until Dorr E. Felt started manufacturing his comptometer, to add a new list of numbers and arrive at a total, the user was first required to ZERO the machine. Then, to add sets of numbers, the user was required to press numbered keys on a keyboard, which would remain depressed. The user would then pull the crank, which caused the numbers to be shown on the wheels. The rotary wheels now showed 3072, press the 4 key in the 3rd column from the right, the 4 key in the 2nd column from right, and the 9 key in the rightmost column. The rotary wheels now show a total of 3521 which. Keyboards typically did not have or need 0 keys, one simply did not press any key in the column containing a zero, trailing zeros, were there by default because when a machine was zeroed, all numbers visible on the rotary wheels were reset to zero. Subtraction was impossible, except by adding the complement of a number, multiplication was a simple process of keying in the numbers one or more columns to the left and repeating the addition process. For example, to multiply 34.72 by 102, key in 3472, pull crank, wheels now show 354144, or 3,541.44 A later adding machine, called the comptometer, did not require that a crank be pulled to add. Numbers were input simply by pressing keys, the machine was thus driven by finger power. Multiplication was similar to that on the machine, but users would form up their fingers over the keys to be pressed. Using the above example, four fingers would be used to press down twice on the 3,4,7 and 2 keys and that finger shape would then move left two columns and press once. Usually a small crank near the wheels would be used to zero them, some adding machines were electromechanical — an old-style mechanism, but driven by electric power. Some ten-key machines had input of numbers as on a modern calculator –30.72 was input as 3,0,7,2 and these machines could subtract as well as add. Some could multiply and divide, although including these operations made the more complex. Those that could multiply, used a form of the old adding machine multiplication method, using the previous example of multiplying 34.72 by 102, the amount was keyed in, then the 2 key in the multiplication key column was pressed
7.
Gasoline
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Gasoline /ˈɡæsəliːn/, known as petrol /ˈpɛtrəl/ outside North America, is a transparent, petroleum-derived liquid that is used primarily as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the distillation of petroleum. On average, a 42-gallon barrel of oil yields about 19 US gallons of gasoline when processed in an oil refinery. The characteristic of a gasoline blend to resist igniting too early is measured by its octane rating. Gasoline is produced in several grades of octane rating, sometimes, gasoline also contains ethanol as an alternative fuel, for economic or environmental reasons. Gasoline, as used worldwide in the vast number of combustion engines used in transport and industry, has a significant impact on the environment. Gasoline may also enter the environment uncombusted, as liquid and as vapors, from leakage and handling during production, transport and delivery, from tanks, from spills. As an example of efforts to control leakage, many storage tanks are required to have extensive measures in place to detect. Gasoline contains benzene and other known carcinogens, Gasoline inhalation can produce an intense high, however the practice is thought to cause severe organ damage, including mental retardation. The first automotive combustion engines, so-called Otto engines, were developed in the last quarter of the 19th century in Germany, the fuel was a relatively volatile hydrocarbon obtained from coal gas. With a boiling point near 85 °C, it was suited for early carburetors. The development of a spray nozzle carburetor enabled the use of less volatile fuels, further improvements in engine efficiency were attempted at higher compression ratios, but early attempts were blocked by knocking. In the 1920s, antiknock compounds were introduced by Thomas Midgley Jr. and Boyd and this innovation started a cycle of improvements in fuel efficiency that coincided with the large-scale development of oil refining to provide more products in the boiling range of gasoline. In the 1950s oil refineries started to focus on high octane fuels, the 1970s witnessed greater attention to the environmental consequences of burning gasoline. These considerations led to the out of TEL and its replacement by other antiknock compounds. Subsequently, low-sulfur gasoline was introduced, in part to preserve the catalysts in modern exhaust systems, Gasoline is the term that is used in North America to refer to the most popular automobile fuel. The Oxford English Dictionary dates the first use to 1863, when it was spelled gasolene and it was never a trademark, although it may have been derived from older trademarks such as Cazeline and Gazeline. Variant spellings of gasoline had been used to refer to raw petroleum since the 16th century, Petrol is the preferred term in most Commonwealth countries
8.
Amplifier
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An amplifier, electronic amplifier or amp is an electronic device that can increase the power of a signal. An amplifier functions by taking power from a supply and controlling the output to match the input signal shape. In this sense, an amplifier modulates the output of the power supply based upon the properties of the input signal, an amplifier is effectively the opposite of an attenuator, while an amplifier provides gain, an attenuator provides loss. An amplifier can either be a piece of equipment or an electrical circuit contained within another device. Amplification is fundamental to modern electronics, and amplifiers are used in almost all electronic equipment. Amplifiers can be categorized in different ways, another is which quantity, voltage or current is being amplified, amplifiers can be divided into voltage amplifiers, current amplifiers, transconductance amplifiers, and transresistance amplifiers. A further distinction is whether the output is a linear or nonlinear representation of the input, amplifiers can also be categorized by their physical placement in the signal chain. The first practical device that could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest. Vacuum tubes were used in almost all amplifiers until the 1960s–1970s when the transistor, invented in 1947, today most amplifiers use transistors, but vacuum tubes continue to be used in some applications. Before the invention of electronic amplifiers, mechanically coupled carbon microphones were used as amplifiers in telephone repeaters. After the turn of the century it was found that negative resistance mercury lamps could amplify, the first practical electronic device that could amplify was the Audion vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. The terms amplifier and amplification were first used for this new capability around 1915 when triodes became widespread, the amplifying vacuum tube revolutionized electrical technology, creating the new field of electronics, the technology of active electrical devices. It made possible long distance lines, public address systems, radio broadcasting, talking motion pictures, practical audio recording, radar, television. For 50 years virtually all electronic devices used vacuum tubes. Early tube amplifiers often had positive feedback, which could increase gain but also make the amplifier unstable, much of the mathematical theory of amplifiers was developed at Bell Telephone Laboratories during the 1920s to 1940s. Other advances in the theory of amplification were made by Harry Nyquist, the vacuum tube was the only amplifying device for 40 years, and dominated electronics until 1947, when the first transistor, the BJT, was invented. Today most amplifiers use transistors, but vacuum tubes are used in some high power applications such as radio transmitters. All amplifiers have gain, a factor that relates the magnitude of some property of the output signal to a property of the input signal
9.
Liquid-crystal display
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A liquid-crystal display is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals. Liquid crystals do not emit light directly, instead using a backlight or reflector to produce images in color or monochrome and they use the same basic technology, except that arbitrary images are made up of a large number of small pixels, while other displays have larger elements. LCDs are used in a range of applications including computer monitors, televisions, instrument panels, aircraft cockpit displays. Small LCD screens are common in consumer devices such as digital cameras, watches, calculators. LCD screens are used on consumer electronics products such as DVD players, video game devices. LCD screens have replaced heavy, bulky cathode ray tube displays in all applications. LCD screens are available in a range of screen sizes than CRT and plasma displays, with LCD screens available in sizes ranging from tiny digital watches to huge. Since LCD screens do not use phosphors, they do not suffer image burn-in when an image is displayed on a screen for a long time. LCDs are, however, susceptible to image persistence, the LCD screen is more energy-efficient and can be disposed of more safely than a CRT can. Its low electrical power consumption enables it to be used in battery-powered electronic equipment more efficiently than CRTs can be, by 2008, annual sales of televisions with LCD screens exceeded sales of CRT units worldwide, and the CRT became obsolete for most purposes. Without the liquid crystal between the filters, light passing through the first filter would be blocked by the second polarizer. Before an electric field is applied, the orientation of the molecules is determined by the alignment at the surfaces of electrodes. In a twisted nematic device, the surface alignment directions at the two electrodes are perpendicular to other, and so the molecules arrange themselves in a helical structure. This induces the rotation of the polarization of the incident light, and this light will then be mainly polarized perpendicular to the second filter, and thus be blocked and the pixel will appear black. By controlling the voltage applied across the liquid crystal layer in each pixel, color LCD systems use the same technique, with color filters used to generate red, green, and blue pixels. The optical effect of a TN device in the state is far less dependent on variations in the device thickness than that in the voltage-off state. Because of this, TN displays with low content and no backlighting are usually operated between crossed polarizers such that they appear bright with no voltage. When no image is displayed, different arrangements are used, for this purpose, TN LCDs are operated between parallel polarizers, whereas IPS LCDs feature crossed polarizers
10.
Vacuum fluorescent display
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A vacuum fluorescent display is a display device used commonly on consumer-electronics equipment such as video cassette recorders, car radios, and microwave ovens. Sometimes named as ice tube indicator, a VFD operates on the principle of cathodoluminescence, roughly similar to a cathode ray tube, but operating at much lower voltages. Each tube in a VFD has a phosphor coated anode that is bombarded by electrons emitted from the cathode filament, in fact, each tube in VFD is a triode vacuum tube because it also has a mesh control grid. Unlike liquid crystal displays, a VFD emits a bright light with high contrast. Cadmium was commonly used in VFDs in the past, but the current RoHS-compliant VFDs have eliminated this metal from their construction, VFDs can display seven-segment numerals, multi-segment alpha-numeric characters or can be made in a dot-matrix to display different alphanumeric characters and symbols. In practice, there is little limit to the shape of the image that can be displayed, the first VFD was the single indication DM160 by Philips in 1959. The first multi-segment VFD was the 1962 Japanese single-digit, seven-segment device, the displays became common on calculators and other consumer electronics devices. In the late 1980s hundreds of millions of units were made yearly, the device consists of a hot cathode, anodes and grids encased in a glass envelope under a high vacuum condition. The cathode is made up of fine wires, coated by alkaline earth metal oxides. These electrons are controlled and diffused by the grids, which are made up of thin metal, if electrons impinge on the phosphor-coated plates, they fluoresce, emitting light. Unlike the orange-glowing cathodes of traditional vacuum tubes, VFD cathodes are efficient emitters at much lower temperatures, the principle of operation is identical to that of a vacuum tube triode. Electrons can only reach a given plate element if both the grid and the plate are at a potential with respect to the cathode. This allows the displays to be organized as multiplexed displays where the grids and plates form a matrix. In the example of the VCR display shown to the right, all of the similar plates in all of the digits are connected in parallel. One by one, the microprocessor driving the display enables a digit by placing a positive voltage on that digits grid, electrons flow through that digits grid and strike those plates that are at a positive potential. The microprocessor cycles through illuminating the digits in this way at a high enough to create the illusion of all digits glowing at once via persistence of vision. Several amateurs have experimented with the possibilities of using VFDs as triodes, the extra indicators are arranged as if they were segments of an additional digit or two or extra segments of existing digits and are scanned using the same multiplexed strategy as the real digits. Some of these extra indicators may use a phosphor that emits a different colour of light, for example, orange
11.
Nixie tube
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A Nixie tube, or cold cathode display, is an electronic device for displaying numerals or other information using glow discharge. The glass tube contains a wire-mesh anode and multiple cathodes, shaped like numerals or other symbols, applying power to one cathode surrounds it with an orange glow discharge. The tube is filled with a gas at low pressure, usually mostly neon and often a little mercury or argon, although it resembles a vacuum tube in appearance, its operation does not depend on thermionic emission of electrons from a heated cathode. It is therefore called a tube, or a variant of neon lamp. Such tubes rarely exceed 40 °C even under the most severe of operating conditions in a room at ambient temperature, the early Nixie displays were made by a small vacuum tube manufacturer called Haydu Brothers Laboratories, and introduced in 1955 by Burroughs Corporation, who purchased Haydu. The name Nixie was derived by Burroughs from NIX I, an abbreviation of Numeric Indicator eXperimental No,1, although this may have been a backronym designed to evoke a mythical creature. Hundreds of variations of design were manufactured by many firms. The Burroughs Corporation introduced Nixie and owned the name Nixie as a trademark, nixie-like displays made by other firms had trademarked names including Digitron, Inditron and Numicator. A proper generic term is cold cathode neon readout tube, though the phrase Nixie tube quickly entered the vernacular as a generic name, Burroughs even had another Haydu tube that could operate as a digital counter and directly drive a Nixie tube for display. This was called a Trochotron, in later form known as the Beam-X Switch counter tube, another name was magnetron beam-switching tube, trochotrons were used in the UNIVAC1101 computer, as well as in clocks and frequency counters. The first trochotrons were surrounded by a cylindrical magnet, with poles at the ends. The field inside the magnet had essentially-parallel lines of force, parallel to the axis of the tube and it was a thermionic vacuum tube, inside were a central cathode, ten anodes, and ten spade electrodes. The magnetic field and voltages applied to the made the electrons form a thick sheet that went to only one anode. Applying a pulse with specified width and voltages to the made the sheet advance to the next anode. A later form of trochotron called a Beam-X Switch replaced the large, glow-transfer counting tubes, similar in essential function to the trochotrons, had a glow discharge on one of a number of main cathodes, visible through the top of the glass envelope. Sets of guide cathodes between the indicating cathodes moved the glow in steps to the main cathode. Types with two or three sets of guide cathodes could count in either direction, a well-known trade name for glow-transfer counter tubes in the United Kingdom was Dekatron. Types with connections to each individual indicating cathode, which enabled presetting the tubes state to any value, were trade named Selectron tubes, however, their construction was cruder, their average lifetime was shorter, and they failed to find many applications due to their complex periphery
12.
RCA
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RCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. General Electric took over the company in late 1985 and split it up the following year, after World War I began in August 1914, radio traffic across the Atlantic Ocean increased dramatically after the western Allies cut the German transatlantic telegraph cables. In 1917 the government of the United States took charge of the owned by the major companies involved in radio manufacture in the United States to devote radio technology to the war effort. All production of equipment was allocated to the U. S. Army, U. S. Navy, U. S. Marine Corps. The War Department and the Navy Department sought to maintain a monopoly of all uses of radio technology. The wartime takeover of all radio systems ended late in 1918, the war ended in November of that year. The ending of the governments monopoly in radio communications did not prevent the War. On 8 April 1919, naval Admiral W. H. G. Bullard, the proposal presented by the government was that if GE created an American-owned radio company, then the Army and Navy would effect a monopoly of long-distance radio communications via this company. This marked the beginning of a series of negotiations through which GE would buy the American Marconi company, the Army and the Navy granted RCA the former American Marconi radio terminals that had been confiscated during the War. Admiral Bullard received a seat on the Board of Directors of RCA for his efforts in establishing RCA, the result was federally-created monopolies in radio for GE and the Westinghouse Corporation and in telephone systems for the American Telephone & Telegraph Company. The first chief officer of RCA was Owen D. Young. RCAs incorporation papers required that a majority of its stock be held by American citizens, as the years went on, RCA either took over, or produced for itself, a large number of patents, including that of the superheterodyne receiver invented by Edwin Armstrong. Over the years, RCA continued to operate international services, under its subsidiary RCA Communications, Inc. GE used RCA as its retail arm for radio sales from 1919, Westinghouse also marketed home radios through RCA until 1930. In 1929, RCA purchased the Victor Talking Machine Company, then the worlds largest manufacturer of phonographs and this included a majority ownership of the Victor Company of Japan. The new subsidiary then became RCA Victor, with Victor, RCA acquired New World rights to the Nipper His Masters Voice trademark. This trademark is used by the British music & entertainment company HMV. RCA began selling the first electronic turntable in 1930, in 1931, RCA Victor began selling 33⅓ rpm records
