"mercury. This was the fluorescent lamp, which is now one of the most widely used lamps in the world. In 1902 Hewitt developed the mercury arc rectifier, the first rectifier that could convert alternating current power to direct current without mechanical means. It was widely used in electric railways, industry, electroplating, and high-voltage direct current (HVDC) power transmission. Although it was largely replaced by power semiconductor devices in the 1970s and 1980s, it is still used in some high power applications. In 1903, the degree of Honorary Doctorate of Science was conferred upon him by the Columbia University in recognition"
"provide power for industrial motors, electric railways, streetcars, and electric locomotives, as well as for radio transmitters and for high-voltage direct current (HVDC) power transmission. They were the primary method of high power rectification before the advent of semiconductor rectifiers, such as diodes, thyristors and gate turn-off thyristors (GTOs) in the 1970s. These solid state rectifiers have since completely replaced mercury-arc rectifiers thanks to their higher reliability, lower cost and maintenance and lower environmental risk. In 1882 Jemin and Meneuvrier observed the rectifying properties of a mercury arc. The mercury arc rectifier was invented by Peter Cooper Hewitt in 1902"
"Fleming valve The Fleming valve, also called the Fleming oscillation valve, was a thermionic valve or vacuum tube invented in 1904 by Englishman John Ambrose Fleming as a detector for early radio receivers used in electromagnetic wireless telegraphy. It was the first practical vacuum tube and the first thermionic diode, a vacuum tube whose purpose is to conduct current in one direction and block current flowing in the opposite direction. The thermionic diode was later widely used as a rectifier — a device which converts alternating current (AC) into direct current (DC) — in the power supplies of a wide"
"Frankenstein movies mercury arc rectifiers are shown . Mercury-arc valve A mercury-arc valve or mercury-vapor rectifier or (UK) mercury-arc rectifier is a type of electrical rectifier used for converting high-voltage or high-current alternating current (AC) into direct current (DC). It is a type of cold cathode gas-filled tube, but is unusual in that the cathode, instead of being solid, is made from a pool of liquid mercury and is therefore self-restoring. As a result, mercury-arc valves were much more rugged and long-lasting, and could carry much higher currents than most other types of gas discharge tube. Invented in 1902 by"
"the primary current. The largest coils used either electrolytic or mercury turbine interrupters. The electrolytic or Wehnelt interrupter, invented by Arthur Wehnelt in 1899, consisted of a short platinum needle anode immersed in an electrolyte of dilute sulfuric acid, with the other side of the circuit connected to a lead plate cathode. When the primary current passed through it, hydrogen gas bubbles formed on the needle which repeatedly broke the circuit. This resulted in a primary current broken randomly at rates up to 2000 breaks per second. They were preferred for powering X-ray tubes. They produced a lot of heat"
"for such as the detection of light levels. In both types, the electrons are accelerated from the cathode to the anode by the electric field in the tube. The simplest vacuum tube, the diode invented in 1904 by John Ambrose Fleming, contains only a heated electron-emitting cathode and an anode. Current can only flow in one direction through the device -- from the cathode to the anode. Adding one or more control grids within the tube allows the current between the cathode and anode to be controlled by the voltage on the grid or grids. These devices became a key"
"the DC system of Thomas Edison and the AC system of George Westinghouse. Practical conversion of power between AC and DC became possible with the development of power electronics devices such as mercury-arc valves and, starting in the 1970s, semiconductor devices as thyristors, integrated gate-commutated thyristors (IGCTs), MOS-controlled thyristors (MCTs) and insulated-gate bipolar transistors (IGBT). The first long-distance transmission of electric power was demonstrated using direct current in 1882 at Miesbach-Munich Power Transmission, but only 1.5 kW was transmitted. An early method of high-voltage DC transmission was developed by the Swiss engineer René Thury and his method was put into"
"was invented in 1904 by the English physicist John Ambrose Fleming. He developed a device he called an ""oscillation valve"" (because it passes current in only one direction). The heated filament, or cathode, was capable of thermionic emission of electrons that would flow to the ""plate"" (or ""anode"") when it was at a higher voltage. Electrons, however, could not pass in the reverse direction because the plate was not heated and thus not capable of thermionic emission of electrons. Later known as the Fleming valve, it could be used as a rectifier of alternating current and as a radio wave"
"Since current can only pass in one direction, such a diode (or ""rectifier"") will convert alternating current (AC) to pulsating DC. Diodes can therefore be used in a DC power supply, as a demodulator of amplitude modulated (AM) radio signals and for similar functions. Early tubes used the filament as the cathode; this is called a ""directly heated"" tube. Most modern tubes are ""indirectly heated"" by a ""heater"" element inside a metal tube that is the cathode. The heater is electrically isolated from the surrounding cathode and simply serves to heat the cathode sufficiently for thermionic emission of electrons. The"
"Although all diodes ""rectify"", the term ""rectifier"" is usually applied to diodes intended for power supply application in order to differentiate them from diodes intended for small signal circuits. A thermionic diode is a thermionic-valve device consisting of a sealed, evacuated glass or metal envelope containing two electrodes: a cathode and a plate. The cathode is either ""indirectly heated"" or ""directly heated"". If indirect heating is employed, a heater is included in the envelope. In operation, the cathode is heated to red heat (800–1000 °C). A directly heated cathode is made of tungsten wire and is heated by current passed"
"application occurred around 1900, when the cat's whisker rectifiers were used in receivers. They consisted of pointed tungsten wire (in the shape of a cat's whisker) whose tip or point was pressed against the surface of a galena (lead sulfide) crystal. The first large area rectifier appeared around 1926 which consisted of a copper(I) oxide semiconductor thermally grown on a copper substrate. Subsequently, selenium films were evaporated onto large metal substrates to form the rectifying diodes. These selenium rectifiers were used (and are still used) to convert alternating current to direct current in electrical power applications. During 1925–1940, diodes consisting"
"thermionic valves. The simplest valve was invented by John Ambrose Fleming while working for the Marconi Company in London in 1904 and named the diode, as it had two electrodes. The diode conducted electricity in one direction only and was used as a radio detector and a rectifier. In 1906 Lee De Forest added a third electrode and invented the first electronic amplifying device, the triode, which he named the ""Audion"". This additional ""control grid"" modulates the current that flows between cathode and anode. The relationship between current flow and plate and grid voltage is often represented as a series"
"Peter Cooper Hewitt Hewitt was born in New York City, the son of New York City Mayor Abram Hewitt and the grandson of industrialist Peter Cooper. He was educated at the Stevens Institute of Technology and the Columbia University School of Mines. In 1901 he invented and patented a mercury-vapor lamp; a gas-discharge lamp that used mercury vapor produced by passing current through liquid mercury. His first lamps had to be started by tilting the tube to make contact between the two electrodes and the liquid mercury; later he developed the inductive electrical ballast to start the tube. The efficiency"
"Power electronics Power electronics is the application of solid-state electronics to the control and conversion of electric power. The first high power electronic devices were mercury-arc valves. In modern systems the conversion is performed with semiconductor switching devices such as diodes, thyristors and transistors, pioneered by R. D. Middlebrook and others beginning in the 1950s. In contrast to electronic systems concerned with transmission and processing of signals and data, in power electronics substantial amounts of electrical energy are processed. An AC/DC converter (rectifier) is the most typical power electronics device found in many consumer electronic devices, e.g. television sets, personal"
"amplification that could easily have the thermionic diodes included in the tube (for example the 12SQ7 double diode triode), and vacuum-tube rectifiers and gas-filled rectifiers were capable of handling some high-voltage/high-current rectification tasks better than the semiconductor diodes (such as selenium rectifiers) that were available at that time. In 1873, Frederick Guthrie observed that a grounded, white hot metal ball brought in close proximity to an electroscope would discharge a positively charged electroscope, but not a negatively charged electroscope. In 1880, Thomas Edison observed unidirectional current between heated and unheated elements in a bulb, later called Edison effect, and was"
"electronic device was the cat's whisker detector, a crude semiconductor diode invented around 1904, solid state electronics really started with the invention of the transistor in 1947. Before that, all electronic equipment used vacuum tubes, because vacuum tubes were the only electronic components that could ""amplify"", an essential capability in all electronics. The replacement of bulky, fragile, energy-wasting vacuum tubes by transistors in the 1960s and 1970s created a revolution not just in technology but in people's habits, making possible the first truly portable consumer electronics such as the transistor radio, cassette tape player, walkie-talkie and quartz watch, as well"
"gas-filled tube device called a thyratron provided a similar electronic switching capability, where a small control voltage could switch a large current. It is from a combination of ""thyratron"" and ""transistor"" that the term ""thyristor"" is derived. Thyristors are mainly used where high currents and voltages are involved, and are often used to control alternating currents, where the change of polarity of the current causes the device to switch off automatically, referred to as ""zero cross"" operation. The device can be said to operate ""synchronously""; being that, once the device is triggered, it conducts current in phase with the voltage"
"resistance made it inefficient in low voltage, high current applications. Until vacuum tube equipment was replaced by transistors in the 1970s, radios and televisions usually had one or more diode tubes. Fleming valve The Fleming valve, also called the Fleming oscillation valve, was a thermionic valve or vacuum tube invented in 1904 by Englishman John Ambrose Fleming as a detector for early radio receivers used in electromagnetic wireless telegraphy. It was the first practical vacuum tube and the first thermionic diode, a vacuum tube whose purpose is to conduct current in one direction and block current flowing in the opposite"
"used. With the introduction of semiconductor electronics, vacuum tube rectifiers became obsolete, except for some enthusiasts of vacuum tube audio equipment. For power rectification from very low to very high current, semiconductor diodes of various types (junction diodes, Schottky diodes, etc.) are widely used. Other devices that have control electrodes as well as acting as unidirectional current valves are used where more than simple rectification is required—e.g., where variable output voltage is needed. High-power rectifiers, such as those used in high-voltage direct current power transmission, employ silicon semiconductor devices of various types. These are thyristors or other controlled switching solid-state"
"replacement thyristor converters. Since 1977, new HVDC systems have used only solid-state devices, in most cases thyristor valves. Like mercury arc valves, thyristors require connection to an external AC circuit in HVDC applications to turn them on and off. HVDC using thyristor valves is also known as Line-Commutated Converter (LCC) HVDC. Development of thyristor valves for HVDC began in the late 1960s. The first complete HVDC scheme based on thyristor valves was the Eel River scheme in Canada, which was built by General Electric and went into service in 1972. On March 15, 1979, a 1920 MW thyristor based direct"
"solution. These experiments led directly to Faraday's two laws of electrochemistry which state: William Sturgeon built an electric motor in 1832 and invented the commutator, a ring of metal-bristled brushes which allow the spinning armature to maintain contact with the electric current and changed the alternating current to a pulsating direct current. He also improved the voltaic battery and worked on the theory of thermoelectricity. Hippolyte Pixii, a French instrument maker, constructed the first dynamo in 1832 and later built a direct current dynamo using the commutator. This was the first practical mechanical generator of electric current that used concepts"
"was a mercury vapor (ex.:5B24) or argon (ex.:328) gas-filled electron tube device with a tungsten filament cathode and a carbon button anode. It operated similarly to the thermionic vacuum tube diode, but the gas in the tube ionized during forward conduction, giving it a much lower forward voltage drop so it could rectify lower voltages. It was used for battery chargers and similar applications from the 1920s until lower-cost metal rectifiers, and later semiconductor diodes, supplanted it. These were made up to a few hundred volts and a few amperes rating, and in some sizes strongly resembled an incandescent lamp"
"granted a patent on application of the phenomenon for use in a dc voltmeter. About 20 years later, John Ambrose Fleming (scientific adviser to the Marconi Company and former Edison employee) realized that the Edison effect could be used as a radio detector. Fleming patented the first true thermionic diode, the Fleming valve, in Britain on November 16, 1904 (followed by in November 1905). Throughout the vacuum tube era, valve diodes were used in almost all electronics such as radios, televisions, sound systems and instrumentation. They slowly lost market share beginning in the late 1940s due to selenium rectifier technology"
"the Edison Effect could be used to detect radio waves. Fleming went on to develop the two-element vacuum tube known as the diode, which he patented on November 16, 1904. After further investivation while working for the Marconi Wireless Telegraph Co., Ltd., Fleming patented the Fleming Valve rectifier in 1904, resulting in the electron tube becoming the basis of modern electronics. William Joseph Hammer William Joseph Hammer (February 26, 1858 – March 24, 1934) was an American pioneer electrical engineer and aviator and he was president of the Edison Pioneers starting in 1908. He was a winner of the Elliott"
"Fleming valve, was invented by John Ambrose Fleming in 1904 as a detector for radio waves in radio receivers, and evolved into a general rectifier. It consisted of an evacuated glass bulb with a filament heated by a separate current, and a metal plate anode. The filament emitted electrons by thermionic emission (the Edison effect), discovered by Thomas Edison in 1884, and a positive voltage on the plate caused a current of electrons through the tube from filament to plate. Since only the filament produced electrons, the tube would only conduct current in one direction, allowing the tube to rectify"
"discovery of asymmetric electrical conduction across the contact between a crystalline mineral and a metal was made by German physicist Ferdinand Braun in 1874. Today, most diodes are made of silicon, but other materials such as gallium arsenide and germanium are used. The most common function of a diode is to allow an electric current to pass in one direction (called the diode's ""forward"" direction), while blocking it in the opposite direction (the ""reverse"" direction). As such, the diode can be viewed as an electronic version of a check valve. This unidirectional behavior is called rectification, and is used to"
"diodes have an inherent advantage over silicon diodes in low voltage circuits. In high-power applications, from 1975 to 2000, most mercury valve arc-rectifiers were replaced by stacks of very high power thyristors, silicon devices with two extra layers of semiconductor, in comparison to a simple diode. In medium-power transmission applications, even more complex and sophisticated voltage sourced converter (VSC) silicon semiconductor rectifier systems, such as insulated gate bipolar transistors (IGBT) and gate turn-off thyristors (GTO), have made smaller high voltage DC power transmission systems economical. All of these devices function as rectifiers. A major area of research is to develop"
"From the 1920s on, research continued on applying thyratrons and grid-controlled mercury arc valves to power transmission. Uno Lamm developed a mercury valve with grading electrodes making them suitable for high voltage direct current power transmission. In 1933 selenium rectifiers were invented. In 1947 the bipolar point-contact transistor was invented by Walter H. Brattain and John Bardeen under the direction of William Shockley at Bell Labs. In 1948 Shockley's invention of the bipolar junction transistor (BJT) improved the stability and performance of transistors, and reduced costs. By the 1950s, higher power semiconductor diodes became available and started replacing vacuum tubes."
"stability of the power system. Alternating current generating systems were known in simple forms from Michael Faraday's original discovery of the magnetic induction of electric current. Faraday himself built an early alternator. His machine was a ""rotating rectangle"", whose operation was ""heteropolar"" - each active conductor passed successively through regions where the magnetic field was in opposite directions. Large two-phase alternating current generators were built by a British electrician, J.E.H. Gordon, in 1882. The first public demonstration of an ""alternator system"" was given by William Stanley, Jr., an employee of Westinghouse Electric in 1886. Sebastian Ziani de Ferranti established ""Ferranti,"
"type of ""switch"" where contacts on the shaft work with ""brush"" contacts to produce direct current. The late 1870s and early 1880s saw electricity starting to be generated at power stations. These were initially set up to power arc lighting (a popular type of street lighting) running on very high voltage (usually higher than 3000 volt) direct current or alternating current. This was followed by the wide spread use of low voltage direct current for indoor electric lighting in business and homes after inventor Thomas Edison launched his incandescent bulb based electric ""utility"" in 1882. Because of the significant advantages"
"dynamo in 1861 (before Siemens and Wheatstone) but didn't patent it as he thought he wasn't the first to realize this. A coil of wire rotating in a magnetic field produces a current which changes direction with each 180° rotation, an alternating current (AC). However many early uses of electricity required direct current (DC). In the first practical electric generators, called ""dynamos"", the AC was converted into DC with a ""commutator"", a set of rotating switch contacts on the armature shaft. The commutator reversed the connection of the armature winding to the circuit every 180° rotation of the shaft, creating"
"the introduction of the more reliable and amplified vacuum tube based radios, the cat's whisker systems quickly disappeared. The ""cat's whisker"" is a primitive example of a special type of diode still popular today, called a Schottky diode. Another early type of semiconductor device is the metal rectifier in which the semiconductor is copper oxide or selenium. Westinghouse Electric (1886) was a major manufacturer of these rectifiers. During World War II, radar research quickly pushed radar receivers to operate at ever higher frequencies and the traditional tube based radio receivers no longer worked well. The introduction of the cavity magnetron"
"experimental high voltage direct current (HVDC) line using mercury arc valves was built between Schenectady and Mechanicville, New York. HVDC had previously been achieved by series-connected direct current generators and motors (the Thury system) although this suffered from serious reliability issues. The first solid-state metal diode suitable for general power uses was developed by Ernst Presser at TeKaDe, Germany, in 1928. It consisted of a layer of selenium applied on an aluminum plate. In 1957, a General Electric research group developed a solid-state p-n-p-n switch device that was successfully marketed in early 1958, starting a revolution in power electronics. In"