Instruct: Given a question, retrieve documents that answer the question.
Query: Who developed the capacitor?
Since capacitors' energy content increases with the square of the voltage, researchers were looking for a way to increase the electrolyte's breakdown voltage. In 1994 using the anode of a 200V high voltage tantalum electrolytic capacitor, David A. Evans developed an "Electrolytic-Hybrid Electrochemical Capacitor". These capacitors combine features of electrolytic and electrochemical capacitors. They combine the high dielectric strength of an anode from an electrolytic capacitor with the high capacitance of a pseudocapacitive metal oxide (ruthenium (IV) oxide) cathode from an electrochemical capacitor, yielding a hybrid electrochemical capacitor. Evans' capacitors, coined Capattery, had an energy content about a factor of 5 higher than a comparable tantalum electrolytic capacitor of the same size. Their high costs limited them to specific military applications.
Capacitors, together with resistors, and inductors, belong to the group of "passive components" used in electronic equipment. Although, in absolute figures, the most common capacitors are integrated capacitors (e.g. in DRAMs or flash memory structures), this article is concentrated on the various styles of capacitors as discrete components.
Industrial espionage was implicated in the capacitor plague, in connection with the theft of an electrolyte formula. A materials scientist working for Rubycon in Japan left the company, taking the secret water-based electrolyte formula for Rubycon's ZA and ZL series capacitors, and began working for a Chinese company. The scientist then developed a copy of this electrolyte. Then, some staff members who defected from the Chinese company copied an incomplete version of the formula and began to market it to many of the aluminium electrolytic manufacturers in Taiwan, undercutting the prices of the Japanese manufacturers. This incomplete electrolyte lacked important proprietary ingredients which were essential to the long-term stability of the capacitors and was unstable when packaged in a finished aluminum capacitor. This faulty electrolyte allowed the unimpeded formation of hydroxide and produced hydrogen gas.
Large capacitor banks (reservoirs) are used as energy sources for the exploding-bridgewire detonators or slapper detonators in nuclear weapons and other specialty weapons. Experimental work is under way using banks of capacitors as power sources for electromagnetic armour and electromagnetic railguns or coilguns.
An electrostatic generator, or electrostatic machine, is an electromechanical generator that produces "static electricity", or electricity at high voltage and low continuous current. The knowledge of static electricity dates back to the earliest civilizations, but for millennia it remained merely an interesting and mystifying phenomenon, without a theory to explain its behavior and often confused with magnetism. By the end of the 17th century, researchers had developed practical means of generating electricity by friction, but the development of electrostatic machines did not begin in earnest until the 18th century, when they became fundamental instruments in the studies about the new science of electricity. Electrostatic generators operate by using manual (or other) power to transform mechanical work into electric energy. Electrostatic generators develop electrostatic charges of opposite signs rendered to two conductors, using only electric forces, and work by using moving plates, drums, or belts to carry electric charge to a high potential electrode. The charge is generated by one of two methods: either the triboelectric effect (friction) or electrostatic induction.
Capacitors may catastrophically fail when subjected to voltages or currents beyond their rating, or as they reach their normal end of life. Dielectric or metal interconnection failures may create arcing that vaporizes the dielectric fluid, resulting in case bulging, rupture, or even an explosion. Capacitors used in RF or sustained high-current applications can overheat, especially in the center of the capacitor rolls. Capacitors used within high-energy capacitor banks can violently explode when a short in one capacitor causes sudden dumping of energy stored in the rest of the bank into the failing unit. High voltage vacuum capacitors can generate soft X-rays even during normal operation. Proper containment, fusing, and preventive maintenance can help to minimize these hazards.
When the capacitor is discharging, the strength of the electric field is decreasing and the common orientation of the molecular dipoles is returning to an undirected state in a process of relaxation. Due to the hysteresis, at the zero point of the electric field, a material-dependent number of molecular dipoles are still polarized along the field direction without a measurable voltage appearing at the terminals of the capacitor. This is like an electrical remanence. The oriented dipoles will be discharged spontaneously over time and the voltage at the electrodes of the capacitor will decay exponentially. The complete discharge time of all dipoles can be days to weeks depending on the material. This "reloaded" voltage can be retained for months, even in electrolytic capacitors, caused by the high insulation resistance in common modern capacitor dielectrics. The discharge of a capacitor and the subsequent reloading can be repeated several times.
Capacitors (often referred to as "caps") have several uses in electric guitars, the most common of which is in the tone control, where it combines with the potentiometer to form a low-pass filter, shorting all frequencies above the adjustable cut-off frequency to ground. Another common use is a small capacitor in parallel with the volume control, to prevent the loss of higher frequencies as the volume pot is turned down. This capacitor is commonly known as "treble bleed cap" and is sometimes accompanied by a series or parallel resistor to limit the amount of treble being retained and match it to the pot's taper.
A vacuum variable capacitor is a variable capacitor which uses a high vacuum as the dielectric instead of air or other insulating material. This allows for a higher voltage rating than an air dielectric using a smaller total volume. However, many dielectrics have higher breakdown field strengths than vacuum: 60-170 MV/m for teflon, 470-670 MV/m for fused silica and 2000 MV/m for diamond, compared with 20-40 MV/m for vacuum. There are several different designs in vacuum variables. The most common form is inter-meshed concentric cylinders, which are contained within a glass or ceramic vacuum envelope, similar to an electron tube. A metal bellows is used to maintain a vacuum seal while allowing positional control for the moving parts of the capacitor.
The basic components needed for the exploding wire method are a thin conductive wire and a capacitor. The wire is typically gold, aluminum, iron or platinum, and is usually less than 0.5 mm in diameter. The capacitor has an energy consumption of about 25 kWh/kg and discharges a pulse of charge density 10 - 10 A/mm, leading to temperatures up to 100,000 K. The phenomenon occurs over a time period of only 10 - 10 seconds.
High-voltage capacitors may catastrophically fail when subjected to voltages or currents beyond their rating, or as they reach their normal end of life. Dielectric or metal interconnection failures may create arcing that vaporizes dielectric fluid, resulting in case bulging, rupture, or even an explosion. Capacitors used in RF or sustained high-current applications can overheat, especially in the center of the capacitor rolls. Capacitors used within high-energy capacitor banks can violently explode when a short in one capacitor causes sudden dumping of energy stored in the rest of the bank into the failing unit. High voltage vacuum capacitors can generate soft X-rays even during normal operation. Proper containment, fusing, and preventive maintenance can help to minimize these hazards.
At the beginning of the 1990s, some Japanese manufacturers started the development of a new, low-ohmic water-based class of electrolytes. Water, with its high permittivity of ε = 81, is a powerful solvent for electrolytes, and possesses high solubility for conductivity-enhancing concentrations of salt ions, resulting in significantly improved conductivity compared to electrolytes with organic solvents like GBL. But water will react quite aggressively and even violently with unprotected aluminum, converting metallic aluminum (Al) into aluminum hydroxide (Al(OH)), via a highly exothermic reaction that gives off heat, causing gas expansion that can lead to an explosion of the capacitor. Therefore, the main problem in the development of water-based electrolytes is achieving long-term stability by hindering the corrosive action of water on aluminum.
The carbon microphone was independently developed around 1878 by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, and most historians credit him with its invention.
The development of thermionic valves starting around 1902, provided an entirely electronic method of amplifying signals. The first practical version of such devices was the Audion triode, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. Since the only previous device which was widely used to strengthen a signal was the relay used in telegraph systems, the amplifying vacuum tube was first called an "electron relay". The terms "amplifier" and "amplification", derived from the Latin "amplificare", ("to enlarge or expand"), were first used for this new capability around 1915 when triodes became widespread.
In 1874, German scientist Karl Ferdinand Braun discovered the "unilateral conduction" across a contact between a metal and a mineral. Indian scientist Jagadish Chandra Bose was the first to use a crystal for detecting radio waves in 1894. The crystal detector was developed into a practical device for wireless telegraphy by Greenleaf Whittier Pickard, who invented a silicon crystal detector in 1903 and received a patent for it on November 20, 1906. Other experimenters tried a variety of other minerals as detectors. Semiconductor principles were unknown to the developers of these early rectifiers. During the 1930s understanding of physics advanced and in the mid 1930s researchers at Bell Telephone Laboratories recognized the potential of the crystal detector for application in microwave technology. Researchers at Bell Labs, Western Electric, MIT, Purdue and in the UK intensively developed point-contact diodes ("crystal rectifiers" or "crystal diodes") during World War II for application in radar. After World War II, AT&T used these in their microwave towers that criss-crossed the United States, and many radar sets use them even in the 21st century. In 1946, Sylvania began offering the 1N34 crystal diode. During the early 1950s, junction diodes were developed.
The first widely used solid-state negative resistance device was the tunnel diode, invented in 1957 by Japanese physicist Leo Esaki. Because they have lower parasitic capacitance than vacuum tubes due to their small junction size, diodes can function at higher frequencies, and tunnel diode oscillators proved able to produce power at microwave frequencies, above the range of ordinary vacuum tube oscillators. Its invention set off a search for other negative resistance semiconductor devices for use as microwave oscillators, resulting in the discovery of the IMPATT diode, Gunn diode, TRAPATT diode, and others. In 1969 Kurokawa derived conditions for stability in negative resistance circuits. Currently negative differential resistance diode oscillators are the most widely used sources of microwave energy, and many new negative resistance devices have been discovered in recent decades.
The first person to use resonant circuits in a radio application was Nikola Tesla, who invented the resonant transformer in 1891. At a March 1893 St. Louis lecture he had demonstrated a wireless system that, although it was intended for wireless power transmission, had many of the elements of later radio communication systems. A grounded capacitance-loaded spark-excited resonant transformer (his "Tesla coil") attached to an elevated wire monopole antenna transmitted radio waves, which were received across the room by a similar wire antenna attached to a receiver consisting of a second grounded resonant transformer tuned to the transmitter's frequency, which lighted a Geissler tube. This system, patented by Tesla 2 September 1897, 4 months after Lodge's "syntonic" patent, was in effect an inductively coupled radio transmitter and receiver, the first use of the "four circuit" system claimed by Marconi in his 1900 patent "(below)". However, Tesla was mainly interested in wireless power and never developed a practical radio "communication" system.
The first microphone that enabled proper voice telephony was the (loose-contact) carbon microphone (then called transmitter). This was independently developed around 1878 by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, and most historians credit him with its invention.
German inventor Johann Philipp Reis designed an early sound transmitter that used a metallic strip attached to a vibrating membrane that would produce intermittent current. Better results were achieved with the "liquid transmitter" design in Scottish-American Alexander Graham Bell's telephone of 1876 – the diaphragm was attached to a conductive rod in an acid solution. These systems, however, gave a very poor sound quality.
The first microphone that enabled proper voice telephony was the (loose-contact) carbon microphone. This was independently developed by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent (after a long legal dispute) in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, and most historians credit him with its invention. The carbon microphone is the direct prototype of today's microphones and was critical in the development of telephony, broadcasting and the recording industries. Thomas Edison refined the carbon microphone into his carbon-button transmitter of 1886. This microphone was employed at the first ever radio broadcast, a performance at the New York Metropolitan Opera House in 1910.
In 1916, E.C. Wente of Western Electric developed the next breakthrough with the first condenser microphone. In 1923, the first practical moving coil microphone was built. The Marconi-Sykes magnetophone, developed by Captain H. J. Round, became the standard for BBC studios in London. This was improved in 1930 by Alan Blumlein and Herbert Holman who released the HB1A and was the best standard of the day.
The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. Julius Edgar Lilienfeld patented a field-effect transistor in 1926 but it was not possible to actually construct a working device at that time. The first practically implemented device was a point-contact transistor invented in 1947 by American physicists John Bardeen, Walter Brattain, and William Shockley. The transistor revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other things. The transistor is on the list of IEEE milestones in electronics, and Bardeen, Brattain, and Shockley shared the 1956 Nobel Prize in Physics for their achievement.
Electric sound recording and reproduction are electrical or mechanical techniques and devices for the inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. Acoustic analog recording is achieved by a small microphone diaphragm that can record sound waves on a phonograph (in which a stylus senses grooves on a record) or magnetic tape. The first practical sound recording and reproduction device was the mechanical phonograph cylinder, invented by Thomas Edison in 1877 and patented in 1878. 
The next major technical development was the invention of the gramophone disc in 1889. For much of the 20th century, records were the most common way of selling sound recordings. The widespread availability of records and the development of radio broadcasting enabled a much larger proportion of people to listen to songs and pieces performed by the top artists, enabling the development of national and even international musical stars. In the 1970s, the compact cassette became a major consumer audio format. Advances in electronic and mechanical miniaturization led to the development of the Sony Walkman, a pocket-sized cassette player introduced in 1979, which allowed consumers to listen to their favourite albums outside of their home.
The capacitor is a development of the Leyden jar and is a device that can store charge, and thereby storing electrical energy in the resulting field. It consists of two conducting plates separated by a thin insulating dielectric layer; in practice, thin metal foils are coiled together, increasing the surface area per unit volume and therefore the capacitance. The unit of capacitance is the farad, named after Michael Faraday, and given the symbol "F": one farad is the capacitance that develops a potential difference of one volt when it stores a charge of one coulomb. A capacitor connected to a voltage supply initially causes a current as it accumulates charge; this current will however decay in time as the capacitor fills, eventually falling to zero. A capacitor will therefore not permit a steady state current, but instead blocks it.
The "film capacitors" were developed together with the growing market of broadcast and electronic equipment technology in the mid-20th century. These capacitors are standardized under the rules of IEC/EN 60384-1 “Capacitors for use in electronic equipment” and different "film materials" have their own sub standards, the IEC/EN 60384-"n" series. The "power capacitors" begin at a power handling capacity of approximately 200 volt-amps, such as for ballast capacitors in fluorescent lamps. The standardization of power capacitors follows the rules of IEC/EN 61071 and IEC/EN 60143-1, and have for various different applications their own sub standards, such as for railway applications.
With the development of plastic materials by organic chemists during the Second World War, the capacitor industry began to replace paper with thinner polymer films. One very early development in film capacitors was described in British Patent 587,953 in 1944. The introduction of plastics in plastic film capacitors was approximately in the following historic order: polystyrene (PS) in 1949, polyethylene terephthalate (PET/"polyester") and cellulose acetate (CA) in 1951, polycarbonate (PC/Lexan) in 1953, polytetrafluoroethylene (PTFE/Teflon) in 1954, polyparylene in 1954, polypropylene (PP) in 1954, polyethylene (PE) in 1958, and polyphenylene sulphide (PPS) in 1967. By the mid-1960s there was a wide range of different plastic film capacitors offered by many, mostly European and US manufacturers. German manufacturers such as WIMA, Roederstein, Siemens and Philips were trend-setters and leaders in a world market driven by consumer electronics.
The easy-to-mold ceramic material facilitated the development of special and large styles of ceramic capacitors for high-voltage, high-frequency (RF) and power applications.
With the development of semiconductor technology in the 1950s, barrier layer capacitors, or IEC class 3/EIA class IV capacitors, were developed using doped ferroelectric ceramics. Because this doped material was not suitable to produce multilayers, they were replaced decades later by Y5V class 2 capacitors.