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Penthode
A pentode is an electronic device having five electrodes. The term most commonly applies to a three-grid amplifying vacuum tube or thermionic valve that was invented by Gilles Holst and Bernard Tellegen, Bernhard D.H. Tellegen in 1926. The pentode (called a ''triple-grid amplifier'' in some literature) was developed from the ''screen-grid tube'' or ''shield-grid tube'' (a type of tetrode tube) by the addition of a grid between the screen grid and the plate. The screen-grid tube was limited in performance as an amplifier due to secondary emission of electrons from the plate. The additional grid is called the ''suppressor grid''. The suppressor grid is usually operated at or near the potential of the cathode and prevents secondary emission electrons from the plate from reaching the screen grid. The addition of the suppressor grid permits much greater output signal amplitude to be obtained from the plate of the pentode in amplifier operation than from the plate of the screen-grid tube a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasitic Oscillation
Parasitic oscillation is an undesirable electronic oscillation (cyclic variation in output voltage or current) in an electronic or digital device. It is often caused by feedback in an amplifying device. The problem occurs notably in RF, audio, and other electronic amplifiers as well as in digital signal processing. It is one of the fundamental issues addressed by control theory. Parasitic oscillation is undesirable for several reasons. The oscillations may be coupled into other circuits or radiate as radio waves, causing electromagnetic interference (EMI) to other devices. In audio systems, parasitic oscillations can sometimes be heard as annoying sounds in the speakers or earphones. The oscillations waste power and may cause undesirable heating. For example, an audio power amplifier that goes into parasitic oscillation may generate enough power to damage connected speakers. A circuit that is oscillating will not amplify linearly, so desired signals passing through the stage will ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-end Audio
High-end audio is a class of consumer home audio equipment marketed to audiophiles on the basis of high price or quality, and esoteric or novel sound reproduction technologies. The term can refer simply to the price, to the build quality of the components, or to the subjective or objective quality of sound reproduction. Definition The distinction between the terms ''high end'' and '' high fidelity'' is not well defined. According to one industry commentator, high-end could be defined as, "Gear below which's price and performance one could not go without compromising the music and the sound."Szabady, Paul (January 2008)"The Rega P3-24 Turntable" ''Stereo Times''Archivedfrom the original on 21 November 2013 Harry Pearson, founder of ''The Absolute Sound'' magazine, is widely acknowledged to have coined the term ''high-end audio''. Costs High-end audio equipment can be extremely expensive. It is sometimes referred to as ''cost-no-object'' equipment. Audiophile equipment can en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valve Sound
Tube sound (or valve sound) is the characteristic sound associated with a vacuum tube amplifier (valve amplifier in British English), a vacuum tube-based audio amplifier. At first, the concept of ''tube sound'' did not exist, because practically all electronic amplification of audio signals was done with vacuum tubes and other comparable methods were not known or used. After introduction of solid state amplifiers, tube sound appeared as the logical complement of transistor sound, which had some negative connotations due to crossover distortion in early transistor amplifiers. However, solid state amplifiers have been developed to be flawless and the sound is later regarded neutral compared to tube amplifiers. Thus the tube sound now means 'euphonic distortion.' The audible significance of tube amplification on audio signals is a subject of continuing debate among audio enthusiasts. (also found in ) Many electric guitar, electric bass, and keyboard players in several genres also pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
7AK7
The 7AK7 is a pentode vacuum tube (thermionic valve). According to its manufacturer, Sylvania, it was "designed for service in electronic computers". The tube was developed in 1948, designed at the request of L. D. Wilson for use in the Whirlwind A whirlwind is a weather phenomenon in which a vortex of wind (a vertically oriented rotating column of air) forms due to instabilities and turbulence created by heating and flow (current) gradients. Whirlwinds occur all over the world and ... computer. Significant attention was directed towards its manufacturing process in order to ensure the part's reliability. Dubbed the "computer tube", it became the standard tube for all computers into the late 1950s. See also * 25L6, another type of tube found in early computers References {{comp-hardware-stub Vacuum tubes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Manchester Baby
The Manchester Baby, also called the Small-Scale Experimental Machine (SSEM), was the first electronic stored-program computer. It was built at the University of Manchester by Frederic Calland Williams, Frederic C. Williams, Tom Kilburn, and Geoff Tootill, and ran its first program on 21 June 1948. The Baby was not intended to be a practical computing engine, but was instead designed as a testbed for the Williams tube, the first truly random-access memory. Described as "small and primitive" 50 years after its creation, it was the first working machine to contain all the elements essential to a modern electronic digital computer. As soon as the Baby had demonstrated the feasibility of its design, a project was initiated at the university to develop it into a full scale operational machine, the . The Mark 1 in turn quickly became the prototype for the Ferranti Mark 1, the world's first commercially available general-purpose computer. The Baby had a 32-bit Word (computer architect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colossus Computer
Colossus was a set of computers developed by British codebreakers in the years 1943–1945 to help in the cryptanalysis of the Lorenz cipher. Colossus used thermionic valves (vacuum tubes) to perform Boolean and counting operations. Colossus is thus regarded as the world's first programmable, electronic, digital computer, although it was programmed by switches and plugs and not by a stored program. Colossus was designed by General Post Office (GPO) research telephone engineer Tommy Flowers to solve a problem posed by mathematician Max Newman at the Government Code and Cypher School (GC&CS) at Bletchley Park. Alan Turing's use of probability in cryptanalysis (see Banburismus) contributed to its design. It has sometimes been erroneously stated that Turing designed Colossus to aid the cryptanalysis of the Enigma. (Turing's machine that helped decode Enigma was the electromechanical Bombe, not Colossus.) The prototype, Colossus Mark 1, was shown to be working in December 1943 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving information about the objects' locations and speeds. Radar was developed secretly for military use by several countries in the period before and during World War II. A key development was the cavity magnetron in the United Kingdom, which allowed the creation of relatively small systems with sub-meter resolution. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EF50
In the field of electronics, the EF50 is an early all-glass wideband remote cutoff pentode designed in 1938 by Philips. It was a landmark in the development of vacuum tube technology, departing from construction ideas of the time essentially unchanged from light bulb designs. Initially used in television receivers, it quickly gained a vital role in British radar and great efforts were made to secure a continuing supply of the device as Holland fell in World War II. The EF50 tube is a 9-pin Loctal-socket device with short internal wires to nine short chromium-iron pins, making it suitable for Very High Frequency (VHF) use. History The EF50 was preceded by RCA's acorn design and several other attempts, such as the "Stahlröhre" (~steel tube) from Telefunken, to reduce inductance in the wire leads, all with some disadvantages. Philips had been working since 1934–1935 on an alternative that would solve the problems of the other bases, and a design that could be produced cheaply a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
12AE10CompactronTube
1 (one, unit, unity) is a number representing a single or the only entity. 1 is also a numerical digit and represents a single unit of counting or measurement. For example, a line segment of ''unit length'' is a line segment of length 1. In conventions of sign where zero is considered neither positive nor negative, 1 is the first and smallest positive integer. It is also sometimes considered the first of the infinite sequence of natural numbers, followed by 2, although by other definitions 1 is the second natural number, following 0. The fundamental mathematical property of 1 is to be a multiplicative identity, meaning that any number multiplied by 1 equals the same number. Most if not all properties of 1 can be deduced from this. In advanced mathematics, a multiplicative identity is often denoted 1, even if it is not a number. 1 is by convention not considered a prime number; this was not universally accepted until the mid-20th century. Additionally, 1 is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power-law
In statistics, a power law is a functional relationship between two quantities, where a relative change in one quantity results in a proportional relative change in the other quantity, independent of the initial size of those quantities: one quantity varies as a power of another. For instance, considering the area of a square in terms of the length of its side, if the length is doubled, the area is multiplied by a factor of four. Empirical examples The distributions of a wide variety of physical, biological, and man-made phenomena approximately follow a power law over a wide range of magnitudes: these include the sizes of craters on the moon and of solar flares, the foraging pattern of various species, the sizes of activity patterns of neuronal populations, the frequencies of words in most languages, frequencies of family names, the species richness in clades of organisms, the sizes of power outages, volcanic eruptions, human judgments of stimulus intensity and many other quantit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Negative Feedback
Negative feedback (or balancing feedback) occurs when some function (Mathematics), function of the output of a system, process, or mechanism is feedback, fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by other disturbances. Whereas positive feedback tends to lead to instability via exponential growth, oscillation or chaos theory, chaotic behavior, negative feedback generally promotes stability. Negative feedback tends to promote a settling to List of types of equilibrium, equilibrium, and reduces the effects of perturbations. Negative feedback loops in which just the right amount of correction is applied with optimum timing can be very stable, accurate, and responsive. Negative feedback is widely used in mechanical and electronic engineering, and also within living organisms, and can be seen in many other fields from chemistry and economics to physical systems such as the climate. General negative feedback ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
