Electronics has hugely influenced the development of modern society. The central driving force behind the entire electronics industry is the semiconductor industry sector, which has annual sales of over $481 billion as of 2018. The largest industry sector is e-commerce, which generated over $29 trillion in 2017. (Full article...)
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The Linn Isobarik DMS (with in-built crossover) in a domestic setting
The Linn Isobarik, nicknamed "Bariks" or "Briks", is a loudspeaker designed and manufactured by Linn Products. The Isobarik is known for both its reproduction of low bass frequencies and being very demanding on amplifiers.
Launched in 1973, the Isobarik DMS, Linn's maiden and flagship loudspeaker was based on and named for the isobaric loading principle invented in the 1950s. The speaker exists also as the Isobarik PMS – destined for the professional market. Although discontinued in 1992, it remains popular among audiophiles. (Full article...)
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A Leslie speaker in a clear plastic cabinet
The Leslie speaker is a combined amplifier and loudspeaker that projects the signal from an electric or electronic instrument and modifies the sound by rotating a baffle chamber ("drum") in front of the loudspeakers. A similar effect is provided by a rotating system of horns in front of the treble driver. It is most commonly associated with the Hammond organ, though it was later used for the electric guitar and other instruments. A typical Leslie speaker contains an amplifier, a treble horn and a bass speaker—though specific components depend upon the model. A musician controls the Leslie speaker by either an external switch or pedal that alternates between a slow and fast speed setting, known as "chorale" and "tremolo".
The speaker is named after its inventor, Donald Leslie, who began working in the late 1930s to get a speaker for a Hammond organ that better emulated a pipe or theatre organ, and discovered that baffles rotating along the axis of the speaker cone gave the best sound effect. Hammond was not interested in marketing or selling the speakers, so Leslie sold them himself as an add-on, targeting other organs as well as Hammond. Leslie made the first speaker in 1941. The sound of the organ being played through his speaker received national radio exposure across the US, and it became a commercial and critical success. It soon became an essential tool for most jazz organists. In 1965, Leslie sold his business to CBS who, in 1980, sold it to Hammond. Suzuki Musical Instrument Corporation subsequently acquired the Hammond and Leslie brands. (Full article...)
The project began with two aims: to prove the practicality of the Williams tube, an early form of computer memory based on standard cathode-ray tubes (CRTs); and to construct a machine that could be used to investigate how computers might be able to assist in the solution of mathematical problems. The first of the series, the Manchester Baby, ran its first program on 21 June 1948. As the world's first stored-program computer, the Baby, and the Manchester Mark 1 developed from it, quickly attracted the attention of the United Kingdom government, who contracted the electrical engineering firm of Ferranti to produce a commercial version. The resulting machine, the Ferranti Mark 1, was the world's first commercially available general-purpose computer. (Full article...)
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Row hammer (also written as rowhammer) is a security exploit that takes advantage of an unintended and undesirable side effect in dynamic random-access memory (DRAM) in which memory cells interact electrically between themselves by leaking their charges, possibly changing the contents of nearby memory rows that were not addressed in the original memory access. This circumvention of the isolation between DRAM memory cells results from the high cell density in modern DRAM, and can be triggered by specially crafted memory access patterns that rapidly activate the same memory rows numerous times.
Late version Quad "ESL-57" loudspeaker with black grilles and rosewood end caps
The Quad Electrostatic Loudspeaker (ESL) is the world's first production full-range electrostatic loudspeaker, launched in 1957 by Quad Electroacoustics, then known as the Acoustical Manufacturing Co. Ltd. The speaker is shaped somewhat like a home electric radiator curved slightly on the vertical axis. They are widely admired for their clarity and precision, but known to be difficult speakers to run and maintain.
The original ESL, in production between 1957 and 1985, has been hailed in Sound & Vision as one of the most important speakers of the 20th century. It was succeeded in 1981 by the ESL-63, which remained in production until 1999. As of 2013, Quad maintains four electrostatic speakers in its range. (Full article...)
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An antimetric electrical network is an electrical network that exhibits anti-symmetrical electrical properties. The term is often encountered in filter theory, but it applies to general electrical network analysis. Antimetric is the diametrical opposite of symmetric; it does not merely mean "asymmetric" (i.e., "lacking symmetry"). It is possible for networks to be symmetric or antimetric in their electrical properties without being physically or topologically symmetric or antimetric. (Full article...)
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Staggered tuning is a technique used in the design of multi-stage tuned amplifiers whereby each stage is tuned to a slightly different frequency. In comparison to synchronous tuning (where each stage is tuned identically) it produces a wider bandwidth at the expense of reduced gain. It also produces a sharper transition from the passband to the stopband. Both staggered tuning and synchronous tuning circuits are easier to tune and manufacture than many other filter types.
The function of stagger-tuned circuits can be expressed as a rational function and hence they can be designed to any of the major filter responses such as Butterworth and Chebyshev. The poles of the circuit are easy to manipulate to achieve the desired response because of the amplifier buffering between stages. (Full article...)
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Constant k filters, also k-type filters, are a type of electronic filter designed using the image method. They are the original and simplest filters produced by this methodology and consist of a ladder network of identical sections of passive components. Historically, they are the first filters that could approach the ideal filter frequency response to within any prescribed limit with the addition of a sufficient number of sections. However, they are rarely considered for a modern design, the principles behind them having been superseded by other methodologies which are more accurate in their prediction of filter response. (Full article...)
Numerically-controlled oscillators offer several advantages over other types of oscillators in terms of agility, accuracy, stability and reliability. NCOs are used in many communications systems including digital up/down converters used in 3G wireless and software radio systems, digital phase-locked loops, radar systems, drivers for optical or acoustic transmissions, and multilevel FSK/PSK modulators/demodulators. (Full article...)
A time-domain reflectometer; an instrument used to locate the position of faults on lines from the time taken for a reflected wave to return from the discontinuity.
A signal travelling along an electrical transmission line will be partly, or wholly, reflected back in the opposite direction when the travelling signal encounters a discontinuity in the characteristic impedance of the line, or if the far end of the line is not terminated in its characteristic impedance. This can happen, for instance, if two lengths of dissimilar transmission lines are joined.
This article is about signal reflections on electrically conducting lines. Such lines are loosely referred to as copper lines, and indeed, in telecommunications are generally made from copper, but other metals are used, notably aluminium in power lines. Although this article is limited to describing reflections on conducting lines, this is essentially the same phenomenon as optical reflections in fibre-optic lines and microwave reflections in waveguides. (Full article...)
The actual impedance may vary quite considerably from the nominal figure with changes in frequency. In the case of cables and other transmission lines, there is also variation along the length of the cable, if it is not properly terminated. (Full article...)
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The Sinclair Sovereign was a high-end calculator introduced by Clive Sinclair's company Sinclair Radionics in 1976. It was an attempt to escape from the unprofitable low end of the market, and one of the last calculators Sinclair produced. Made with a case of pressed steel that a variety of finishes, it cost between £30 and £60 at a time when other calculators could be purchased for under £5. A number of factors meant that the Sovereign was not a commercial success, including the cost, high import levies on components, competition from cheaper calculators manufactured abroad, and the development of more power-efficient designs using liquid-crystal displays. Though it came with a five-year guarantee, issues such as short battery life limited its usefulness. The company moved on to producing computers soon afterwards.
The Electro-Dynamic Light Company of New York was a lighting and electrical distribution company organized in 1878. The company held the patents for the first practical incandescent electric lamp and electrical distribution system of incandescent electric lighting. They also held a patent for an electric meter to measure the amount of electricity used. The inventions were those of Albon Man and William E. Sawyer. They gave the patent rights to the company, which they had formed with a group of businessmen. It was the first company in the world formally established to provided electric lighting and was the first company organized specifically to manufacture and sell incandescent electric light bulbs.
Man, an attorney from New York City, supplied money for experimentation to Sawyer, an electrical engineer. This partnership developed into the Electro-Dynamic Light Company that brought in other investors that became partners. Sawyer devised a unique electrical distribution system where electrical power could be obtained anywhere in the city from an electrical generator with the turn of a switch to light up electric lamps to produce glowing light like a gas lamp. It was unique in that it produced this power without consumers having to maintain local galvanic batteries and at a fraction of the cost of producing the same lighting as from gas lamps. Other features of the system were that safety devices were built in to prevent the early destroying of the other electric lamps in the circuit should there be a power surge due to a lamp burning up early and leaving the distribution circuit. The patents for the Man and Sawyer system were in place before any other electrical companies had similar systems. (Full article...)
There is a critical value of transformer coupling coefficient at which the frequency response of the amplifier is maximally flat in the passband and the gain is maximum at the resonant frequency. Designs frequently use a coupling greater than this (over-coupling) in order to achieve an even wider bandwidth at the expense of a small loss of gain in the centre of the passband. (Full article...)
Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential. The capacitance of the majority of capacitors used in electronic circuits is several orders of magnitude smaller than the farad. The energy (measured in joules) stored in a capacitor is equal to the work done to charge it.
In a capacitor, there are two conducting electrodes which are insulated from one another. The charge on the electrodes is +Q and -Q, and V represents the potential difference between the electrodes. The SI unit of capacitance is the farad; 1 farad = 1 coulomb per volt.
The capacitance can be calculated if the geometry of the conductors and the dielectric properties of the insulator between the conductors are known, such as above, where; C is the capacitance in farads, ε is the permittivity of the insulator used (or ε0 for a vacuum), A is the area of each plane electrode in square metres, d is the separation between the electrodes in metres. The equation is a good approximation if d is small compared to the other dimensions of the electrodes.
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