Electronic devices have hugely influenced the development of many aspects of modern society, such as telecommunications, entertainment, education, health care, industry, and security. The main driving force behind the advancement of electronics is the semiconductor industry, which in response to global demand continually produces ever-more sophisticated electronic devices and circuits. The semiconductor industry is one of the largest and most profitable sectors in the global economy, with annual revenues exceeding $481 billion in 2018. The electronics industry also encompasses other sectors that rely on electronic devices and systems, such as e-commerce, which generated over $29 trillion in online sales in 2017. (Full article...)
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Telephone cable containing multiple twisted-pair lines The primary line constants are parameters that describe the characteristics of conductive transmission lines, such as pairs of copper wires, in terms of the physical electrical properties of the line. The primary line constants are only relevant to transmission lines and are to be contrasted with the secondary line constants, which can be derived from them, and are more generally applicable. The secondary line constants can be used, for instance, to compare the characteristics of a waveguide to a copper line, whereas the primary constants have no meaning for a waveguide.
The constants are conductor resistance and inductance, and insulator capacitance and conductance, which are by convention given the symbols R, L, C, and G respectively. The constants are enumerated in terms of per unit length. The circuit representation of these elements requires a distributed-element model and consequently calculus must be used to analyse the circuit. The analysis yields a system of two first order, simultaneous linear partial differential equations which may be combined to derive the secondary constants of characteristic impedance and propagation constant. (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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Foster's reactance theorem is an important theorem in the fields of electrical network analysis and synthesis. The theorem states that the reactance of a passive, lossless two-terminal (one-port) network always strictly monotonically increases with frequency. It is easily seen that the reactances of inductors and capacitors individually increase with frequency and from that basis a proof for passive lossless networks generally can be constructed. The proof of the theorem was presented by Ronald Martin Foster in 1924, although the principle had been published earlier by Foster's colleagues at American Telephone & Telegraph.
The theorem can be extended to admittances and the encompassing concept of immittances. A consequence of Foster's theorem is that zeros and poles of the reactance must alternate with frequency. Foster used this property to develop two canonical forms for realising these networks. Foster's work was an important starting point for the development of network synthesis. (Full article...)
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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...)
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Sinclair Executive Type 1
The Sinclair Executive was the world's first "slimline" pocket calculator, and the first to be produced by Clive Sinclair's company Sinclair Radionics. Introduced in 1972, the calculator was produced in at least two versions with different keyboard markings; a variant called the Sinclair Executive Memory was introduced in 1973.
Its small size was made possible by pulsing current to the Texas Instruments TMS1802 "calculator on a chip" integrated circuit, reducing the power consumption more than tenfold. The Executive was highly successful, making £1.8 million of profit for Sinclair and winning a Design Council Award for Electronics. (Full article...)
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Figure 1. Waveguide slotted line Slotted lines are used for microwave measurements and consist of a movable probe inserted into a slot in a transmission line. They are used in conjunction with a microwave power source and usually, in keeping with their low-cost application, a low cost Schottky diode detector and VSWR meter rather than an expensive microwave power meter.
Slotted lines can measure standing waves, wavelength, and, with some calculation or plotting on Smith charts, a number of other parameters including reflection coefficient and electrical impedance. A precision variable attenuator is often incorporated in the test setup to improve accuracy. This is used to make level measurements, while the detector and VSWR meter are retained only to mark a reference point for the attenuator to be set to, thus eliminating entirely the detector and meter measurement errors. The parameter most commonly measured by a slotted line is SWR. This serves as a measure of the accuracy of the impedance match to the item under test. This is especially important for transmitting antennas and their feed lines; high standing wave ratio on a radio or TV antenna can distort the signal, increase transmission line loss and potentially damage components in the transmission path, possibly even the transmitter. (Full article...)
The image method of filter design determines the properties of filter sections by calculating the properties they would have in an infinite chain of identical sections. In this, the analysis parallels transmission line theory on which it is based. Filters designed by this method are called image parameter filters, or just image filters. An important parameter of image filters is their image impedance, the impedance of an infinite chain of identical sections. (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...)
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A 10 dB 1.7–2.2 GHz directional coupler. From left to right: input, coupled, isolated (terminated with a load), and transmitted port. Power dividers (also power splitters and, when used in reverse, power combiners) and directional couplers are passive devices used mostly in the field of radio technology. They couple a defined amount of the electromagnetic power in a transmission line to a port enabling the signal to be used in another circuit. An essential feature of directional couplers is that they only couple power flowing in one direction. Power entering the output port is coupled to the isolated port but not to the coupled port. A directional coupler designed to split power equally between two ports is called a hybrid coupler.
Directional couplers are most frequently constructed from two coupled transmission lines set close enough together such that energy passing through one is coupled to the other. This technique is favoured at the microwave frequencies where transmission line designs are commonly used to implement many circuit elements. However, lumped component devices are also possible at lower frequencies, such as the audio frequencies encountered in telephony. Also at microwave frequencies, particularly the higher bands, waveguide designs can be used. Many of these waveguide couplers correspond to one of the conducting transmission line designs, but there are also types that are unique to waveguide. (Full article...)
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The Nakamichi Dragon is an audio cassette deck that was introduced by Nakamichi in 1982 and marketed until 1994. The Dragon was the first Nakamichi model with bidirectional replay capability and the world's first production tape recorder with an automatic azimuth correction system; this feature, which was invented by Philips engineers and improved by Niro Nakamichi, continuously adjusts the azimuth of the replay head to minimize apparent head skew and correctly reproduce the treble signal present on the tape. The system allows the correct reproduction of mechanically skewed cassettes and recordings made on misaligned decks. Apart from the Dragon, similar systems have only been used in the Nakamichi TD-1200 car cassette player and the Marantz SD-930 cassette deck.
At the time of its introduction, the Dragon had the lowest-ever wow and flutter and the highest-ever dynamic range, losing marginally to the former Nakamichi flagship the 1000ZXL in frequency response. Competing models by Sony, Studer, Tandberg and TEAC that were introduced later in the 1980s sometimes surpassed the Dragon in mechanical quality and feature set but none could deliver the same mix of sound quality, flexibility and technological advancement. The Dragon, despite inherent issues with long-term reliability, remained the highest point of compact cassette technology. (Full article...)
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Galaxy S III in white
The Samsung Galaxy S III (unofficially known as the Samsung Galaxy S3) is an Androidsmartphone designed, developed, and marketed by Samsung Electronics. Launched in 2012, it had sold more than 80 million units overall, making it the most sold phone in the S series. It is the third smartphone in the Samsung Galaxy S series.
It is distinguished from its predecessor by its larger and higher-resolution screen, higher storage options, a larger battery, and a video camera with stereo audio recording for a spatial effect on headphones and external speakers. While the picture and video resolutions of the camera stayed the same, its launching speed and shutter lag improved. (Full article...)
m-derived filters or m-type filters are a type of electronic filter designed using the image method. They were invented by Otto Zobel in the early 1920s. This filter type was originally intended for use with telephone multiplexing and was an improvement on the existing constant k type filter. The main problem being addressed was the need to achieve a better match of the filter into the terminating impedances. In general, all filters designed by the image method fail to give an exact match, but the m-type filter is a big improvement with suitable choice of the parameter m. The m-type filter section has a further advantage in that there is a rapid transition from the cut-off frequency of the passband to a pole of attenuation just inside the stopband. Despite these advantages, there is a drawback with m-type filters; at frequencies past the pole of attenuation, the response starts to rise again, and m-types have poor stopband rejection. For this reason, filters designed using m-type sections are often designed as composite filters with a mixture of k-type and m-type sections and different values of m at different points to get the optimum performance from both types. (Full article...)
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Sinclair Scientific calculator photographed c. 1974
The Sinclair Scientificcalculator was a 12-function, pocket-sized scientific calculator introduced in 1974, dramatically undercutting in price other calculators available at the time. The Sinclair Scientific Programmable, released a year later, was advertised as the first budget programmable calculator.
Significant modifications to the algorithms used meant that a chipset intended for a four-function calculator was able to process scientific functions, but at the cost of reduced speed and accuracy. Compared to contemporary scientific calculators, some functions were slow to execute, and others had limited accuracy or gave the wrong answer, but the cost of the Sinclair was a fraction of the cost of competing calculators. (Full article...)
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Air stripline is a form of electrical planar transmission line whereby a conductor in the form of a thin metal strip is suspended between two ground planes. The idea is to make the dielectric essentially air. Mechanical support of the line may be a thin substrate, periodical insulated supports, or the device connectors and other electrical items.
Air stripline is most commonly used at microwave frequencies, especially in the C band. Its advantage over standard stripline and other planar technologies is that its air dielectric avoids dielectric loss. Many useful circuits can be constructed with air stripline and it is also easier to achieve strong coupling between components in this technology than with other planar formats. It was invented by Robert M. Barrett in the 1950s. (Full article...)
In electromagnetics and communications engineering, the term waveguide may refer to any linear structure that guides electromagnetic waves. However, the original and most common meaning is a hollow metal pipe used for this purpose.
The electromagnetic waves in (metal-pipe) waveguide may be imagined as travelling down the guide in a zig-zag path, being repeatedly reflected between opposite walls of the guide. For the particular case of rectangular waveguide, it is possible to base an exact analysis on this view. Propagation in dielectric waveguide may be viewed in the same way, with the waves confined to the dielectric by total internal reflection at its surface.
... that Chicony, known primarily as a keyboard manufacturer, entered the computer-manufacturing business with the Rabbit 286 in 1988?
Consumer showcase
The GeForce 6600 (NV43) was officially launched on August 12th, 2004, several months after the launch of the 6800 Ultra. With half the pixel pipelines and vertex shaders of the 6800 GT, and a smaller 128-bit memory bus, the lower-performance and lower-cost 6600 is the mainstream product of the GeForce 6 series. The 6600 series retains the core rendering features of the 6800 series, including SLI. Equipped with fewer rendering units, the 6600 series processes pixel data at a slower rate than the more powerful 6800 series.
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