Topic: Electronics

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๐Ÿ”— Phoebus Cartel

๐Ÿ”— Technology ๐Ÿ”— Business ๐Ÿ”— Electronics ๐Ÿ”— Energy ๐Ÿ”— Home Living

The Phoebus cartel existed to control the manufacture and sale of incandescent light bulbs. They appropriated market territories and fixed the useful life of such bulbs. Corporations based in Europe and America founded the cartel on January 15, 1925 in Geneva. They had intended the cartel to last for thirty years (1925 to 1955). The cartel ceased operations in 1939 owing to the outbreak of World War II. The cartel included manufacturers Osram, General Electric, Associated Electrical Industries, and Philips, among others.

The Phoebus cartel created a notable landmark in the history of the global economy because it engaged in large-scale planned obsolescence to generate repeated sales and maximize profit. It also reduced competition in the light bulb industry for almost fifteen years. Critics accused the cartel of preventing technological advances that would produce longer-lasting light bulbs. Phoebus based itself in Switzerland. The corporation named itself Phล“bus S.A. Compagnie Industrielle pour le Dรฉveloppement de l'ร‰clairage (French for "Phoebus, Inc. Industrial Company for the Development of Lighting").

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๐Ÿ”— Two capacitor paradox

๐Ÿ”— Electronics

The two capacitor paradox or capacitor paradox is a paradox, or counterintuitive thought experiment, in electric circuit theory. The thought experiment is usually described as follows: Two identical capacitors are connected in parallel with an open switch between them. One of the capacitors is charged with a voltage of V i {\displaystyle V_{i}} , the other is uncharged. When the switch is closed, some of the charge Q = C V i {\displaystyle Q=CV_{i}} on the first capacitor flows into the second, reducing the voltage on the first and increasing the voltage on the second. When a steady state is reached and the current goes to zero, the voltage on the two capacitors must be equal since they are connected together. Since they both have the same capacitance C {\displaystyle C} the charge will be divided equally between the capacitors so each capacitor will have a charge of Q 2 {\displaystyle {Q \over 2}} and a voltage of V f = Q 2 C = V i 2 {\displaystyle V_{f}={Q \over 2C}={V_{i} \over 2}} . At the beginning of the experiment the total initial energy W i {\displaystyle W_{i}} in the circuit is the energy stored in the charged capacitor:

W i = 1 2 C V i 2 {\displaystyle W_{i}={1 \over 2}CV_{i}^{2}} .

At the end of the experiment the final energy W f {\displaystyle W_{f}} is equal to the sum of the energy in the two capacitors

W f = 1 2 C V f 2 + 1 2 C V f 2 = C V f 2 = C ( V i 2 ) 2 = 1 4 C V i 2 = 1 2 W i {\displaystyle W_{f}={1 \over 2}CV_{f}^{2}+{1 \over 2}CV_{f}^{2}=CV_{f}^{2}=C({V_{i} \over 2})^{2}={1 \over 4}CV_{i}^{2}={1 \over 2}W_{i}}

Thus the final energy W f {\displaystyle W_{f}} is equal to half of the initial energy W i {\displaystyle W_{i}} . Where did the other half of the initial energy go?

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๐Ÿ”— Capacitor plague โ€“ Wikipedia

๐Ÿ”— Electronics ๐Ÿ”— Guild of Copy Editors

The capacitor plague was a problem related to a higher-than-expected failure rate of non-solid aluminum electrolytic capacitors, between 1999 and 2007, especially those from some Taiwanese manufacturers, due to faulty electrolyte composition that caused corrosion accompanied by gas generation, often rupturing the case of the capacitor from the build-up of pressure.

High failure rates occurred in many well-known brands of electronics, and were particularly evident in motherboards, video cards, and power supplies of personal computers.

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๐Ÿ”— Evolved antenna

๐Ÿ”— Telecommunications ๐Ÿ”— Radio ๐Ÿ”— Electronics ๐Ÿ”— Engineering

In radio communications, an evolved antenna is an antenna designed fully or substantially by an automatic computer design program that uses an evolutionary algorithm that mimics Darwinian evolution. This procedure has been used in recent years to design a few antennas for mission-critical applications involving stringent, conflicting, or unusual design requirements, such as unusual radiation patterns, for which none of the many existing antenna types are adequate.

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๐Ÿ”— Asynchronous (Clockless) CPU

๐Ÿ”— Computing ๐Ÿ”— Electronics ๐Ÿ”— Electrical engineering

An asynchronous circuit, or self-timed circuit, is a sequential digital logic circuit which is not governed by a clock circuit or global clock signal. Instead it often uses signals that indicate completion of instructions and operations, specified by simple data transfer protocols. This type of circuit is contrasted with synchronous circuits, in which changes to the signal values in the circuit are triggered by repetitive pulses called a clock signal. Most digital devices today use synchronous circuits. However asynchronous circuits have the potential to be faster, and may also have advantages in lower power consumption, lower electromagnetic interference, and better modularity in large systems. Asynchronous circuits are an active area of research in digital logic design.

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๐Ÿ”— Plasma Antenna

๐Ÿ”— Telecommunications ๐Ÿ”— Radio ๐Ÿ”— Electronics ๐Ÿ”— Engineering

A plasma antenna is a type of radio antenna currently in development in which plasma is used instead of the metal elements of a traditional antenna. A plasma antenna can be used for both transmission and reception. Although plasma antennas have only become practical in recent years, the idea is not new; a patent for an antenna using the concept was granted to J. Hettinger in 1919.

Early practical examples of the technology used discharge tubes to contain the plasma and are referred to as ionized gas plasma antennas. Ionized gas plasma antennas can be turned on and off and are good for stealth and resistance to electronic warfare and cyber attacks. Ionized gas plasma antennas can be nested such that the higher frequency plasma antennas are placed inside lower frequency plasma antennas. Higher frequency ionized gas plasma antenna arrays can transmit and receive through lower frequency ionized gas plasma antenna arrays. This means that the ionized gas plasma antennas can be co-located and ionized gas plasma antenna arrays can be stacked. Ionized gas plasma antennas can eliminate or reduce co-site interference. Smart ionized gas plasma antennas use plasma physics to shape and steer the antenna beams without the need of phased arrays. Satellite signals can be steered or focused in the reflective or refractive modes using banks of plasma tubes making unique ionized gas satellite plasma antennas. The thermal noise of ionized gas plasma antennas is less than in the corresponding metal antennas at the higher frequencies. Solid state plasma antennas (also known as plasma silicon antennas) with steerable directional functionality that can be manufactured using standard silicon chip fabrication techniques are now also in development. Plasma silicon antennas are candidates for use in WiGig (the planned enhancement to Wi-Fi), and have other potential applications, for example in reducing the cost of vehicle-mounted radar collision avoidance systems.

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๐Ÿ”— Nyquist Frequency

๐Ÿ”— Electronics

In signal processing, the Nyquist frequency (or folding frequency), named after Harry Nyquist, is a characteristic of a sampler, which converts a continuous function or signal into a discrete sequence. For a given sampling rate (samples per second), the Nyquist frequency (cycles per second) is the frequency whose cycle-length (or period) is twice the interval between samples, thus 0.5 cycle/sample. For example, audio CDs have a sampling rate of 44100 samples/second. At 0.5 cycle/sample, the corresponding Nyquist frequency is 22050 cycles/second (Hz). Conversely, the Nyquist rate for sampling a 22050 Hz signal is 44100 samples/second.

When the highest frequency (bandwidth) of a signal is less than the Nyquist frequency of the sampler, the resulting discrete-time sequence is said to be free of the distortion known as aliasing, and the corresponding sample rate is said to be above the Nyquist rate for that particular signal.

In a typical application of sampling, one first chooses the highest frequency to be preserved and recreated, based on the expected content (voice, music, etc.) and desired fidelity. Then one inserts an anti-aliasing filter ahead of the sampler. Its job is to attenuate the frequencies above that limit. Finally, based on the characteristics of the filter, one chooses a sample rate (and corresponding Nyquist frequency) that will provide an acceptably small amount of aliasing. In applications where the sample rate is pre-determined (such as the CD rate), the filter is chosen based on the Nyquist frequency, rather than vice versa.

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๐Ÿ”— Antifuse, the opposite of a fuse

๐Ÿ”— Electronics

An antifuse is an electrical device that performs the opposite function to a fuse. Whereas a fuse starts with a low resistance and is designed to permanently break an electrically conductive path (typically when the current through the path exceeds a specified limit), an antifuse starts with a high resistance, and programming it converts it into a permanent electrically conductive path (typically when the voltage across the antifuse exceeds a certain level). This technology has many applications.

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๐Ÿ”— All American Five radio receivers

๐Ÿ”— Electronics

The term All American Five (abbreviated AA5) is a colloquial name for mass-produced, superheterodyne radio receivers that used five vacuum tubes in their design. These radio sets were designed to receive amplitude modulation (AM) broadcasts in the medium wave band, and were manufactured in the United States from the mid-1930s until the early 1960s. By eliminating a power transformer, cost of the units was kept low; the same principle was later applied to television receivers. Variations in the design for lower cost, shortwave bands, better performance or special power supplies existed, although many sets used an identical set of vacuum tubes.

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๐Ÿ”— Resistorโ€“Transistor Logic (RTL)

๐Ÿ”— Electronics

Resistorโ€“transistor logic (RTL) (sometimes also transistorโ€“resistor logic (TRL)) is a class of digital circuits built using resistors as the input network and bipolar junction transistors (BJTs) as switching devices. RTL is the earliest class of transistorized digital logic circuit; it was succeeded by diodeโ€“transistor logic (DTL) and transistorโ€“transistor logic (TTL).

RTL circuits were first constructed with discrete components, but in 1961 it became the first digital logic family to be produced as a monolithic integrated circuit. RTL integrated circuits were used in the Apollo Guidance Computer, whose design begun in 1961 and which first flew in 1966.

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