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Bias Tee
A bias tee is a three-port network used for setting the DC biasing, bias point of some electronic components without disturbing other components. The bias tee is a diplexer. The low-frequency port is used to set the bias; the high-frequency port passes the radio-frequency signals but blocks the biasing levels; the combined port connects to the device, which sees both the bias and RF. It is called a ''tee'' because the 3 ports are often arranged in the shape of a T. Design Conceptually, the bias tee can be viewed as an ideal capacitor that allows alternating current, AC through but blocks the direct current, DC bias and an ideal inductor that blocks AC but allows DC. Although some bias tees can be made with a simple inductor and capacitor, wideband bias tees are considerably more complicated because practical components have Parasitic element (electrical networks), parasitic elements. Bias tees are designed for transmission-line environments. Typically, the characteristic impedance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biasing
In electronics, biasing is the setting of DC (direct current) operating conditions (current and voltage) of an electronic component that processes time-varying signals. Many electronic devices, such as diodes, transistors and vacuum tubes, whose function is processing time-varying ( AC) signals, also require a steady (DC) current or voltage at their terminals to operate correctly. This current or voltage is called ''bias''. The AC signal applied to them is superposed on this DC bias current or voltage. The operating point of a device, also known as bias point, quiescent point, or Q-point, is the DC voltage or current at a specified terminal of an active device (a transistor or vacuum tube) with no input signal applied. A bias circuit is a portion of the device's circuit that supplies this steady current or voltage. Overview In electronics, 'biasing' usually refers to a fixed DC voltage or current applied to a terminal of an electronic component such as a diode, transistor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Connector
Components of an electrical circuit are electrically connected if an electric current can run between them through an electrical conductor. An electrical connector is an electromechanical device used to create an electrical connection between parts of an electrical circuit, or between different electrical circuits, thereby joining them into a larger circuit. The connection may be removable (as for portable equipment), require a tool for assembly and removal, or serve as a permanent electrical joint between two points. An adapter can be used to join dissimilar connectors. Most electrical connectors have a genderi.e. the male component, called a ''plug'', connects to the female component, or ''socket''. Thousands of configurations of connectors are manufactured for power, data, and audiovisual applications. Electrical connectors can be divided into four basic categories, differentiated by their function: * ''inline'' or ''cable'' connectors permanently attached to a cable, so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phantom Power
Phantom power, in the context of Professional audio, professional audio equipment, is Direct current, DC electric power equally applied to both signal wires in Balanced line, balanced microphone cables, forming a phantom circuit, to power microphones that contain active electronic circuitry. It is best known as a convenient power source for condenser microphones, though many active DI unit, direct boxes also use it. The technique is also used in other applications where power supply and signal communication take place over the same wires. Phantom power supplies are often built into mixing consoles, microphone preamplifiers and similar equipment. In addition to powering the circuitry of a microphone, traditional condenser microphones also use phantom power for polarizing the microphone's transducer element. History Phantom powering was first used for copper wire-based landline, telephone landlines since the introduction of the rotary dial telephone in 1919. One such applicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gyrator
A gyrator is a passivity (engineering), passive, Linear circuit, linear, lossless, two-port network, two-port electrical lumped-element model, network element proposed in 1948 by Bernard D. H. Tellegen as a hypothetical fifth linear element after the resistor, capacitor, inductor and transformer#Ideal transformer, ideal transformer. Unlike the four conventional elements, the gyrator is Reciprocity (electrical networks), non-reciprocal. Gyrators permit network synthesis filters, network realizations of two-(or-more)-Port (circuit theory), port devices which cannot be realized with just the four conventional elements. In particular, gyrators make possible network realizations of isolator (microwave), isolators and circulators. Gyrators do not however change the range of one-port devices that can be realized. Although the gyrator was conceived as a fifth linear element, its adoption makes both the ideal transformer and either the capacitor or inductor redundant. Thus the number of neces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plain Old Telephone Service
Plain old telephone service (POTS), or publicly offered telephone service, is basic Voice band, voice-grade telephone service. Historically, POTS has been delivered by Analog signal, analog signal transmission over copper loops, but the term also describes Backward compatibility, backward-compatible analog connections offered by digital telephone systems. Copper loop POTS was the standard service offering from telephone companies in the United States from 1876 until 1988, when the Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) was introduced, followed by the development of mobile phone, cellular telephone systems and voice over internet protocol (VoIP). Despite the advent of these technologies, copper loop POTS remains a basic form of residential and small business connection to the telephone network in many parts of the world. The term encapsulates a technology that has been available since the introduction of the public telephone system in the late 19th c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telephone Line
A telephone line or telephone circuit (or just line or circuit industrywide) is a single-user circuit on a telephone communication system. It is designed to reproduce speech of a quality that is understandable. It is the physical wire or other signaling medium connecting the user's telephone apparatus to the telecommunications network, and usually also implies a single telephone number for billing purposes reserved for that user. Telephone lines are used to deliver consistent landline telephone service and digital subscriber line (DSL) phone cable service to the premises. Telephone overhead lines are connected to the public switched telephone network. The voltage at a subscriber's network interface is typically 48 V between the ring and tip wires, with tip near ground and ring at –48 V. In the United States In 1878, the Bell Telephone Company began using two-wire circuits, called the local loop, from each user's telephone to end offices, which performed a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Over Ethernet
Power over Ethernet (PoE) describes any of several technical standard, standards or ad hoc systems that pass electric power along with data on twisted-pair Ethernet cabling. This allows a single cable to provide both a data connection and enough electricity to power networked devices such as wireless access points (WAPs), IP cameras and VoIP phones. Techniques There are several common techniques for transmitting power over Ethernet cabling, defined within the broader Institute of Electrical and Electronics Engineers (IEEE) IEEE 802.3, 802.3 standard since 2003. The three techniques are: *''Alternative A'', which uses the same two of the four Balanced line, signal pairs that 10BASE-T and 100BASE-TX use for data in typical Cat 5, Cat 5 cabling. *''Alternative B'', which separates the data and the power conductors for 10BASE-T/100BASE-TX, making troubleshooting easier. *''4PPoE'', which uses all four twisted pairs in parallel, increasing the achievable power. ''Alterna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triode
A triode is an electronic amplifier, amplifying vacuum tube (or ''thermionic valve'' in British English) consisting of three electrodes inside an evacuated glass envelope: a heated Electrical filament, filament or cathode, a control grid, grid, and a Plate electrode, plate (anode). Developed from Lee De Forest's 1906 Audion, a partial vacuum tube that added a grid electrode to the thermionic diode (Fleming valve), the triode was the first practical electronic amplifier and the ancestor of other types of vacuum tubes such as the tetrode and pentode. Its invention helped make amplified radio technology and long-distance telephony possible. Triodes were widely used in consumer electronics devices such as radios and televisions until the 1970s, when transistors replaced them. Today, their main remaining use is in high-power Radio frequency, RF amplifiers in Transmitter, radio transmitters and industrial RF heating devices. In recent years there has been a resurgence in demand for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transistor
A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch electrical signals and electric power, power. It is one of the basic building blocks of modern electronics. It is composed of semiconductor material, usually with at least three terminal (electronics), terminals for connection to an electronic circuit. A voltage or Electric current, current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Some transistors are packaged individually, but many more in miniature form are found embedded in integrated circuits. Because transistors are the key active components in practically all modern electronics, many people consider them one of the 20th century's greatest inventions. Physicist Julius Edgar Lilienfeld proposed the concept of a field-effect transisto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microchannel Plate Detector
A microchannel plate (MCP) is used to detect single particles (electrons, ions and neutrons) and photons (ultraviolet radiation and X-rays). It is closely related to an electron multiplier, as both intensify single particles or photons by the multiplication of electrons via secondary emission. Because a microchannel plate detector has many separate channels, it can provide spatial resolution. Basic design A microchannel plate is a slab made from resistive material (most often glass) 0.5 to 2mm thick with a regular array of tiny tubes (microchannels) leading from one face to the other. The microchannels are typically 5-20 micrometers in diameter, parallel to each other and enter the plate at a small angle to the surface (8-13° from normal). Plates are often round disks, but can be cut to any shape from sizes 10mm up to 200mm. They may also be curved. Operating mode At non-relativistic energies, single particles generally produce effects too small to enable their direct det ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photodiodes
A photodiode is a semiconductor diode sensitive to photon radiation, such as visible light, infrared or ultraviolet radiation, X-rays and gamma rays. It produces an electrical current when it absorbs photons. This can be used for detection and measurement applications, or for the generation of electrical power in solar cells. Photodiodes are used in a wide range of applications throughout the electromagnetic spectrum from visible light photocells to gamma ray spectrometers. Principle of operation A photodiode is a PIN structure or p–n junction. When a photon of sufficient energy strikes the diode, it creates an electron–hole pair. This mechanism is also known as the inner photoelectric effect. If the absorption occurs in the junction's depletion region, or one diffusion length away from it, these carriers are swept from the junction by the built-in electric field of the depletion region. Thus holes move toward the anode, and electrons toward the cathode, and a photocurre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
