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Vackář Oscillator
A Vackář oscillator is a wide range variable frequency oscillator (VFO) which has a near constant output amplitude over its frequency range. It is similar to a Colpitts oscillator or a Clapp oscillator, but those designs do not have a constant output amplitude when tuned. Invention In 1949, the Czech engineer Jiří Vackář published a paper on the design of stable variable-frequency oscillators (VFO). The paper discussed many stability issues such as variations with temperature, atmospheric pressure, component aging, and microphonics. For example, Vackář describes making inductors by first heating the wire and then winding the wire on a stable ceramic coil form. The resulting inductor has a temperature coefficient of 6 to 8 parts per million per degree Celsius. Vackář points out that common air variable capacitors have a stability of 2 parts per thousand; to build a VFO with a stability of 50 parts per million requires that the variable capacitor is only 1/40 of the tu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lampkin Oscillator
Lampkin is an English surname. Notable persons with this surname * Arthur Lampkin (born circa 1938), English former professional motorcycle racer * Cam Lampkin (born 2001), American football player * Charles Lampkin (1913–1989), American actor, musician and lecturer * Chrissy Lampkin, participant of an American reality television series Love & Hip Hop ''Love & Hip Hop'' is a media franchise that consists of several reality television series broadcast on VH1. The shows document the personal and professional lives of several hip hop and R&B musicians, performers, managers, and record producers ... * Daisy Elizabeth Adams Lampkin (1883–1965), American suffragette * Dougie Lampkin (born 1976), English motorcycle trials rider * Jeff Lampkin (born 1959), American former professional boxer * Kevin Lampkin (born 1972), English former professional footballer * Martin Lampkin (1950–2016), English former professional motorcycle competitor * Nahru Lampkin (born 1962), Ame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resonant Frequency
Resonance is a phenomenon that occurs when an object or system is subjected to an external force or vibration whose frequency matches a resonant frequency (or resonance frequency) of the system, defined as a frequency that generates a maximum amplitude response in the system. When this happens, the object or system absorbs energy from the external force and starts vibrating with a larger amplitude. Resonance can occur in various systems, such as mechanical, electrical, or acoustic systems, and it is often desirable in certain applications, such as musical instruments or radio receivers. However, resonance can also be detrimental, leading to excessive vibrations or even structural failure in some cases. All systems, including molecular systems and particles, tend to vibrate at a natural frequency depending upon their structure; when there is very little damping this frequency is approximately equal to, but slightly above, the resonant frequency. When an oscillating force, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transconductance
Transconductance (for transfer conductance), also infrequently called mutual conductance, is the electrical characteristic relating the current through the output of a device to the voltage across the input of a device. Conductance is the reciprocal of resistance. Transadmittance (or transfer admittance) is the AC equivalent of transconductance. Definition Transconductance is very often denoted as a conductance, , with a subscript, , for ''mutual''. It is defined as follows: : g_\text = \frac For small signal alternating current, the definition is simpler: : g_\text = \frac The SI unit for transconductance is the siemens, with the symbol S, as in conductance. Transresistance Transresistance (for transfer resistance), also infrequently referred to as mutual resistance, is the dual of transconductance. It refers to the ratio between a change of the voltage at two output points and a related change of current through two input points, and is denotated as : : r_\text = \ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuned Circuit
An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, is an electric circuit consisting of an inductor, represented by the letter L, and a capacitor, represented by the letter C, connected together. The circuit can act as an electrical resonator, an electrical analogue of a tuning fork, storing energy oscillating at the circuit's resonant frequency. LC circuits are used either for generating signals at a particular frequency, or picking out a signal at a particular frequency from a more complex signal; this function is called a bandpass filter. They are key components in many electronic devices, particularly radio equipment, used in circuits such as oscillators, filters, tuners and frequency mixers. An LC circuit is an idealized model since it assumes there is no dissipation of energy due to resistance. Any practical implementation of an LC circuit will always include loss resulting from small but non-zero resistance within the components and co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Choke (electronics)
In electronics, a choke is an inductor used to block higher-frequency alternating currents (AC) while passing direct current (DC) and lower-frequency ACs in a circuit. A choke usually consists of a coil of insulated wire often wound on a magnetic core, although some consist of a doughnut-shaped ferrite bead strung on a wire. The choke's impedance increases with frequency. Its low electrical resistance passes both AC and DC with little power loss, but its reactance limits the amount of AC passed. The name comes from blocking—"choking"—high frequencies while passing low frequencies. It is a functional name; the name "choke" is used if an inductor is used for blocking or decoupling higher frequencies, but the component is simply called an "inductor" if used in electronic filters or tuned circuits. Inductors designed for use as chokes are usually distinguished by not having low-loss construction (high Q factor) required in inductors used in tuned circuits and filtering appli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resonant Circuit
An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, is an electric circuit consisting of an inductor, represented by the letter L, and a capacitor, represented by the letter C, connected together. The circuit can act as an electrical resonator, an electrical analogue of a tuning fork, storing energy oscillating at the circuit's resonant frequency. LC circuits are used either for generating signals at a particular frequency, or picking out a signal at a particular frequency from a more complex signal; this function is called a bandpass filter. They are key components in many electronic devices, particularly radio equipment, used in circuits such as oscillators, filters, tuners and frequency mixers. An LC circuit is an idealized model since it assumes there is no dissipation of energy due to resistance. Any practical implementation of an LC circuit will always include loss resulting from small but non-zero resistance within the components and connecti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JFET
The junction field-effect transistor (JFET) is one of the simplest types of field-effect transistor. JFETs are three-terminal semiconductor devices that can be used as electronically controlled switches or resistors, or to build amplifiers. Unlike bipolar junction transistors, JFETs are exclusively voltage-controlled in that they do not need a biasing current. Electric charge flows through a semiconducting channel between ''source'' and ''drain'' terminals. By applying a reverse bias voltage to a ''gate'' terminal, the channel is '' pinched'', so that the electric current is impeded or switched off completely. A JFET is usually conducting when there is zero voltage between its gate and source terminals. If a potential difference of the proper polarity is applied between its gate and source terminals, the JFET will be more resistive to current flow, which means less current would flow in the channel between the source and drain terminals. JFETs are sometimes referred to a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seiler Oscillator
Seiler (German for "roper") is a surname. Notable people with the surname include: * Alexander Seiler I (1819–1891), Swiss Hotel Pioneer * Hermann Seiler (1876–1961), Swiss Hotel Pioneer & Politician * Jack Seiler (born 1963), American politician and Mayor of Fort Lauderdale, Florida * Kerim Seiler (born 1974), Swiss artist and architect * Lewis Seiler (1890–1964), American film director * Lutz Seiler (born 1963), German poet and novelist * Paul Seiler (1945–2001), American football player * Reinhard Seiler (1909–1989), German Luftwaffe pilot * Robert Eldridge Seiler (1912–1998), American judge on the Missouri Supreme Court * Sebastian Seiler (1810–1890), German journalist * Sonny Seiler (1933–2023), American attorney and bulldog owner See also * Sailer (other) * Sayler * Seyler * Seiler Instrument & Mfg. Co. * Seiler Pianofortefabrik GmbH Seiler Pianofortefabrik GmbH is a piano manufacturer in Kitzingen, Germany. The company was founded by Eduard Sei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Frequency Oscillator
A variable frequency oscillator (VFO) in electronics is an oscillator whose frequency can be tuned (i.e., varied) over some range. It is a necessary component in any tunable radio transmitter and in receivers that work by the superheterodyne principle. The oscillator controls the frequency to which the apparatus is tuned. Purpose In a simple superheterodyne receiver, the incoming radio frequency signal (at frequency f_) from the antenna is ''mixed'' with the VFO output signal tuned to f_, producing an intermediate frequency (IF) signal that can be processed downstream to extract the modulated information. Depending on the receiver design, the IF signal frequency is chosen to be either the sum of the two frequencies at the mixer inputs ( up-conversion), f_+f_ or more commonly, the difference frequency (down-conversion), f_-f_. In addition to the desired ''IF'' signal and its unwanted image (the mixing product of opposite sign above), the mixer output will also contain the t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barkhausen Stability Criterion
In electronics, the Barkhausen stability criterion is a mathematical condition to determine when a linear electronic circuit will oscillate. It was put forth in 1921 by German physicist Heinrich Barkhausen (1881–1956). It is widely used in the design of electronic oscillators, and also in the design of general negative feedback circuits such as op amps, to prevent them from oscillating. Limitations Barkhausen's criterion applies to linear circuits with a feedback loop. It cannot be applied directly to active elements with negative resistance like tunnel diode oscillators. The kernel of the criterion is that a complex pole pair must be placed on the imaginary axis of the complex frequency plane if steady state oscillations should take place. In the real world, it is impossible to balance on the imaginary axis; small errors will cause the poles to be either slightly to the right or left, resulting in infinite growth or decreasing to zero, respectively. Thus, in practi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insertion Loss
In telecommunications, insertion loss is the loss of signal power resulting from the insertion of a device in a transmission line or optical fiber and is usually expressed in decibels (dB). If the power transmitted to the load before insertion is ''P''T and the power received by the load after insertion is ''P''R, then the insertion loss in decibels is given by, :IL(\mathrm) = 10 \log_ Electronic filters Insertion loss is a figure of merit for an electronic filter and this data is generally specified with a filter. Insertion loss is defined as a ratio of the signal level in a test configuration without the filter installed (\left\vert V_1 \right\vert) to the signal level with the filter installed (\left\vert V_2 \right\vert). This ratio is described in decibels by the following equation: :\mbox = 10 \log_ = 20 \log_ For passive filters, \left\vert V_2 \right\vert will be smaller than \left\vert V_1 \right\vert. In this case, the insertion loss is positive and measure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
