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40-477: By interpreting an input musical waveform , the Video Music translates the levels of musical intensity and mellowness into colors and shapes that are output to a graphical display. The console is attached to an audio source and then operated by an adhesive-backed switch box that is glued to the back of a television display. Audio signal visualizations take the basic form of a two-part diamond. The outer part represents

80-733: A bridge circuit . The cathode-ray oscilloscope works by amplifying the voltage and using it to deflect an electron beam from a straight path, so that the deflection of the beam is proportional to the voltage. A common voltage for flashlight batteries is 1.5 volts (DC). A common voltage for automobile batteries is 12 volts (DC). Common voltages supplied by power companies to consumers are 110 to 120 volts (AC) and 220 to 240 volts (AC). The voltage in electric power transmission lines used to distribute electricity from power stations can be several hundred times greater than consumer voltages, typically 110 to 1200 kV (AC). The voltage used in overhead lines to power railway locomotives

120-430: A capacitor ), and from an electromotive force (e.g., electromagnetic induction in a generator ). On a macroscopic scale, a potential difference can be caused by electrochemical processes (e.g., cells and batteries), the pressure-induced piezoelectric effect , and the thermoelectric effect . Since it is the difference in electric potential, it is a physical scalar quantity . A voltmeter can be used to measure

160-413: A constant period . The term can also be used for non-periodic or aperiodic signals, like chirps and pulses . In electronics, the term is usually applied to time-varying voltages , currents , or electromagnetic fields . In acoustics, it is usually applied to steady periodic sounds — variations of pressure in air or other media. In these cases, the waveform is an attribute that is independent of

200-607: A television screen or recorded on a VCR by using a balun converter. The Video Music hooks up to a TV through an RF switchbox. The other hook ups are left and right RCA jack inputs that hook up to an audio amplifier's RCA outputs. The face is a brushed metal plate and the sides are particle board with walnut veneer. The unit is turned on by pushing a power button, and visualization is controlled by five potentiometer knobs and 12 additional push-buttons . The knob controls are as follows: The push button controls are as follows: The last four buttons have an auxiliary function when

240-423: A well-defined voltage between nodes in the circuit, since the electric force is not a conservative force in those cases. However, at lower frequencies when the electric and magnetic fields are not rapidly changing, this can be neglected (see electrostatic approximation ). The electric potential can be generalized to electrodynamics, so that differences in electric potential between points are well-defined even in

280-463: Is a well-defined voltage across the inductor's terminals. This is the reason that measurements with a voltmeter across an inductor are often reasonably independent of the placement of the test leads. The volt (symbol: V ) is the derived unit for electric potential , voltage, and electromotive force . The volt is named in honour of the Italian physicist Alessandro Volta (1745–1827), who invented

320-548: Is affected by thermodynamics. The quantity measured by a voltmeter is the negative of the difference of the electrochemical potential of electrons ( Fermi level ) divided by the electron charge and commonly referred to as the voltage difference, while the pure unadjusted electrostatic potential (not measurable with a voltmeter) is sometimes called Galvani potential . The terms "voltage" and "electric potential" are ambiguous in that, in practice, they can refer to either of these in different contexts. The term electromotive force

360-427: Is between 12 kV and 50 kV (AC) or between 0.75 kV and 3 kV (DC). Inside a conductive material, the energy of an electron is affected not only by the average electric potential but also by the specific thermal and atomic environment that it is in. When a voltmeter is connected between two different types of metal, it measures not the electrostatic potential difference, but instead something else that

400-417: Is defined so that negatively charged objects are pulled towards higher voltages, while positively charged objects are pulled towards lower voltages. Therefore, the conventional current in a wire or resistor always flows from higher voltage to lower voltage. Historically, voltage has been referred to using terms like "tension" and "pressure". Even today, the term "tension" is still used, for example within

440-547: Is the joule per coulomb , where 1 volt = 1 joule (of work) per 1 coulomb of charge. The old SI definition for volt used power and current ; starting in 1990, the quantum Hall and Josephson effect were used, and in 2019 physical constants were given defined values for the definition of all SI units. Voltage is denoted symbolically by Δ V {\displaystyle \Delta V} , simplified V , especially in English -speaking countries. Internationally,

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480-475: Is the difference in electric potential between two points. In a static electric field , it corresponds to the work needed per unit of charge to move a positive test charge from the first point to the second point. In the International System of Units (SI), the derived unit for voltage is the volt (V) . The voltage between points can be caused by the build-up of electric charge (e.g.,

520-530: Is the intensity of the electric field. In this case, the voltage increase from point A to point B is equal to the work done per unit charge, against the electric field, to move the charge from A to B without causing any acceleration. Mathematically, this is expressed as the line integral of the electric field along that path. In electrostatics, this line integral is independent of the path taken. Under this definition, any circuit where there are time-varying magnetic fields, such as AC circuits , will not have

560-450: Is the sum of the voltage between A and B and the voltage between B and C . The various voltages in a circuit can be computed using Kirchhoff's circuit laws . When talking about alternating current (AC) there is a difference between instantaneous voltage and average voltage. Instantaneous voltages can be added for direct current (DC) and AC, but average voltages can be meaningfully added only when they apply to signals that all have

600-399: The frequency , amplitude , or phase shift of the signal. The waveform of an electrical signal can be visualized in an oscilloscope or any other device that can capture and plot its value at various times, with suitable scales in the time and value axes. The electrocardiograph is a medical device to record the waveform of the electric signals that are associated with the beating of

640-427: The heart ; that waveform has important diagnostic value. Waveform generators , that can output a periodic voltage or current with one of several waveforms, are a common tool in electronics laboratories and workshops. The waveform of a steady periodic sound affects its timbre . Synthesizers and modern keyboards can generate sounds with many complicated waveforms. Simple examples of periodic waveforms include

680-430: The voltaic pile , possibly the first chemical battery . A simple analogy for an electric circuit is water flowing in a closed circuit of pipework , driven by a mechanical pump . This can be called a "water circuit". The potential difference between two points corresponds to the pressure difference between two points. If the pump creates a pressure difference between two points, then water flowing from one point to

720-423: The "Auto" button is pushed. In this mode, three of these buttons represent Solid, Hole and Ring. When the unit is in auto, it will retain the shape of one of those three shapes. The fourth button is "Auto All". This sends the unit into semi-automatic mode, cycling through shape, horizontal and vertical options but not affecting the user-set gain, color or contour settings. Developed under the codename Project Mood ,

760-468: The Video Music system's switch box featured a 75 Ohm pass-through F connector allowing the television antenna or cable to remain attached and thereby eliminating the tiresome process of detaching and reattaching the cable every time the user switched from watching normal television broadcasts to using the visualizer. Any audio source may be used for visualization including Atari's video game system audio, and visualizations can either be watched "live" on

800-402: The Video Music unit was designed by Robert Brown, a developer of the home version of Pong . According to Atari design engineer, Al Alcorn , when Atari was on tour promoting the device, a Sears representative asked what the developers were smoking when they invented it. With that, a technician stepped forward holding up a lit joint . In March 1978, the unit was described in a patent under

840-413: The circuit are not negligible, then their effects can be modelled by adding mutual inductance elements. In the case of a physical inductor though, the ideal lumped representation is often accurate. This is because the external fields of inductors are generally negligible, especially if the inductor has a closed magnetic path . If external fields are negligible, we find that is path-independent, and there

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880-431: The device with respect to a common reference point (or ground ). The voltage drop is the difference between the two readings. Two points in an electric circuit that are connected by an ideal conductor without resistance and not within a changing magnetic field have a voltage of zero. Any two points with the same potential may be connected by a conductor and no current will flow between them. The voltage between A and C

920-446: The electric field in the region exterior to each component is conservative, and voltages between nodes in the circuit are well-defined, where as long as the path of integration does not pass through the inside of any component. The above is the same formula used in electrostatics. This integral, with the path of integration being along the test leads, is what a voltmeter will actually measure. If uncontained magnetic fields throughout

960-428: The electric field, rather than to differences in electric potential. In this case, the voltage rise along some path P {\displaystyle {\mathcal {P}}} from r A {\displaystyle \mathbf {r} _{A}} to r B {\displaystyle \mathbf {r} _{B}} is given by: However, in this case the "voltage" between two points depends on

1000-413: The following, where t {\displaystyle t} is time , λ {\displaystyle \lambda } is wavelength , a {\displaystyle a} is amplitude and ϕ {\displaystyle \phi } is phase : The Fourier series describes the decomposition of periodic waveforms, such that any periodic waveform can be formed by

1040-516: The left audio channel while the right channel is represented by the inner part. Varying colors and shapes provide a wide variety of patterns, designs, and images depending on the audio sample played. After the unit is powered on, a toggle switch may be used to select between "TV" (music visualization inactive), and "Game" (music visualization active). When in the "Game" position, visual data is broadcast on VHF channel 3 by default, but may be set to channel 4 . Unlike Atari's previous video game systems,

1080-508: The name "Audio activated video display". It is considered to have been commercially unsuccessful and production was discontinued after only one year on the market. The Video Music system was reviewed in Video magazine as part of a special "VideoTest Report" in 1978. The reviewers gave it mild but positive coverage, describing it as "a well-constructed machine and an interesting component to be used as an adjunct to stereo sound," but warning that "once

1120-471: The novelty wears off the display can become somewhat monotonous." The same report recommended it for "those who find it relaxing, stimulating, or therapeutic to watch psychedelic displays ." Waveform In electronics , acoustics , and related fields, the waveform of a signal is the shape of its graph as a function of time, independent of its time and magnitude scales and of any displacement in time. Periodic waveforms repeat regularly at

1160-407: The other will be able to do work, such as driving a turbine . Similarly, work can be done by an electric current driven by the potential difference provided by a battery . For example, the voltage provided by a sufficiently-charged automobile battery can "push" a large current through the windings of an automobile's starter motor . If the pump is not working, it produces no pressure difference, and

1200-424: The path taken. In circuit analysis and electrical engineering , lumped element models are used to represent and analyze circuits. These elements are idealized and self-contained circuit elements used to model physical components. When using a lumped element model, it is assumed that the effects of changing magnetic fields produced by the circuit are suitably contained to each element. Under these assumptions,

1240-697: The phrase " high tension " (HT) which is commonly used in thermionic valve ( vacuum tube ) based and automotive electronics. In electrostatics , the voltage increase from point r A {\displaystyle \mathbf {r} _{A}} to some point r B {\displaystyle \mathbf {r} _{B}} is given by the change in electrostatic potential V {\textstyle V} from r A {\displaystyle \mathbf {r} _{A}} to r B {\displaystyle \mathbf {r} _{B}} . By definition, this is: where E {\displaystyle \mathbf {E} }

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1280-430: The points across which the voltage is measured. When using a voltmeter to measure voltage, one electrical lead of the voltmeter must be connected to the first point, one to the second point. A common use of the term "voltage" is in describing the voltage dropped across an electrical device (such as a resistor). The voltage drop across the device can be understood as the difference between measurements at each terminal of

1320-414: The presence of time-varying fields. However, unlike in electrostatics, the electric field can no longer be expressed only in terms of the electric potential. Furthermore, the potential is no longer uniquely determined up to a constant, and can take significantly different forms depending on the choice of gauge . In this general case, some authors use the word "voltage" to refer to the line integral of

1360-415: The same frequency and phase. Instruments for measuring voltages include the voltmeter , the potentiometer , and the oscilloscope . Analog voltmeters , such as moving-coil instruments, work by measuring the current through a fixed resistor, which, according to Ohm's law , is proportional to the voltage across the resistor. The potentiometer works by balancing the unknown voltage against a known voltage in

1400-527: The sum of a (possibly infinite) set of fundamental and harmonic components. Finite-energy non-periodic waveforms can be analyzed into sinusoids by the Fourier transform . Other periodic waveforms are often called composite waveforms and can often be described as a combination of a number of sinusoidal waves or other basis functions added together. Voltage Voltage , also known as (electrical) potential difference , electric pressure , or electric tension

1440-465: The symbol U is standardized. It is used, for instance, in the context of Ohm's or Kirchhoff's circuit laws . The electrochemical potential is the voltage that can be directly measured with a voltmeter. The Galvani potential that exists in structures with junctions of dissimilar materials is also work per charge but cannot be measured with a voltmeter in the external circuit (see § Galvani potential vs. electrochemical potential ). Voltage

1480-401: The turbine will not rotate. Likewise, if the automobile's battery is very weak or "dead" (or "flat"), then it will not turn the starter motor. The hydraulic analogy is a useful way of understanding many electrical concepts. In such a system, the work done to move water is equal to the " pressure drop" (compare p.d.) multiplied by the volume of water moved. Similarly, in an electrical circuit,

1520-400: The voltage between two points in a system. Often a common reference potential such as the ground of the system is used as one of the points. In this case, voltage is often mentioned at a point without completely mentioning the other measurement point. A voltage can be associated with either a source of energy or the loss, dissipation, or storage of energy. The SI unit of work per unit charge

1560-465: The work done to move electrons or other charge carriers is equal to "electrical pressure difference" multiplied by the quantity of electrical charges moved. In relation to "flow", the larger the "pressure difference" between two points (potential difference or water pressure difference), the greater the flow between them (electric current or water flow). (See " electric power ".) Specifying a voltage measurement requires explicit or implicit specification of

1600-612: Was first used by Volta in a letter to Giovanni Aldini in 1798, and first appeared in a published paper in 1801 in Annales de chimie et de physique . Volta meant by this a force that was not an electrostatic force, specifically, an electrochemical force. The term was taken up by Michael Faraday in connection with electromagnetic induction in the 1820s. However, a clear definition of voltage and method of measuring it had not been developed at this time. Volta distinguished electromotive force (emf) from tension (potential difference):

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