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grid

 
(grĭd) pronunciation
n.
    1. A framework of crisscrossed or parallel bars; a grating or mesh.
    2. A cooking surface of parallel metal bars; a gridiron.
  1. Something resembling a framework of crisscrossed parallel bars, as in rigidity or organization: The city's streets form a grid.
  2. A pattern of regularly spaced horizontal and vertical lines forming squares on a map, a chart, an aerial photograph, or an optical device, used as a reference for locating points.
  3. Electricity.
    1. An interconnected system for the distribution of electricity or electromagnetic signals over a wide area, especially a network of high-tension cables and power stations.
    2. A corrugated or perforated conducting plate in a storage battery.
    3. A network or coil of fine wires located between the plate and the filament in an electron tube.
  4. Football. The gridiron.
  5. Sports. The starting positions of cars on a racecourse.
  6. Printing. A device in a photocomposition machine on which the characters used in composition are etched.

[Short for GRIDIRON.]

gridded grid'ded adj.

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(1) Any interconnected set of nodes such as the electric power network or a communications network.

(2) "The Grid" is a nickname for Internet2. See Internet2.

(3) In a vacuum tube or gas-filled electron tube, the grid is a perforated electrode through which electrons may pass. The term typically refers to the control grid in a triode, tetrode or pentode vacuum tube. In these cases, the grid is used to control the amount of current flow between the cathode and plate (anode). As the voltage potential is varied on the control grid, the amount of current allowed to pass through also varies. Relatively small fluctuations in the grid's potential can control substantially larger amounts of current flow through the tube. This phenomenon is referred to as "gain." Tetrodes and pentodes use additional grids to regulate current flow and effect gain. See screen grid and suppressor grid.

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A pattern of intersecting horizontal and vertical lines. In word processing tables, the grid, which represents cell borders, can be displayed or hidden. In graphics programs, users can choose to enable or disable the “snap to grid” feature. When it is turned on, objects are automatically aligned with the nearest horizontal and/or vertical line of the grid. Grid intervals can usually be set by the user.

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1. See gridiron.
2. See grillage.
3. In surveying, closely-spaced reference lines which are perpendicular to each other; elevations usually are taken at the intersections of these lines.


(DOD) 1. Two sets of parallel lines intersecting at right angles and forming squares; the grid is superimposed on maps, charts, and other similar representations of the Earth's surface in an accurate and consistent manner in order to permit identification of ground locations with respect to other locations and the computation of direction and distance to other points. 2. A term used in giving the location of a geographic point by grid coordinates. See also military grid; military grid reference system.

i. The system of two sets of parallel lines uniformly spaced and crossing at 90° to each other to form a pattern of squares. This grid is designed so that any point on the map can be designated by its latitude and longitude or by its grid coordinates, and a reference in one system can be converted into a reference in another system. Such grids are usually identified by the name of the particular projection for which they are designated. See universal transverse Mercator’s grid.
ii. The electrodes in an electron tube between the cathode and the anode that permit and direct the passage of electrons or ions.
iii. Two sets of mutually perpendicular lines dividing a map or chart into squares or rectangles to permit the location of any point by a system of rectangular coordinates as in a military grid, world geographic reference system, or GEOREFF. See GEOREFF.

A GEOREFF grid. This is superimposed on map.


A GEOREFF grid. This is superimposed on map.

iv. Pertaining to or measured from a reference grid, such as a grid azimuth, grid latitude, or grid meridian.

noun
noun

A bicycle. (1922 —) .
Coast to Coast 1942 'I'll walk and wheel the bike, and if my dad's home he can drive out in the car to meet me.' 'Gosh, no!' you said. 'Here, you go on, on my grid, an' I'll do the walking' (1943).



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Control grid

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The control grid is an electrode used in thermionic valves (vacuum tubes) used to modulate the flow of electrons in the cathode to anode or plate circuit.

Contents

Operation

A relatively small variation in voltage on the control grid causes a significantly large variation in anode current. The presence of a resistor in the anode circuit causes a large variation in voltage to appear at the anode. Thus the device will function as an amplifier.

The addition of just a single control grid to a diode valve produces a triode.

Construction

The grid in the first triode valve consisted of a zig-zag piece of wire placed between the filament and the anode. This quickly evolved into a helical grid placed between a single strand filament (or later, a cylindrical cathode) and a cylindrical anode. The grid is usually made of a very thin wire that can resist high temperatures and is not prone to emitting electrons itself. Molybdenum alloy with a gold plating is frequently used. It is wound on soft copper sideposts, which are swaged over the grid windings to hold them in place. A 1950s variation is the frame grid, which winds very fine wire onto a rigid stamped metal frame. This allows the holding of very close tolerances, so the grid can be placed closer to the filament (or cathode).

Effects of grid position

By placing the control grid closer to the filament/cathode relative to the anode, a greater amplification results. This degree of amplification is referred to in valve data sheets as the amplification factor. It also results in higher transconductance, which is a measure of the anode current change versus grid voltage change. The noise figure of a valve is inversely proportional to its transconductance; higher transconductance generally means lower noise figure. Lower noise can be very important when designing a radio or television receiver.

Multiple control grids

A valve can contain more than one control grid. The hexode contains two such grids, one for a received signal and one for the signal from a local oscillator. The valve's inherent non-linearity causes not only both original signals to appear in the anode circuit, but also the sum and difference of those signals. This can be exploited as a frequency-changer in superheterodyne receivers.

Grid variations

A variation of the control grid is to produce the helix with a variable pitch. This gives the resultant valve a distinct non-linear characteristic. This is often exploited in R.F. amplifiers where an alteration of the grid bias changes the mutual conductance and hence the gain of the device. This variation usually appears in the pentode form of the valve, where it is then called a variable-mu pentode or remote-cutoff pentode.

One of the principal limitations of the triode valve is that there is a capacitance between the grid and the anode. A phenomenon known as the Miller Effect causes this capacitance to be magnified in proportion to the amplification factor of the valve. This can severely limit the upper operating frequency. This can be overcome by the addition of a screen grid, however in the later years of the tube era, constructional techniques were developed that rendered this 'parasitic capacitance' so low that triodes operating in the upper VHF bands became possible. The Mullard EC91 operated at up to 250 MHz.

References

  • [1] (regarding variable mu)

Translations:

Grid

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Dansk (Danish)
n. - rist, skelet, net, gitter, linienet
v. tr. - opdele i felter

idioms:

  • starting grid    startområde

Nederlands (Dutch)
rooster, wildrooster, startplaatsen (autorace), rek, raster, netwerk van elektra-/ gasvoorzieningen

Français (French)
n. - grille, (gén, Géog) quadrillage, (GB) réseau, grille de départ, (Électron) grille, (US) terrain de football américain
v. tr. - quadriller

idioms:

  • starting grid    grille de départ

Deutsch (German)
n. - Gitter, Rost, Netz
v. - eingittern, mit einem Gitter versehen

idioms:

  • starting grid    Startplatz

Ελληνική (Greek)
n. - πλέγμα, σχάρα, δικτύωμα, δικτυωτό, δίκτυο, ηλεκτρικό δίκτυ

idioms:

  • starting grid    αρχικό πλέγμα

Italiano (Italian)
reticolato, rete

idioms:

  • starting grid    posizioni di partenza (in una competizione)

Português (Portuguese)
n. - grade (f), grelha (f), placa (f) de acumulador (Eletr.)

idioms:

  • starting grid    grade (m) de largada (Desp.)

Русский (Russian)
решетка, координатная сетка, сеть электропередач, энергосистема, вещательная сеть

idioms:

  • starting grid    место старта автомобильных гонок

Español (Spanish)
n. - enrejado, reja, rejilla, verja, red, cuadrícula, parrilla
v. tr. - poner rejas o parrillas

idioms:

  • starting grid    línea de salida en una carrera automovilística, grilla de partida

Svenska (Swedish)
n. - galler, (kraft)ledningsnät, galler (elektr. el. radio), rutor, bagagehållare, stålskelett (byggn.)

中文(简体)(Chinese (Simplified))
格子, 烤架, 铁丝网, 极板网栅, 画格子

idioms:

  • starting grid    汽车比赛的发车点排列

中文(繁體)(Chinese (Traditional))
n. - 格子, 烤架, 鐵絲網, 極板網柵
v. tr. - 畫格子

idioms:

  • starting grid    汽車比賽的發車點排列

한국어 (Korean)
n. - 격자, 격자 눈금, 미식 축구 경기장
v. tr. - 격자 모양을 만들다

日本語 (Japanese)
n. - 格子, 格子状荷台, グリッド, 焼き網, 鉄灸

idioms:

  • starting grid    グリッド

العربيه (Arabic)
‏(الاسم) شبك من القضبان الحديديه او الخشبيه, شبكه خطوط‏

עברית (Hebrew)
n. - ‮רשת ריבועים במפה, סריג, שבכה, סורג, רשת קווי חשמל, אספקת גז וכו', אסכלה, רשת רחובות מלבנית, מגרש לכדורגל אמריקאי, אלקטרודה המעבירה זרם חשמלי בין אלקטרודות אחרות‬
v. tr. - ‮שרטט רשת ריבועים על‬


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grid

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Math
mathworld.wolfram.com
 
 
 
Related topics:
Potter-Bucky grid
grid heading (navigation)
grid latitude (navigation)

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