diode

/duy"ohd/, n. Electronics.
a device, as a two-element electron tube or a semiconductor, through which current can pass freely in only one direction.
[1919; DI-1 + -ODE2]

* * *

Electronic device that has two electrodes (anode and cathode) and that allows current to flow in only one direction, resisting current flow in the other.

An applied voltage can cause electrons to flow in only one direction, from the cathode to the anode, and then back to the cathode through an external circuit. Diodes are used especially as rectifiers
and to vary the amplitude of a signal in proportion to the voltage in a circuit, as in a radio or television receiver. The most familiar diodes are vacuum tubes and semiconductor diodes. Semiconductor diodes, the simplest of semiconductor devices, consist of two electrodes and a sandwich of two dissimilar semiconducting substances (a p-n junction). Such diodes form the basis for more complex semiconductor devices (including transistors) used in computers and other electronic equipment. Semiconductor diodes include light-emitting diodes and laser diodes; the latter emit laser light, useful for telecommunications via fibre optics and for reading compact discs.

* * *

      evacuated glass or metal electron tube containing two electrodes—a negatively charged cathode and a positively charged anode. It is used as a rectifier and as a detector in electronic circuits such as radio and television receivers. When a positive voltage is applied to the anode (or plate), electrons emitted from the heated cathode flow to the plate and return to the cathode through an external power supply. If a negative voltage is applied to the plate, electrons cannot escape from the cathode, and no plate current flows. Thus, a diode permits electrons to flow from cathode to plate but not from plate to cathode. If an alternating voltage is applied to the plate, current flows only during the time when the plate is positive. The alternating voltage is said to be rectified, or converted to direct current (DC).

 In the indirectly heated cathode type of tube shown in the illustration—>, the electron source consists of a metallic cylinder, usually nickel, coated with a good electron emitter, such as a mixture of barium and strontium oxides. The heat is provided by a coil of wire (heater) located inside the cylinder but insulated from it. In the directly heated cathode, the heater wire itself serves as the source of electrons and is referred to as the filament.

      Solid-state rectifier devices, which permit current flow in only one direction and which have largely replaced the vacuum type, are also frequently referred to as diodes.

* * *


Universalium. 2010.

Look at other dictionaries:

  • diode — diode …   Dictionnaire des rimes

  • diode — [ djɔd ] n. f. • 1932; de di et ode; cf. cathode ♦ Techn. Composant électronique redresseur de courant alternatif. ⇒ valve. Électron. Tube électronique à deux électrodes (⇒ anode, cathode). Diode à gaz, pour le redressement de puissance. Diode à… …   Encyclopédie Universelle

  • diode — 1886, from Gk. di twice + hodos way (see CEDE (Cf. cede)) …   Etymology dictionary

  • diode — ► NOUN Electronics 1) a semiconductor device with two terminals, typically allowing the flow of current in one direction only. 2) a thermionic valve with two electrodes. ORIGIN from DI (Cf. ↑di ) + a shortened form of ELECTRODE(Cf. ↑electrode) …   English terms dictionary

  • diode — [dī′ōd΄] n. [ DI 1 + ODE1] an electronic device with two electrodes, as either an electron tube with an anode and a cathode or a transistor with a pn junction, used mainly as a rectifier since it conducts current in only one direction …   English World dictionary

  • Diode — Figure 1: Closeup of a diode, showing the square shaped semiconductor crystal (black object on left) …   Wikipedia

  • Diode — La diode (du grec di deux, double ; hodos voie, chemin) est un composant électronique. C est un dipôle non linéaire et polarisé (ou non symétrique). Le sens de branchement de la diode a donc une importance sur le fonctionnement du circuit… …   Wikipédia en Français

  • Diode — Schaltzeichen einer Diode und Abbildungen üblicher Gehäuse mit Markierung der Kathode. Kennzeichnung der positiven (+) und negativen (−) Seite bei Beschaltung in Durchlassrichtung. Eine Diode ist ein elektrisches Bauelement, das Strom nur in… …   Deutsch Wikipedia

  • Diode — Zweipolröhre; Vakuumdiode; ungesteuerter Gleichrichter; Röhrendiode * * * Di|o|de 〈f. 19; El.〉 früher eine Elektronenröhre, heute ein Halbleiterbauelement mit einer Grenzschicht zw. zwei Halbleitermaterialien zum Gleichrichten od. Richtungsleiten …   Universal-Lexikon

  • diode p-i-n — pin diodas statusas T sritis fizika atitikmenys: angl. intrinsic barrier diode; p i n diode vok. p i n Diode, f rus. p i n диод, m pranc. diode à barrière intrinsèque, f; diode p i n, f …   Fizikos terminų žodynas

  • Diode — diodas statusas T sritis automatika atitikmenys: angl. diode vok. Diode, f rus. диод, m pranc. diode, f …   Automatikos terminų žodynas

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.