- Industry: Aviation
- Number of terms: 16387
- Number of blossaries: 0
- Company Profile:
Aviation Supplies & Academics, Inc. (ASA) develops and markets aviation supplies, software, and books for pilots, flight instructors, flight engineers, airline professionals, air traffic controllers, flight attendants, aviation technicians and enthusiasts. Established in 1947, ASA also provides ...
A semiconductor device used as an electrically controlled switch. Two of the most widely used thyristors are silicon controlled rectifiers (SCRs) and triacs. An SCR is a semiconductor device that does not normally allow electrons to flow through it in either direction. However, if a pulse of voltage of the correct polarity is applied to a third electrode, the gate, the SCR conducts in its forward direction.
The SCR continues to conduct until the voltage across it drops to zero. Once electrons stop flowing through it, the SCR remains shut off until another pulse of voltage is applied to its gate. The triac begins to conduct when a pulse of voltage of either polarity is applied to its gate. Once conducting, it can be turned off only by reducing the voltage across it to a value low enough to stop the current flowing through it.
Industry:Aviation
A semiconductor device whose electrical resistance varies with its temperature. The resistance of a thermistor material decreases as its temperature increases. Thermistor materials are used in fire detection systems. When the thermistor is cold, its resistance is high, but when it is heated in a fire, its resistance drops enough to operate the fire warning system.
Industry:Aviation
A semiconductor diode doped with a larger amount of impurity than is used in an ordinary diode. A tunnel diode has a negative resistance region. Forward current increases with an increase in forward voltage until peak current is reached. At this point, forward current decreases with an increase in forward voltage until a valley is reached. This region of decreasing forward current, with an increase in forward voltage, is called the negative resistance region. Tunnel diodes are used as high-speed switching diodes.
Industry:Aviation
A semiconductor diode having a layer of P-silicon and a layer of N-silicon. Between these two layers is a thin layer of undoped silicon called intrinsic silicon. PIN diodes are used in high-frequency switching circuits because of their ability to turn on and off at an extremely fast rate.
Industry:Aviation
A semiconductor diode whose ability to conduct in a forward direction is determined by the amount of light falling on the PN junction.
Industry:Aviation
A semiconductor diode whose conduction characteristics change when its PN junction is exposed to light. A photodiode in total darkness acts as an open circuit; no current can flow.
Industry:Aviation
A semiconductor material, either silicon or germanium, that has been doped with a few parts per million of an impurity atom having three electrons in its valence shell.
Boron, aluminum, gallium, and indium are elements used to dope silicon and germanium to make P-type material.
Industry:Aviation
A semiconductor used as a triggering device for a triac. A diac acts in much the same way as two zener diodes installed back to back, with one forward biased and the other reverse biased. No current can flow through the diac until the breakdown voltage of the reverse-biased diode is reached. When this breakdown voltage is reached, the diac immediately turns on and allows the gate current for the triac to flow.
Industry:Aviation
A semifinished mass of steel formed from an ingot in the process of being rolled into a billet.
Industry:Aviation
A semipermanent, semicontinuous front, separating air masses of tropical and polar origins.
Industry:Aviation
