Definition of Terms used by Engineers
"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

'Aa' to 'Ac', 'Ad' to 'Af', 'Ag' to 'Al', 'Am',
'An' to 'Ao', 'Ap' to 'As', 'At' to 'Az',

A. The symbol for gain. Looking for Acronyms or Abbreviations.

Abort. To cut-off or stop an action.

Absolute Address. The location of a storage element.

Absolute Gain. The ratio of the signal level at the output of the device to that of its input under a specified set of operating conditions.

Absolute Maximum Rating. The electrical rating at or above which damage to the device will occur, to include supply voltage, input/ and output voltages and junction temperature [among others found in a data sheet]. Stress ratings that do not imply functional operation.

Absorption. Dissipation of radio or sound waves as they interact with matter. The absorbing of light waves without reflection or refraction.

Absorption, Law. In Boolean algebra, the law which states that the odd term will be absorbed when a term is combined by logical multiplication with the logical sum of that term and another term, or when a term is combined by logical addition with the logical product of one term and another term (for example, A(A + B) = A + AB = A).

Absorption Wavemeter. An instrument used to measure audio frequencies. Refer to Manufacturers of Test Equipment.

ABS Plastic. A type of plastic formed by Acrylonitrilt Butadiene Styrene and other chemicals. See [Fire Retardant Materials]

AB Switch. A device used to switch an incoming cable to either an 'A' output or 'B' output. Before the wide-spread introduction of dual output video cards, AB Switches were in common use with VGA outputs to switch from one monitor to another. However AB switches were produced to switch many types of cable interfaces, as in switching from one RS232 output to another, or switching between TV antennas as shown in the graphic to the right.

AC. See Alternating Current.

Accelerated Life Testing. A test used to subject a component, device or system to extreme conditions to determine the useful life of the device under test [DUT], which includes operating at elevated temperatures to simulate long term operation.

Accelerating Anode. An electrode charged several thousand volts positive and used to accelerate electrons toward the front of a Cathode-Ray Tube.

Acceleration Servosystem. A servo-system that controls the acceleration (rate of change in velocity) of a load.

Accelerometer. A device that measures the acceleration to which it is subjected and develops a signal proportional to it. Manufacturers of Accelerometers and other sensor vendors.

Acceptor Impurity. An impurity which, when added to a semiconductor, accepts one electron from a neighboring atom and creates a hole in the lattice structure of the crystal. Also called Trivalent Impurity.

Access Bus. Is a low speed 4-wire serial bus once used on Personal Computers. Access.Bus uses the I2C [IIC] bus as the electrical hardware interface. The Access bus has a maximum speed is 100kbps over a maximum cable distance of 10 meters, however a repeater may be used. The 4 wires of the interface bus are power/ground, Send Data [SDA] and Serial Clock [SCL]. Refer to the following page for a description of the Access Bus interface page.

Accessory. An assembly of a group of parts or a unit which is not always required for the operation of a set or unit as originally designed but serves to extend the functions or capabilities of the set, such as headphones for a radio set supplied with a loudspeaker, a separate power unit for use with a set having a built-in power supply, or a remote control unit for use with a set having integral controls.

Access Time. The difference in time between when data is requested and when data is delivered. The time lapsed between a given command and when the function is performed. The time for the [disk drive] access arm to reach the desired track and the delay for the rotation of the disk to bring the required sector under the read-write mechanism.

AC Coupling. The interconnection between two circuits through a capacitor, transformer or other device which passes AC voltage but blocks any DC component. C3 in the circuit to the right is a DC blocking capacitor.

AC Coupled Amplifier. An amplifier circuit that uses AC Coupling to block DC between amplifier stages. In the circuit to the right, C3 blocks the DC component of Q1 from effecting the operation of Q2. This circuit style is also called RC coupling, with the resistors also affecting the signal between stages. Same as DC Blocking.

Accumulator. A register that both stores a number and adds to other numbers loaded into the register.

AC generator. [Alternator] A rotating machine that converts mechanical energy into alternating current.

Acknowledge Character. [ACK] A transmission control character transmitted by the receiving station.

AC Line Voltage. See Line voltage.

Acorn Tube. A small tube, used in low power uhf circuits, with closely spaced electrodes and no base. The tube is connected to its circuits by short wire pins that are sealed in a glass or ceramic envelope. See the graphic below in the right side-bar.

Acoustic Noise. The unintended sound a component produces while operating. Some fields apply this to mean an audible sound, while other fields take it to mean any sound.

Acoustics. The science of sound.

Acoustic Wave. A sound wave.

AC Power Plug. A male connector designed to carry 120v or 240 volts. Also see Power Plug.

AC Resistance. The opposition to the flow of current with out regard to phase shift or complex impedance.

Acquisition. The process of acquiring synchronism.

Acquisition Time. In a communications system, the time interval required to attain [clock] synchronism.

Active Component. A component that draws current or some type of gain. Refer to Active Components.

Active Filter. A filter that uses an amplifier in addition to passive components. For example an Active Low Pass Filter Circuit.

Active High. Refers to a non-inverted output, the output is true when high and false when low. When the Sum-of-Products expression is true the output is high.

Active low. Refers to an inverted output, the output is true when low and false when high. When the Sum-of-Products expression is true the output is low.

Active Pullup. A transistor or FET used to pull a line high instead of a resistor. Active Pull-ups are common within ICs, but they are not designed to sink much current [weak pull-up].

Active Serial Interface. A term used with programming an FPGA. In the Active Serial [AS] configuration scheme, Altera FPGAs are configured with serial configuration devices. Also called Active Serial Mode, or Active Serial Scheme; where Active Serial may be Abbreviated as AS. Related terms include Passive Serial Interface, and JTAG Interface.

Actuating force. The force applied to the actuator to operate the contacts. The force required to operate a mechanical switch.

Actuator. The part of a switch that is acted upon to cause the switch to change contact connections; for example, toggle, pushbutton, and rocker. The mechanism of the switch or housing which, when moved as intended, will operate the contacts.

PC motherboard

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