Electronic Engineering Dictionary

Ambient Noise Level. The level of acoustic noise existing at a given location, such as in a room, in a compartment, or at a place out of doors.

Ambient Temperature. The temperature of the air or liquid surrounding any object. The surrounding temperature such as the temperature of air surrounding a conductor in a compartment or within a piece of equipment. Ambient temperature is the air temperature measured below a [semiconductor] device, in an environment of substantially uniform temperature, cooled only by natural air convection, and not materially affected by reflective and radiant surfaces.

American Wire Gauge. [AWG] The standards adopted in the United States for the measurement of wire sizes. AWG Chart

Ammeter. An instrument for measuring the amount of electron flow (in amperes). The instrument may measure direct current flow, alternating current flow or both depending on its construction. [Companies that produce Test Equipment]

Ampacity. Current-carrying capacity of electric conductors expressed in amperes [see AWG Copper Wire table]. The current in amperes that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Also refer to the AWG Aluminum Wire table for conductor ampacity. The maximum amount of current a wire can carry safely without overheating

Amperage. The strength of an electrical current, measured in amperes

Ampere. The basic unit of electrical current. Applying one volt across a one ohm resistor will cause a current of one ampere to flow. The letter 'I' is used to denote current.

Ampere-Hour. [Ah] Defined as a current of one ampere flowing for one hour. Multiply the current in amperes by the time of flow in hours, the result is the total number of ampere-hours. Quantity of electricity or measure of charge. (1 Ah = 3600 C [Coulomb]).

Ampere-Turn. [At] The magnetomotive force developed by 1 ampere of current flowing through a coil of one turn. Ampere-Turns is the the current times the number of wire turns in a coil.

Amperite [Ballast] Tube. A current-controlling resistance device designed to maintain substantially constant current over a specified range of variation in applied voltage or resistance of a series circuit.

Amplidyne. A DC generator in which a small dc voltage applied to field windings controls a large output voltage from the generator. In effect, an amplidyne is a rotary amplifier that often times produces gain of approximately 10,000.

Amplification. The process of increasing a signal in amplitude (as of voltage or current). The ratio of output magnitude to input magnitude in a device that is intended to produce an output that is an enlarged reproduction of its input.

Amplification Factor. The voltage gain of an amplifier with no load on the output.

Amplifier. The device that provides amplification (the increase in current, voltage, or power of a signal) without appreciably altering the original signal. Refer here for Transistor Amplifier Circuits. An electronic component that boosts the voltage or power level of a signal that is a linear replica of the input signal, but with greater power or voltage level, and sometimes with an impedance transformation.

Amplifier Types

Amplifier Nonlinearity. The inability of an amplifier to reproduce an output which is proportional to the input.

Amplitude. The size of a signal as measured from a reference line to a maximum value above or below the line. Generally used to describe voltage, current, or power. The magnitude of a signal quantity from its zero value.

Amplitude Distortion. Distortion that is present in an amplifier when the amplitude of the output signal fails to follow exactly any increase or decrease in the amplitude of the input signal. Distortion occurring in a system, subsystem, or device when the output amplitude is not a linear function of the input amplitude under specified conditions.

Amplitude Equalizer. A corrective network that is designed to modify the amplitude characteristics of a circuit or system over a desired frequency range.

Amplitude Equalization. The process of reducing frequency response distortion by the introduction of compensation networks to over come the differences in attenuation at various frequencies.

Amplitude Frequency Response. The variation in gain or attenuation of a system over frequency.

Amplitude Modulation. Any method of varying the amplitude of an electromagnetic carrier frequency in accordance with the intelligence to be transmitted. A modulation system which varies the amplitude of the carrier in step to the amplitude changes of a modulating signal.

Amplitude Modulation

Modulation in which the amplitude of a carrier wave is varied in accordance with some characteristic of the modulating signal. Note: Amplitude modulation implies the modulation of a coherent carrier wave by mixing it in a nonlinear device with the modulating signal to produce discrete upper and lower sidebands, which are the sum and difference frequencies of the carrier and signal. The envelope of the resultant modulated wave is an analog of the modulating signal. The instantaneous value of the resultant modulated wave is the vector sum of the corresponding instantaneous values of the carrier wave, upper sideband, and lower sideband. Recovery of the modulating signal may be by direct detection or by heterodyning.

Amplitude Modulator. A circuit which performs the function of modulating one signal with another to produce an AM signal. Read more about a Transistor Amplitude Modulator Circuit.

Amplitude Range. The upper and lower limits of amplification.

Amplitude Response. The maximum amplitude over a frequency range.

Amplitude Shift Keying. [ASK] Amplitude modulation of digital information.

Amplitude Stability. Amplitude stability refers to the ability of the oscillator to maintain a constant amplitude in the output waveform.

AM Receiver. A receiver that decodes an Amplitude Modulated signal to recover encoded information. Read more about how an AM Receiver functions, including a graphic.

AM Rejection Ratio. The ratio of the recovered audio output produced by a desire FM signal of specified level and duration to the recovered audio output produced by an unwanted AM signal of specified amplitude and modulating index.

AM Suppression. Refer to AM Rejection Ratio.