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SENSITIVITY—(1) For an ammeter, the amount of current that will cause full-scale deflection of the
meter. (2) For a voltmeter, the ratio of the voltmeter resistance divided by the full-scale reading of the
meter; expressed in ohms per volt [3] [16]. (3) The ability of a receiver to reproduce very weak signals.
The greater the receiver sensitivity, the weaker the signal that can be reproduced [17]. (4) Efficiency of
a microphone. Describes microphone power delivered to a matched-impedance load as compared to the
sound level being converted. Usually expressed in terms of the electrical power level [12].
SENSITIVITY TIME CONTROL (STC)—A circuit that varies the gain of a receiver as a function of time
[18].
SERIES CIRCUIT—An arrangement where electrical devices are connected so that the total current must
flow through all the devices; electrons have one path to travel from the negative terminal to the positive
terminal [1].
SERIES-CONNECTED DUPLEXER—A configuration in which the tr spark gap is connected in series in
one leg of the transmission line one-half wavelength away from the T-junction [18].
SERIES-DIODE DETECTOR—The semiconductor diode in series with the input voltage and the load
impedance. Sometimes called a VOLTAGE-DIODE DETECTOR [12].
SERIES-FED OSCILLATOR—An oscillator in which dc power is supplied to the amplifier through the
tank circuit or a portion of the tank circuit [9].
SERIES LIMITER—A diode connected in series with the output, in which the output is taken across the
resistor. Either the positive or negative alternation of the input wave is eliminated [9].
SERIES-NEGATIVE LIMITER—A diode connected in series with the output, in which the output is
taken across the resistor. It eliminates the negative alternation of the input wave [9].
SERIES-PARALLEL CIRCUIT—A circuit that consists of both series and parallel networks [1] [9].
SERIES PEAKING—A technique used to improve high-frequency response in which a peaking coil is
placed in series with the output signal path [8].
SERIES-POSITIVE LIMITER—A diode connected in series with the output, in which the output is taken
across a resistor. It eliminates the positive alternation of the input wave [9].
SERIES-RESONANT CIRCUIT—A resonant circuit in which the source voltage is connected in series
with a capacitor and an inductor (also in series) to furnish a low impedance at the frequency at which
the circuit is resonant [9] [10].
SERIES VOLTAGE REGULATOR—A regulator with a regulating device that is in series with the load
resistance [7].
SERIES-WOUND MOTORS AND GENERATORS—Machines in which the armature and field
windings are connected in series with each other [5].
SERVOAMPLIFIER—Either ac or dc amplifiers used in servosystems to build up signal strength. These
amplifiers usually have relatively flat gain versus frequency response, minimum phase shift, low output
impedance, and low noise level [15].
SERVOMOTOR—An ac or dc motor used in servosystems to move a load to a desired position or at a
desired speed. The ac motor is usually used to drive light loads at a constant speed, while the dc motor
is used to drive heavy loads at varying speeds [15].
