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) The ability of a receiver to reproduce very weak signals.
The greater the receiver sensitivity, the weaker the signal that can be reproduced . (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 .
SENSITIVITY TIME CONTROL (STC)A circuit that varies the gain of a receiver as a function of time
SERIES CIRCUITAn 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
SERIES-CONNECTED DUPLEXERA 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 .
SERIES-DIODE DETECTORThe semiconductor diode in series with the input voltage and the load
impedance. Sometimes called a VOLTAGE-DIODE DETECTOR .
SERIES-FED OSCILLATORAn oscillator in which dc power is supplied to the amplifier through the
tank circuit or a portion of the tank circuit .
SERIES LIMITERA 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 .
SERIES-NEGATIVE LIMITERA 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 .
SERIES-PARALLEL CIRCUITA circuit that consists of both series and parallel networks  .
SERIES PEAKINGA technique used to improve high-frequency response in which a peaking coil is
placed in series with the output signal path .
SERIES-POSITIVE LIMITERA 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 .
SERIES-RESONANT CIRCUITA 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  .
SERIES VOLTAGE REGULATORA regulator with a regulating device that is in series with the load
SERIES-WOUND MOTORS AND GENERATORSMachines in which the armature and field
windings are connected in series with each other .
SERVOAMPLIFIEREither 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 .
SERVOMOTORAn 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 .