THERMAL RUNAWAYA conduction that exists when heat causes more electron-hole pairs to be
generated, which, in turn, causes more heat and which may eventually cause diode destruction .
THERMAL TRIP ELEMENTA circuit breaker trip element that uses the increased bending of a
bimetallic strip caused by increased current to open a circuit .
THERMIONIC EMISSIONEmission of electrons from a solid body as a result of elevated temperature
THERMISTOR(1) A semiconductor device whose resistance varies with temperature . (2) A type of
bolometer characterized by a decrease in resistance as the dissipated power increases .
THERMOCOUPLEA junction of two dissimilar metals that produces a voltage when heated .
THERMOCOUPLE METER MOVEMENTA meter movement that uses the current induced in a
thermocouple by the heating of a resistive element to measure the current in a circuit; used to measure
ac or dc .
THERMOPLASTICA synthetic mixture of rosins that is flexible and used as an insulting material.
Generally used as an insulator for low- and medium-range voltages .
THETAThe Greek letter ( ) used to represent phase angle .
THICK FILM COMPONENTSPassive circuit components (resistors and capacitors) having a thickness
of 0.001 centimeter .
THIN FILM COMPONENTSPassive circuit elements (resistors and capacitors) deposited on a substrate
to a thickness of 0.0001 centimeter .
THREE-ELEMENT ARRAYAn array with two parasitic elements (reflector and director) and a driven
THREE-DIMENSIONAL RADAR (3D)A radar set that measures the range, bearing and altitudes of a
THROWIn a switch, the number of different circuits each pole can control; for example, single throw and
double throw .
THYRATRONA gas tube used as a modulator switching device .
THYRATRON TUBEA gas-filled triode in which a sufficiently large positive pulse applied to the
control grid ionizes the gas and causes the tube to conduct, after which the control grid has no effect in
conduction  .
TICKLER COILA small coil connected in series with the collector or plate circuit of a transistor or tube
and inductively coupled to the base or grid-circuit coil to establish feedback (regeneration) .
TIME CONSTANTTime required for an exponential quantity to change by an amount equal to 63.2
percent of the total change that can occur  .
TIME-DIVISION MULTIPLEXINGThe process that periodically samples the full 360 degrees of each
sine wave. The sample can be of a received signal or of a signal to be transmitted .