Parallel resonant circuit
containing only a coil and a
capacitor. Both the coil and
capacitor store electrical
energy for part of each cycle.
tantalum capacitor
Electrolytic capacitor having a
tantalum foil anode. Able to
have a large capacity in a small
package.
tap
Electrical connection to some
point other than at the ends of
a resistor or inductor.
tapered
Nonunifrom distribution of
resistance per unit length
throughout the element of a
potentiometer.
technician
Expert in troubleshooting
circuit and system malfunctions.
Along with a thorough knowledge
of test equipment and how to use
it to diagnose problems, the
technician is also familiar with
how to repair or replace faulty
components. Technicians
basically translate theory into
action.
telegraphy
Communication between two points
by sending and receiving a
series of current pulses either
through wire or by radio.
telemetry
Transmission of instrument
readings to a remote location
either by wire or by radio.
telephone
Apparatus designed to convert
sound waves into electrical
waves which are sent to and
reproduced data distant point.
telephone line
Wires existing between
subscribers and central stations
in a telephone system.
telephony
Telecommunications system
involving the transmission of
speech information, allowing two
or more persons to communicate
verbally.
teletypewriter
Electric typewriter that like a
teleprinter can produce coded
signals corresponding to the
keys pressed or print characters
corresponding to the coded
signals received.
television
System that converts both audio
and visual information into
corresponding electrical signals
which are then transmitted
through wires or by radio waves
to a receiver which reproduces
the original information.
telex
Teletypewriter exchange service.
temperature coefficient
of frequency
Rate at which frequency changes
with temperature.
tera
(T) Metric prefix that
represents 1012.
terminal
Point at which electrical
connections are made.
tesla
(T) Unit of magnetic flux
density. (1 tesla = 1 Wb/m2).
test
Sequence of operations intended
to verify the correct operation
or malfunctioning of a piece of
equipment or system.
thermal relay
Relay activated by a heating
element.
thermal runaway
Problem that can develop in an
amplifier when an increase in
temperature causes an increase
in collector current. The
increase in collector current
causes a further increase in
temperature and so on. Unless
the circuit is designed to
prevent this condition, the
device can be driven into
saturation.
thermal stability
The ability of a circuit to
maintain stable characteristics
in spite of increased
temperature.
thermistor
Temperature sensitive
semiconductor that has a
negative temperature coefficient
of resistance. As temperature
increases, resistance decreases.
thermocouple
Temperature transducer
consisting of two dissimilar
metals welded together at one
end to form a junction that when
heated will generate a voltage.
thermometry
Relating to the measuring of
temperature.
thermostat
Device that opens or closes a
circuit in response to changes
in temperature.
Thevenin's theorem
Theorem that replaces any
complex network with a single
voltage source in series with a
single resistance.
thick-film capacitor
Capacitor consisting of two
thick-film layers of conductive
film separated by a deposited
thick-layer dielectric film.
thick film resistor
Fixed value resistor consisting
of thick-film resistive element
made from metal particles and
glass powder.
thin film capacitor
Capacitor in which both the
electrodes and the dielectric
are deposited in layers on a
substrate.
thin film detector
(TFD) A temperature detector
containing a thin layer of
platinum and used for precise
temperature readings.
three phase supply
AC supply that consists of three
AC voltages 120° out of phase
with each other.
threshold
Minimum point at which an effect
is produced or detected.
threshold voltage
For an enhancement MOSFET, the
minimum gate source voltage
required for conduction of
source drain current.
thyristor
A term used to classify all four
layer semiconductor devices.
SCRs and triacs are examples of
thyristors.
time constant
(t) Time required for a
capacitor in an RC circuit to
charge to 63% of the remaining
potential across the circuit.
Also time required for current
to reach 63% of maximum value in
an RL circuit. Time constant of
an RC circuit is the product of
R and C. Time constant of an RL
circuit is equal to inductance
divided by resistance.
time division
multiplexing
(TDM) Transmission of two or
more signals on the same path,
but at different times.
time-domain analysis
A method of representing a
waveform by plotting amplitude
over time.
toggle switch
Spring loaded switch that is put
in one of two positions either
on or off.
tolerance
Permissible deviation from a
specified value normally
expressed as a percentage.
TO package
Cylindrical, metal can type of
package of some semiconductor
components.
toroidal coil
Coil wound on a doughnut shaped
core.
transconductance
Also called mutual conductance.
Ratio of a change in output
current to the change in input
voltage that caused it.
transducer
Device that converts energy from
one form to another.
transformer
Inductor with two or more
windings. Through mutual
inductance, current in one
winding called a primary will
induce current into the other
windings called secondaries.
transformer coupling
Also called inductive coupling.
Coupling of two circuits by
means of mutual inductance
provided by a transformer.
transistor
Term derived from "transfer
resistor." Semiconductor device
that can be used as an amplifier
or as an electronic switch.
transmission
Sending of information.
transmission line
Conducting line used to transmit
signal energy between two
points.
transmitter
Equipment used to achieve
transmission.
triac
Bidirectional gate controlled
thyristor similar to an SCR, but
capable of conducting in both
directions. Provides full wave
control of AC power.
triangular wave
A repeating wave that has equal
positive going and negative
going ramps. The ramps have
linear rates of change with
time.
trigger
Pulse used to initiate a circuit
action.
triggering
Initiation of an action in a
circuit which then functions for
a predetermined time. Example:
The duration of one sweep in a
cathode ray tube.
trimmer
Small value variable capacitor,
resistor or inductor used to
fine tune a larger value.
trivalent element
One having three valence
electrons. Used as an impurity
in semiconductor material to
produce p-type material. Most
commonly used trivalent elements
are: Aluminum, Gallium and
Boron.
troubleshooting
Systematic approach to locating
the cause of a fault in an
electronic circuit or system.
tuned circuit
Circuit that can have its
component values adjusted so
that it responds to one selected
frequency and rejects all
others.
tunnel diode
Heavily doped junction diode
that has negative resistance in
the forward direction of its
operating range.
turn-off time
Sum of storage time and fall
time.
turn-on time
Sum of delay time and rise time.
turns ratio
Ratio of the number of turns in
the secondary winding of a
transformer to the number of
turns in the primary winding.
two phase
Two repeating waveforms having a
phase difference of 90°
