tank circuit
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
Non uniform 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.