DICTIONARY OF ELECTRONICS

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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: 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°

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