Time it takes the falling edge of a pulse to go from 90% of peak voltage to 10% of peak voltage.
farad
The basic unit of capacitance.
feedback
A portion of the output signal of an amplifier which is connected back to the input of the same amplifier.
feedback amplifier
An amplifier with an external signal path from its output back to its input.
ferrite
A powdered, compressed and sintered magnetic material having high resistivity. The high resistance makes eddy current losses low at high frequencies.
ferrite bead
Ferrite composition in the form of a bead. Running a wire through the bead increases the inductance of the wire.
ferrite-core inductor
An inductor wound on a ferrite core.
ferrites
Compound composed of iron oxide, a metallic oxide and ceramic. The metal oxides include zinc, nickel, cobalt or iron.
ferrous
Composed of and or containing iron. A ferrous metal exhibits magnetic characteristics as opposed to non-ferrous material.
fiber optics
Laser's light output carries information that is conveyed between two points by thin glass optical fibers.
field effect transistor
(FET) A voltage controlled transistor in which the source to drain conduction is controlled by gate to source voltage.
filament
Thin thread of carbon or tungsten which produces heat or light with the passage of current.
filter
Network consisting of capacitors, resistors and/or inductors used to pass certain frequencies and block others.
flip flop
A bistable multivibrator. A circuit which has two output states and is switched from one to the other by means of an external signal (trigger).
floating ground
Conmmon connection in a circuit that provides a return path for current but is not connected to an earth ground.
flow soldering
Flow or wave soldering technique in large scale electronic assembly to solder all the connections on a printed circuit board by moving the board over a wave of molten solder.
flux
Material used to remove oxide films from the surface of metals in preparation for soldering.
flux
In magnetism, the magnetic field consisting of lines of force.
flux density
The concentration of magnetic lines of force. Determines strength of the magnetic field.
flywheel effect
Sustaining effect of oscillation in anLC circuit.
forward bias
A PN junction bias which allows current to flow through the junction. Forward bias decreases the resistance of the depletion layer.
free electrons
Electrons that are not in any orbit around a nucleus.
free runing multivibrator
A multivibrator that produces a continuous output waveform without any signal input. A square wave generator used to produce a clock signal.
frequency
Rate of recurrence of a periodic wave. Measured in Hertz (cycles per second).
frequency meter
Meter used to measure frequency of periodic waves.
frequency multiplier
A harmonic conversion circuit in which the frequency of the output signal is an exact multiple of the input frequency.
frequency response
Indication of how well a circuit responds to different frequencies applied to it.
frequency response curve
A graph of amplitude over frequency indicating a circuit response to different frequencies.
frequency-division multiplex
(FDM) Transmission of two or more signals over a common path by using a different frequency band for each signal.
frequency-domain analysis
A method of representing a waveform by plotting its amplitude against frequency.
full scale deflection
(FDS) Deflection of a meter's pointer to the farthest position on the scale.
full wave rectifier
Rectifier that makes use of the full AC wave in both the positive and negative half cycles.
function generator
Signal generator that can produce sine, square, triangle and sawtooth output waveforms.
fundamental frequency
Lowest frequency in a complex waveform.
fuse
A protective device in the current path that melts or breaks when current exceeds a predetermined maximum value.
