fall time - 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 resistively. 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 - Common 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 an LC 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 running 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-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.
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.
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
saw tooth 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.