AI-4
TUNING FORK—A two-pronged mechanical device that is designed to vibrate only at its
natural frequency. In electronics, it is used primarily to determine the correct speed of a
motor.
UNIJUNCTION TRANSISTOR (UJT)—A three-terminal, semiconductor device with a
negative-resistance characteristic that is used in switching circuits, oscillators, and wave-
shaping circuits.
VOLUME UNIT (VU)—Unit of measurement of a complex audio signal such as voice or music.
A 0 level is referenced to 1 milliwatt of power into a 600-ohm load.
WAVEMETERS—(1) Calibrated resonant circuits that are used to measure frequency. (2) An
instrument for measuring the wavelength of an rf wave.
ZENER DIODE—A pn-junction diode designed to operate in the reverse-bias breakdown
region.
