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Oscillators are
amplifiers with such a
large amount of positive
feedback that they
produces an output
signal with no signal
applied to the input.
The output amplitude is
determined by the gain
of the amplifier and the
feedback circuit.
Oscillators can produce
sine waves, the
frequency of which is
determined by TUNED
CIRCUITS.
Tuned circuits consist
of a capacitor and
inductance.
Square wave oscillators
use resistors and
capacitors to determine
the frequency of
oscillation.
Ideally the frequency of
an oscillator should be
stable, but due to
temperature variations
and mechanical vibration
this may not be so.
Precautions are taken
against frequency DRIFT.
"Howl round", caused by
placing a microphone too
close to a loudspeaker,
is an audio oscillation
caused by positive
feedback.
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