| 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.
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.
"Howl round", caused by placing a microphone too close to a loudspeaker, is an audio oscillation caused by positive feedback. |
Copyright Graham Knott 1999