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COLPITTS OSCILLATORS
Unlike the inductive bridge circuits, in the colpitts oscillator circuit
the sensor acts as the resonating coil for the oscillator. The proximity
of the targets to the sensor coil pulls the oscillator, changing its frequency
(small change not used) and amplitude (large change) of modulation. The
signal is half-wave rectified (AC to DC) and filtered to obtain an analog
voltage proportional to the target position. The analog voltage output
can be varied by adjustment of the gain. The input power is diode protected
and regulated to provide a clean low noise signal. The output is short-circuit
current protected.
The output of a colpitts circuit is typically non-linear. Kaman's KD-2440
product is based on the colpitts oscillator circuit.
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