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.