VEHICLE DETECTOR WITH SERIES RESONANT OSCILLATOR DRIVE

摘要

An inductive sensor (12) is driven by a series resonant oscillator circuit (16) to produce an oscillator signal having a frequency which is a function of inductance of the inductive sensor. An inductive load, which includes the sensor, is connected in series with a capacitive impedance (112, 114, 210). Power to the series resonant circuit formed by the inductive load and the capacitive impedance is controlled as a function of current in the series circuit as sensed by a current sensor. A detection system provides a detector output based upon the frequency of the oscillator signal.