Inductive proximity detector with adjustable frequency.

摘要

The detector has a detection coil for metal objects, forming part of an oscillator circuit. The oscillator excites the oscillating circuit at a constant frequency, signal processing circuit acts on signal generated by the oscillating circuit and the output circuit includes an amplifier. The detector also includes a circuit for tuning the frequency of the oscillating circuit with the frequency of the oscillator. The tuner (13) is an amplifier (17) arranged in parallel with the oscillating circuit (11), so as to receive at the input the voltage signal (VLC) of the latter. The tuning amplifier has its output feedback through an inductive or capacitive impedance (20) and its gain adjusted by a variable impedance (18) so as to tune the frequency (FLC) of the oscillating circuit to that of the oscillator (F). <IMAGE>