Inductive proximity switch with oscillator which feeds transmitter coil

摘要

Two sensor coils (7, 8) are arranged int he alternating field in immediate difference circuit, for determining the difference of the voltages (U1, U2) induced in the two sensor coils. The oscillator (1) is operated with a frequency between 5 and kHz pref. between 20 and 50 kHz. The proximity switch is designed for working in two operating modes. The proximity switch in the first operating mode responds only to a non iron trigger and in the second operating mode, only to an iron or ferrite trigger. The proximity switch has respectively separate output channels (5, 6) for the both operating modes. The proximity switch is provided with a changeover unit (18) controlled by a pulse generator (17), for the changing over of the two operating modes.