Sensor for ferromagnetic materials

摘要

In a sensor for ferromagnetic materials according to Patent... (Application P3114352.0), in which a body is placed onto a piezoceramic plate and piezoelectric voltages are produced across the electrodes of the plate due to the magnetic interaction between the ferromagnetic material and this body, noise voltages produced by interfering influences such as vibrations, shocks and so forth are compensated for by the fact that two plates are used which are arranged or constructed in such a manner that noise voltages of almost equal magnitude are produced across the electrodes of both plates but useful voltages only occur across the electrodes of one plate. <IMAGE>