Electromagnetic sensor for detecting the number of revolutions, the rotational speed and physical variables, to be derived therefrom, of a shaft

摘要

An electromagnetic tachometer of particularly simple design consists of one or more permanent magnets mounted on the end of a rotating shaft, and of a core which is arranged at a distance of approximately 7 mm and is suddenly demagnetised at a given magnetising field strength and triggers a voltage pulse in a coil. This voltage pulse can be processed in an electronic circuit, and specifies information on the number of revolutions, rotational speed and physical variables to be derived.