Apparatus having floating magnet unit with light reflecting mirror for

Abstract

A detector of ferromagnetic materials having a permanent magnet floating in a contaier and restrained under the influence of a soft ferrite mass spaced below it to rotatable movement about a vertical axis centrally of the container. The magnet has a normal at rest position from which it is rotatable when a ferromagnetic material moves through its magnetic field. The magnet carries a curved mirror onto the concaved face of which a light beam is focused, and which beam in an at rest normal position of the magnet is reflected by the mirror onto a zero point of an observer's readout scale. When the magnet is caused to rotate from its at rest position by a ferromagnetic material moving through its magnetic field, the light beam is caused to move away from the zero point; and when the ferromagnetic material has moved out of the magnetic field, the magnet and light beam return to their normal positions but with some oscillation before doing so. Electro-magnets associated with the magnet are subject to energization by an attendant, and when energized they serve to curb such oscillation.