Abstract: A proximity sensor is provided with a means for directly measuring parameters of a proximity sensor coil which permit the determination of both the AC and DC resistances of the coil. These parameters are then used to determine a discriminator value magnitude according to a mathematical relationship that has been predetermined through previous analysis of empirical data for the particular coil and application intended for the proximity sensor. In one particular application of the present invention, the rear AC resistance is utilized and is added to the DC resistance after the DC resistance has been mathematically altered by a preselected factor. Alternative embodiments of the present invention can also utilize the imaginary AC component of the impedance either by itself or in conjunction with the rear AC component of the impedance.

Abstract: A switching circuit is disclosed which provides a plurality of switches which can be caused to open or close, a controller which can selectively draw current from a plurality of power sources connected in electrical communication with the switches and isolating devices connecting the switches to the controller. The controller is connected to a regulator and to one voltage interconnection and the regulator is connected to another voltage interconnection by two conductive paths which control individual switches that are associated with individual power supplying loads.

Abstract: A controlled electronic switching circuit having a plurality of switches for switching external load circuits at least one of which provides electrical power for the control arrangement and there being at least one switch electrically isolated from the control arrangement. The circuitry, operated as a proximity switch, can be arranged to distinguish between the proximity of ferromagnetic and non-ferromagnetic material objects using a metal layer between the proximity sensing circuit and the object, which layer can be a deposited metal film.