Patent ID: 10514476

Abstract:
A device is provided. The device includes one or more of a radially-wound coil, a hall-effect sensor, a power source, and a control circuit. The radially-wound coil is configured to produce a first magnetic field in response to a DC current applied to the coil. The hall-effect sensor includes a sensor output that indicates proximity of a magnet to the hall-effect sensor. The magnet produces a second magnetic field and the sensor output indicates proximity in response to a sum of a strength of the first magnetic field and a strength of the second magnetic field at the hall-effect sensor exceeds a trip level. The radially-wound coil is in fixed proximity to the hall-effect sensor. The power source is coupled to the hall-effect sensor and is configured to provide power that alternates between on and off voltages to the hall-effect sensor. The control circuit is configured to receive the sensor output and in response provide the DC current to the radially-wound coil in order to control a polarity of the first magnetic field to detect the magnet.