Abstract: A method and apparatus for operating an powered, air-purifying respirator. The apparatus includes an air mask, an air pump, a hose connecting the mask to the air pump, a magnetic actuator disposed on a portion of the hose that engages a housing of the air pump and a controller that provides a predetermined air flow from the pump to the mask based upon a magnetic flux from the actuator.

Abstract: An angular position sensor (100) for determining angular position includes a shaft (105) having a threaded portion (108), and a structure for engaging an external application (119). The shaft (105) includes a first permanent magnet (114). A nut (116) is threaded on the threaded portion (108). The nut (116) is formed from a first magnetic permeable material or includes a second permanent magnet (118). At least one constraint (122) is coupled to the nut (116) for preventing rotational movement of the nut (116) while allowing linear motion of the nut (116). A first magnetic sensor (120) is positioned along a length of the threaded portion (108) of the nut (116) for measuring a linear position of the nut (116). A second magnetic sensor (124) is provided for measuring an angular position of the shaft (105).