Abstract: A liquid level shutoff control for minimum level control of conductive fluids. A pair of electrodes are disposed in the liquid at the minimum level desired for the fluid. The electrodes provide a conductive path for a high frequency electrical signal and circuits energize a controlled load such as a liquid heating or mixing apparatus whenever the electrodes are in contact with the fluid. Failure of the control circuit results in shut off of the controlled load thereby providing fail-safe minimum level control.

Abstract: A device for sensing and indicating the direction of motion of a moving member. A discontinuity is formed on a moving member. Two sensors capable of detecting the discontinuity are spaced apart a distance less than the width of the discontinuity. Logic circuitry determines which sensor detection occurs before both sensors produce coincident detections. The sensor detection occurring before coincidence unambiguously indicates the direction of motion. A gating circuit produces an output signal for one direction of motion and a second signal for the opposite direction of motion.

Abstract: An ignition system for a rotary piston engine uses the position of the rotary piston to generate the ignition timing pulse. A sensor is mounted in the wall of the epitrochoidal housing at a point opposite a rotor apex seal when the piston is at the maximum advance position. The timing signal is delayed by appropriate circuits and triggers high voltage generating circuits that provide igniting voltages to the trailing and leading ignition plugs at the proper time.