Abstract: A differential float control is provided by a single switch and a single float wherein a vertical guide tube contains a magnetically operated switch, and a free float surrounds the tube and rises and falls with the liquid level and carries two magnets. As the float moves in one direction the switch is magnetically latched closed by one magnet and remains closed until unlatched by the other magnet as the float returns in the opposite direction. The switch may be normally open, or normally closed, so that movement of the float may provide any desired circuit sequence for operating a liquid level controlling pump or the like for maintaining the liquid level within prescribed limits.

Abstract: A position sensing system having one or more magnetically operated switches at predetermined spaced locations and a magnet attached to a carrier moving along a path adjacent thereto and as the carrier passes each switch, magnetically latching it in one condition until the carrier returns in the opposite direction and unlatches it. The switches may be unlatched open or latched closed, or any combination, as the carrier travels past the switches in one direction and shifted to the opposite condition when the carrier moves in the opposite direction.

Abstract: A liquid level sensor having a vertical guide tube with one or more magnetically operated switches therein at vertically spaced locations and a free float thereon which rises and falls with the liquid level and as it passes each switch magnetically latches it in one condition until the float returns in the opposite direction and unlatches it. The switches may be normally open, normally closed, or any combination, so that movement of the float past the switches may provide any desired circuit sequence.