Magnetically activated multiple switch level detector

An apparatus for detecting position comprising in combination:

• (a) an elongated tubular container;
• (b) a first elongated electrically conducting member disposed within the elongated tubular container intermediate first and second extremities of the elongated tubular container in a fluidic vessel;
• (c) a second elongated electrically conducting member disposed within the elongated tubular container intermediate said first and second extremities of the elongated tubular container, wherein at least one of the first and second elongated electrically conducting members has a high specific ohmic resistance;
• (d) a plurality of normally open switches disposed pivotally in groove means in an elongated dielectric within the elongated tubular container at regular intervals intermediate said first and second extremities of the elongated tubular container, each of said plurality of normally open switches providing electrical connection between said first and second elongated electrically conducting member when said normally open switch is closed;
• wherein the earth's gravitational pull acting on the normally open switch keeps the normally open switch at open position in the absence of a magnetic force field, and a magnetic force field generally perpendicular to the lengthwise direction of the elongated tubular container closes the normally open switch and thus establishes electrical connection between said first and second elongated electrically conducting members;
• (e) a marker guided by the elongated tubular container in a sliding floating relationship wherein said marker slidable over a distance intermediate said first and second extremities of the elongated tubular container indicate positions to be detected, said marker including at least one magnet producing a magnetic force field generally perpendicular to the lengthwise direction of the elongated tubular container;
• (f) means for measuring ohmic resistance of first electrical circuit comprising first portions of said first and second elongated electrically conducting members intermediate first extremities of said first and second elongated electrically conducting members and said marker, and one or more of the normally open switches closed by the magnetic force field produced by said marker;
• and for measuring ohmic resistance of second electrical circuit comprising second portions of said first and second elongated electrically conducting members intermediate second extremities of said first and second elongated electrically conducting members and said marker, and said one or more of the normally open switches closed by the magnetic force field produced by said marker;
• and
• (g) means for converting values of ohmic resistances of said first and second electrical circuits into information on position of said marker wherein conversion from said values of ohmic resitances to said information on position is independent of ohmic resistance contributed by said one or more of the normally open switches closed by the magnetic force field produced by said marker.