Hall-cell liquid level detector

A liquid level detector comprised of a column of Hall-cells adapted to be mounted vertically in a liquid containing tank, a magnet being adapted to move in a vertical direction adjacent to said vertical column of Hall-cells, a float means for maintaining said magnet at the level of said liquid so that the output of said each Hall-cell produces a certain electrical response only when said magnet is adjacent the corresponding of said Hall-cells;

• a summing means, the outputs of said Hall-cells being electronically connected by said summing means to a signal output terminal,said summing means being for producing a particular signal at said signal output terminal at the time that any one of said Hall-cells produces said certain electrical response;
• a ring connected shift register, an output from each stage of said shift register having a connection to a separate one of said Hall-cells;
• and an electronic means for clocking said shift register, for continuously circulating one bit through said shift register and for sequentially applying electrical power via said connections to said Hall-cells so that with respect to the time that said circulating bit resides in a predetermined one of said shift register stages, the time of the occurence of said signal at said signal output terminal, is a unique indication of the height in said tank of said liquid level.

A liquid level detector comprising:

• a column of Hall-cells adapted to be mounted vertically in a tank containing liquids;
• a plurality of magnets each being adapted to move vertically at a substantially fixed spacing from said column of Hall-cells;
• a float means for maintaining a first of said magnets at the surface of a first of said liquids, for maintaining a second of said magnets at the surface of a second and less dense than said first of said liquids to increase the magnetic field at the Hall-cells adjacent to said first and second magnets, respectively, and an electronic means for sequentially applying DC power to each of said Hall-cells in said column, and for sensing, shaping and summing the outputs of all said Hall-cells, whereby the time periods, between said applying DC power to a particular predetermined one of said Hall-cells and the occurence in said summed outputs of a Hall-cell output signal that is characteristic of a Hall-cell in the field of said adjacent magnet, provides unique indications of said liquid levels.