Water resistivity sensor

A sensor unit for measuring the resistivity of water contained in a tank comprising:

• a pair of electrodes generating a signal proportional to the resistivity of the water;
• electrode carrying means for carrying said pair of electrodes through said tank so as to cause said electrodes to contact the water;
• circuit means in communication with said pair of electrodes, said circuit means comprising a reference circuit sequentially providing successive voltage values corresponding to successive resistivity values, and a voltage comparator connected to said pair of electrodes and to said reference circuit for comparing said signal from said pair of electrodes to each said successive voltage values so as to determine that one of said successive voltage values approximates said signal from said pair of electrodes, whereby the resistivity of the water is determined;
• and
• display means connected to said circuit means for displaying the resistivity of the water.

A water resistivity sensor for indicating the resistivity of water comprising:

• generator means for generating a signal;
• printed circuit electrode means connected to said generator means and being positioned in said water for receiving said signal and providing an output signal proportional to the resistivity of said water;
• circuit means for processing said output signal of said printed circuit electrode means and issuing an output signal corresponding to the resistivity of said water, wherein said circuit means comprises a reference circuit sequentially providing successive voltage values corresponding to respective successive resistivity values, and a voltage comparator connected to said electrode means and to said reference circuit for comparing said output signal of said electrode means to each said respective successive voltage value so as to determine that one of said successive voltage values approximates said output signal of said electrode means, whereby to determine said resistivity of said water;
• and
• display means responsive to said output signal of said circuit means for numerically displaying said resistivity of said water.