Patent
Oscillator circuit for providing a conductivity ratio of sea water
TLDR
An oscillator circuit wherein two conductivity cells are arranged in a circuit to provide a conductivity ratio which is converted into a linear variation of the period or frequency of the oscillator is described in this article.Abstract:
An oscillator circuit wherein two conductivity cells are arranged in a circuit to provide a conductivity ratio which is converted into a linear variation of the period or frequency of the oscillator.read more
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Patent
Sensor and sensor system for liquid conductivity, temperature and depth
Guy J. Farruggia,Allan B. Fraser +1 more
TL;DR: In this paper, the authors measured liquid conductivity and temperature in respective sensitivity fields that are collocated, i.e., in volumes that nearly match by mathematical, geometrical, or functional criteria.
Patent
Methods and circuits for measuring the conductivity of solutions
TL;DR: Improved circuits for measuring the conductivity of a solution confined between two electrodes in a cell compensate for series capacitance and parallel capacitance between the electrodes as discussed by the authors, and the feedback resistance is then selected so that the gain of the feedback loop is responsive to the range of the resistivity of the solution.
Patent
Liquid conductivity measuring circuit
TL;DR: In this paper, a liquid conductivity measuring circuit with power-save features is described for use with a four electrode conductivity cell having two potential electrodes and two current electrodes positioned in the cell in spaced relation in a particular sequence with a first operational amplifier having its output connected and its inputs connected via an isolating capacitor and a buffer amplifier and a voltage setting resistance to a source of square-wave voltage.
Patent
Liquid conductivity measurement system using a variable-frequency AC voltage
TL;DR: In this article, a liquid conductivity measurement system is described that accurately measures a liquid's conductivity over a range spanning at least several orders of magnitude using just a single sensor, but minimizing the adverse effects of capacitive and other non-linear factors on the conductivities measurement.
Patent
Apparatus and method for measuring conductivity
TL;DR: In this paper, a sine wave excitation potential is applied to the series combination of a reference resistance and a conductivity cell to compensate for series capacitance and parallel capacitance.
References
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Patent
Voltage controlled oscillator
Gordon F Bremer,William F. Acker +1 more
TL;DR: In this article, the threshold voltage of a comparator is periodically varied abruptly to produce oscillations, and the frequency of oscillations is electrically varied by varying the period between threshold voltage changes.