The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 03, 1978
Filed:
Oct. 11, 1977
Theodore R Barben, II, Carson City, NV (US);
Thomas-Barben Instruments, Carson City, NV (US);
Abstract
In a four electrode conductivity sensor, each pair of electrodes is coupled to a respective one of two operational amplifier circuits that establish a fixed potential relationship between the two potential electrodes so that current flow between the two current electrodes is maintained directly proportional to the conductivity of the solution. Specifically a direct or alternating excitation voltage is applied to the positive input of one operational amplifier, while the other receives a fixed reference potential input. The operational amplifiers supply a unity gain, noninverted output to the respective current carrying electrodes, while the potential electrodes are directly connected to the feedback input of the respective amplifier. The current flow between the current electrodes is measured as a voltage signal across a resistor with the operational amplifier output and remains directly proportional to the conductivity of the solution in which the electrodes are immersed, regardless of fouling of the electrodes by solution impurities and electrolysis effects. An alternating current excitation input can be applied through a coupling capacitor with each electrode also connected through a coupling capacitor to provide direct current that eliminates ground loop problems in the installation and use of metering and control equipment.