Conductivity measuring method, circuit and conductivity measuring instrument

Abstract

The invention is applicable to the field of solution measurement, and provides a conductivity measuring method. The method comprises the following steps: generating an alternating-current square wave signal; amplifying the alternating-current square wave signal; connecting the amplified square wave signal to one end of an electrode through a wire, and generating an alternating electric field in electrolyte solution; detecting a weak alternating current signal generated by the electrolyte solution at the two ends of the electrode of a conductivity instrument through the other end of the electrode; converting the weak alternating current signal into an alternating voltage signal; rectifying and filtering the alternating voltage signal to get a stable direct voltage signal; and converting the direct voltage signal into a corresponding conductivity and displaying the conductivity. According to the invention, a detected signal is judged so as to make a relay switch the frequency, amplitude and detection range of an input square wave signal, control on software cost and hardware cost of the instrument is achieved, and the service life of the electrode is prolonged.

Description

technical field [0001] The invention belongs to the field of solution measurement, and in particular relates to a conductivity measurement method, a circuit and a conductivity measurement instrument. Background technique [0002] Conductivity is an electrical physical quantity to measure the conductivity of aqueous solution. It is the reciprocal of resistivity. It is generally expressed by the Greek letter κ (or γ), and κ=1 / ρ. In general, the measurement temperature of electrical conductivity is the standard temperature (25°C). In liquids, the conductivity of water is an important indicator of water quality. The measurement of conductivity is widely used in daily production and life, such as measuring the conductivity of drinking water to detect the concentration of electrolytes contained in the water, and measuring the conductivity of coastal groundwater to check the degree of intrusion of seawater into the groundwater. , You can also use the method of measuring conductiv...

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Problems solved by technology

[0005] The purpose of the embodiments of the present invention is to provide a conductivity measurement method, aiming at solving the problem that the existing two-electrode method is used to detect conductivity, and the square wave signal frequency and square wave signal amplitude cannot be automatically switched, and the excitation signal is output for a long time, which affects the electrode. The problem of working life

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