Integrable conductivity measuring device
First Claim
1. A conductivity measuring device for measuring the electric conductivity of liquids, said conductivity measuring device comprising:
- a current source connectable to two current electrodes arranged for feeding a current with a rectangular waveform into the liquid, wherein said current does not contain any net DC component anda measuring circuit connected to two voltage electrodes for determining the voltage drop between the voltage electrodes which is dependent on the electric conductivity of the investigated liquid, wherein the measuring circuit is a switched capacitor circuit having a measuring capacitor, a feedback circuit with a feedback capacitor and feedback discharge switch arranged in a feedback branch thereof, and a switch mechanism connecting the measuring capacitor, in time-dependency with the current having the rectangular waveform, in one switching condition to the voltage electrodes and in another switching condition to the inputs of the feedback circuit.
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Abstract
A conductivity measuring device for measuring the electric conductivity ofiquids has a current source device with current electrodes connectable thereto, via which a current can be fed into the liquid, and a measuring circuit connected to two voltage electrodes.
In order to reduce measuring errors on account of polarization effects, the current source device in accordance with the invention, generates the current having the rectangular waveform, wherein the measuring circuit is implemented as switched capacitor circuit comprising a measuring capacitor being connectable to and disconnectable from the voltage electrodes via a switch arrangement in time dependency of the path of the current having the rectangular waveform.
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Citations
9 Claims
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1. A conductivity measuring device for measuring the electric conductivity of liquids, said conductivity measuring device comprising:
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a current source connectable to two current electrodes arranged for feeding a current with a rectangular waveform into the liquid, wherein said current does not contain any net DC component and a measuring circuit connected to two voltage electrodes for determining the voltage drop between the voltage electrodes which is dependent on the electric conductivity of the investigated liquid, wherein the measuring circuit is a switched capacitor circuit having a measuring capacitor, a feedback circuit with a feedback capacitor and feedback discharge switch arranged in a feedback branch thereof, and a switch mechanism connecting the measuring capacitor, in time-dependency with the current having the rectangular waveform, in one switching condition to the voltage electrodes and in another switching condition to the inputs of the feedback circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification