SALINE TESTER Russian patent published in 2009 - IPC G01N27/22 

FIELD: instrument engineering.

SUBSTANCE: invention can be used in metrology as a standard instrument in verification and calibration of lower-accuracy measurement instruments, as well as in certification of test solutions. The tester comprises a generator output of which is connected to the input of a switch and to the reference input of a synchronous detector output of which is connected to a display unit, conductivity converter comprising a first core with a first winding, a second core with second and third windings, a first probe wherein there is a cavity filled with analysed or reference liquid and which covers the first and second cores with the third core with a fourth winding, a second probe wherein there is a cavity filled with reference liquid and which covers the third core, with the first outputs of the first, second, third and fourth windings are connected to a common bus. The second output of the first winding is connected to the first output of the switch. The second output of the third winding is connected to the input of an amplifier output of which exit is connected to the signal input of the synchronous detector. Besides, the tester includes a resistor characterised that to improve measurement accuracy, a fourth core with fifth and sixth windings covered with a second probe, a second switch and voltage-to-number converter. The first outputs of the fifth and sixth windings are connected to the common bus, the second output of the first switch is connected to the second output of the fourth winding. The power input of the voltage-to-number converter is connected to the output of the generator. And the output of the voltage-to-number converter is connected through the resistor to the output of the second switch the first output of which is connected to the second output of the second winding. The second output of the second switch is connected to the second output of the fifth winding, and the second output of the sixth winding is connected to the second input of the amplifier.

EFFECT: invention provides higher measurement accuracy by improving sensitivity of the conductivity converter that is ensured by higher conversion factor of probes.

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