GB1051129A - - Google Patents

Abstract

1,051,129. Measuring conductivity of liquids. COMMISSARIAT A L'ENERGIE ATOMIQUE. Feb. 24,1964 [Feb. 22, 1963], No.7569/64. Heading GIN. An arrangement ror measuring liquid conductivity employs two circuits each having a pair of electrodes and a standard resistor, the resistance of one resistor being e.g. 100 times that of the other, and each circuit covers a different range of conductivities wherein a linear relationship exists between a voltage e (Figs. 2 and 3) and electrolyte resistance r between its electrode pair (Curves S 1 , S 2 ); the voltages e being added in the arrangement, whereby a corresponding curve S is obtained (i.e. the sum of curves S 1 , S 2 ), which is linear for an extended range of conductivities. The arrangement comprises electrodes 1 and 3 (Fig.2) and a common electrode 2 connected in series with standard resistors 5, 6 to the secondary windings 4, 4 of a transformer TF which is energized e.g. at 1500 c/s by a phase shift type oscillator including transistors T 1 , T 2 in assembly A. The potentials e, e 2 at electrodes 1 and 3 respectively are fed to two impedance matching circuits, including transistors T 3 , T 4 , T 5 in an assembly B, and are added by a transformer 7 the output of which is rectified in an assembly C which includes a transistor T 6 pulsed at the oscillator frequency. The rectified voltage is then fed to a conventional measuring circuit D including a meter 8 suitably calibrated in conductivity units. The assemblies A, B and C may be in one housing adjacent to the electrodes and remote from the assembly D. There may be more than two circuits each having a different value standard resistor, to extend the measuring range.