PH METER TESTER

PURPOSE:To test easily and surely by discriminating a false point of pH, by supplying constant voltage through series resistance corresponding to each stage of pH value in high impedance and low impedance. CONSTITUTION:A pH tester is provided with a resistance 3 consisting of resistances R1, R2- connected to a constant voltage power source 1 in series and switched by a rotary switch 4 and series resistances 6, 7 etc. connected its middle point to a terminal C are provided to the resistance 3 in parallel. Voltage corresponding to each stage of pH value from the switch 4 is outputted from a terminal (b) connecting to a terminal (a) and a high resistance 5 in low impedance and high impedance. On occasion of not showing the normal value by a pH meter at controlling time of sensitivity, each terminal (b), (c) are connected to connecting terminals (e), (f) of electrodes 8, 9 of the pH meter and high impedance voltage is inputted in the same way at measuring time of pH. Further, when the normal value is shown by a measuring part 10, it is decided that the electrodes 8, 9 are abnormal and when the abnormal value is shown, it is decided that on and after the terminals (e), (f) are abnormal. And, the abnormal point of either lead wires 11, 12 or the part 10 is distinguished in the same way by connecting the terminal (a) and the terminal (b), (c) to each terminal (g), (h) of the part 10.