| 摘要 |
PURPOSE:To prevent the exceeding of a DC voltage, which is applied on a water electrode, beyond a non-operating region, by connecting a diode and a resistor between water detecting electrodes in the reverse direction with respect to PUT. CONSTITUTION:A series circuit of a diode 12 and a resistor 13 is connected to a water electrode 1 in parallel. A cathode K of the diode 12 is connected to the side of resistors 3 and 4. When a voltage, which is applied on the water electrode 1, is V+, the potential is decreased owing to the parallel connection of the resistor 4. When the voltage is V-, the potential is also decreased owing by to the parallel connection of the resistor 3. A DC component VDC does not exceed the non-operating region of the water electrode 1. Therefore, the water electrode 1 is not corroded even for usage in a long time. Thus the water can be detected reliably for the long period. |
