| 摘要 |
PURPOSE:To obtain an inexpensive water detecting circuit, by providing an oscillating circuit driven by a DC power source and an electrode for measuring electric resistance of water, so that AC can be applied between water and the electrode while using the DC power source. CONSTITUTION:A water detecting circuit is constituted of an oscillating circuit part, an AC converting circuit part and a detecting circuit part. In case when an output of an oscillating circuit 2 has become V1=''H''.V2=''L'', transistors 18, 24 are turned on in an AC converting circuit 13, voltage of a positive pole and a negative pole is applied to a water electrode 14-b and 14-a, respectively, and on the contrary, in case of V1=''L''.V2=''H'', transistors 18, 26 are turned on, voltage of a positive pole and a negative pole is applied to the water electrode 14-a and 14-e, respectively, and in this case, if the impedance between the water electrode 14-a and 14-b is low, a current I1 flows, is amplified by a transistor 27, and an alarm 28 is driven. Accordingly to this constitution, AC can be applied between water and the electrode, even when DC is used, therefore, an inexpensive water detecting circuit is obtained. |
