| 摘要 |
PURPOSE:To keep the activity of an electrochemical type sensor by changing over the power from an external circuit and the potential from an inner storage battery on the basis of the first and second pulse signals using reduced power by detecting that the signal from a sensor voltage detection means is changed to one direction or to the other direction by the first and second pulse generating circuits to respectively generate the first and second pulses. CONSTITUTION:An electrochemical sensor S is connected between transmission lines C and a battery 11 is set to a battery holder in a state receiving no operating potential from a sensor operating potential supply circuit N and a timer circuit 14 outputs the first signal T1 by the power of the battery 11. A switching transistor Tr16 operated by said signal and power is supplied to the exciting coil 9R on the reset side of a latching relay 9 from the battery 11 and a contact piece 10 is changed over to the circuit N. By this operation, the sensor S is connected to the circuit N and a measuring circuit M. Next, the second signal T2 is outputted from the circuit 14 after a predetermined time is elapsed and a switching element 15 is operated and the potential of a voltage detection circuit 2 is set to earth potential and the relay 9 is made operable by turning the signal T1 OFF. |
