| 摘要 |
PURPOSE:To obtain a gas leak alarming stably operated even if temp. dependence due to the kind of gas and the irregularity of heater 4 are not considered, by constantly controlling the temp. of a sensor 3 by providing the heater, a heater voltage control circuit and a thermocouple. CONSTITUTION:A thermocouple 16 for detecting the temp. of a sensor 3 is embedded in the sensor 3 and connected to a heater voltage control circuit 5 so as to constantly control the output thereof whereupon an element temp. is made constant regardless of a circumferential temp., voltage and high concn. gas. When combustible gas is contacted with the sensor 3, the potential at the connection point with a resistor 10 and, when it becomes higher than the potential at the connection point D of resistors 17, 18 each for applying a reference level, a voltage discriminating circuit 19 and a drive circuit 13 are operated to alarm the gas leakage by a lamp 14 and a buzzer 15. |
