| 摘要 |
PROBLEM TO BE SOLVED: To provide a gas leakage alarm that operates with a commercial AC power source to prevent a false alarm caused by fluctuation of a power source voltage. SOLUTION: The commercial AC power source is supplied to a transformer 4 from an insertion plug 3, and an AC voltage reduced by the transformer 4 is supplied to a gas sensor 2. A power source voltage Vd of the transformer 4 is supplied to a control part 1. A sensor output Vs generated between a connection point of a reference element Rr and a sensor element Rs, and a connection point of a resistor R1 and resistor R2 of the gas sensor 2 is amplified by a differential amplifier A1, and is supplied to the control part 1. The AC power source of the transformer 4 is rectified by a rectification circuit 8, and is supplied to an alarm buzzer 5 and an LED 6. When the variation of the power source voltage Vd is 8V or more, a mask mode is set. During the mask time for three seconds, no alarm is output even when the sensor output Vs reaches an alarm value. COPYRIGHT: (C)2011,JPO&INPIT |
