| 摘要 |
A gas alarm device consists of a semiconductor sensor(Se), a comparator(IC) comparing inverted voltage(Va) and non-inverted voltage(Vb) and producing output to base of transistor to trigger alarm, and a relay connected between emitter and earth of the transistor to drive a fan for blowing out gas. This system also has a temperature compensator having a thermistor(TH) and can detects a small amount of gas by adjusting VR2.
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