Triac gas - smoke alarm circuit schematic

Published:2012/10/24 21:29:00 Author:Ecco | Keyword: Triac , gas - smoke alarm | From:SeekIC

In the event of combustible gas, the conductance of TGS308 gas sensor increases, and the voltage is removed through the potentiometer RP1 slide point, and its value is increased from normal 3V rms to 20V. This elevated voltage is added to transistor VT1 through diode and 4.7kΩ resistor, so that VT1 gets conduction, then Triacs 2N6070A gets conduction. Thus, the full-wave AC voltage drives H to produce up to 90dB alarm sound. H is Detal6003168 24V AC alarm. When gas disappears from the sensor, the circuit is restored to the original state, so the alarm automatically stops.



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