Combustible gas alarm circuit

Posted on Mar 28, 2007

Combustible gas alarm circuit is shown. Circuit by the gas sensor, multivibrator and audio output roads. Multivibrator integrated circuit by the NAND gate way inside two NAND g

Combustible gas alarm circuit
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ates lu, IC2 and the external screen resistive and capacitive components. The audio output circuit consists of resistors Rs, audio amplification tube VT and speaker BL composition. (2) works when the room is no contaminated gas or combustible gas concentration within the allowable range (below the limit), the gas sensors a, b end the resistance between the larger, b-side (IC1s O feet) the output voltage is low, the multivibrator does not work, Jan microphone BL no sound. When the combustible gas (gas or natural gas) leak, combustible gas concentration in the room exceeds the limit value, the b-side air tit sensor output voltage is higher than the switching voltage of IC1, multivibrator work from pin output oscillation lC signal. The VT signal after amplification, to promote the speaker microphone BL alarm. Adjust the resistance value Rz make gas sensors c, d between the voltage 4.5V.

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