Explosive Gas Detector Circuit

Posted on Mar 25, 2013

A gas sensor (TGS823 from Allegro Electronics, Cornwall Bridge, CT 06754) conducts in the presence of explosive gases. U5 is a voltage-to- frequency converter that produces a frequency proportional to the sensor conductance. The output frequency ranges from 100 IIz in clean air to 8 kHz in a contaminated atmosphere. The dc voltage from the sensor also drives bar graph LED U7 and comparators U4-b and U4-c to sense present caution and danger levels.

Explosive Gas Detector Circuit
Click here to download the full size of the above Circuit.

Ul drives an ac load up to 100 mA (relay, indicator,.alarm, etc.).

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