Gas and smoke detector

Posted on Feb 26, 2013

This circuit can detect smoke and a number of gases (CO, CO2, methane, coal gas and others) with a 10 ppm sensitivity. It uses a heated surface semiconductor sensor. Detection occurs when the gas concentration increase causes a decrease of the sensor element internal resistance

Gas and smoke detector
Click here to download the full size of the above Circuit.

The switch in series with the SCR is used for resetting the alarm.

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