This gas sensor circuit was found in July 1976 Radio Electronics magazine. The TGS sensor was a common type at the time. Note the power supply to the circuit.
This circuit provides an output of 5 to 10 V at its output from inputs of 1.5 to 4.5 V. The output...
This circuit was found in Maxim's documentation from the 90's. The frequency of the circuit is...
Found in American documentation from the 1990s, this circuit has active cycle control. The basic...