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, which appears at various points in this section and on the website with minor...
Motorola suggests this circuit in an 80's documentation. The circuit uses an inverter to produce a...
This circuit uses a 7812 and another regulator integrated circuit that is not very common...