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.
The presented circuit is used in Power supply to increase the voltage output. The voltage output...
The frequency of the LC resonant circuit must be the same as that of the crystal and the JFET...
This amplifier can be used for public-address or other applications. Three transistors of the time...