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.
Found in National Semiconductor documentation from the 90s, this circuit makes use of components from...
This circuit was originally designed to measure capacitance with an ICL7107 but can be used with...
The TDA7000 is a Philips integrated circuit that contains a complete FM receiver with the need for...