Found in a1967 Ferranti documentation, this circuit uses an operational amplifier from that time. The circuit uses a LDR as a sensor and has a null setting.
This amplifier for automotive use is suggested by the Philips Databook of 1990. The integrated circuit...
This circuit is used in transceivers, enabling input selection by diode switching through polarity...
Suitable for operation with high impedance microphones, this circuit was found in American...