This circuit has a correction or linearity adjustment. We found it in Ferranti's transistor manual from 1974. Transistors are general-purpose types at the time.
This general purpose circuit was found in a Popular Electronics. It is intended for detecting the...
This circuit controls a relay in a bistable way by touching the sensors type NF (CH3) and NO...
Found in ancient American documentation, this circuit uses an operational amplifier of the time,...