This circuit is from American documentation from 1970. It can be designed with a BC558 and for the operational, we can use equivalents. The FET can be the BF245.
This circuit was found in Japanese documentation from the 1960s. It is a commercial circuit with...
This circuit with 5 V power was suggested by Motorola's Linear Databook of 1990. The circuit has...
This circuit was found in an English magazine from 1977. Signal inputs and outputs must be...