This circuit is from a factory manual from the 80s. The circuit can be implemented with modern operationals. The supply must be symmetrical, and the diode is general-purpose.
This stage was used in old audio ampliiers and radios from the 1950s and 1960s. It uses one of the...
Found in a 90s R-E Experimenter Handbook, this amplifier uses an integrated circuit from that...
We find this circuit in an American 1980s documentation. The unijunction transistor may be the...