The use of field effect transistors in this circuit improves its performance. This configuration is from a 1975 circuit manual. The transistor can be any general-purpose FET such as MPF102 or BF245.
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...