This high quality circuit with complementary symmetry was found in an Electronics World of 1966. It can be made with modern transistors like the BD or TIP series.
Using a CA3130 operational amplifier, this circuit from a 1977 documentation can handle low...
This circuit has a maximum output current of 5 A, and the 2N3055 must have an excellent heat sink....
The sensor diode used in this circuit is the common type of germanium. Experiments may be made...