This circuit was found in an Electronics World of 1966. It has a range of 5 to 25 000 Hz at 1 dB and the diagram includes the power supply.
The circuit shown in figure 8 is an application suggestion for ISL8107, a new integrated circuit from...
This good quality amplifier found in a 1982 documentation has a traditional complementary output...
Found in old documentation, this circuit has only the most difficult component to obtain the PUT....