This circuit was found in a 1964 documentation. It shows how to achieve automatic gain control for an oscillator. The transistors are of the time and the circuit controls signals from 2.6 to 3.1 kHz.
This amplifier was obtained in an Electronics Now based on the LM1875. The circuit must be powered...
The block shown in the figure, although it is known to many readers, is not always in everyone's memory...
This high-power circuit was found in a documentation from the 90s. The circuit can use more...