Found in an American publication from 1968, this circuit can be made based on a TIP42 that must be mounted on a heat sink. The transformer is 25 V with a current of 3 to 4 A.
This circuit with automatic gain control was found in the July 1988 issue of Radio Electronics magazine....
This circuit makes use of older operational amplifiers, but can be designed on the basis of modern...
Found in an old American publication, this is one of many possible configurations for an analog...