We found this circuit in the November 1975 issue of Radio Electronics magazine. It uses a digital module from the time with several adjustments. The power supply must have the indicated voltage.
Obtained in an Electronic Design from 1968, this circuit has the voltages determined by the zener...
In the figure we have an amplifier step configuration with a transistor suggested by a 1985...
The circuit in the figure below is suggested by Sanyo and provides 10 W power at 4 ohms and 6.8 W...