We had found this circuit in a January 1961 Radio Electronics Magazine. Using it is possible to take measures from the gain of transistor with a common a multimeter.
This circuit for controlling high power in the AC network was found in a Motorola documentation from 1968....
This amplifier is specifically designed for portable radio and recorders with a 4 ohms load....
This circuit was found in a 1973 Radio Elettronica magazine. The Italian magazine no longer...