This circuit is from an American 1967 documentation and can be implemented with modern equivalent transistors. The circuit serves as a Q multiplier.
We find this circuit in an old documentation, but it can be implemented with modern equivalent...
An interesting option is the one that makes use of the MC3373 integrated circuit and which is...
This circuit can drive a loudspeaker with near 1 W of Power from 6 to 9 V supplies. The circuit...