This amplifier step for small signals can use any general-purpose transistor like the BC548. The circuit can be powered by voltages from 6 to 12 V.
In the figure, from a documentation from the 70s, we have a few-watt amplifier for general use....
This highly sensitive light sensor was found in a 1970 General Electric documentation. The circuit...
This simple audio oscillator produces signals reproduced on a loudspeaker, in a frequency range...