This Schmitt trigger was found in old documentation. The transistors can be of the general-purpose type like BC548 or even 2N2222.
We found this oscillator that can supply up to 3 A of output in the 1982 SGS linear integrated circuit...
This amplifier is specifically designed for portable radio and recorders with a 4 ohms load....
This application is not modern since few computers have parallel ports. But you can use this...