This driver for audio signals using the TAA435 integrated circuit was found in Philips 1968 documentation. The integrated circuit is difficult to obtain today.
The frequency of this circuit depends on C1 and, for the indicated values, it is 1 kHz. Equivalent...
This configuration with the LM383 appears elsewhere on this site. The circuit shown was obtained...
This circuit was obtained from HAM Radio magazine in an 80's issue. The FETs are types of the time...