This circuit was found in a Philips documentation from 1967. The circuit uses components from the time that have current equivalents such as BC548 for transistors.
This circuit is suggested by Motorola, using a 4N26 type coupler and an MC1733 type operational....
Texas Instruments' low power operational amplifiers OPAx196 can be found on Mouser Electronics....
This is the power step of the previous circuit. Output transistors must be mounted on good heat...