This linear oscillator was found in a 1968 publication. The operational amplifier is from that time. Both the FET and the integrated support current equivalents.
This circuit is from an English magazine of 1977. The circuit is still current, just using BC547...
The adjustment of the maximum load voltage is made in the trimpot. The circuit is from 1994...
In the figure we have the conventional configuration of a differential amplifier with the...