This interesting benchtop circuit was found in the May 1977 issue of Radio Electronics magazine. The circuit has frequency adjustment, and the waveform selected by a switch.
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...