Found in old documentation, this oscillator operates with high voltage. The diode must be of the appropriate type with low current and an inverse voltage of at least 100 V.
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...