Found in a 1967 Electronic Design, this circuit changes the phase of a signal in 8 different ways, given by the formulas next to the diagram. Equivalent general-purpose transistors can be used.
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...