Found in a 1970 EEE, this circuit generates signals that depend on the C1 capacitor. Transistors are general-purpose types.
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...