This circuit was found in a 90's EDN. The circuit has a well-known configuration. The voltage obtained depends on the number of diodes. Capacitors depend on the desired current.
Found in a 1965 Radio Shack documentation this oscillator can be used with modern general purpose...
In the figure we have the way to use a single control voltage to act on two varicaps...
Found in a 90s documentation, this switch that is also sensitive enough to operate capacitively uses...