This time base circuit for the oscilloscope was obtained from an Electronics Now from the 90s. The circuit is intended to control the cathode ray tube of old oscilloscopes.
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...