This circuit was obtained from a 90s Radio Electronics. The value of R1 determines the scale according to the table next to the diagram. The power suppley must be symmetrical.
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...