Found in a 90’s Popular Electronics, this circuit can use other power MOSFETs. The transformer has a primary according to the desired continuous voltage at the output.
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...