Found in a manual of integrated circuits from the 90s, this circuit makes use of that time components. It is indicated to limit the current in 6 V chargers.
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...