Found in a 90s Popular Electronics, this circuit can power a miniature railroad with voltages of 15 V and currents up to 1 A. The circuit has soft start effects.
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...