This very high voltage generator for photographing the aura was found in the special edition of Radio Electronics Eerimenter magazine from 1990. The circuit uses a car ignition coil.
Varactor diodes are our varicaps of today. This circuit for switching signals in an RF circuit was found...
This Hughes circuit is from 1968. Equivalent modern components can be used. The input impedance is...
This circuit digitally counts input pulses. The circuit from a November 1970 Radio Electronics uses...