This circuit turns off when switch S1 is opened. The circuit is from the 1989 Radio Electronics Experimenter edition; The triac must be controlled according to the load.
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...