This circuit for controlling a model of an elevator via wire was found in the December 1997 issue of Electronics Now magazine. DC motors must be rated at the voltage of the transformers.
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...