This circuit was found in a 1967 US publication. In it we have the implementation of a ring counter using only relays. Relay free contacts can trigger indicator lamps or LEDs.
This time base circuit for the oscilloscope was obtained from an Electronics Now from the 90s. The...
This telegraph microtransmitter for a frequency determined by the coil and the crystal was found...
This digital to analog converter circuit was found in the July 1991 issue of Radio Electronics magazine....