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 circuit using components that are still common in our market was found in a 1987...
This circuit was obtained in a 1998 publication, but it can be easily assembled. The circuit...
Found in a 73 magazine for radio amateurs of the 90s, this circuit provides a 2 kV voltage with 7.5...