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.
The configuration shown in the figure is a second order filter (12 dB per octave) with an...
This transmitter, indicated for espionage applications, is permanently powered by the power grid....
This circuit was obtained in an old French publication from the 80s. The maximum power of the lamp...