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.
Found in old documentation, this circuit uses components that are still common on the market. The...
This circuit activates a relay by activating one of a series of optical sensors that can be...
We found this circuit in a 1996 publication. Equivalent components can be tried, especially in the...