This circuit is from 1964 documentation but can be easily implemented based on current components. Input waveforms and detection are shown next to the diagram.
This SCR circuit, which can also be used for signaling places, was found in old American...
This circuit was obtained from an article in Radio Electronics magazine in October 1966. It...
We found this circuit in a 1966 documentation. The circuit is intended for a door opening system by the...