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 circuit can turn-on (only) a load (relay or lamp) when S1 is pressed. The circuit can be used as...
The circuit shown uses the LM324, but can be implemented with other operational ones. The source...
This circuit was obtained from a 1977 magazine, but can still be mounted using BC548 for TR1 and...