We found this circuit in an Electronic Engineering of the 90s. The circuit can be implemented with any logic and next to the diagram the truth table for the indications is given.
This basic Schmitt trigger was found in an American publication from 1968. The circuit uses...
This circuit is from an American 1964 documentation. Transistors of the time are used, but modern...
This simple circuit uses small speakers for both listening and speaking (microphone). The feeding is...