Suggested by Sprague in the 90's documentation, this circuit applies to AC motors. The documentation does not indicate the maximum engine power that can be controlled.
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...