This circuit is from a 1968 Electronic Design. The characteristics of the output transformer are not given and the transistors are of the time. The circuit provides a power of a few watts.
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...