This circuit with the PA7601 was found in a 1967 Philco-Ford documentation. The circuit has a pass band from 45 to 120 MHz.
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...