This selectivity multiplier circuit for 455 kHz IF receivers was found in American documentation from the 1980s. The circuit requires a symmetrical power supply.
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...