This high-gain circuit was found in an American publication from the 1990s. The circuit can use general purpose transistors and powered from a source or battery.
This circuit is from the 1983 Intersil Databook. In it we have the use of the ICL7135 as an AD...
This MW radio circuit with varicap tuning was found in an English documentation from 1989. The...
This circuit was found in an American publication from the 70s, but it can be assembled with more...