We found this circuit in the Radio Electronics Handbook magazine special edition of 1992. The circuit uses an optocoupler as an electronic potentiometer.
This sensitive voltage measuring circuit has a very high input resistance, of the order of Mohms,...
This circuit was found in 2003 documentation, but all components used are still current. The alarm...
This circuit, which operates with frequency up to a few tens of megahertz, is from a 1976...