Found in American documentation from the 1980s, this circuit can be designed with equivalent components. The microphone can be of the piezoelectric type.
The circuit shown in the figure is suggested by ON Semiconductor (www.onsemi.com), based on its...
September 2016 - can be found at Mouser Electronics the new amplifiers with digital variable gain...
This simple 1-transistor audio preamplifier appeared in the June 1968 Radio Electronics magazine. The...