The circuit shown was found in an American documentation from 1964. The circuit uses transistors of the time and the indicators are small lamps.
We found this audio preamplifier circuit with a 741 operational in a 1976 publication. However,...
The arranjment sohon Bellow, and simulated in the Multisim Blue allows to see in the oscloscope...
This 2005 circuit was found in an English publication and can be implemented with virtually any...