This circuit can be used as an amplifier for musical instruments or even with your cell phone. The circuit is old and was found in the 1990 edition of Radio Electronics Experimenter magazine.
Found in American documentation, this circuit from the 90s uses components from that time. The...
This circuit was found in a 1980s documentation. The operational amplifier is of a common type at the...
This simple audio and RF signal tracker was found in a Japanese publication in 1967. The...