This circuit produces a signal that has the waveform of the sound produced by or near the banjo. The circuit is from an 80's American documentation. The signal must come from an ordinary guitar.
We found this configuration in the Linear Applications Handbook of the National Semiconductor of...
This circuit is an application for an operational amplifier with field effect transistors from...
This circuit was found in an old Radio Electronics, but can still be assembled as the components are...