Here is the main (audio) part of the well-known Ibanez Tube Screamer TS808 / TS9 / ITS8 (replica) guitar pedal. The original device also includes commutation circuit containing a trigger using two BJT and a pair of n-type J-FET (2SK44SP) which sources have a half Vcc potential so they can be closed alternatively (due to the trigger state) by pulling their gates to the ground so that providing a path for AC signal component through the main circuit (drive, active mode) or routing it directly to the output stage (bypass mode). You can use this sumulation to watch how this device affects the signal. Potentiometers from left to right are: Drive, Tone, Level. It can be also useful to determine the amount of 50Hz hum coming from AC adapter to the circuit. Because of high gain level of the all audio path (pedal + guitar amp) DC power supply voltage expected to be clean enough and must not contain any significant amount of 50/60 Hz and its harmonics
