This fuzz effect for guitars was found in an American 1980s documentation. The transistors may be the BC549 and should be battery powered for noise sensitivity. Diodes are commonly used.
This light comparator is of the window type already explored on this website in several...
Using the integrated circuit DCP01051D this circuit was found in the magazine Electronics Now of...
This filter with the operational 741 passes the frequency range between 300 Hz and 3,400 Hz. This...