I plan on building a diy guitar pedal based on this schematic, but I'm not sure what the circled part could be. My electrotechnics profesor told me that I need a Time
Schematics | General Guitar Gadgets
from schematic to reality
Guitar Effects Schematics & Projects
Designing a classic OD-1/TS-808/SD-1 Overdrive – Electric Druid
Build Your Own Effect Pedals - Rat (Part 1) Schematic - YouTube