this is my first post here, so if I'm doing something wrong please tell me. I'm making a project about guitar pedals, and I have a very basic understanding of electronics, so I'm having a hard time understanding some of the logic behind the schematic I have.

My questing is, why would I need to connect the battery to the jack input? My original question was why would I need a stereo jack input if a guitar uses a mono jack, but looking at the schematic just made things worst for me.

Thank you for your time

I'm making a guitar pedal project, and I have a very basic understanding of electronics, so I'm having a hard time understanding some of the logic behind the schematic I have.

Why would I need to connect the battery to the jack input? 

My original question was why would I need a stereo jack input if a guitar uses a mono jack, but looking at the schematic just made things worse for me.