Hi,
I saw this schematic last night and searched for that part I've mentioned with 2 red squares, for 2 hours but didn't find a schematic exactly like that. I want to know the components and their models that used in that big red square, and also know what's that triangle I've mentioned in little square and why is it there?
I'm not sure, the far left looks like an audio jack. I don't think it's a barrel jack. I don't know what the little arrow means there, maybe it means the positive part of the jack.
The jack carries 2 conductors. The artist drew a tiny triangle. If it's a diode then it appears to be pointing the wrong way. Perhaps the drawing software lacked conventional electronic symbols. Or perhaps it is intended to indicate that the jack can contain switched contacts, if desired.