Please note: Although this question involves EEG, I don't expect anyone here to be knowledgeable in this area! This is a simple electronics question!
I'm trying to understand the circuitry devised in this DIY EEG Instructable. The main thing that jumps out to me is that - at no discernable point - do the analog signals (generated by your brain and then subsequently amplified) get transformed into digital signals via some ADC/converter. But obviously, by the time they reach the Processing program, they must be digital.
It appears that the author is recommending feeding the signals into a laptop via RCA jacks. Is this where the analog-to-digital conversion is taking place, or am I missing something?!