Can I have help understanding this schematic?
I am in the process of building an infrared motion detector. I've finished the infrared transmitter but I haven't been able to start on the receiver yet because the schematic has confused me. One part of the circuit, on the lower-right of the corner, appears not to be connected with the rest of the circuit at all. Until I understand how the two parts interact with each other, I can't continue building.
I am still something of an amateur when it comes to solid-state circuitry; maybe someone who's more experienced will know what this means?