I have MCP607. I even tried to built it my adding the voltages at the initial stages. Here is the new schematic attached. I gives 600mv at 0mv input. But at the extreme it fails like +413 should give 100mv and -413 mv should give 1100.
Their is the differene of 50mv on both side.
hi,
Looked at your drawing, where did you connect the probe.?
Also would a minimum pH of 2 thru to 14 be acceptable.?