This circuit buffers and amplify a pH sensor output voltage so it can be monitored and trended using an arduino. The voltage on the top left which is the ph probe can go from ➕ to ➖ 1.25 volts giving an output between 0 and 5 volts from the second op amp. 0 volts in from a pH 7 solution gives and output of 2.5 volts.
