Note there is no connection to pin 8 or 4 (Vss and Vdd) on the uppermost op-amp - as there is in the bottom one.
The circuit is not working - there is never any voltage at A0 - leading me to think there is something wrong with the top "half" of the circuit.
I have not used op amps before. It strikes me as odd there is no ground connection and no voltage supply to the op amp in this half of the circuit.
Is it likely just an omission in the schematic (i.e. should I connect up pin 4 and 8 as in the bottom op-amp), or is this a valid application for an op-amp, and I have some other issue?
Cheers in advance.