We have a need to build a circuit to read Conductivity/EC measurements.
We have referenced your earlier discussion on related subjects and built the circuit (attached is the diagram), with one change where LMV341(op-amp) is replaced with LM2904.
Our EC probe is from Sensorex make and model CS200.
During the testing, the output is measured as 1.38 V for any given solution, there is variation if the reading at all. When the sensor is in the air the reading is 552mV.
We have further tested with different types of waveforms, frequencies and voltages but the output stays constant.
Could you help us to identify our mistake?
Additionally, can you share any additional material that would help us?
Thank you in advance