Hi there
I bought 2 CS525L, and I installed them in a small river with a number of other probes. When I read the electrical signal of CS525L got a reading of 10 units of PH and I have a proof probe that gives me about 6 pH units (my system uses a CR1000 to read the probes). I took only CS525L read the probe in a CR850 and it showed me a reading of 6 pH units. I took a sample of river water and I brought it to the lab and tested the probe .... it read 10 pH units in the same CR850, but that was a source of 12V, and the field I used a 12V battery. Then i took the CR850 and i put it in a battery and the problem was gone again .I reckon I have a network of electrical interference (I use a 220V AC power to 12V DC).
Does anyone have any idea how can I get rid of the inference of the power grid, and anyone else had a similar problem?
P.S. The probe is far from the power source (about 10 meters)
The CS525 is susceptible to electrical noise. It would be interesting to see your program, also, how you are calibrating to get the pH units. In the lab you should not have a noise issue. I would suggest you place the probe in a pH7 buffer solution and record the mV output. Rinse the sensor then place it in the stream sample. If you expect to see a pH 6 in the stream sample, the pH 7 solution should be around 2700 mV and the pH 6 of the sample should give you about 2400 or 2500 mV. Also, when you talk about a 12 VDC power source, is this the power source for the datalogger? The sensor needs a 5 VDC source.
Hi there
I used the program suggested by Campbell to calibrate the probes with two different calibration solutions pH 4 and 7.
The reading on the solution of 7 reads about 2700mV, and a solution of 4 2300mV reads, more or less. To test the calibration, we have another solution in the laboratory calibration of pH of 10 in which, after adjustment, we put the probes, and the reading was the correct pH (9.98).
The 12VDC power supply, is the power source that is connected to the datalogger and use the 5V source to power the probe.