Maker Pro
Maker Pro

Need help with pH sensor

Hello,

I'm using the E201-C pH probe, which outputs an analog voltage level corresponding to a pH value, like any other pH sensor. I am going through some trouble callibrating it, though. Here's what I'm doing and where I'm stuck at:

-Since the board comes with an offset potentiometer, I short-circuited the BNC connector to simulate a pH reading of exactly 7, then adjusted the voltage output to 2.5V

-Then, I removed the short circuit and immersed the probe into a pH 4 solution, and got a reading of 2.10V

-Afterwards, I immersed the probe into a pH 8.1 solution, and the reading was 2.28V

Now, here's the problem: from what I've read, an acidic solution should produce a voltage higher than the neutral one. The voltage values obtained here don't make much sense to me. Note: I'm cleaning the probe between one testing and the next one, and waiting even longer than the response time to measure the voltage.

Any help would be much appreciated
 
Top