Main project - PH probes and live PH measurements

To be able to live measure PH i’ll try to hook up a PH probe to my arduino.

Possible obstacles

There are a few possible problems to be aware of: PH Probes need calibration. How often? Can it live measure during one round of fermentation and then calibration?

Does the material of the probe influence the ferment (fermentation + reactive metals don’t go well together)

Setting up the PH probe

Calibrating the analog sensor

I started by following this tutorial about setting up the PH probe.

My pinout is as follow:

V+ - Arduino 5V PO – Arduino A0 Gnd – Arduino Gnd

(Plaatje Arduino)

I short-circuit the BNC connector to stimulate a neutral PH7.

(plaatje BNC)

Then i used the following code and screw the POT until i got a value of 2,50v (2,51/2,51 in my case)

(plaatje code)

Now the resistance/input signal is calibrated.

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Next i hooked up the PH probe and let it sit in distilled water (PH7)

(plaatje probe)

I used the following code to read the measured PH value

(plaatje code)

After waiting for a couple of minutes to stabilize it gave me a reading of 8,75.

I checked with the digital PH meter which gave me a reading of 7,02.