I've recently bought a pH sensor, which is connected through BNC and hooked up to my Arduino. I've also read through some of the topics on these forums already, but nothing seems to help me out so far. I keep having the same voltages read from the sensor regardless of different pH buffers
So I've adjusted the offset to 2.5V (2.568V) with a short-circuiting in side. After that I connect the probe to the BNC and placed it in both of the buffers, with cleaning the probe properly in between.
The 5V is connected to V+, Ground to ground and A0 to P0 of the arduino Uno Rev3 and pH sensor respectively.
However, The voltage outputs remain between 2.627 and 2.637. The following code is used for the voltage:
int ph_pin = A0; //This is the pin number connected to Po
void setup() {
Serial.begin(9600);
}
void loop() {
int measure = analogRead(ph_pin);
Serial.print("Measure phpin: ");
Serial.print(measure);
double voltage = 5 / 1024.0 * measure; //classic digital to voltage conversion
Serial.print("\tVoltage: ");
Serial.println(voltage, 3);
delay(2000);
}
Am I doing something wrong? Thank you for the help in advance!
Yes, I've connected both grounds to GND on the arduino. I also tried it with one ground connected separately, but didn't help either.
I am trying to calibrate the sensor using the pH buffers, but that's where the problem is. The voltage doesn't change. According to the guidelines you have to create an inner connection with the inner and outer part of the BNC and turn the voltage back to 2.5V with the potentiometer. This step works, but it doens't let me turn the voltage further down. However, I don't think that's where the problem is. Corrrect me if I'm wrong though.
After that you have to connect up the BNC pH probe and:
(pH sensor ---> arduino)
V+ --> 5V
Ground --> GND
P0 --> A0 (or another analogue port)
That's how they are wired up, but no change at all unfortunately. The baseline voltage (2.5 V) goes slightly up though when I connect the pH probe with the BNC. This will result in a voltage of 2.627-2.637 V.
Test it with a vinegar solution and a baking soda solution. You should see a clear change in the voltage - some 150 mV change, higher voltage for lower pH (a pH probe is doing some -59 mV per pH point, this sensor board doesn't amplify this voltage change).
hello did you find any solutions to this? , because I am facing the same problem also I am a beginner . At module calibration when short circuit the inner and the outer pin at bnc connector I get 2.5volt so I suppose that the module works fine?
