Meassure PH of water

I brought this ph module from ebay. But this gives me ghost outputs. They are not stable. I have no idea how to use this. Anyone have experience with this module? help me :slight_smile:

You need to connect a pH probe to the module.

looks like a classical two op. amps circuit. You will have to calibrate first. The two (blue) variable resistors are for calibration. The output is analog so you will have to calibrate that voltage on Arduino as well. If is 0 - 5 V the pH=7 would be 2.5V, etc.

hope it helps,
MaLi

MaLi:
looks like a classical two op. amps circuit. You will have to calibrate first. The two (blue) variable resistors are for calibration. The output is analog so you will have to calibrate that voltage on Arduino as well. If is 0 - 5 V the pH=7 would be 2.5V, etc.

hope it helps,
MaLi

Thank you buddy. Can you provide me a code for this? Do i need to connect Po pin to analog input of arduino?

jremington:
You need to connect a pH probe to the module.

+1

sahanhasitha:
I brought this ph module from ebay. But this gives me ghost outputs. They are not stable. I have no idea how to use this. Anyone have experience with this module? help me :slight_smile:

Vph-=Vzener/2

p_AOUT is output of PH. connect digital multimeter to confirm.

Calibrite meter.

This is you first post. I would suggest searching these forums for pH. There is a wealth of information available.

Look at Atlas-Scientific.com for help as well. They sell interface modules and give Arduino code for their use.

  • E0:Base line voltage
  • R:Ideal gas constant.
  • T:Temperature in Kelvin.
  • F:Faraday constant.

Temperature in Kelvin here is temperature of water, not temperature of environment (air) .

Atlas-Scientific.com's product & above product are failed here.

sonnyyu:

Calibrite meter.

OK thank you i ll calibrate it :slight_smile:

Make sure you store the probe in the correct fluid. It has been
a long time since I used one of these so I don't recall if it was some
buffer solution or just DI water??
If you are using the Rt in the schematic to measure temperature,
make sure it tracks the temperature of what you're measuring.
Dwight

sahanhasitha:
I brought this ph module from ebay. But this gives me ghost outputs. They are not stable. I have no idea how to use this. Anyone have experience with this module? help me :slight_smile:

That means that your reading is jumping around.
How much are they jumping around? Show us about 20 readings so we can see.

You may want to add more capacitors to the power busses, and maybe try one on the analog pin.
What analog pin are you using?
can you show us the script (in code tags </>) ?