I decided to add a pH sensor for my arduino controlled aquarium.
I bought the PH4502C pH sesor module.
The accuracy isnt very good, so I started thinking about upgrading the module.
Its my first meeting with opamps and amplifiers so I have just basic knowledge and Im unsure about my thoughts.
I hope to get more precise readings when I modify the module for measuring pH 4-10 (I dont need 0-14) to get more resolution.
I studied the circuit. Int the next picture is written by black color what I know about the board and by red color is what I would change.
If I understand how opamp works that would change the pH- voltage to 0,05-0,5V regulated by pot instead of 0,45-2,6V. And the amplification of P0 would be 11x instead of 3x (I counted with 10x then but whatever ) So the voltage for pH 4-10 would be 0,8-4,2V. Or maybe i can chose different resistors and go even further.
Would that work like that? Or is there something more which is above my level? I didnt studied the datasheets of the TLC4502 opamp because I really dont understand it.
One bad thing is that full range of the measurement (pH 0-14) would go to -1,5V to 6,5V but that in normal operation cant happen...or should I add some diodes for protection?
Big thanks to everyone who will try to help me.
I hope that its not totaly dumb idea.
PS: I just realised i totaly overlooked the TL431 D3. Some kind of voltage reference which I also dont know anything about. I will just post it now and look at it later. Maybe it isnt even problem.