need help in terpretting this circuit

[aliyesami]

I found this article on internet but I need to understand few things , first of all i dont know how the following calculations work , author is referring to some value "X" but what is X?

Assuming X=4.7 and output range should be 0.5v
5.7 x .414 = 2.36x2=4.72 total swing voltage
Vaout = 5v = Vin + Voffset - offset range acid side
Vbout =0v = 2.64 > Voffset >0 -(-) 2.36 = 2.36 Lets pick 2.5v for our offset

Voffset = 2.5v
,

https://sparkyswidgets.com/portfolio-item/ph-probe-interface

 

[barry]

That is a REALLY confusing article. It's not you, it's the author.

I think what that guy is trying to say is: X is the ratio of the two gain resistors in a non-inverting opamp, so that the gain of the opamp is 1+X.

He could have found a more confusing way of presenting this, but I'm not sure how.

 

[aliyesami]

so if iam using 3.3v instead of 5v how would i go about calculating what the Voffset for me would be?