Well, I understand Ohm's law and I know that a voltage divider is a linear circuit that produces an output voltage that is a fraction of its input voltage and that calculating Thevenin equivalences derive from the Thévenin's theorem, discovered or more accurately rediscovered by Mr Léon Charles Thévenin, a French telegraph engineer.
Just jocking!
I got that from Wikipedia, just a moment ago.
But I understand Ohm's law! At least partially!
Anyway, by pointing me to those concepts, in a way, you already show me how to fish. Thanks. I'll try to undrestand those new things (to me).
About the schematic, It is the one you offer to post eleminating the full scale adjustment.
Alain