Sup guys. Just have looked at tds-meter Arduino code and can't understand one thing:

Code: Select all

Where does this formula come from? And how did you calculate this coefficients?```
tdsValue=(133.42*compensationVolatge*compensationVolatge*compensationVolatge - 255.86*compensationVolatge*compensationVolatge + 857.39*compensationVolatge)*0.5;
```