vvarrior:
I am using 3.3v instead of 5v because I need to shut off the sensor. I am testing the electrical conductivity of water, as well as pH. Testing conductivity throws off the pH reading.And just to clarify, I want to use 3.3/1024 instead of 1023?
The 3.3 and 5 V values are specific to the analog to digital converter module inside your microprocessor system (--- and ... the A-to-D converter does contain a D-to-A as well). Eg.... the arduino nano A-to-D converter is based on a 5V voltage range, right?
This just means, you need to know in advance whether the hardware's voltage range is 5V or 3.3V. This is generally not a user-setting. It's determined by the hardware you have.
So if you're using an uno or mega, or nano, then the voltage range is 5V. So the voltage resolution will be 5/1024 (in the hardware).
Correct ....... use 5/1024 .... not 5/1023.