Is there a best value of potentiometer to use on the analog pins of an Arduino (Uno/Nana/Mega etc). I'm using it just to make an analog value, so wiper= middle pin, other 2 go to gnd and 5v.
I suppose given the nature of the usage of the pots, they may all be doing the same thing, given the fact that the resistance going to +v and gnd will always be opposite. They create a potential divider. Do the values matter with an Arduino?
What are your thoughts on this?
Did you read about I=U/R ?
I have heard about the relationship of course. I write it as I = V / R.
Practically, any pot value from 1k to 100 k will suffice. Of course, 1k will drain a battery a lot faster than 100k, but if you're using a wall wart for power, no big deal.
If you want to get down and dirty, look into input impedance - the input impedance of the analog input is in parallel with both sides of your divider, so there's a minor contributed nonlinearity. Your Arduino only has a 10 bit ADC, so the granularity of the conversion probably makes that nonlinearity pretty much invisible.
Also, your biggest source of errors will be the use of "5V" as the reference(not terrible if using 9V into Vin and minimizing your overall power dissipation, worse if depending on USB voltage) - switch to a better reference for improvements in your measurements.
Why is that?
The A/D returns the same value from a pot position, independent of the value of VCC.
Because pot and A/D of (most) Arduinos are ratiometric.
Use 10k linear pots (10kB).
Higher values can give crosstalk between A/D inputs if you use more than one pot.
There are of course ways to fix that with code.
Leo..
I did blur over a common detail. Most newbies immediately convert their A/D counts to a voltage, and the assumption that the reference is 5.0 is legion.
And yes, in a multi-input system, there is the risk of crosstalk. To be truthful, again I skipped a detail, which is the double-reading of inputs to attain clean, repeatable values.
No excuses.