Please help a noob re. analogue inputs

Hi everyone. I'm a musician and a complete electronics noob, but I'm trying to realise a project with an Arduino board.

I understand the concept of A/D conversion using the board, i.e. 10-bit conversion = 1024 possible values = ~0.005V per value based on 5V supply. Suppose I wanted to use a variable resistor through an analogue pin to get a value into my PC. I would want the highest resolution as practicable. If the variable resistor's maximum resistance is too small, this will reduce the resolution. If the variable resistor's maximum resistance is too great, I wouldn't be able to utilise the entire throw of the pot before the converted value would reach 0.

Therefore, what is the optimum resistance of a variable resistor to have the greatest possible digital resolution whilst at the same time being able to use the whole physical range of the pot?

From some deduction (pure guesswork and intuition perhaps?), this value would be in the hundreds rather than thousands of Ohms, would it not? I am currently looking at buying a linear sensor/pot with a resistance of 1.7kOhm. Is this far too great a value of resistance?

Thanks in advance.

Hi James, the pot should be connected as a voltage divider. That is, the center tap (slider) of the pot goes to the arduino pin, and one end goes to 5v the other end goes to ground. Connected like this, the voltage on the arduino pin is determined by the relative value of the resistance from the center tap to +5v and ground. The pot value determines how much current will flow through the pot so you want to select a value that doesn't draw more than necessary, but enough to deliver a reliable reading.

10k is a common choice for a pot but 20k is also a good choice. Values lower than these draw more current than necessary, values higher are outside the recommended range stated in the datasheet

Have fun!

Many thanks, mem.