What kind of potentiometer do I need?

[kvid]

What kind of potentiometer do I need to control the current on the circuit in the attcahment. Would 47k logarithmic potentiometer do the job for up to 2.5A? What kind of potentiometer do in need to get to 3A?

The attached snip is from the page 11.

https://www.maxonmotor.com.au/medias/sys_master/root/8825195921438/367661-DEC-Module-24-2-Operating-Instructions-En.pdf

[flynwill]

You probably want a linear taper pot, not a log taper pot.  The log pot will spend the majority of its rotation at either very close to zero speed or full speed depending on which way you wire it.  Their example shows a 10k pot so clearly that will work fine.  47k will probably work but will be a bit non linear given the ~100k input impedance listed.

[Simon]

Yes a linear pot. The the main of the very few reasons you would use a log pot is for volume control because our ears have a log response so using a linear pot as a volume control will make it hard to control the volume in exactly the same way putting a log pot on this controller that has a linear response. A log pot counter matches our ears "interpretation" of sound power giving an apparent linear response.

The same is true of our eyes. Many sensors also have a non linear response (thermistor), the real world is never a linear one but most people devising circuits that talk to each other use a linear scale.

[MatthewEveritt]

I disagree, te resistance-current relationship of the values in that table is roughly exponential , a log pot would likely make for a far smoother control.

[flynwill]

Oops, you are correct, I completely mis-read the original poster's post and assume he was seeking a pot for the speed control.