Potentiometer Suggestions
 

What would be the best type of potentiometer to get for an arm that will move between half to one revolution, and check whether the arm is positioned up or down. The mounting location would be directly on the arm axis. I don't know if i'm missing information but if you need it I will get it.

Re: Potentiometer Suggestions
 

I prefer these.

http://www.andymark.com/product-p/am-2899.htm

Re: Potentiometer Suggestions
 

Potentiometers with much more than 1/2 turn are unusual, though there are a few, such as this 10-turn pot from Jameco. Less expensive than an absolute encoder, but you'll lose most of the dynamic range as you're only using one revolution, and it's easier to break. OBTW the sweep is the contact farthest from the shaft, not the one in the middle like most pots.

Re: Potentiometer Suggestions
 

more than a half turn is unusual? That's not been my experience...

Go to Digikey, and put in your search terms on their potentiometer page. You can get anything from 230 degrees to 3600 degrees rotation, including continuous turn pots.

Personally, I look at what we need for the application, add a bit for safety (no sense breaking it by trying to turn it too far), and order what we need.

Re: Potentiometer Suggestions
 

I didn't mean rare. The point is that if you want more than half a turn you're going to have to specifically identify potentiometers with that feature, not just pick one up out of the bin of generic parts or hit radio shack.