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I need something to work as an input for a rotary device. It must be able to rotate continously, accurate to a degree of rotation, and so that any extra full rotation will have no effect on the input, a+360 is the same as a. With no limit of rotations as well.

So I have found no potentiometer that does that. And rotary encoders never have so many levels. I thought about doing it mechanically, and the using something kind of pressure potentiometer like this one https://www.sparkfun.com/products/8678 to transmit any rotation of my mechanical device to the surface of the potentiometer. This is the best I could come with, but if I could find something better, and specially less expensive, it would be great. Is there any standard device to do this?

Thanks in advance.

EDIT: Ok, so found, thank you to the answers, the rotary encoders that seem to be what I'm looking for. My doubt is: what I will be using as the input is the global position of the encoder, the degrees to which it's rotated, and not how it's being rotated, left or right, which is what the incremental that I've seen do. Are there any more types of these things? Or does an incremental one tell you how much it's rotating?

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    \$\begingroup\$ electronics.stackexchange.com/questions/8282/… may be what you're looking for? \$\endgroup\$
    – pjc50
    Commented May 12, 2013 at 16:04
  • \$\begingroup\$ @pjc50 Thank you for the info, that looks like the right way, although the ones I'm finding are expensive, ovr 30$ \$\endgroup\$
    – MyUserIsThis
    Commented May 12, 2013 at 16:28
  • \$\begingroup\$ Is the system you are constructing based on a motor spinning so that maybe a cheap device could work but you have two of them with one covering the dead area of the first and vice versa? \$\endgroup\$
    – Andy aka
    Commented May 12, 2013 at 16:45
  • \$\begingroup\$ @Andyaka No it's not. It's just the input. It's a rotary dial that must be able to tell me the degrees 0 to 360 to which it's rotated, with a precision of 1 degree. \$\endgroup\$
    – MyUserIsThis
    Commented May 12, 2013 at 17:24
  • \$\begingroup\$ Do you need to detect changes in position while your device is powered off? You may need an absolute encoder rather than an incremental encoder, though it's unclear from your description as to exactly what you require. Incremental encoders are generally less expensive, but can't give you angular position at powerup without some help. \$\endgroup\$
    – HikeOnPast
    Commented May 12, 2013 at 18:06

2 Answers 2

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I am surprised that you cannot find a rotary encoder good to one degree, but I do not know a whole lot about them. A 10 to 1 gear train can improve the resolution by a factor of 10. Or a stepper motor can be used as a rotary encoder with 360/(steps per rotation) accuracy. A 1.8 degree stepper is almost there.

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  • \$\begingroup\$ Absolute rotary encoders generally aren't that good. I would think the ideal approach would be to combine a continuous-rotation pot with a rotary encoder; e.g. use a five-bit rotary encoder where the bottom four bits count 0-15, twenty-four times per revolution, and the fifth bit is active for about 12 of those counts near the "wrap" point on the pot. When the fifth input is inactive, the pot would indicate which of the 24 zones the unit is in; when it's active, it would indicate that it's in the zone where the pot can't be trusted. \$\endgroup\$
    – supercat
    Commented May 13, 2013 at 15:18
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Inclinometers would probably better fit your goal: http://www.google.com/search?ie=UTF-8&oe=utf-8&q=inclinometer+angle

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