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Comment by HeyLaughingBoy

5 days ago

It's amazing how many parts they fit into such a tiny space, isn't it? Those things are little marvels.

It's a potentiometer most of the time, BTW. Encoders are on the spendy "digital servos"

Yeah, it was a potentiometer. Is an encoder not simply any device that provides a signal proportional to its position or displacement? It had wiper arms (brushes?) that dragged along a conducting surface on a PCB below the rotor.

  • An encoder is a device that encodes the position -- absolute or relative -- of its shaft as a set of digital outputs.

    Most common type uses optical sensors internally, although there are also magnetic types. A quadrature encoder is the most popular and provides two output signals, phase separated by 90 degrees. The phase separation allows the reader to determine which direction the shaft is moving.

    A potentiometer used for position feedback is usually just called a potentiometer. I guess it's technically an encoder, but I don't think I've ever heard it referred to that way.

    There are also resolvers, discussed somewhere else in this thread, but we won't go there!

    HTH

    • > A potentiometer used for position feedback is usually just called a potentiometer. I guess it's technically an encoder, but I don't think I've ever heard it referred to that way.

      I have absolutely seen potentiometers called encoders in industrial applications. The underlaying technology is irrelevant. Encoders and revolvers are just transducers of position.