Continuous-rotation angle servo

So I bought an MG996r online to replace a dead one in my robot dog, and I always test my new servos by hand and then by using sweep.

When testing this one by hand, I found that I could turn it all the way around - like the end stops were gone. It just kept turning and turning. The seller had said nothing about this, and I thought maybe they sent me a broken motor, or maybe this is how they make theirs, or maybe its a scam.

However, when I loaded up sweep, it went back and forth like a regular servo. I even tested it with my robot dog’s code; no difference from a regular 180’ servo. It could even support my robot’s weight when powered on, so there’s definitely some form of position feedback.

I don’t think there is a gear train allowing it multiple turns, given that the motor works at the same speed as any other one.

How does this work? I thought the internal potentiometer limits the rotation.

EDIT: This servo was $12, while most of my servos were $8 or below. Although, I do buy them in bulk, so that does drop their price. But still, it seems like a big difference.

Take the dead one apart and see how it is constructed.

Tom… :grinning: :+1: :coffee: :australia:

I already did, it has a potentiometer, a small DC motor, a bunch of metal gears, a small circuit board, and some wires.

I haven’t taken apart the new motor, but maybe it uses some form of non-limited potentiometer, maybe one where the wiper can cross from one end of the circular track back onto the other end again?
Or maybe it uses a rotary encoder, hall effect sensors, etc.

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