R/C servos that provide positional feedback to controller ?

Are there off-the-shelf hobby type servos on the market that can give feedback regarding their position? I'm thinking along the lines of a servo based arm that can be manually positioned, then have
that position recorded so it can be played back later. I know I could hook up some extra wires to the pot and read the values that way, but I was looking for something ready-made.
Just a thought ...
And thanks ! JCD
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pogo wrote:

Yes. I understand many of the new digital servos have read-back methods. The one I remember used a very short pulse to tell the servo to give a pulse back, the length of which corresponded to the current position.
Okay, it was the HSR8498 I looked at. See http://web.ukonline.co.uk/r.ibbotson/files/HSR8498HB%20Servo.pdf , the section on "Position Feedback", and you can read exactly about what I mean.
This feature was intended (best I gather) for a "learn" positioning, because the servo doesn't drive while this short pulse is active. That let's you move the servo to a position, and have the system read the desired position.
While this would still be considered a hobbiest servo, these new digital servos aren't exactly cheap.
HTH's
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you may also want to see what the signal look like from the center pin of the potentiometer it uses for feedback, it may be a ramp of some sort as part of their timing system, but it also just might be a variable voltage.
dan
pogo wrote:

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