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Old Feb 19, 2012, 04:38 AM
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Joined Jun 2011
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Radar antenna rotator.

Hi,
Has anyone dabbled with continuous rotation servos for rotating radar antenna? I can do slow movement (up to about 180 degrees) with a standard servo and a small micro but from what I'm reading the continuous servos are forward reverse control only and have little speed adjustment. Any ideas?

Cheers,
David
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Old Feb 19, 2012, 06:20 AM
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Romania, Galati, Galati
Joined Jun 2010
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Remove the potentiometer and the mechanical travel limitator and you've got an unlimited rotation servo. You can adjust the speed (in both directions) from very low (3-6rpm) to as high as the servo can(30-100rpm).
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Old Feb 19, 2012, 10:37 PM
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Hi Zen09,
Thanks for the reply.
I was aware of the changes required -
Swap the potentiometer for two equal resistors of the approx same value (2.2K?)
Remove any mechanical restrictions to allow 360 rotation.

For the speed control are you varying the servo pulse width or the motor supply?
I was of the understanding that changing the pulse width to achieve speed change was somewhat erratic and that all the change would take place in the 100uS about the central stop position.

Cheers,
David
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Old Feb 20, 2012, 03:57 AM
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Romania, Galati, Galati
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By varying the servo pulse width you adjust the speed of the motor, the servo is like a two way brushed ESC, with a feedback potentiometer so that it knows where to stop.
I don't know exactly what precision can you expect on the high side, but at low speed it's pretty precise.
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Old Feb 20, 2012, 10:09 PM
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Hi Zen09,
Thanks for getting back. I guess I will just have to try modifying a servo and write some test code to try it.
If it works out OK I have some friends in the warship group who will be pleased to learn of a method to rotate their radar dishes at the correct rpm.

Cheers,
David
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