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Old 05-11-2008, 07:05 PM
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AlexN
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Computer controlled instrument rotators...

Where can one buy a computer controlled rotator for a reasonable amount of money... I've seen the ones for the RCOS, and i think that $2490US is a bit over the top..

Does anyone have ideas on how to make one, or where to get a reasonably priced on.. Preferably one controlled via ascom drivers...

I've got everything computer controlled now, apart from this, and whilst its lazy of me to not want to get out of my chair and rotate the camera to frame things, it would just be nice to be able to do it all from the PC.... One more step towards a fully robotic setup.
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Old 05-11-2008, 07:17 PM
TrevorW
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Way to many toys Alex talk about armchair astronomer

Cheers
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Old 05-11-2008, 07:34 PM
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thats the way I like it...

I need to train a monkey or a robot to set up my scopes and get it all polar aligned.. then I'll be set.
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Old 05-11-2008, 07:45 PM
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Bassnut (Fred)
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Oh yeah, I hear you Alex, a nice addition to automation.

Have a look at this http://www.optecinc.com/optec_023.htm

The 2" model is US$1100 and 3" US$2150, a QHY8 may fit the 2", dunno, way cheaper than the RCOS anyway.

Ive heard they work well.
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Old 05-11-2008, 08:22 PM
Ian Robinson
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Why not rig up a dc motor that is connected to microprocessor chip (need not be something expensive) that detects the DEC angle from any preexisting digital setting circles (or your computer , you are computerised afterall) and calculates the right rate of field derotation , converts that to the correct duty cycle and controls the rate of tube rotation via a pulse width modulated motor control circuit or a suitable vibrator circuit.


The motor could drive the instrument tube (which is separate from the nosepiece) via a high precision belt or matched pair of belts.

If you are handy with a soldering iron and have access to a circuity simulator program, it wont be all that hard to design a suitable circuit to do all the above , given a bit electronics knowledge.
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Old 05-11-2008, 08:35 PM
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Fred, the QHY8 will surely fit in the 2" one.. Brilliant.. at under half the cost of the RCOS I think thats going to be a go in a few months time..
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Old 05-11-2008, 08:39 PM
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Ian, This is not a field de-rotator... This is so I can rotate the camera to correctly frame an object from the imaging PC, for example, to rotate the camera to the correct position so as to fit M31 into the field, or to fit M20+M8 etc... not so it can clean up field deterioration due to tube rotation.
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Old 05-11-2008, 09:14 PM
Ian Robinson
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Quote:
Originally Posted by AlexN View Post
Ian, This is not a field de-rotator... This is so I can rotate the camera to correctly frame an object from the imaging PC, for example, to rotate the camera to the correct position so as to fit M31 into the field, or to fit M20+M8 etc... not so it can clean up field deterioration due to tube rotation.

Same kit will do that , just ignore the comment about connecting to the DSS and calculating the right rotation rate, just select the angle wanted and hey presto if the rotator works properly , it'll go there as fast as you want.

A zero duty cycle will stop the motor.
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Old 06-11-2008, 12:05 AM
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Could a Meade fielf derotator do the same thing, possibly you could use it for equipment rotation instead of Field Derotation.
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Old 06-11-2008, 05:46 AM
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Merlin66 (Ken)
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Probably could, but these things are NOT cheap!!
What about the gizmo Bert had for focusing the canon lenses?? A stepper motor belt on a Crayford focuser?? The Revelation one I had was capable of easy rotation and had a locking screw?????
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