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Use a "Celestron Logic Drive" on a Super Polaris

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#1 rdn

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Posted 26 October 2012 - 07:27 PM

I have a Super Polaris mount. I would like to add a motor drive for tracking. My budget is small, and I hope it might be possible to use a "Celestron Logic Drive", or the similar "Celestron R/A Single Axis Motor Drive for the AstroMaster Telescope" which I can buy on Ebay for about $35. Thanks for any comments, or thoughts based on your experience.

#2 Brian Risley

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Posted 27 October 2012 - 07:45 AM

Haven't tried one on an SP, but they do work most EQ-2/EQ-3 mounts. Biggest issue is finding a way to mount it. They have variable speed control and direction reversal, so finding the correct speed/direction is just a matter of experimentation. The other issue is some sort of clutch setup, as the release knob on these units can be in a hard to reach place and without a clutch, you can't use manual slow mo, only release the main lock and then manually position it.
Brian

#3 *skyguy*

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Posted 27 October 2012 - 12:00 PM

Welcome to the CloudyNights Forums

The Celestron Logic Drive works well on my Vixen Polaris mount. The "Celestron R/A Single Axis Motor Drive for the AstroMaster Telescope" might fit, but the tracking rate won't be a perfect match since the gear ratios between the two mounts is different.

#4 rdn

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Posted 26 November 2012 - 03:03 PM

Thank you both. It sounds like I should proceed with it. I could have used a drive last night looking at the nearly full moon with a 6mm eyepiece, and then at Jupiter. Beautiful views, but galloping targets!

#5 Starhawk

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Posted 27 November 2012 - 03:03 PM

A lot of these mounts have 130:1 gear ratios instead of the Vixen 144:1 ratio. I put a CG-4 motor set on my Vixen Polaris by gearing it with a 20:22 ratio to take the 130:1 motors to the 144:1 speed.

-Rich

#6 *skyguy*

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Posted 27 November 2012 - 04:59 PM

A lot of these mounts have 130:1 gear ratios instead of the Vixen 144:1 ratio. I put a CG-4 motor set on my Vixen Polaris by gearing it with a 20:22 ratio to take the 130:1 motors to the 144:1 speed.

-Rich


Rich,

That's a great solution to the gearing differences between the two mounts. I've heard that you can change the crystal in the handcontroller to get close to the vixen drive rate ... but not precisely. Can you post some additional information and pictures on how you accomplished the drive rate changes? Thanks ...

Jim

#7 Geo.

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Posted 27 November 2012 - 10:53 PM

A lot of these mounts have 130:1 gear ratios instead of the Vixen 144:1 ratio. I put a CG-4 motor set on my Vixen Polaris by gearing it with a 20:22 ratio to take the 130:1 motors to the 144:1 speed.


Think you find that the Polaris RA worm whell has 130 teeth. The SP is 144.

Somewhere on CN there is a thread on using the logic drive on a CG-5, which also has a 144 tooth wheel. So the correct speed can be obtained. Maybe you'll want to go to a geared coupling so the drive can be mounted as the SP's drive was there's lots of room there. Drawing below may help.

The logic drive has a really simple control circuit. I cloned one and found it gave a wide range of speed adjustment. My build covers about a square inch after eliminating the power and reversing switches.

By mixing and matching with various DC motors and gear reductions you can probably match any need. The opamp will handle up to 40v, but the switching transistor would have to be upgraded to handle much more current. I have some 3 amp MOSFETs around. I'll have to play with it some more. Blue smoke to follow...

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#8 Starhawk

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Posted 28 November 2012 - 08:08 PM

No, Polaris is 144:1. The Super Polaris is, also, but I don't have one.

-Rich

#9 Starhawk

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Posted 28 November 2012 - 10:22 PM

Here is my Polaris with vixen dovetail clamp, heavy duty altitude adjustment, and 2-axis motor drive.

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#10 Starhawk

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Posted 28 November 2012 - 10:25 PM

Gear drive pix

-Rich

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#11 Starhawk

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Posted 28 November 2012 - 10:26 PM

Details.

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#12 Starhawk

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Posted 28 November 2012 - 10:28 PM

More gear detail.

-Rich

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