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 Post subject: Vixen sp mount
PostPosted: Sun May 08, 2011 3:54 pm 
Hi all,
I have just aquired this fine Celestron c8 and the Vixen sp mount. The mount is a good quality, very sturdy well built thing complete with motors and a hand controller. I was wondering if anyone knew of or had any ideas on if it would be possible to control this from a laptop or a goto handset ?? In the celestron manual that came with it it does mention that a celestron sky sensor handset can be attached but I guess that this would need a different set of motors ? Im not sure......also this mount is a good few years old and not sure how easy it would be to get hold of one of these now. ...... I am happy at the moment being able just to control the mount with the handset to find targets and dont really need to operate it from computer but just thinking how cool it would be being able to run it from stellarium or a similar program ....... I do however realise that this is a longshot but any ideas would be gratefully accepted.


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File comment: Vixen sp mount plus celestron c8 and webcam and slr lense.
scopeandmount.jpg
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 Post subject: Re: Vixen sp mount
PostPosted: Mon May 09, 2011 9:03 pm 
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Location: Adlington
Dean,
Looks a great combination you've got. With the Celestrons its collimation, collimation, collimation! Don't avoid it.
As far as goto upgrades - I've used the AWR but it is over the top for a Polaris mount There is an ioptron kit:
http://www.ioptron.com/index.cfm?select ... 29228e98b6
but I've never seen it.
I seem to recall COAA did a cheap system a few years back but cannot now find a reference to it. I am sure Ste Fielding was looking at it for his SP mount.
David


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 Post subject: Re: Vixen sp mount
PostPosted: Tue May 10, 2011 8:12 pm 
Thanks for that David, I will check it out ......There is hope ....... better get to grips with polar alignement first though and using this mount properly I think or else no matter what computer I attach it to its still going to be futile !!


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 Post subject: Re: Vixen sp mount
PostPosted: Wed May 11, 2011 8:07 am 
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Dean, after some research with Google, it appears that there may be another option - which will be a lot cheaper in hardware, but much more labour-intensive to get it going...

One implementation of the Bartels Scope-Drive system (http://www.bbastrodesigns.com/BBAstroDesigns.html) uses a dedicated PC to control the stepper-motors in a 2-axis mount. This PC supplies real-time signals via its parallel (LPT) port, so it needs to boot in DOS (rather than Windows) - so an old (> 10 years) laptop should be ideal.
And this control PC may then accept Go-To instructions from your main PC running Stellarium or whatever...

If you're interested in prusuing this option and can find a suitable PC, I'll help out with building the electronic interface between the LPT port and the motors.
And if we can get it going, perhaps a few more of our BAS members with 2-axis motors may want to follow suit?


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 Post subject: Re: Vixen sp mount
PostPosted: Wed May 11, 2011 8:21 am 
Sounds like a plan Ross ..... thanks for offering to help out, I will look into it this evening and see if I can source an old laptop ...... may even post in the forum to see if anyone has one they no longer need .....


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 Post subject: Re: Vixen sp mount
PostPosted: Thu May 12, 2011 8:58 pm 
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Dean,
I found that reference to the COAA system - WINCTC. It is Windows based but it is not as cheap as I remembered!!!!!
http://www.coaa.co.uk/winctc.htm


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 Post subject: Re: Vixen sp mount
PostPosted: Thu May 12, 2011 9:17 pm 
Thanks David that looks spot on .......


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 Post subject: Re: Go-To with standard EQ stepper-motors?
PostPosted: Fri Nov 18, 2011 9:56 am 
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rwilkinson wrote:
the Bartels Scope-Drive system (http://www.bbastrodesigns.com/BBAstroDesigns.html) uses a dedicated PC to control the stepper-motors in a 2-axis mount.
And if we can get it going, perhaps a few more of our BAS members with 2-axis motors may want to follow suit?

Well, I finally got round to doing some tests with this, having built an interface to try with the stepper-motor on the Society's EQ2 mount.
But I soon discovered a fundamental limitiation with this idea: the gearing between the RA axis and the motor. In the EQ2 (and presumably EQ5 and VixSP too) the gearing is designed so that the stepper-motor can drive the axis at up to 8x the sidereal rate (for guiding and centring), but not at the several degrees per second which would be required for slewing around the sky in Go-To mode, so given the limitation of the maximum motor speed, it would take tens of minutes to slew across the sky! :(

So now we can understand why those Go-To upgrade kits include new motor and gear assemblies: these are designed to drive the axes much faster for slewing, and then drop into slow microstepping mode for tracking.


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 Post subject: Re: Vixen sp mount
PostPosted: Fri Nov 18, 2011 9:01 pm 
So, it can be done, just slow for slewing from one object to another ? ......... how about if you release the clutches and pointed your scope in the general direction and then set it going ? I appreciate this does kind of dampen the point of a go-to but if you dont mind the wait then at least it does do the job ........ still marvellous thaty you were able to figure out a way .......


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 Post subject: Re: Vixen sp mount
PostPosted: Sat Nov 19, 2011 2:27 pm 
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Well Dean, remember that if it takes tens of minutes for each slew, then it will probably be getting light by the time you've finished your initial alignment! ;)

And if you were to release the clutches, then you'd instantly lose the alignment.

So star-hopping really is much quicker!


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