Motor drive for Dobs (16" in particular)

prova · #1 19-11-2007, 12:29 PM

just wondering do they exist and do they work well for very high mag views of the moon, planets, etc?

netwolf · #2 19-11-2007, 01:03 PM

Commercial solutions ServoCat or SiderealTechnology are the two that jump up to mind. Both can be used for slewing and tracking, for goto you need a Computer or DSC to control them. The two DSC's that work with both is our very own Aussie made ArgoNavis, and the US Sky Commander.

Then there is the one that started it all Mel Bartel's stepper system, you can either buy it or build it yourself with some surplus parts. This system requries a computer running Dos to run Mel's controll software for goto and tracking.

For any of the above some amount of DIY is requried and you can also add surplus parts to the mix to save some money on the motors and gear boxes. Have a Look at Gototelescopes.com Lenord his site has lots of conversions he has done and helped do.

ServoCat + AN is the most popular system for the Big Dobs. You could start just with the AN as a DSC system and later invest in the ServoCat.
The Siderealtech system can work out cheaper if you get surplus motors and bits.

The AN is arguably the best accessory you could get for your DOB.

Regards
Fahim

iceman (Mike) · #3 19-11-2007, 01:12 PM

You could also get an EQ platform that sits under your dob base - sejanus said in another thread he was quoted $895 US for one from Roundtableplatforms.com

I had a smaller one for my 10" dob and loved it.

prova · #4 19-11-2007, 01:19 PM

hmm, they look quite handy mike ..

could another option be to mount a 16" OTA onto let's say an EQ6?
would that work a little better than a 16" Lightbridge (for eg.) with motor drive?

just getting a few ideas for a friend

iceman (Mike) · #5 19-11-2007, 01:20 PM

No, you can't get a 16" newtonian OTA for a start - the largest is the 12" solid tube. It's been discussed previously about putting a 12" LB on an EQ6 - it's really not meant for that. The flex and stability problems would be a nightmare.

prova · #6 19-11-2007, 01:57 PM

right, so basically anything larger than a 12" must be Dob mounted?

iceman (Mike) · #7 19-11-2007, 01:59 PM

Practically, yes. You will see very large telescopes on VERY large mounts, but we're talking $50k+ mounts here.

prova · #8 19-11-2007, 02:04 PM

in that case, i foresee a new thread being started of which is the best value for money 16" Dob -

Lightbridge or the GSO when it's finally released ..

rmcpb (Rob) · #9 19-11-2007, 02:17 PM

The equatorial platform is absolutely brilliant for high power observing. I can leave mine at about 300x and it keeps the object in the FOV of a plossl for many miuntes of observing. Fantastic invention which really lets you study the object

As for setting up, just level it and point it to true south using a compass is all you need for visual use.

Satchmo · #10 19-11-2007, 05:00 PM

Quote:

Originally Posted by prova

just wondering do they exist and do they work well for very high mag views of the moon, planets, etc?

Surprised no one mentioned the DOb Driver. Its been around for years and currently USD $699.

http://homepages.accnorwalk.com/tddi...000/page3.html

I used one for about a year on my 14" but now its gathering dust as running a drive takes extra care and charged batteries and in the end `lentil power' won out . Thats John Dobson speak for `hand-pushing'

Mark

netwolf · #11 19-11-2007, 05:15 PM

Eq Platforms are a very good option. How did i miss that and how did i forget to mention Dob driver. Man this brings back memories. I think my first 500 posts were centered on this subject.

You should head over hear and join, lots of information on various designs in the file section. As well as spreadsheets on calculating stuff. You can search out my old threads on this subject as i linked quiet a number of sights illustrating the making of these.
http://tech.groups.yahoo.com/group/eqplatforms/

Perhaps the best Commercial options are

http://www.equatorialplatforms.com/ Expensive. Better to buy 2nd hand from someone who has similar latitude on Astromart.

As mentioned previously roundtabel platforms, perhaps the one we know best. Mike used his to produce amazing results.

Johnsonian platforms allow latitude adjustment but unfortunately he is out of the business. Second hand ones do turn up on Astromart.

As mentioned Matt from T&A in Adeliade did make some headway on this but i am uncertain if it took off or not. You can ring and ask him. I know he had a prototype but was still working on the Electronics.

If you have the DIY skill then you can more than likely knock one up easily.

Regards
Fahim

Barrykgerdes · #12 21-11-2007, 04:52 PM

Quote:

Originally Posted by Satchmo

Surprised no one mentioned the DOb Driver. Its been around for years and currently USD $699.

http://homepages.accnorwalk.com/tddi...000/page3.html

I used one for about a year on my 14" but now its gathering dust as running a drive takes extra care and charged batteries and in the end `lentil power' won out . Thats John Dobson speak for `hand-pushing'

Mark

Hi Mark

I had one of those DDR2 drivers about 13 years ago. I had an 8" dob in those days. It still exists, My daughter has it in Adelaide.

I spent many months modifing my DOB mount with ball bearing rollers and preloaded centre spindle for the azm platform and ball races for the alt yokes. The operation was very smooth and the DDR2 used to drive it quite effectively.

I then wrote a program in Qbasic to drive it as an automatic go to telescope, complete with ngc/Ic catalogue, Star catalogue and moon and planet calculator. I wrote a two star alignment routine that even used to print out the coords of my location. (not "quite" as "accurate" as a GPS)

The basic movement of the scope in track mode was a bit jumpy because the program was originally clocked every second from the computer clock. When I got a faster computer I worked out a routine synched by the computer clock that updated the position every 1/10 second. This smoothed the tracking nicely.

I then came into some money and bought a 10" LX200 so the Dob was given away! Ah! they were the days (nights).

Barry

TheCrazedLog · #13 23-11-2007, 09:39 AM

Quote:

Originally Posted by Barrykgerdes

I then wrote a program in Qbasic to drive

Good heavens man! What is wrong with you?! PERL is bad enough, we won't talk about BASH, but QBASIC?!?

Barrykgerdes · #14 23-11-2007, 10:18 AM

Quote:

Originally Posted by TheCrazedLog

Good heavens man! What is wrong with you?! PERL is bad enough, we won't talk about BASH, but QBASIC?!?

When I started with computers BASIC was the only language in Commodores. Segas, IBM PCs etc and I had to learn it or else. I am not a programmer and would rather do something else with my time. However I did find it easy to write simple mathmatically orientated programs and progressed to Qbasic because it was available and read my GWBASIC programs. Graphics (and GUI's) are not necessary for getting an answer in text which all I need in computer programs. You can't teach an old dog new tricks as they say and I am well into the "old" catergory.

Barry