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Back in the early 90's before "goto" telescopes became common I bought a DOB11 driver for my 8" dobsonian. I did not buy all the attachments because I was able to make my own much better. I think the DOB11 is still available!
The DOB11 consisted of a box containg a simple processor and drivers for two stepper motors. When all the parts were fitted the Idea was that you pointed at an object and manually tracked for a few minutes and it would calculate a path and follow this for an hour or so.
The DOB11 can also be connected to a LPT port on a computer and they supplied a basic "BASIC" program to make the telescope into an alt/azm goto telescope. This did kind of work but it was cumbersome and messy to operate. Lap tops were only in their infancy and not a real option.
The main problem with the system was slippage of friction drives and the computer drive sent alternate alt and azm commands every second. Of course once you had the magnification up to about 150 the tracking path was a staircase.
I set about improving the problems. First by making the DOB mount into a stable alt/azm platform with preloaded ball races on all rotating axes. Then designed belt drives to get rid of the slippage, I never completed the azimuth belt drive because I bought a 10" LX200 that made the whole project redundant.
I next wrote a new program to drive the DOB11 (still in BASIC) that gave me a better two star alignment routine, an update every .1 seconds and a hand controller that worked off the games port (awfully slow). This worked but as I said before it was a messy thing to set up at any time and I had just got my LX200 so I stopped all development.
However I did document all the things I did. Particularly the upgrades and I think I still have the drive program.
It was a fun project at the time but not worth the trouble considering the availbilty of simpler commercial goto systems for fork and German equatorial mounts.
Further to this I also experimented with stepper drives salvaged from old MFM HDD's. They were much faster than those from FDD's. I made a controller for the motors and a computer program but never put them on a mount. However they looked good spinning doing an automatic alignment routine and then a psuedo track!
Barry
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