Conversion of a GSO 680 Dobson 8" 200/1200mm telescope with GoTo to an observatory

Product Description
Customer Tip - Our customers always send us great suggestions and feedback.
Thank you very much for that. We really appreciate such feedback. But read for yourself:
Here's a picture of a GSO 680 Dobson 8" 200/1200mm telescope with GoTo, which was converted into an observatory.
"In July 2015, I purchased the GSO 680 Dobson 8" in the "DeLuxe" version from the telescope specialists. I am very satisfied with this purchase and enjoy the device a lot. Since then, it has undergone a series of upgrades and has become the centerpiece of my stationary "ministry observatory."

When I handed over my Dobson, Mr. Kloss said that the smooth-running azimuth pivot bearing was the first thing I would soon want to replace with a plain bearing:

It turned out very differently.
My first, very inexpensive modifications were the addition of sturdy carrying handles on the left and right sides of the original Dobsonian and the installation of three plastic leveling feet, similar to those used for installing built-in kitchen furniture. This allowed me to transport, set up, and quickly align the tripod even on damp and uneven terrain. The baseplate stayed dry even on wet grass thanks to the relatively high feet.

The "DeLuxe" tripod I purchased from you features high-quality mechanical bearings both horizontally and vertically, as well as other components that allow for the simple installation of a very powerful and high-precision motor controller. The whole thing should work smoothly even when changing the eyepiece from the lightweight NED 8mm 1 1/4" weighing 166g to my "gravitational lens" Maxvision 34mm 68° 2" weighing 785g. Unfortunately, my workshop equipment is only that of a "better do-it-yourselfer," and I'm not particularly skilled at it, so I had to come up with a simple solution. The only external service: Since I don't own a lathe, a friend machined two plastic wheels for the azimuth adjustment to a diameter of 72.0 mm. For all other production steps, however, I managed with a jigsaw and a bench drill.

I then fully motorized the device with a material cost of ≤ €350.

The control system is based on CNC components made in China, which can be found incredibly cheaply on eBay these days: Each axis has two powerful NEMA 23 (76 mm) stepper motors and a 4.5 A controller with ≤ 256x microstepping for parallel operation of these motors. The azimuth is adjusted directly via two friction wheels, while the alt axis is adjusted via two GT-2 toothed belts – each 850 mm long. These gearless axis drives are "force-symmetrical" and virtually backlash-free. The motorized focuser on the focuser is implemented with a smaller NEMA 17 motor and controller with only ≤ 16x microstepping. The additional motorized focuser on the focuser cost an additional ≤ €40.

All control and motorization components are mounted on the inside of the tripod. The entire system is child-proof and virtually indestructible.

The entire system was initially designed for 230V mains operation. Operation, setup, and calibration require a small netbook running Windows 7 or 10, special CNC software, and a control board with a microprocessor, I/O for motor drivers, a handheld controller, emergency stop, and a USB port.

This initially made it possible to control the telescope with the handheld controller and adjustable speeds from "jogging" to fine adjustment at V=185x via step switches.

Because the motorized telescope was quite heavy (approx. 30 kg), and there wasn't a good spot on our property for a clear panoramic view anyway, I finally set it up stationary on the garage roof. For this purpose, a stable base made of cement on Styrofoam boards (approx. €60) was placed over the tar tray, and the tripod was firmly anchored to four of the boards, weighing a total of approximately 60 kg, using four of the aforementioned leveling feet. Since then, the Dobsonian base plate has been permanently and storm-proof horizontally aligned with a maximum deviation of +/- 0.1° using a large circular bubble.

The original tripod supplied is plastic-coated. However, I didn't trust it to withstand the elements in the field for long periods due to the coarse-grained chipboard used under the coating. So, for the motorized version, I ended up making a copy out of weatherproof 18mm plywood, waterproofing it, painting it twice with garden furniture varnish, and relocating all the components (≤ €120).
Creating a weatherproof enclosure for the telescope on the garage roof gave me a lot of headaches. Grill covers, garbage bags, etc., as recommended online, were tried and failed. A segmented tower made of weatherproof plywood (≤ €140), completed in early December 2016, has provided perfect protection ever since, is easy to handle even in the dark, and is secured to the heavy cement slabs with brackets, making it storm- and theft-proof. The crucial element, however, is a waterproof 10W/230V heating foil (€15), similar to that used for amphibians in terrariums.

This is pushed directly under the primary mirror after stargazing and ensures constant air convection in the tower. This keeps everything nice and dry in ANY weather. The €25 annual electricity costs for this permanent heating are worth my telescope. I keep eyepieces, filters, netbook, etc. in a separate aluminum case with a foam insert in my house. I hang the case with a shoulder strap so that both hands are free when I climb onto the roof via a HYMER fire escape with back protection and a homemade bridge platform with railing. Despite the one-time special price, this convenient solution was the most expensive item in my cabinet at almost €500 including the 230V cable. But seniors shouldn't be climbing over wobbly ladders or tripping over the edge of the flat roof anymore – especially not in the dark ;-)

After all, I've had two small solar panels lying around from a camping project for a while. My son donated his used STECA Solsum 8.8 controller and two 12V batteries for 24V solar operation for Christmas.
This solution eliminated the annoying power cable. The sun charges the batteries during the day for about 5-6 hours of continuous operation. Even in winter, wearing a tank suit, I comfortably gazed for over 2 hours at -8°C. The new technology had no problems at all in these temperatures.

Now the real challenges begin: writing software for GoTo and tracking. For this example, I first have to learn the development language C# (Microsoft Visual Studio), which is new to me. So far, I've only managed to create a small app for manual GoTo: I read the position of the object in the top left corner of Stellarium. Using a small app displayed at the bottom right, I see the current position and move the telescope to the target using the handheld controller.

After an initial calibration, I achieve a deviation of ≤ +/- 0.2° in the sky during positioning. This can and will be significantly improved.