Digital Setting Circles

Long story short, I own a really nice 12″ Dobsonian telescope, but I live in an area of high light pollution. This makes it difficult to find many objects. I decided I wanted to add some digital setting circles (DSC) to my scope, but all the commercial solutions were $500+ and often had really crappy user interfaces.

After doing some research I realized that it wouldn’t be too difficult to attach two CUI AMT11 encoders ($30/each) to my telescope. I then wanted a way to use SkySafari on my iPad to locate objects with it’s DSC feature. This meant I needed a way to connect the encoders to my iPad over WiFi.

The initial phase will be an encoder-to-wifi bridge so I can use SkySafari with my AD12- similar to the $250 Astrodevices Nexus. I don’t have GoTo on my scope (honestly, I don’t feel the need for that right now and I’m not sure how easy it would be to add to my scope), but for a few dollars more, my design will be able to support 2x serial ports and camera shutter control- just like the Nexus. The only thing I’m not sure about support yet is USB connectivity to certain models of goto controllers.

One little feature I have planned is the ability to use a button on a remote (so you can hold it in your hand) to “lock” the encoder values. The idea is that when you’re doing a 2 star alignment, you can lock the values so you don’t have to worry about knocking the scope or anything while you reach over to the iPad and click a button. I’m open to other ideas as well, so feel free to make any suggestions. :)

The actual cost of my board + components for just the encoder-to-wifi feature should be around $100 and it’s all open source!

Here are some pictures of what the current board design (subject to change) looks likes:

TeensyDSC v0.5.1 PCB Design
TeensyDSC v0.5.1 PCB Design
TeensyDSC v0.5.1 Schematic
TeensyDSC v0.5.1 Schematic
   
TeensyDSC v0.5 PCB Top
TeensyDSC v0.5 PCB Top
TeensyDSC v0.5 PCB Bottom
TeensyDSC v0.5 PCB Bottom
TeensyDSC is only about the size of a deck of cards.
TeensyDSC is only about the size of a deck of cards.
TeensyDSC Ports
TeensyDSC Ports
   
TeensyDSC Simple (populated) Top
TeensyDSC Simple (populated) Top
TeensyDSC Simple (populated) Bottom
TeensyDSC Simple (populated) Bottom
   
Alt encoder and Wireless DSC module powered by a USB battery pack
Alt encoder and Wireless DSC module powered by a USB battery pack
My Digital Settings Circles setup using SkySafari on the iPad
My Digital Settings Circles setup using SkySafari on the iPad

For more info, check out Teensy DSC on Github or my blog posts with the TeensyDSC tag.

13 thoughts on “Digital Setting Circles

  1. I was very interested in DSC that you have created.
    I want to buy a finished product.
    Please tell me Payment method and the price.

    • Hi Takito,

      Price for a PCB with all the components soldered on and it pre-programmed for your telescope is $160 USD + shipping. I accept PayPal. For that price, I also include the small plastic enclosure that you see in the photos above, but without any cut outs for the ports- you’ll have to do that yourself.

  2. Hi !

    I came across this while looking for DSC ideas for my Z8. I know this is an old post but can you post some pics about how you mounted the CMT11s? The Alt looks like it is screwed on top of the knob. How about the Az encoder?
    Did you use gears?
    TIA

      • Thanks

        Did you use the whole mounting kit from Astrosystems, or just parts of it.
        In particular did you have to replace/reverse the centre bolt on the base so
        to be able to attach the arm? Or did centre bolt stay in the original direction
        with the knob on top. I am trying to figure out if the arm/gear can be attached
        above or below the ball bearing/washers on the center bolt.

        • I used the whole kit. I would recommend you contact him via phone and place your order and NOT do it over the internet. If you don’t need the post/mount for the DSC computer you can save $$$ since he charges extra to ship the post.

          The arm only holds the encoder body in place so it doesn’t rotate. The kit comes with a new T-nut and knob for the Az which allows mounting the encoder. For the Az what you want is the encoder to be fixed to the dob base and the encoder body attached to the rocker box. That way as you move the Az axis, the encoder can track the movement. For reliability, I had to use blue loctite on the Az bolt/knob so it didn’t slip when moving the scope- the bolt tends to loosen over time which ruins the accuracy.

          If you have a drill press (or a steady hand + hand drill) and a 1″ drill bit you can drill out the center of one Alt knob yourself and not ship it to him for modification.

  3. Thanks for the details. I am still figuring out the design, and was finding it hard to
    figure out how to connect the encoder to the Az axis bolt given the knob on top setup of Zhumell.
    Orion has the bolt reversed already and all the kits for Apertura/Zhumell seem to reverse the bolt so that the open end of the bolt is accessible for mounting. I was wondering if yours does it that way too.

    It is also good to know about the blue locite and the phone order of parts.

  4. Aaron:

    I found your TeensyDSC project while looking for a Advansed Astromaster DSC for my old Celestron C8.

    My eyes are not as good as they used to be but I still love to get the C8 out on clear nights.

    I have some experience with arduino’s and have interest in your project as a alternative to the Celestron Advanced Astromaster DSC as they hav become rather hard to find. My question is is there coding changes that would be required to use your DSC on the C8 fork mount in polar alignment. Also I use Stellarium 0.15.1 on my laptop as my star guide, do you think the interface will work with it.

    • Assuming your C8 has encoders for RA/Dec and connected to the Astromaster via a RJ45 plug then the hardware should be compatible with the TeensyDSC. That’s because the TeensyDSC doesn’t understand RA/Dec or Alt/Az, but only “tics” on the encoder.

      The bigger question is Stellarium. I don’t use Stellarium myself (I use SkySafari) and so I’m not familiar with it. However, I couldn’t find any way of telling it to connect to either an Orion Intelliscope or “Basic DSC” option like I can with SkySafari. TeensyDSC doesn’t emulate the protocol of the Astromaster DSC and isn’t compatible with Stellarium. Of course, I may just not of found the correct menu? Stellarium doesn’t seem that intuitive to me so that’s possible.

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