DIY Stepper Controller

This is a DIY circuitry for driving telescope’s stepper motor for precise motion control.

It uses an Arduino Uno board and an L293D-based stepper motor driver IC. The stepper motor is then coupled with a suitable drive train attached on to a telescope’s fine adjustment knob.

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Once you’ve built the circuit above and uploaded the sketch to the board, blinking lights should indicate that the controller is working and ready to track the skies!

To get a copy of the sketch, please email eteny@nightskyinfocus.com.

Related links:
1990 Kenko NES Equatorial Mount
Ultra-Portable DIY Tracker

Night Sky in Focus | Astronomy and Amateur Radio
© Anthony Urbano | Manila, Philippines

15 thoughts on “DIY Stepper Controller”

    1. The mount uses a 6-wire (unipolar) stepper motor, but operated in 4-wire (bipolar) mode, leaving two wires (the center taps) unconnected. Good luck!

  1. I was looking for more information about clock drives and I came across your page.

    I am very interested in building an Arduino based motor controller like yours and I wanted to ask you if your design is based on a specific clock drive or if it can be used with other clock drives or stopper motors with different specifications.

    Last year a built a barn door tracker using a 4 RPM motor (geared down to 1 RPM) and even though it worked well for wide field images of 25mm, it can’t handle more than that before star trails are evident and also it is a hassle to have to adjust the velocity at the beginning of each session.

    During Christmas, my wonderful wife got me an Ioptron Skytracker and I must say that I am not too impressed with it at all because it is not very accurate (even though is supposed to be using an Arduino system). This is the reason why I would like to build a my own tracker (based on the Ioptron Skytracker design as opposed to a barn door design) which would enable me to track without having to rewind. I would also be adding an auto guiding port to use with a stand alone auto guider since the idea is to build a very portable system. I have two little girls and I cannot justify spending so much money on a commercial mount, so I will be happy to build a tracker on my own in order to continue my passion with astrophotography.

    Now, I have no idea where to begin! I much appreciate your time and input.

    1. Hi Sebastian,

      A microcontroller-based driver (such as an Arduino) should work with any stepper motor, drive train/gearbox, and most tracker configurations since the tracking rate can be easily specified. It should also work with well any well-built barn door tracker setup.

      I know someone (a local enthusiast) who seems to be getting good resullts with an Ioptron :) Are you certain you are properly polar-aligned, or the camera is properly balanced (i.e., the east side is slightly heavy)? Before you modify the tracker, we must be certain that you have narrowed the problem down to incorrect tracking rate (as this is the only thing that will render a tracker inaccurate).

      I would be happy to be of help.

      Eteny

    2. Hi Eteny,

      Thank you very much for the prompt response and the willingness to help! =)

      What I am really interested in doing, is building a microcontroller based driver with an autoguiding system the way you did, although I would prefer a stand alone auto guider since want to keep things simple and without having to use a laptop.

      I have two options in mind, one is a tracker system based on the Ioptron Skytracker and the other is a friction drive system based on the Fornax10 light mount ii. Although the tracker would be nice since there is no need to rewind it.

      Let me know your thoughts and where you think I should start. I have experience building telescopes, etc, but I have no experience when it comes to electronics and Arduino coding at all. Having said that, part of the reason I want to do this is to learn about Arduino which seems to be a pretty amazing platform.

      Thank you!

    3. When you say you want to build a tracker based on Ioptron or Fornax10, do you mean (1) building something similar (especially, fabricating your own gear system/gearbox mechanism) or (2) using already existing parts from those trackers and simply replace the circuit boards (since any commercially-available tracker is already equipped with rather decent gearbox). Anyway, let me know if you are modifying or building from scratch.

      There are key steps here: (1) you need to build a board that can make a motor spin at a constant speed, (2) look for a suitable gear system/drive configuration, (3) attach the motor to the gear system/drive, (4) spend some nights “adjusting” the motor’s speed, and (5) finally testing your tracker.

      Try to watch tutorials on stepper motors and Arduinos :)

  2. Hi Anthony,

    In response to your reply. First of all, sorry for the confusion…When I say that I would like to build a tracker based on the Ioptron or Fornax, I mean building a tracker using existing parts but not necessarily from those trackers.

    The other alternative is to replace the circuit board of my Ioptron Skytracker with an Arduino board that has been coded to yield less than 1 arc min of PE and also add a auto guide port. If this can be done, it would actually be even better since like you said, the Ioptron Skytracker already has a very decent gearbox system already.

    Thank you!
    Sebastian

    1. I would advise against replacing the circuit board of Ioptron (or any other tracker for that matter) esp if it is not broken. I am sure their engineers have already programmed those boards to track as precisely as possible. Have you ruled out the possibility that you are simply not properly polar aligned? It is a very real possibility that your tracker is in perfect working order, and what causes the trailing has something to do with polar alignment.

      In achieving polar alignment, simply pointing at Polaris is not enough. Do you know how to perform the drift alignment method? If you want to build a tracker, first you should learn how to polar align. Otherwise, even the best and most accurate trackers in the world will be rendered useless.

      Anyway, assuming that you have achieved a proper polar alignment yet the tracker is still ‘not very accurate’, then perhaps you have reached the limit of the tracker’s capability, and replacing the circuit board will not do any good. You need to upgrade to a better (larger, more sturdy, better gear reduction, and more expensive) tracker by buying one or building one.

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