AVR Barn Door Tracker for Astrophotography


[ZigZagJoe's] first foray into astrophotography is this impressive AVR barn door tracker, which steps up his night sky photo game without emptying his bank account. If you’ve never heard of astrophotography, you should skim over its Wikipedia page and/or the subreddit. The idea is to capture images otherwise undetectable by the human eye through longer exposures. Unfortunately, the big ball of rock we all inhabit has a tendency to rotate, which means you need to move the camera to keep the night sky framed up.

Most trackers require precision parts and fabrication, which was out of [ZigZagJoe's] grasp. Instead, he found a solution with the Cloudbait Observatory model, which as best as we can tell looks vaguely similar to the tracker we featured last year. Unlike last year’s build—which uses an ATmega32u4 breakout board— [ZigZagJoe's] tracker uses an ATTiny85 for the brains, running a pre-configured table that determines step rate against time.

You’re probably asking “Where are the pictures?” It seems that [ZigZagJoe] has been plagued by clouds recently, but he promises they are forthcoming. Head over to his build thread on reddit for more details on the project’s design and hopefully future posts with some pictures. And swing by this site for a bunch of files on building your own.


  1. Willaim says:

    Saver2 — ZigZagJoe? thats awesome man. Neat project on the cheap as well.

    • Willaim says:

      I’m actually kinda suprised HaD hasnt featured his Saver2 app. (Maybe the legality?) It allows the interception of Streamed music from multiple free music services, He even has an awesome Pandora player with it just go to his site they listed with just the main URL

      • zigzagjoe says:

        I think it’s more that HAD is a hardware hack site rather than software. Besides, it’d be embarrassing, haven’t really had the time or motivation to do much on saver2 lately… Soon(tm)

  2. mh says:

    Obviously his next hack have to be a cloud-dispersing or weather-control device of sorts.

    • Reggie says:

      A cloud detector with a thermopile would be the best idea, look for the direction the clouds are travelling, in offset the thermopile to look a few degrees behind the tracker target, when the temperature rises (clouds are warmer than clear skies), stop taking pictures, temperature drops, resume picture taking.

  3. Trav says:

    Nice rig. I did the same thing, but my software was a lot simpler. It just ran the stepper at a consistent rate. The best thing is to take the tangent error into effect.

    New astronomical equipment is always plagued by clouds. The bigger/nicer the scope or the more work you put into it, the longer the clouds last.

  4. You could also obtain constant angular velocity if you simply use a curved bolt, instead of a straight one. Then you could use a constant-speed motor. Example:


  5. echodelta says:

    Like auto chicken coop doors I thought this somehow kept animals in nighttime confinement. How does an Alt-Az mount become a barn door?

  6. Biomed says:

    Old and venerable. Glad it’s still being taught and used. Anyone interested in this is welcome to join me for a night out with the stars. Great for raising a family.

  7. zigzagjoe says:
  8. Jim in IA says:

    Those things work great. I built one decades ago. Still have it. I need to get it out and try it with my newer lighter camera.

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