Sun-Seeking Sundial Self-Calibrates In No Time

Sundials, one of humanity’s oldest ways of telling time, are typically permanent installations. The very good reason for this is that telling time by the sun with any degree of accuracy requires two-dimensional calibration — once for cardinal direction, and the other for local latitude.

[poblocki1982] is an amateur astronomer and semi-professional sundial enthusiast who took the time to make a self-calibrating equatorial ‘dial that can be used anywhere the sun shines. All this solar beauty needs is a level surface and a few seconds to find its bearings.

Switch it on, set it down, and the sundial spins around on a continuous-rotation servo until the HMC5883L compass module finds the north-south orientation. Then the GPS module determines the latitude, and a 180° servo pans the plate until it finds the ideal position. Everything is controlled with an Arduino Nano and runs on a 9V battery, although we’d love to see it run on solar power someday. Or would that be flying too close to the sun? Check out how fast this thing calibrates itself in the short demo after the break.

Not quite portable enough for you? Here’s a reverse sundial you wear on your wrist.

25 thoughts on “Sun-Seeking Sundial Self-Calibrates In No Time

    1. It’s unique, it’s non-obvious, a roomful of geniuses couldn’t have come up with it in a month, it climbed right out of the box and crawled underneath it. Imagine if we could apply this kind of thinking to the major problems of the world today. I know, maybe Africa wouldn’t be short of drinking water if they just bought vodka and boiled off the alcohol !!

  1. Next level: also use the longitude information and correct for magnetic declination.
    Then, use the calendar information to do the analemma correction too.

    And, heck, since you have power and servos, you may as well put a sun-simulating LED on it to run it at night too.

  2. “…although we’d love to see it run on solar power someday.” All sundials use “solar power” in that they can’t operate without sunlight, and this one is no different, it just uses a 9V for setup.

  3. Forget the GPS time-seekers. This is utterly charming.

    However, only of much use if the sundial is regularly moved and only really shows its true utility when it is moved great distances. Most of my projects just sit on the shelf.

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