Tell Time With a Reverse-Sundial Watch

[Xose Pérez] set out to make a sundial wristwatch by combining a magnetometer a small nylon bolt for the gnomon, but it doesn’t work like you’d think. Instead of using the magnetometer to point the sundial north, you angle the watch until the bolt’s shadow matches the white line on the PCB, and the ATmega328P computes the azimuth of the sun and determines the time thereby. To display the time he used one of those QDSP-6064 bubble displays, because sundials are retro.

His description of the project build includes a lot of fun anecdotes, like him attempting to solder the LCC connections of the HMC5883 magnetometer before giving up and making use of Seeedstudio’s PCBA service. He got 10 boards back with the ATmega and magnetometer populated while leaving the rest for [Xose] to fill in.

One fun detail of the project? You can’t tell what time it is without the sun, but you can’t read the bubble display in bright sunlight.

If you’re looking for more watch projects we’ve published, check out this wrist-controlled watch, the Chronio DIY watch, and this cool nixie-tube watch.

We Didn’t Know the Sun Could Do Digital

You don’t get much more old school than a sundial, and more new school than 3D printing. So, it is nice to see these two combined in this impressive project: the 3D printed digital sundial. We have seen a few sundial projects before, ranging from LED variants to 3D printed ones, but this one from [Julldozer] takes it to a new level.

In the video, he carefully explains how he designed the sundial. Rather than simply create it as a static 3D model, he used OpenSCAD to build it algorithmically, using the program to create the matrix for each of the numbers he wanted the sundial to show, then to combine these at the appropriate angle into a single, 3D printable model. He has open-sourced the project, releasing the OpenSCAD script for anyone who wants to tinker or build their own. It is an extremely impressive project, and there is more to come: this is the first in a new podcast series called Mojoptix from [Julldozer] that will cover similar projects. We will definitely be keeping an eye on this series.

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Modern Spin on an Old Technology

It seems that the longer a technology has been around, the more likely it is that all of the ideas and uses for that technology will be fleshed out. For something that’s been around for around 5500 years it must be especially rare to teach an old dog new tricks, but [Sebastian] has built a sundial that’s different from any we’ve ever seen.

Once done with all of the math for the sundial to compute its angles and true north based on his latitude and longitude, [Sebastian] used Autodesk Inventor to create a model. From there it was 3D printed, but the interesting part here is that the 3D printer allowed for him to leave recesses for numbers in the sundial. The numbers are arranged at such angles inside the sundial so that when it’s a particular hour, the number of the hour shines through the shadow of the sundial which creates a very unique effect. This would be pretty difficult to do with any machine tools but is easily accomplished via 3D printing.

[Sebastian] wanted a way to appreciate the beauty of time, and he’s certainly accomplished that with this new take on  the sundial! He also wonders what it would be like if there was a giant one in a park. This may also be the first actual sundial build we’ve featured. What does that mean? Check out this non-pv, sun-powered clock that isn’t a sundial.

Thanks to [Todd] for the tip!

[Jack]’s solar-powered clock

Hack A Day’s own [Jack Buffington] finally finished the solar clock he built for the laser cutter giveaway.

[Jack] has been putting up the build log on his blog, and now the project is finally complete. The clock operates entirely on solar power. Instead of fancy-smanchy electronics, this clock puts a new spin on the very old school sundial. A box outside [Jack]’s house captures sunlight and focuses it onto an array of optical fibers. These fibers transmit the sunlight though the wall and to the face of the clock. Only a portion of the fibers are lit at any one time, and these correspond to the time of day. With a lot of confusing fiber routing, the clock can indicate the time of day by lighting up the clock face.

We covered the nascent beginnings of this project when it was still a glimmer in [Jack]’s eye, and we’ve got to hand it to him. This is a really creative project, and the addition of the ‘daylight savings time lever’ is the icing on the cake. Check out the video after the break for a great explanation of how the clock actually works, and be sure to check out the project on BuildLounge.

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A solar clock that isn’t a sundial

Hack a Day’s very own [Jack Buffington] is throwing his hat into the ring for the Buildlounge laser cutter giveaway with his solar clock that isn’t a sundial.

The theory behind [Jack]’s clock is pretty simple. The light from the sun will be captured by a camera obscura/pinhole camera. The sun’s rays shine on dozens of optical fibers that lead indoors and up to the clock. These glass fibers go to pinholes in the face of the clock which light up, showing the time.

[Jack] already cut out the face of the clock on his (awesome) home-made CNC router. He hasn’t gotten around to cutting out the mechanics of the clock face so the clock can be adjusted throughout the year. We’re okay with that, because we’re really not ready to see [Jack] fiddle with his gnomon. At least before [Jack] gets his hand on the Buildlounge laser.

The next major hurdle of the build is the solar collector that collects light into different optical fibers. That’s going to involve a lot of math using the equatorial coordinate system. Help is available, though.

Check out [Jack] cutting the clock face on his router after the break.

Continue reading “A solar clock that isn’t a sundial”

Prototyping the Bulbdial clock

Evil Mad Scientist posted a story about what went into developing the Bulbdial clock. We think the Bulbdial is one of the best pieces of kit out there for many reasons; using colored shadows for each hand is a brilliant idea, the design is clever and uses a low parts count, and the concentric rings that make it work also add to the aesthetic. But after seeing the original wood prototype it had crossed our minds that developing those circular PCBs isn’t the easiest thing to pull off. To save on board cost, the first run didn’t have the center routed out, but rather used almost-touching holes drilled during manufacture and finished by hand during assembly. They also go on to discuss the use of Charlieplexing to reduce part count and the search for a suitable diffuser for the clock face.

The Bulbdial clock comes to life


Evil Mad Scientist Laboratories has built the bulbdial clock, an idea originated by Ironic Sans.  It’s basically a high definition indoor sundial. The LEDs arranged in a circle shine a light on the peg in the middle casting a shadow, just like a sundial. There are 3 colors of rings, allowing for hour, minute, and second shadows. This isn’t the first time that Ironic Sans has seen ideas come to reality. There were the pre pixelated reality show clothes and the sneaky histogram hidden message system. While it is a cute idea, it isn’t really new. People have been patenting this idea for a while.