An Atomic Pendulum Clock Accurate Enough For CERN

January 28, 2023 by Dan Maloney 31 Comments

That big grandfather clock in the library might be an impressive piece of mechanical ingenuity, and an even better example of fine cabinetry, but we’d expect that the accuracy of a pendulum timepiece would be limited to a sizable fraction of a minute per day. Unless, of course, you work at CERN and built “the most accurate pendulum clock on the planet.”

While we’re in no position to judge [Daniel Valuch]’s claim, we’re certainly inclined to believe him, mainly because the 1950s-era Czechoslovakian pendulum clock his project was based on, the Elektročas HH3, was built specifically as a master clock for labs, power plants, and broadcast use. The pendulum of this mid-century beauty is made of the alloy invar, selected for its exceptionally low coefficient of thermal expansion. This ensures the pendulum doesn’t change length with temperature, but it still only brings the clock into the 0.1 second/day range.

Clearly that’s not good enough for a clock at CERN, the European Laboratory for Nuclear Research, where [Daniel] works as an RF engineer. With access to a 10-MHz timebase from a cesium fountain atomic clock — no less a clock than the one that’s used to define the SI second, by the way — [Daniel] looked for ways to sync the clock up to it. Now, we know what you’re thinking — he must have used some kind of PLL to give an electromagnetic “kick” to the bob to trim the pendulum’s period. Good guess on the PLL, but the trimming method is a little cruder — [Daniel] uses a stepper motor attached to the clock’s frame to pay out or retract a length of fine chain into a cardboard dish attached to the pendulum’s rod. The change in mass changes the pendulum’s center of gravity, which changes its effective length, and allows the clock to be tuned a couple of seconds per day.

It seems like [Daniel] is claiming that his chain-corrected clock won’t drift more than a second from the cesium clock for 158 million years. Again, we’ll take his word for it, but it’s a wonderfully ad hoc approach to tuning the clock, and we appreciate its simplicity.

The Times They Are A-Chaining

January 28, 2023 by Al Williams 6 Comments

If [Bob Dylan] had seen [Pgeschwi]’s bike chain clock, it might have influenced the famous song. The clock uses a stepper motor and a bike chain to create a clock that has a decidedly steampunk vibe. Despite the low-tech look, the build uses 3D printing and, of course, a bike chain.

The clock doesn’t just show the time. There is a contraption to show the day of the week, and a pendulum shows the current phase of the moon. The visible wiring is all old-school brass wire on the wood base. [Pgeschwi] is considering changing out all the 3D printed parts for brass ones, so this may be just an early prototype of the final product, but it still looks great.

The design used common tools, including Tinkercad and an online gear generation tool. There are a lot of details you wouldn’t suspect until you tried to build something like this yourself. For example, making the chain reliably go in both directions required a timing belt to synchronize the top gears. Getting the numbers on the chain to pass by the gears.

It is hard to tell from the picture, but there’s an LED under the 10-minute marks that shows the unit’s digits of the time. There are no markings for it yet, but in the picture, the time is actually 4:09.

We love unusual clocks, and we see plenty of them. From Fibonacci clocks to magnetic field line clocks, we love them all.

Binary Watch Rocks A Bare PCB With Pride

January 26, 2023 by Lewin Day 18 Comments

Most of us learn to read digital clocks first, which display the time in obvious numbers. Analog clocks are often learned later, with the hands taking our young brains a little longer to figure out. Once you’ve grown into a 1337h4XX0r, though, you’re ready to learn how to read a binary watch. Then you can build your own, just like [taifur] did.

The watch rocks a simplistic, bare bones design with the PCB acting as the body of the device itself. It’s not great for water resistance, or even incidental contact, but it’s a sharp look with the golden traces on display. The heart of the operation is a ATmega328P, as seen in the popular Arduino Uno, and it’s paired with a DS3231M real-time clock module to keep accurate time. 13 SMD LEDs are charged with displaying the time in binary format, with [taifur] choosing to spec a classic red color for the build. The watch is powered via a CR2032 coin cell, which you’re best advised not to swallow. So far, [taifur] has found the watch will last for over a month before the battery is tapped out.

It’s a fun build, and one that looks good when paired with a classic NATO watch strap in green. If, however, you desire a watch that definitely won’t last a month on a single coin cell, you can always build a Nixie watch instead. Video after the break.

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Knitting Clock Makes You A Scarf For Next Year

January 23, 2023 by Navarre Bartz 17 Comments

Time got a little wibbly wobbly during these pandemic years. Perhaps we would’ve had a more tangible connection to it if [Siren Elise Wilhelmsen]’s knitting clock had been in our living rooms.

Over the course of a year, [Wilhelmsen]’s clock can stitch a two meter scarf by performing a stitch every half hour. She says, “Time is an ever forward-moving force and I wanted to make a clock based on times true nature, more than the numbers we have attached to it.” Making the invisible visible isn’t always an easy feat, but seeing a clock grow a scarf is reminiscent of cartoon characters growing a beard to organically communicate the passage of time.

We’d love some more details about the knitting machine itself, but that seems like it wasn’t the focus of the project. A very small run of these along with a couple prototypes were built, with a knitting grandfather clock now occupying the lobby of The Thief hotel in Oslo.

If you’re looking for more knitting machines, checkout this Knitting Machine Rebuild or Knitting 3D Models Into Stuffies.

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3D Printed Berlin Uhr Is An Attractive Germanic Clock

January 18, 2023 by Lewin Day 22 Comments

As much as Big Ben steals the spotlight when it comes to big public clocks, the Berlin Uhr is a much beloved digital communal timepiece. [RuudK5] developed their own 3D printed replica of this 1980s German icon.

The revision we see today is the [RuddK5]’s third attempt at replicating the Berlin Uhr. The clock features a design with four linear elements with a round light on top. The top light is responsible for blinking the seconds. The lowest line has four lights, each indicating one minute, while the next line has eleven lights, marking out five-minute intervals. Above that, the top two lines represent one hour and five hour blocks respectively. It’s a display unlike most other clocks out there, but when you learn it, it’s easy enough to use.

[RuddK5]’s replica relies on addressable LED strips to serve as the individual lighting elements. The strips are placed inside a 3D printed housing that is a scale replica of the real thing. Running the show is an ESP32 microcontroller, which is charged with getting accurate time updates from an NTP server.

Great design really does shine through, and this clock looks just as appealing at the small scale as it does lofted on a pole over the city of Berlin. If you prefer to read out the time in a simpler fashion though, we’ve featured plenty of clocks like that, as well!

Organic Fibonacci Clock Is All About The Spiral

January 12, 2023 by Lewin Day 5 Comments

Whether you’re a fan of compelling Tool songs, or merely appreciate mathematical beauty, you might be into the spirals defined by the Fibonacci sequence. [RuddK5] used the Fibonacci curve as the inspiration for this fun clock build.

The intention of the clock is not to display the exact time, but to give a more organic feel of time, via a rough representation of minutes and hours. A strip of addressable LEDs is charged with display duty. The description is vague, but it appears that the 24 LEDs light up over time to show the amount of the day that has already passed by. The LEDs are wound up in the shape of a Fibonacci spiral with the help of a 3D printed case, and is run via a Wemos D1 microcontroller board.

It’s a fun build, and one that we can imagine would scale beautifully into a larger wall-hanging clock design if so desired. It at once could display the time, without making it immediately obvious, gradually shifting the lighting display as the day goes on.

We’ve seen other clocks rely on the mathematics of Fibonacci before, too. If you’ve cooked up your own fun clock build, don’t hesitate to let us know!

Triple Zone Clock Tells Time In Style

January 6, 2023 by Kristina Panos 9 Comments

Although the cutoff for saying ‘Happy New Year’ is somewhere around today, there’s still plenty of time to reminisce about 2022 and all that we accomplished. Hackaday alum [Jeremy Cook] spent much of last year designing and building a triple-zone PCB clock, dubbed the 742 clock. It is called so because of all the 7-segments, and then 42 from the height in millimeters of each PCB. Also because it’s 24 backwards, and if we may be so bold, because 42.

If this looks familiar, it’s because we covered the single-panel version a few months ago. Much like that one, the triple time zone clock is controlled by a single Wemos D1 mini, and the other two panels are chained to the primary board. This version has a frame made of 20/20 extrusion with nice 3D printed caps on the ends to finish off the look.

As with the single-panel clock, this one uses bared-FR4 PCBs to diffuse the LEDs, and the effect looks really nice. We particularly like the capacitive corners that control the clock and the colors, which change throughout the day when left to their own devices. Be sure to check out the build video after the break.

Are you really into LEDs? Consider building a Berlin clock.

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