Move Over Cesium Clock, Optical Clocks Are Taking Over

March 26, 2021 by Al Williams 26 Comments

We normally think of atomic clocks as the gold standard in timekeeping. The very definition of a second — in modern times, at least — is 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of a stationary cesium-133 atom at a temperature of 0K. But there is a move to replace that definition using optical clocks that are 100 times more accurate than a standard atomic clock.

In recent news, the Boulder Atomic Clock Optical Network — otherwise known as BACON — compared times from three optical clocks and found that the times differed a little more than they had predicted, but the clocks were still amazingly accurate relative to each other. Some of the links used optical fibers, a method used before. But there were also links carried by lasers aimed from one facility to another. The lasers, however didn’t work during a snowstorm, but when they did work the results were comparable to the optical fiber method.

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Clock-of-Clocks Adds Light-Pipe Hands For Beauty And Function

March 19, 2021 by Dan Maloney 8 Comments

We’ve gotten used to seeing “meta clocks,” clocks that use an array of analog clock faces and piece together characters using the hands of the clocks. They’re very clever, and we always like to see them, especially when they come with detailed build instructions like this one does.

What’s also nice about [Erich Styger]’s “MetaClockClock” display is the twist on the original concept. Where most clock-of-clocks depend on the contrast between the hands and the faces of the analog movements, [Erich] added light to the mix. Hidden inside the bezel of each clock is a strip of RGB LEDs; coupled with the clear acrylic hands of the clock, which act as light pipes, each clock can contribute different shapes of different colors to the display. Each clock is built around a dual-shaft stepper motor of the kind used in car dashboard gauges; the motors each live on a custom PCB, while the LEDs are mounted on a ring-shaped PCB of their own. Twenty-four of the clocks are mounted in a very nice walnut panel, which works really well with the light-pipe hands. The video below shows just some of the display possibilities.

[Erich] has documented his build process in extreme detail, and has all the design files up on GitHub. We won’t say that recreating his build will be easy — there are a lot of skills needed here, from electronics to woodworking — but at least all the information is there. We think this is a beautiful upgrade to [Erich]’s earlier version, and we’d love to see more of these built.

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A Discrete Logic Word Clock

March 12, 2021 by Chris Lott 26 Comments

Self-acclaimed computer nerd [Kevin Koster] was tired of designing new TTL-logic clocks before finishing his previous designs. So he finally buckled down and completed this unique word clock, which uses only a handful of TTL chips. We can’t disagree with his friends who complained that they can’t read [Kev]’s handwriting, so perhaps this diagram will make it clearer.

Besides being a nice logic-only project, this will give an example to younger folks how much effort went into things which are so simple to implement today. We don’t see a Karnaugh map on the project page for sorting out the logic diodes driving the minutes LEDs. If [Kev] did it on the fly, as the rat’s nest of diodes on the schematic would suggest, we’re not sure whether to scold him or be impressed (he does redraw that logic very neatly on a separate sheet).

No worries about high speed wiring on this project. The main oscillator derives time from the 50 Hz AC transformer power supply, and outputs a reference clock signal of 16.7 mHz (not MHz), or once per minute. This is divided down to 3.3 mHz for the 5-minutes counter and again to 277 uHz for the hour counter. If you live in a 60 Hz power mains country, you’d have to modify the oscillator section. Or you could contact [Kev] on his site, as he is considering making this available as a kit worldwide. If you like word clocks, we’ve covered quite a few of them before, including this crazy-complex rear-projection one.

The IEEE Builds A Smart Watch

March 6, 2021 by Al Williams 24 Comments

It used to be that building your own watch was either a big project or it meant that you didn’t really care about how something looked on your wrist. But now with modern parts and construction techniques, a good-looking smart watch isn’t out of reach of the home shop. But if you don’t want to totally do it yourself, you can turn to a kit and that’s what [Stephen Cass] did. Writing in IEEE Spectrum, he took a kit called a Watchy and put it through its paces for you.

Watchy is an open source product that uses an ESP32, an E-ink display, and costs about $50. The display is 1.5 inches — good enough for a watch — and it has a real time clock, a vibration motor, an accelerometer, and four buttons. The whole thing runs on a 200 mAh lithium polymer battery. The charger is microUSB and you can also upload software to it using the usual Arduino tools.

However, [Stephen] found that none of the examples he tried would work at first. He found problems with the Mac software, but he also had problems under Windows. The answer? Switching to a Raspberry Pi seemed to work and once the watch was wiped clean, the Mac tools would work, too. It sounds like this isn’t a common problem, but he has to erase the watch with the Pi before each programming cycle.

Unlike a normal Arduino program, all the work in a typical Watchy program happens in setup() so the watch can mostly sleep and it updates the 200×200 typically just once a minute. As an example, [Stephan] wrote a watch face that uses an old Irish alphabet to tell time. He plans to add code to grab online data, too, and the phone has support for connecting wirelessly and parsing JSON to make tasks like that easier.

We always thought the EZ430-Chronos was a good-looking watch, but its screen is dated now. You can also pick up a lot of cheap import watches that can be hacked.

Circle Full Of LEDs Becomes A Clock

February 27, 2021 by Rich Hawkes 5 Comments

Building a clock of some sorts seems to be a time honored tradition for hackers and LED clocks seem one of the most popular. You can build anything from a seven-segment display to a binary clock or something even more fancy. [Clueless] found a circle of LED rings online and with made an LED version of an analog clock.

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This Slimline Word Clock Uses Laser Etching To Keep Things Simple

February 21, 2021 by Dan Maloney 1 Comment

Judging by the tips we get, it seems like the popularity of word clocks has perhaps started falling off lately. But back at peak word clock, we were seeing dozens of designs, some better than others. This simple but classy word clock seems to benefit from all that prior art, making the design just about as simple as it can get while still looking great.

The main tool for [t0mg]’s build is a laser cutter, which is a great choice for keeping the design simple. The tricky part of word clocks is getting the “word search” matrix executed cleanly, and we’ve seen everything from laser-cut wood to inkjet prints, and even commercially produced PCBs, used for the job. [t0mg] opted instead to spray paint a piece of glass and etch away the characters with the laser, which results in superb text quality. Etching the underside of the glass also has the advantage of protecting the paint layer while giving the finished clock a glossy face that really looks nice. Under the template lie layers of MDF that hold the Neopixel strips and act as light guides, while an ESP32 and RTC perform timekeeping and LED-driving duties. [t0mg] finished off the clock with a nice web interface to set the clock, change the colors, and perform maintenance functions. The video below shows the software in use.

We really think this clock looks great, and for those with access to a laser cutter, it seems like a great way to go about building your own.

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Tuning Fork Keeps This Throwback Digital Clock Ticking

February 13, 2021 by Dan Maloney 37 Comments

Whatever kind of clock you’re interested in building, you’re going to need to build an oscillator of some sort. Whether it be a pendulum, a balance wheel, or the atomic transitions of cesium or rubidium, something needs to go back and forth in a predictable way to form the timebase of the clock. And while it might not make the best timepiece in the world, a tuning fork certainly fits the bill and makes for a pretty interesting clock build.

One of the nice things about this build is that [Kris Slyka] got their inspiration from a tuning fork clock that we covered a while back — we love it when someone takes a cool concept and makes it their own. While both clocks use a 440 Hz tuning fork — that’s an A above middle C for the musically inclined — [Kris] changed up the excitation method for their build. She used a pair of off-the-shelf inductors, placed near the ends of each arm and bridged by a strong neodymium magnet to both sense the 440-Hz vibrations and to provide the kick needed to keep the fork vibrating.

As for the aesthetic of the build, we think [Kris] really nailed it. Using through-hole components, old-school seven-segment displays, and a home-etched PCB, she was able to capture a retro look that really works. The RS-232 port and the bell jar enclosure complete the feel, although we’re not sure about the custom character set [Kris] designed — it’s cool and all, but makes it hard for anyone else to read without a little practice. Regardless, this is a fun build, and we’d imagine the continuous tone coming from the clock is pretty pleasing.

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