clock

647 Articles

There Are No LEDs Around The Face Of This Clock

March 10, 2026 by 8 Comments

This unusual clock by [Moritz v. Sivers] looks like a holographic dial surrounded by an LED ring, but that turns out to not be the case. What appears to be a ring of LEDs is in fact a second hologram. There are LEDs but they are tucked out of the way, and not directly visible. The result is a very unusual clock that really isn’t what it appears to be.

The face of the clock is a reflection hologram of a numbered spiral that serves as a dial. A single LED – the only one visibly mounted – illuminates this hologram from the front in order to produce the sort of holographic image most of us are familiar with, creating a sense of depth.

The lights around the circumference are another matter. What looks like a ring of LEDs serving as clock hands is actually a transmission hologram made of sixty separate exposures. By illuminating this hologram at just the right angle with LEDs (which are mounted behind the visible area), it is possible to selectively address each of those sixty exposures. The result is something that really looks like there are lit LEDs where there are in fact none.

[Moritz] actually made two clocks in this fashion. The larger green one shown here, and a smaller red version which makes some of the operating principles a bit more obvious on account of its simpler construction.

If it all sounds a bit wild or you would like to see it in action, check out the video (embedded below) which not only showcases the entire operation and assembly but also demonstrates the depth of planning and careful execution that goes into multi-exposure of a holographic plate.

[Moritz v. Sivers] is no stranger to making unusual clocks. In fact, this analog holographic clock is a direct successor to his holographic 7-segment display clock. And don’t miss the caustic clock, nor his lenticular clock.

Continue reading “There Are No LEDs Around The Face Of This Clock” →

Building A Super-Compact Cistercian Numerals Clock

March 8, 2026 by 12 Comments

Around the thirteenth century CE, European society was in the midst between transitioning from Roman numerals to the Arabic numerals that we use today. Less remembered are the Cistercian numerals, which [BigCrimping] used for their most recent project in the form of a rather unique clock.

The Cistercian numeral system was developed by the Cistercian monastic order in the 13th century, forming a rather unique counterpoint to the Arabic numeral system. Although Arabic numerals are already significantly more compact than Roman numerals, Cistercian numerals up the ante by being capable of displaying any number between 1 and 9,999 with a single glyph.

Although for a simple 24-hour clock you don’t need to use more than a fraction of the possible glyphs, there is the complication of the Cistercian numerals not having a zero glyph, but that invites an even better take. For the version that [BigCrimping] made there are namely two glyphs that encode date and time, with the left glyph a counter for blocks of two hours and the right for seconds from 1 through 7200.

The clock is based around MAX6969 LED drivers and an ESP32 MCU on a custom PCB, with the design files including the 3D-printed enclosure available in the repository.

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Tech In Plain Sight: Projection Clocks

February 23, 2026 by 12 Comments

You wake up in the middle of the night. Is it time to get up? Well, you can look at the nightstand clock. Unless your partner is in the way. Whoops. Even then, without your glasses, the time is just a fuzzball of light. You could ask Alexa, but that’s sure to wake your partner, too. The answer is a projection clock. In its modern form, it shoots a digital time display on a wall or ceiling with digits so large that you don’t need your glasses. If you can see the ceiling, you can tell what time it is.

New Tech

A modern invention, of course. No, not really. According to [Roger Russel], a UK patent in 1909 used an analog clock face and lightbulbs to project the clock face and hands on the ceiling. Unfortunately, [Roger’s] website is no more, but the Wayback Machine is on the job. You can see a device of the same type at the British Museum.

A modern projection clock on the ceiling.

In 1938, [Leendert Prins] filed for a patent on a similar projection clock. Sometimes known as “ceiling clocks” or “night clocks,” these devices often have a regular clock visible as well as a way to project the time. In the old days, this was often an image of a translucent analog clock lit up by light bulbs. In the modern era, it is almost always either LEDs or an LCD with a halogen backlight. Of course, there are many variations. A clock might use numbers on a rotating drum with a lamp behind it, for example.

Development

It isn’t hard to imagine someone putting a pocket watch in a magic lantern as a prototype. In general, some bright light source has to pass through a condenser lens. The light then travels through the LCD or translucent clock face. Finally, a projector lens expands the image.

We couldn’t find much about the actual history of old projection clocks outside of [Roger’s] defunct website. But if you can project an image and build a clock, all you need is the idea to combine them.

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Restoration Of Antique Clock With Unique Oscillator

February 13, 2026 by 8 Comments

The classic design of a mechanical clock generally consists of a display, a way to store energy, a way to release that energy at regular intervals, and a mechanism to transmit it where it needs to go. Most of us might be imagining a pendulum or a balance wheel, but there have been many other ways to maintain a reliable time standard with a physical object beyond these two common methods. This clock, for example, uses a rolling ball bearing as its time standard and [Tommy Jobson] discusses its operation in depth during a restoration.

The restoration of this clock, which [Tommy] theorizes was an amateur horological project even when it was new, starts by dismantling the clock nearly completely. The clock was quite dirty, so in addition to being thoroughly cleaned it also needed a bit of repair especially involving a few bent pins that stop the table’s rotation. These pins were replaced with stronger ones, and then everything in the clock’s movement was put back together. The tray carrying the ball bearing needed to be cleaned as well, and [Tommy] also added a lacquer to help preserve the original finish as long as possible. From there it was time to start calibrating the clock.

The ball bearing itself rolls back and forth along an inclined plane on a series of tracks. When it gets to the end it hits a lever which lets a bit of energy out of the movement, tilting the table back in the other direction to repeat the process. This is a much more involved process for getting an accurate time interval than a pendulum, so [Tommy] had a lot of work to do here. But in the end he was able to bring it back to life with an accuracy fairly close to a pendulum clock.

Ball bearings are a pretty popular medium for clock builds even in the modern era. This one uses them in a unique display, and a more recent version goes even further by using marbles to display digits directly.

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A Simple Desktop Pomodoro Timer

February 7, 2026 by 7 Comments

Pomodoro timers are a simple productivity tool. They help you work in dedicated chunks of time, usually 25 minutes in a sitting, before taking a short break and then beginning again. [Clovis Fritzen] built just such a timer of his own, and added a few bonus features to fill out its functionality.

The timer is based around the popular ESP32-S2 microcontroller, which has the benefit of onboard WiFi connectivity. This allows the project to query the Internet for things like time and date updates via NTP, as well as weather conditions, and the value of the Brazilian Real versus the American dollar. The microcontroller is paired with an SHT21 sensor for displaying temperature and humidity in the immediate environment, and an e-paper display for showing timer status and other relevant information. A button on top of the device allows cycling between 15, 30, 45, and 60 minute Pomodoro cycles, and there’s a buzzer to audibly call time. It’s all wrapped up in a cardboard housing that somehow pairs rather nicely with the e-paper display aesthetic.

If Pomodoro is your chosen method of productivity hacking, a project like this could suit you very well. We’ve featured a few similar builds before, too. Continue reading “A Simple Desktop Pomodoro Timer” →

The clock and the rebuilt calculator from which its VFD was donated.

An RPN Calculator And A Bonus VFD Clock From Casio Revival

January 5, 2026 by 15 Comments

Have you heard the saying “the problem is the solution”? It seems to originate in the permaculture movement, but it can apply equally well to electronics. Take the problem [shiura] had: a Casio Mini CM-602 that had let out the magic smoke. The solution was a twofer: rebuild the Casio into a modern number cruncher with Reverse Polish Notation (RPN), and save the Vacuum Fluorescent Display (VFD) for a gorgeous WiFi clock.

[shiura]’s write-up includes a helpful guide for reverse engineering the pins on this sort of VFD, if you don’t happen to have the same model calculator (or VFD tube) they’re working with. If you’ve done this sort of thing, you know what to expect: power it up and kill power to the pins, one by one, to map out which segments or characters go out, thereby identifying the anodes and grid electrodes. The cathodes had already been ID’d from looking at the PCB. After that it’s just a matter of wiring the VFD to an ESP32 via a transistor array to get the voltages right, and voila! Clock. The code and case design files for this clock — including an editable .blend — are available via GitHub.

The calculator half of the project is an incredibly elegant hack that relies on the fact that the Casio’s CPU has the same pin pitch as modern micros: 2.54 mm, or 0.1″, so an RP2040 zero can sit in the footprint of the original CPU, scanning the keypads with its GPIO. Then an I2C display is separately wired up to replace the clockified VFD. Perhaps some driver circuitry for the VFD died, or [shiura] salvaged the display before deciding to save the calculator, because otherwise we see no reason why this brain transplant couldn’t be done while keeping the original display. Admittedly having two lines on the display instead of one make the “new” calculator a tad more usable. The code for that is also available on GitHub, and while the readme is in Japanese, machine translations have gotten pretty good and the code is quite readable on its own.

Longtime readers will likely be familiar with [shiura]’s work, with a number of finely crafted clocks having been featured from the Japanese maker, along with vintage pocket computer repairs. Bringing both together makes this twin hack particularly on-brand.

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Reverse Sundial Still Tells Time

December 10, 2025 by 11 Comments

The Dutch word for sundial, zonnewijzer, can be literally translated into “Sun Pointer” according to [illusionmanager] — and he took that literal translation literally, building a reverse sundial so he would always know the precise location of our local star, even when it is occluded by clouds or the rest of the planet.

The electronics aren’t hugely complicated: an ESP32 dev board, an RTC board, and a couple of steppers. But the craftsmanship is, as usual for [illusionmanager], impeccable. You might guess that one motor controls the altitude and the other the azimuth of the LED-filament pointer (a neat find from AliExpress), but you’d be wrong.

This is more like an equatorial mount, in that the shaft the arrow spins upon is bent at a 23.5 degree angle. Through that hollow shaft a spring-steel wire connects the arrow to one stepper, to drive it through the day. The second stepper turns the shaft to keep the axis pointed correctly as Earth orbits the sun. See the demo video embedded below for full details.

Either way you can get an arrow that always points at the sun, but this is lot more elegant than an alt-az mount would have been, at the expense of a fiddlier build.  Given the existence of the orrery clock we featured from him previously, it’s safe to say that [illusionmanager] is not afraid of a fiddly build. Doing it this way also lets you read the ticks on the base just as you would a real sundial, which takes this from discussion piece to (semi) usable clock.

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