clock hacks

1018 Articles

A Diffraction Grating Makes This Clock Readable

June 3, 2026 by 7 Comments

We’ve seen just about every possible way to make a clock here at Hackaday over the years. So it’s rare to have a first, but here we are with [Twisted & Tinned], who’s made a novel clock with a diffraction grating.

The display of the clock looks for all the world like a jumble of LEDs, that is, until you place the grating in front of it. Those LEDs are addressable multi-color parts, and each digit is generated at a different color all on top of each other. The grating splits out these colors, resulting in a magical set of floating LED figures.

Behind those LEDs is a Pi Pico, but that’s just one of many microcontrollers that could have powered this project. It’s the use of the diffraction grating in a novel way with those LEDs that makes the difference, and we rather like it. He’s also managed to get the grating pattern in the 3D printed surround for a shimmering look, by printing directly onto a diffraction grating sheet. That in particular is a technique we’ve looked at before in detail.

Continue reading “A Diffraction Grating Makes This Clock Readable” →

A black-and-white clock face is shown. The numerals are ranged around the right edge of the clock. One pointer extends from the center of the clock, and one is on the left side of the face.

A Clock Inspired By Failed Cognitive Tests

May 27, 2026 by 85 Comments

One simple screening tool for cognitive impairment is the clock-drawing test (CDT): the patient is provided with a printed circle and asked to draw a clock face with the hands pointing to a certain time. Depending on how the clock is drawn, this could indicate a variety of different disorders, particularly dementia, with a particular deformity in the drawing sometimes pointing to a specific issue. These failed tests inspired [John Silvia] to create a clock with a unique, disordered face.

The numerals in this clock face are placed exclusively along the right half of the clock (in the test, this can be a sign of damage to the right parietal lobe, or of executive dysfunction caused by dementia), and out of order. The hour hand is controlled by a servo motor, and the minute hand is mounted on a separate, commercially-purchased clock mechanism on the left-hand side of the face.

The frame for the clock and the face are 3D-printed, and the servo motor is controlled by an ESP32-C3 with an RTC module. To minimize power draw, a MOSFET disconnects the servo motor from power except for the once-per-hour position update. Once per month, the ESP32 connects to Wi-Fi to synchronize to NTP time, otherwise remaining in a low-power state – even its indicator LEDs are disconnected to save power. These efforts paid off: when the servo isn’t active, it draws only about 160 µA, and a set of three AA NiMH cells lasts about a year.

Since the servo motor draws most of the power budget, it wouldn’t make much difference, but the ESP32’s co-processor can also be used for ultra-low-power projects. For a happier take on a drawing-related clock, check out one of these projects.

Building An Analog Meter Watch

May 23, 2026 by 18 Comments

Most conventional analog watches have two or three hands, covering hours, minutes, and seconds (where present). [Sahko] has built a different kind of analog watch that creatively displays the time with just one. 

The build is based around a simple analog coil meter, which, at its heart, just sweeps its needle across a scale based on the voltage input to the device. A Raspberry Pi Pico is employed to drive the meter through a digital-to-analog converter. Pressing the buttons on the outside of the device tells the watch to display hours, minutes/seconds, or the current month or day of the week. With a single needle, only one parameter can be displayed at a time, but that’s just a compromise you accept for having a cool unique analog dial watch.

Another cool touch in the design is that the dial backer isn’t just a printed piece of paper—it’s a custom PCB, which has a much nicer, hardier finish. The case of the watch is also CNC milled out of aluminum and bead blasted for a quality surface finish, adding a nice industrial touch to the build.

This is a great example of a custom watch with quality fit and finish. The attention to detail really pays off in terms of feel. We’ve seen other watch projects use similar construction techniques before, too.

Continue reading “Building An Analog Meter Watch” →

A render of the moon, on a circular display.

Put The Moon On Your Desk

May 20, 2026 by 8 Comments

Most people take the Moon for granted, not considering its slow cycle where the sun gradually illuminates different parts of it. A recent project from [Karsten Mueller] helps you keep our nearest celestial neighbor in mind by putting a tiny version on your desk. (German)

The device itself is made with a circular display, an ESP32-S3, and a simple 3D printed case. But the interesting part is the software — it’s not just a moon phase display, it actually takes your local time, latitude and longitude into account. The resulting image is an approximation of what the moon looks like if you were to look at it, even if you wouldn’t actually be able to see it, such as when it is obscured by the Earth or barely visible during the daylight sky. Initially the project actually used a photograph of the Moon that [Karsten] personally snapped, but there’s also an option to pull the imagery from NASA.

The original write-up is in German, but there’s also an English page for the project on Hackaday.io, and the source is available on GitHub if you’d like to put one together yourself.

Voltmeter Clock Has The Time Dialled In

May 18, 2026 by 30 Comments

You could make a clock with three hands spinning about nested central shafts. If you did that, we probably wouldn’t publish it on Hackaday unless you really found a way to make it interesting. Make a clock out of voltmeters, however, and that usually catches our eye. [lcamtuf] has done just that.

The heart of the build is an AVR128DB28 microcontroller, an 8-bit microcontroller that is still currently in production. It runs at 8MHz, and drives a series of three Baomain 65C5 voltmeters to display hours, minutes, and seconds. Each has a custom printed face with the correct number of 13 or 61 divisions as needed. The voltmeters are driven by a continuous stream of 1-bit pulses with a software-controlled duty cycle determining exactly how far the needle moves. Yes, it’s using simple pulse width modulation, coded by hand by [lcamtuf] to do the job. All the components are wrapped up in a beautiful wooden case, with delicately kerf-bent panels to create the attractive curved lines.

We’ve featured similar builds before, too. As it turns out, hackers just really love clocks and old-school dials. Video after the break, which is worth watching for the rollover behaviour alone.

Continue reading “Voltmeter Clock Has The Time Dialled In” →

Salvaged VFDs In Nixie-Like Clock

May 16, 2026 by 6 Comments

In between the Nixie tube era of the 50s and 60s and the advent of multi-digit vacuum fluorescent displays (VFDs) common in 80s and 90s consumer technology, there was a brief time in the early 70s where single-digit VFDs were commonplace. Superficially these devices look like Nixie tubes, but have a number of advantages to them including lower voltage, lower power requirements, and lower cost. [maurycyz] recently found a number of these salvaged from old calculators and used them to build a retro-themed clock.

[maurycyz] was not able to find datasheets for this display, but was able to reverse-engineer each of the digits. Similar to vacuum tubes there is a heater which has a few ohms of resistance, and from there each of the segments of the digit can be deduced by probing the 13 signal wires. These are analog devices in some respects, so a lot of experimentation had to go into driving the displays to find their optimal conditions. A quartz crystal was used for timekeeping with an AVR128DA28 microcontroller chosen to provide control for the digits, using seven pins as segment drivers and four as grid drivers. Each digit uses around 0.14 watts, so with all four digits on it can consume a little over half a watt. A simple wood enclosure rounds out the build.

As Nixie supply wears thin, VFDs like this can be an excellent stopgap or replacement while still building retro-themed displays like this clock or this calculator which uses similar VFDs for each digit.

It’s A Water Clock, Jim, But Not As We Know It — It Has Digits

May 11, 2026 by 14 Comments

Guess what time it is– that’s right, clock time! It’s always clock time, and when it’s clock time at Hackaday the weirder the better. So, how about a water clock that’s not actually a water clock? The water here has nothing to do with timekeeping, but is what’s driving the display. Fair to say that [Strange Inventions] is living up to the name of his YouTube channel.

You can get the idea from the header image: each digit is formed by a fifteen-segment display made up of glass bottles. A stepper-driven peristaltic pump and some membrane-pump boosters fills the bottles as needed with dyed water, while emptying is accomplished simply by having a servo dump the water into a trough. It’s an interesting, albeit messy, way to generate a display.

It wasn’t the original idea– well, the bottles were the original concept, but flipping them was not. Dumping the bottles has the advantage of not needing oodles of pumps or taking five minutes to sequentially fill and drain the bottles at each digit. The linkage to get the servo to flip all nine bottles in one go took some troubleshooting– we can relate, since the physical half of such projects usually is the hard part– but after many modifications the 3D printed mechanism worked, and we think the results are worth it.

If you’re looking for the other kind of water clock, we featured one of those before, too. This one is also of ancient style, but makes use of modern electronics. It occurs to us that if one was really, really ambitious, they could expand this [Strange] project into a very damp flip-dot style display. Continue reading “It’s A Water Clock, Jim, But Not As We Know It — It Has Digits” →