clock hacks

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2025 One Hertz Challenge: Drop The Beat (But Only At 60 BPM)

July 28, 2025 by 1 Comment

Mankind has been using water to mark the passage of time for thousands of years. From dripping stone pots in Ancient Egypt to the more mechanically-complicated Greco-Roman Clepsydrae, the history of timekeeping is a wet one — and it makes sense. As an incompressible fluid, water flows in very predictable patterns. If you fill a leaky pot with water and it takes an hour to drain, it will also take an hour the next time you try. One Hertz Challenge entrant [johnowhitaker] took this idea in a different direction, however, with an electromechanical clock that uses dripping water as an indicator.

This clock uses a solenoid to briefly pop the plunger out of a water-filled syringe. This allows a drop to fall from the tip, into a waiting beaker. In addition to the satisfying audio indication this produces, [johnowhitaker] added a bit of food coloring to the dripping water for visual flair. The entire thing is controlled by a Raspberry Pi Pico and a motor driver board, so if you’ve got some spare parts lying about and would like to build your own be sure to head over to the project page and grab the source code.

While this clock isn’t exactly here for a long time (either the syringe will eventually empty or the beaker will overflow), it’s certainly here for a good time. [John] and commenters on his project even have ideas for the next steps: a 1/60 Hz beaker changer, and a 1/600 Hz spill cleaner. Even so, the first couple of drops hitting the beaker produce a lovely lava lamp-esque cloud that is a joy to watch and has us thinking about other microfluidics projects we’ve seen.

And remember — it’s not too late to enter the 2025 One Hertz Challenge!

2025 One-Hertz Challenge: Clock Calibrator

July 28, 2025 by 8 Comments

Wall clocks! Are they very accurate? Well, sometimes they are, and sometimes they lose minutes a day. If you’ve got one that needs calibrating, you might like this device from [Lauri Pirttiaho].

Most cheap wall clocks use very similar mechanisms based around the Lavet-type stepper motor. These are usually driven by a chip-on-board oscillator that may or may not be particularly accurate.

[Lauri] desired a way to tune up these cheap clocks by using GPS-level timing accuracy. Thus began a project based around a CY8KIT evaluation board from Cypress. The microcontroller is paired with a small character LCD as a user interface, and hooked up to a cheap GPS module with an accurate 1-pulse-per-second (1PPS) timing output. The concept is simple enough. Clock drift is measured by using counters in the microcontroller to compare the timing of the GPS 1PPS output and the pulses driving the Lavet-type stepper motor. The difference between the two can be read off the device, and used to determine if the wall clock is fast or slow. Then one need only use a trimmer capacitor to tweak the wall clock’s pulse rate in order to make it more accurate.

Few of us spend much time calibrating low-cost wall clocks to high levels of accuracy. If that sounds like a fun hobby to you, or your name is Garrus, you would probably find [Lauri]’s device remarkably useful. Believe it or not, this isn’t the first clock calibrator we’ve seen, either. Meanwhile, if you’ve brewed up your own high-accuracy timing hardware, feel free to let us know on the tipsline.

2025 Hackaday One Hertz Challenge

2025 One-Hertz Challenge: Shadow Clock

July 26, 2025 by No comments

You can buy all kinds of conventional clocks that have hands and numbers for easy reading. Or, like [Fabio Ricci], you could build yourself something a little more esoteric, like this neat shadow clock.

The heart of the build is an ESP8266 microcontroller, which gets the current time via Wi-Fi by querying an NTP time server. It also uses a DS3231 real-time clock module as a backup, keeping accurate time even when a network connection is unavailable.

Time is displayed via a 60-pixel ring of WS2812B addressable LEDs. These 60 LEDs correspond to the usual per-minute graduations that you would find on a regular clock. Current hour is displayed by lighting the corresponding LED red, while minutes are shown in blue and seconds in white. It’s called a “shadow clock” because of its method of activation. IR distance sensors are used to activate the time display when a hand or finger is placed near the clock. As Fabio puts it, “shadow play” will make the clock display the time. Otherwise, it switches to be a simple round device on the wall that displays colorful animations.

It’s a neat build that looks quite unassuming as a decor piece, and yet it also serves as an easy-to-read timepiece. We’ve seen LEDs put to all sorts of good uses in clock builds around these parts. Meanwhile, if you’ve found your own unique way to display the time—either in readable fashion, or totally oblique—don’t hesitate to let us know.

2025 Hackaday One Hertz Challenge

2025 One-Hertz Challenge: A Clock Sans Silicon

July 26, 2025 by 12 Comments

Just about every electronic device has some silicon semiconductors inside these days—from transistors to diodes to integrated circuits. [Charles] is trying to build a “No-Silicon digital clock” that used none of these parts. It looks like [Charles] is on the way to success, but one might like to point out an amusing technicality. Let’s dive in to the clock!

Instead of silicon semiconductors, [Charles] is attempting to build a digital clock using valves (aka tubes). More specifically, his design relies on seven dekatrons, which are the basic counting elements of the clock. By supplying the right voltages to the various cathodes of the dekatrons, they can be made to step through ten (or sometimes twelve) stable states, used as simple memory elements which can be used as the basis for a timepiece. [Charles] will set up the first dekatron to divide down mains frequency by 5 or 6 to get down to 10 Hz, depending on whether the supply is 50 Hz or 60 Hz. The next dekatron will step down 10 times to 1 Hz, to measure seconds. The next two will divide by ten and six to count minutes, while a further two will divide the same way to create an impulse per hour. A final dekatron will divide by 12 to count the hours in a day.

Naturally, time will be displayed on Nixies. While silicon semiconductors are verboten, [Charles] is also considering the use of some germanium parts to keep the total tube count down when it comes to supporting hardware. Also, [Charles] may wish to avoid silicon, but here’s the thing about tubes. They use glass housings, and glass is made of silicon.

Cheeky technicalities aside, it’s a great project that promises to create a very interesting clock indeed. Progress is already steaming along and we can’t wait to see the finished product. We’ve seen dekatrons put to good use before, too. If you’re cooking up your own practical projects with mid-century hardware, don’t hesitate to let us know!

2025 Hackaday One Hertz Challenge

2025 One Hertz Challenge: A Discrete Component Divider Chain

July 25, 2025 by 23 Comments

Most of us know that a quartz clock uses a higher frequency crystal oscillator and a chain of divider circuits to generate a 1 Hz pulse train. It’s usual to have a 32.768 kHz crystal and a 15-stage divider chain, which in turn normally sits inside an integrated circuit. Not so for [Bobricius], who’s created just such a divider chain using discrete components.

The circuit of a transistor divider is simple enough, and he’s simply replicated it fifteen times in surface mount parts on a PCB with an oscillator forming the remaining square in a 4 by 4 grid. In the video below the break we can see him measuring the frequency at each point, down to the final second. It’s used as the timing generator for an all transistor clock, and as we can see it continues that trend. Below the break is a video showing all the frequencies in the chain.

This project is part of our awesome 2025 One Hertz Challenge, for all things working on one second cycles. Enter your own things that go tick and tock, we’d live to see them!

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2025 One-Hertz Challenge: Pokémon Alarm Clock Tells You It’s Time To Build The Very Best

July 22, 2025 by 3 Comments

We’ve all felt the frustration of cheap consumer electronics — especially when they aren’t actually cheap. How many of us have said “Who designed this crap? I could do better with an Arduino!” while resisting the urge to drop that new smart doorbell in the garbage disposal?

It’s an all-too familiar thought, and when it passed through [Mathieu]’s head while he was resetting the time and changing the batteries in his son’s power-hungry Pokémon alarm clock for the umpteenth time, he decided to do something about it.

The only real design requirement, imposed by [Mathieu]’s son, was that the clock’s original shell remained. Everything else, including the the controller and “antique” LCD could go. He ripped out the internals and installed an ESP32, allowing the clock to automatically sync to network time in the event of power loss. The old-school LCD was replaced with a modern, full-color TFT LCD which he scored on AliExpress for a couple of Euros.

Rather than just showing the time, the new display sports some beautiful pixel art by Woostarpixels, which [Mathieu] customized to have day and nighttime versions, even including the correct moon phase. He really packed as much into the ESP32 as possible, using 99.6% of its onboard 4 MB of flash. Code is on GitHub for the curious. All in all, the project is a multidisciplinary work of art, and it looks well-built enough to be enjoyed for years to come.

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2025 One-Hertz Challenge: It’s Hexadecimal Unix Time

July 21, 2025 by 9 Comments

[danjovic] came up with a nifty entry for our 2025 One-Hertz Challenge that lands somewhere between the categories of Ridiculous and Clockwork. It’s a clock that few hackers, if any, could read on sight—just the way we like them around here!

The clock is called Hexa U.T.C, which might give you an idea why this one is a little tricky to parse. It displays the current Unix time in hexadecimal format. If you’re unfamiliar, Unix time is represented as the number of non-leap seconds that have ticked by since 1 January 1970 at 00:00:00 UTC. Even if you can turn the long hex number into decimal in your head, you’re still going to have to then convert the seconds into years, days, hours, minutes, and seconds before you can figure out the actual time.

The build relies on an ESP32-S2 module, paired with a 7-segment display module driven by the TM1638 I/O expander. The ESP32 syncs itself up with an NTP time server, and then spits out the relevant signals to display the current Unix time in hex on the 7-segment displays.

It’s a fun build that your programmer friends might actually figure out at a glance. As a bonus it makes an easy kicking-off point for explaining the Year 2038 problem. We’ve featured other similar Unix clocks before, too. Video after the break.

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