The Time Clock Has Stood The Test Of Time

January 8, 2026 by 32 Comments

No matter the item on my list of childhood occupational dreams, one constant ran throughout: I saw myself using an old-fashioned punch clock with the longish time cards and everything. I now realize that I have some trouble with the daily transitions of life. In my childish wisdom, I somehow knew that doing this one thing would be enough to signify the beginning and end of work for the day, effectively putting me in the mood, and then pulling me back out of it.

But that day never came. Well, it sort of did this year. I realized a slightly newer dream of working at a thrift store, and they use something that I feel like I see everywhere now that I’ve left the place — a system called UKG that uses mag-stripe cards to handle punches. No it was not the same as a real punch clock, not that I have experience with a one. And now I just want to use one even more, to track my Hackaday work and other projects. At the moment, I’m torn between wanting to make one that uses mag-stripe cards or something, and just buying an old punch clock from eBay.

I keep calling it a ‘punch clock’, but it has a proper name, and that is the Bundy clock. I soon began to wonder how these things could both keep exact time mechanically, but also create a literal inked stamp of said time and date. I pictured a giant date stamper, not giant in all proportions, but generally larger than your average handheld one because of all the mechanisms that surely must be inside the Bundy clock. So, how do these things work? Let’s find out.

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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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Interconnected circuits for controlling the clock

Tick, Tock, Train Station Clock

December 31, 2025 by 9 Comments

We’ve seen a few H-bridge circuits around these parts before, and here’s another application. This time we have an Old Train Station Clock which has been refurbished after being picked up for cheap at the flea market. These are big analog clocks which used to be common at railway stations around the world.

This build uses an ESP32 C3-mini microcontroller (PDF) in combination with an A4988 Microstepping Motor Driver (PDF). The logic is handled with MicroPython code. The A4988 provides two H-bridge circuits, one for each of two stepper motors, only one of which is used in this build.

The controller for this clock needs to send an alternating positive then negative DC pulse every minute to register that a minute has passed so the clock can update its hour hand and minute hand as appropriate. The ESP32 and the A4988 H-bridge cooperate to make that happen. The wifi on the ESP32 C3-mini is put to good use by facilitating the fetching of the current time from the internet. On an hourly basis the clock gets the current time with a HTTP call to a time server API, for whatever is suitable for your time zone.

Thanks to [PiotrTopa] for writing in to let us know about his project. If you’re interested in learning more about H-bridge applications be sure to check out Introduction To The H-bridge Motor Controller and A H-Bridge Motor Controller Tutorial Makes It Simple To Understand.

Bare Metal STM32: Increasing The System Clock And Running Dhrystone

December 18, 2025 by 9 Comments

When you start an STM32 MCU with its default configuration, its CPU will tick along at a leisurely number of cycles on the order of 8 to 16 MHz, using the high-speed internal (HSI) clock source as a safe default to bootstrap from. After this phase, we are free to go wild with the system clock, as well as the various clock sources that are available beyond the HSI.

Increasing the system clock doesn’t just affect the CPU either, but also affects the MCU’s internal buses via its prescalers and with it the peripherals like timers on that bus. Hence it’s essential to understand the clock fabric of the target MCU. This article will focus on the general case of increasing the system clock on an STM32F103 MCU from the default to the maximum rated clock speed using the relevant registers, taking into account aspects like Flash wait states and the APB and AHB prescalers.

Although the Dhrystone benchmark is rather old-fashioned now, it’ll be used to demonstrate the difference that a faster CPU makes, as well as how complex accurately benchmarking is. Plus it’s just interesting to get an idea of how a lowly Cortex-M3 based MCU compares to a once top-of-the line Intel Pentium 90 CPU.

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Hackaday Podcast Episode 349: Clocks, AI, And A New 3D Printer Guy

December 12, 2025 by 2 Comments

Hackaday Editors Elliot Williams and Al Williams met up to cover the best of Hackaday this week, and they want you to listen in. There were a hodgepodge of hacks this week, ranging from home automation with RF, volumetric displays in glass, and some crazy clocks, too.

Ever see a typewriter that uses an ink pen? Elliot and Al hadn’t either. Want time on a supercomputer? It isn’t free, but it is pretty cheap these days. Finally, the guys discussed how to focus on a project like Dan Maloney, who finally got a 3D printer, and talked about Maya Posch’s take on LLM intelligence.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download the human-generated podcast in mostly mono, but sometimes stereo, MP3.

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Trace Line Clock Does It With Magnets

December 8, 2025 by 9 Comments

We love a good clock project, and [byeh_ in] has one with a design concept we don’t believe we have seen before. The Trace Line Clock has smooth lines and a clean presentation, with no sockets or visible mechanical fixtures.

Reading the clock is quite straightforward once one knows what is going on. At its heart, the unmarked face is much like any other analog clock face, and on the inside is a pretty normal clock movement. The inner recessed track on the face represents hours, and the outer is minutes. The blue line connects the two, drawing a constantly changing line.

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Get To The Games On Time With This Ancient-Style Waterclock

December 3, 2025 by 2 Comments

One easy way to make a very accurate clock is with a WiFi-enabled microcontroller like an ESP32 and a display: set up NTP, and you’ll never be off by more than a minute. This water clock project by [Liebregts] is not like that — there are no electronics to speak of, and if the clock is ever in sync to within a single minute, well, we’d be surprised.

We’re impressed to see it working regardless. Sure, it’s not exactly high-tech; the floating siphon mechanism [Liebregts] is using to get a steady flow out of the main reservoir dates back to 250 BC. On the other hand, since this style of time keeper has been out of fashion since the fall of Rome, [Liebregts] couldn’t just grab something off GitHub or ask ChatGPT to design it for them. This is real human engineering. The reservoir is even scaled to the four-hour timing of [Liebregts] workday — it gets refilled at lunch along with its maker.

The water clock in all its glory, plus diagrammatic labels.

In a clever build detail, the floating siphon tube also holds a pointer to an hour indicator. For minutes, his mechanism seems unique, though it’s related to another ancient trick, the Pythagorean cup. Pythagoras’s devious cup had a hidden siphon that spilled its contents if you filled it beyond a set level, and so does the secondary reservoir of [Liebregts] water clock.

Since the secondary reservoir is linked to a counterweight with a pivot, it goes up and down over the course of approximately 5 minutes — but rather than linking that to another linear indicator, [Liebregts] is using that mechanism to advance a saw-toothed gear that is marked with 5-12 in analog-clock fashion for a touch of modernity. See it in action in the demo video below.

That last part might confuse a time traveler from Ancient Rome or Greece, but they’d instantly recognize this creation as a clock, which many modern observers might not. Still, once they learn to read it you can be sure that [Liebergts]’s friends will never be late to a gladiator fight again — and not just because Constantine banned them in 325 AD. Apparently nobody listened to that ban anyway.

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