A sine wave and triangle wave on a black background

2025 One Hertz Challenge: Op-Amp Madness

Sometimes, there are too many choices in this world. My benchtop function generator can output a sine, square, or saw wave anywhere from 0.01 Hz up to 60 MHz? Way too many choices. At least, that’s what we suspect [Phil Weasel] was thinking when he built this Analog 1 Hz Sinewave Generator.

Rendering of a PCB
A KiCad rendering of [Phil]’s design
[Phil]’s AWG (which in this case stands for Anything as long as it’s a 1 Hz sine Wave Generator) has another unique feature — it’s built (almost) entirely with op-amps. A lot of op-amps (37, by our count of the initial schematic he posted). His design is similar to a Phased Locked Loop (PLL) and boils down to a triangle wave oscillator. While a 1 Hz triangle wave would absolutely satisfy judges of the One Hertz Challenge, [Phil] had set out to make a sine wave. Using a feedback loop and some shaping/smoothing tricks (and more op-amps), he rounded off the sharp peaks into a nice smooth sine wave.

Sometimes we make things much more complicated than we need to, just to see if we can. This is one of those times. Are there much simpler ways to generate a sine wave? Yes — but not exclusively using op-amps! This entry brings stiff competition to the “Ridiculous” category of the 2025 One Hertz Challenge.

Hexagonal Lighting Brings A Touch Of Elegance To The Workshop

Sometimes, we’re faced with what should be simple household tasks that we choose to make more difficult. Sure, you could buy a clock, hang it on your wall, and move on with your day, or could spend a week or two building the perfect one. [Nejc Koncan] was in one such situation recently when he needed some new overhead lighting. He wanted hexagonal lights — and since none of the off-the-shelf solutions met his exacting requirements, he built his own.

Unlike most of the cycling RGB hexagonal lighting solutions available on the market, [Nejc] wanted elegant white outlines that he could control via HomeAssistant. After some careful design and quite a bit of trial-and-error, he ended up with a highly modular and very professional-looking installation. The hexagons are constructed from LED strips set into aluminum extrusions, with junction PCBs at each intersection. To complete the look, all of the strips and wiring are hidden by diffusers that slot into the extrusions — and of course, the whole thing is open source.

We see lots of lighting projects here at Hackaday, and even other hexagonal lights — but this might just be one of the most refined. Sometimes it’s worth the extra effort to build a totally over-engineered custom solution.

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

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: 555 Timer Gets A Signal From Above

One of the categories we chose for the One Hertz Challenge is “Could Have Used a 555.” What about when you couldn’t have, but did anyway? The 555 is famously easy to use, but not exactly the most accurate timer out there — one “ticking” at 1 Hz will pulse just about once per second (probably to within a millisecond, depending on the rest of the circuit), but when you need more precise timing, the 555 just won’t cut it. Not on its own, anyway.

An Allan deviation plot
Allan Deviation can be a bit confusing, but generally — lower is more accurate

This entry by [burble] shows us how the humble 555 can hold its own in more demanding systems with some help from a GPS receiver. He used the One Pulse per Second (1PPS) output from a GPS module to discipline the 1 Hz output from a 555 by modulating the control voltage with a microcontroller.

Okay, this sounds a bit like baking a cake by buying a cake, scraping all the icing off, then icing it yourself, but what better way to learn how to ice a cake? The GPS-disciplined 555 is way more accurate than a free running one — just check out that Allan Deviation plot. While the accuracy of the standard 555 begins to decrease as oscillator drift dominates, the GPS-disciplined version just keeps getting better (up to a point — it would also eventually begin to increase, if the data were recorded for long enough). Compared to other high-end oscillators though, [burble] describes the project’s accuracy in one word: “Badly.”

That’s okay though — it really is a fantastic investigation into how GPS-disciplined oscillators work, and does a fantastic job illustrating the accuracy of different types of clocks, and some possible sources of error. This project is a great addition to some of the other precision timekeeping projects we’ve seen here at Hackaday, and a very fitting entry to the competition. Think you can do better? Or much, much worse? You’ve got a few weeks left to enter!

Fusing Cheap EBay Find Into A Digital Rangefinder

One of the earliest commercially-successful camera technologies was the rangefinder — a rather mechanically-complex system that allows a photographer to focus by triangulating a subject, often in a dedicated focusing window, and and frame the shot with another window, all without ever actually looking through the lens. Rangefinder photographers will give you any number of reasons why their camera is just better than the others — it’s faster to use, the focusing is more accurate, the camera is lighter — but in today’s era of lightweight mirrorless digitals, all of these arguments sound like vinyl aficionados saying “The sound is just more round, man. Digital recordings are all square.” (This is being written by somebody who shoots with a rangefinder and listens to vinyl).

While there are loads of analog rangefinders floating around eBay, the trouble nowadays is that digital rangefinders are rare, and all but impossible to find for a reasonable price. Rather than complaining on Reddit after getting fed up with the lack of affordable options, [Mr.50mm] decided to do something about it, and build his own digital rangefinder for less than $250.

Part of the problem is that, aside from a few exceptions, the only digital rangefinders have been manufactured by Leica, a German company often touted as the Holy Grail of photography. Whether you agree with the hype or consider them overrated toys, they’re sure expensive. Even in the used market, you’d be hard-pressed to find an older model for less than $2,000, and the newest models can be upwards of $10,000.

Rather than start from scratch, he fused two low-cost and commonly-available cameras into one with some careful surgery and 3D printing. The digital bits came from a Panasonic GF3, a 12 MP camera that can be had for around $120, and the rangefinder system from an old Soviet camera called the Fed 5, which you can get for less than $50 if you’re lucky. The Fed 5 also conveniently worked with Leica Thread Mount (LTM) lenses, a precursor to the modern bayonet-mount lenses, so [Mr.50mm] lifted the lens mounting hardware from it as well.

Even LTM lenses are relatively cheap, as they’re not compatible with modern Leicas. Anyone who’s dabbled in building or repairing cameras will tell you that there’s loads of precision involved. If the image sensor, or film plane, offset is off by the slightest bit, you’ll never achieve a sharp focus — and that’s just one of many aspects that need to be just right. [Mr.50mm]’s attention to detail really paid off, as the sample images (which you can see in the video below) look fantastic. Continue reading “Fusing Cheap EBay Find Into A Digital Rangefinder”

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

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.

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

Pulling At Threads With The Flipper Zero

Gone are the days when all smart devices were required an internet uplink. The WiFi-enabled IoT fad, while still upon us (no, my coffee scale doesn’t need to be on the network, dammit!) has begun to give way to low-power protocols actually designed for this kind of communication, such as ZigBee, and more recently, Thread. The downside of these new systems, however, is that they can be a bit more difficult in which to dabble. If you want to see just why your WiFi-enabled toaster uploads 100 MB of data per day to some server, you can capture some network traffic on your laptop without any specialized hardware. These low-power protocols can feel a bit more opaque, but that’s easily remedied with a dev board. For a couple of dollars, you can buy Thread radio that, with some additional hacking, acts as a portal between this previously-arcane protocol and your laptop — or, as [András Tevesz] has shown us, your Flipper Zero.

He’s published a wonderful three-part guide detailing how to mod one such $10 radio to communicate with the Flipper via its GPIO pins, set up a toolchain, build the firmware, and start experimenting. The guide even gets into the nitty-gritty of how data is handled transmitted and investigates potential attack vectors (less worrying for your Thread-enabled light bulb, very worrying for your smart door lock). This project is a fantastic way to prototype new sensors, build complicated systems using the Flipper as a bridge, or even just gain some insight into how the devices in your smart home operate.

In 2025, it’s easier than ever to get started with home automation — whether you cook up a solution yourself, or opt for a stable, off-the-shelf (but still hackable) solution like HomeAssistant (or even Minecraft?). Regardless of the path you choose, you’ll likely wind up with devices on the Thread network that you now have the tools to hack.