2025 Hackaday One Hertz Challenge

27 Articles

Most complex blinking light

2025 One Hertz Challenge: 16-Bit Tower Blinks At One Hertz

July 23, 2025 by 3 Comments

We’ve seen our share of blinking light projects around here; most are fairly straightforward small projects, but this entry to the 2025 One Hertz Challenge is the polar opposite of that approach. [Peter] sent in this awesome tower of 16bit relay CPU power blinking a light every second.

There’s a lot to take in on this project, so be sure to go look at the ongoing logs of the underlying 16-bit relay CPU project where [Peter] has been showing his progress in creating this clicking and clacking masterpiece. The relay CPU consists of a stack of 5 main levels: the top board is the main control board, the next level down figures out the address calculations for commands, under that is the arithmetic logic unit level, under the ALU is the output register where you’ll see a 220 V lamp blinking at 1 Hz, and finally at the base are a couple of microcontrollers used for a clock signal and memory. [Peter] included oscilloscope readings showing how even with the hundreds of moving parts going on, the light is blinking within 1% of its 1 Hz goal.

It’s worth noting that while [Peter] has the relay CPU blinking a light in this setup, the CPU has 19 commands to program it, enabling much more complex tasks. Thanks for the amazing-sounding entry from [Peter] for our One Hertz Challenge. Be sure to check out some of the other relay computers we’ve featured over the years for more clicking goodness.

2025 Hackaday One Hertz Challenge

Continue reading “2025 One Hertz Challenge: 16-Bit Tower Blinks At One Hertz” →

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.

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

2025 One-Hertz Challenge: ZX Spectrum Is Now A Z80 Frequency Counter

July 18, 2025 by 1 Comment

The ZX Spectrum is perhaps most fondly remembered as a home computer and a games machine. [Tito] has grabbed the faithful black plastic box and turned it into a frequency counter as an innovative entry to our 2025 One Hertz Challenge.

The code was prepared in assembly using ZASM—a Z80 online assembler. It works in quite a simple manner. The code runs for one second at a time, counting rising edges on the EAR port of the ZX Spectrum. Those edges are added up to determine the frequency in question, and the job is done. [Tito] has tested the code and found it’s capable of reading frequencies up to 20 KHz. Since it runs on a one second period, it’s thus eligible for entry by meeting the requirements of the One Hertz Challenge. Code is available on Github for the curious.

The ZX Spectrum has a clock speed of 3.5 MHz, meaning it’s not exactly the tool of choice if you’re reading faster signals. We’ve seen similar done before. In any case, this project was a great way to exercise assembly coding skills and to bust out some classic Speccy hardware—and that’s always a good time. If you’ve got your own retrocomputer hacks brewing up in the lab, don’t hesitate to let us know!

2025 Hackaday One Hertz Challenge

2025 One-Hertz Challenge: HP Logic Probe Brought Into The Future

July 18, 2025 by 3 Comments

[Robert Morrison] had an ancient HP 545A logic probe, which was great for debugging SMT projects. The only problem was that being 45 years old, it wasn’t quite up to scratch when it came to debugging today’s faster circuitry. Thus, he hacked it to do better, and entered it in our 2025 One Hertz Challenge to boot!

[Robert’s] hack relied on the classic logic probe for its stout build and form factor, which is still useful even on today’s smaller hardware. Where it was lacking was in dealing with circuits running at 100 MHz and above. To rectify this, [Robert] gave the probe a brain transplant with a Sparkfun Alorium FPGA board and a small display. The FPGA is programmed to count pulses while measuring pulse widths and time, and it then drives the display to show this data to the user. There’s also a UART output, and [Robert] is actively developing further logic analyzer features, too.

You might be questioning how this project fits in the One Hertz Challenge, given it’s specifically built for running at quite high speeds. [Robert] snuck it in under the line because it resamples and updates the display on a once-a-second basis. Remember, as per the challenge site—”For this challenge, we want you to design a device where something happens once per second.” We’re giving you a lot of leeway here!

Often, old scopes and probes and other gear are really well built. Sometimes, it’s worth taking the best of the old physical hardware and combining it with modern upgrades to make something stout that’s still useful today. Meanwhile, if you’re cooking up your own neo-retro-logic probes, don’t hesitate to notify the tipsline!

2025 Hackaday One Hertz Challenge
Improved Jumping Bean

2025 One Hertz Challenge: Building A Better Jumping Bean

July 17, 2025 by 4 Comments

Do you feel nostalgia for a childhood novelty toy that had potential but ultimately fell short of its promise? Do you now have the skills to go make a better version of that toy to satisfy your long-held craving? [ExpensivePlasticCrap] does and has set off on a mission to make a better jumping bean.

Jumping beans, the phenomenon on which the novelty of [ExpensivePlasticCrap]’s childhood is based, are technically not beans, and their movement is arguably not a jump — a small hop at best. The trick is that the each not-a-bean has become the home to moth larvae that twitches and rolls on the ground as the larvae thrash about, trying to move their protective shells out of the hot sun.

The novelty bean was a small plastic pill-like capsule with a ball bearing inside what would cause the “bean” to move in unexpected ways as it rolled around. [ExpensivePlasticCrap]’s goal is to make a jumping bean that lives up to its name.

Various solenoids and motors were considered for the motion component of this new and improved bean. Ultimately, it was a small sealed vibrating motor that would be selected to move the bean without getting tangled in what was to become a compact bundle of components.

An ATtiny microcontroller won out over discrete components for the job of switching the motor on and off (once per second), for ease of implementation. Add this along with a MOSFET, battery and charging board for power into a plastic capsule, and the 1  Hz jumping bean was complete.

[ExpensivePlasticCrap] offers some thoughts on how to get more jump out of the design by reducing the weight of the build and giving it a more powerful source of motion.

If insect-inspired motion gets you jumping, check out this jumping robot roach and these tiny RoboBees.

2025 Hackaday One Hertz Challenge

Announcing The 2025 Hackaday One Hertz Challenge

June 26, 2025 by 56 Comments

It’s about time! Or maybe it’s about time’s reciprocal: frequency. Whichever way you see it, Hackaday is pleased to announce, just this very second, the 2025 One Hertz Challenge over on Hackaday.io. If you’ve got a device that does something once per second, we’ve got the contest for you. And don’t delay, because the top three winners will each receive a $150 gift certificate from this contest’s sponsor: DigiKey.

What will you do once per second? And how will you do it? Therein lies the contest! We brainstormed up a few honorable mention categories to get your creative juices flowing.

  • Timelords: How precisely can you get that heartbeat? This category is for those who prefer to see a lot of zeroes after the decimal point.
  • Ridiculous: This category is for the least likely thing to do once per second. Accuracy is great, but absurdity is king here. Have Rube Goldberg dreams? Now you get to live them out.
  • Clockwork: It’s hard to mention time without thinking of timepieces. This category is for the clockmakers among you. If your clock ticks at a rate of one hertz, and you’re willing to show us the mechanism, you’re in.
  • Could Have Used a 555: We knew you were going to say it anyway, so we made it an honorable mention category. If your One Hertz project gets its timing from the venerable triple-five, it belongs here.

We love contests with silly constraints, because you all tend to rise to the challenge. At the same time, the door is wide open to your creativity. To enter, all you have to do is document your project over on Hackaday.io and pull down the “Contests” tab to One Hertz to enter. New projects are awesome, but if you’ve got an oldie-but-goodie, you can enter it as well. (Heck, maybe use this contest as your inspiration to spruce it up a bit?)

Time waits for no one, and you have until August 19th at 9:00 AM Pacific time to get your entry in. We can’t wait to see what you come up with.

2025 Hackaday One Hertz Challenge