I studied physics in college, and I’m always surprised how fundamental some of the concepts are. Take waves for example. You really wouldn’t expect the same underlying concept to be at work on surface of a pond, the string of a guitar, light passing through two slits, and then in the probabilistic behavior of electrons orbiting inside nuclei. But here we are, in a world filled with wave-like phenomena.

What little control theory I know, I’ve learned in the school of hard knocks. But it’s equally amazing that the same basic concepts govern the tuning of car shock absorbers, PID controllers, active audio filters, and other more complex systems where feedback matters. Crucial in all of these systems is the judicious balance of amplification and damping.

And last week on vacation, learning to drive a covered wagon pulled by a heavy draft horse, I saw the same patterns again. The horse likes to pull, and when the wagon comes over the crest of the top of a hill, it starts to roll forward into his harness, pushing him from behind. This makes the horse uneasy, and he slows down, the wagon pushes him harder, and positive feedback gets out of control.

The man who was teaching me to drive the wagon said, “it’s not like a car” in that you don’t tap the brakes to slow down and then let go. Rather, you hold on the brakes for a lot longer than you think is necessary – until the horse tells you that he feels like pulling again – and then you let up only a tiny bit at a time. Otherwise, you end up in the under-damped case, where you let the wagon go too much, it slows the horse, you slam the brakes, the horse pulls hard, and you let up on the brakes, and the cycle continues anew.

What he meant by “not like a car” was that the brakes aren’t just slowing down the wagon, they’re adding damping to keep the horse-wagon system from oscillating. Once that clicked in my mind, everything was smooth sailing. After a couple of days, I even started adding some feed-forward to my mental PID controller, letting the brakes go a little bit more when the horse was approaching the bottom of a hill, and he obviously wanted to pick up a little more speed before the grade ahead.

The horse seemed happy that I was finally getting it, but I don’t think he had any understanding of tuning PID loops. He did have me pondering, on a long stretch of rolling hills on a summer morning, if there were a good minimal set of patterns that explained a maximal breadth of phenomena. I’m starting with the physics of waves and the control of feedback systems, but what’s next?

Last week, Elliot got his foot stepped on by a 1.5 metric ton draft horse, and boy is he glad to be back to the relative safety of podcasting! Joining him today is Jenny List, no stranger to farm life, who has been trodden by a cow. It’s going to be one of those podcasts, folks.

Another thing the two hosts have in common is a love for the mystery of the numbers station. But did you know that GPS satellites, for the last 20 years, have broadcast literally millions of secret messages to everyone on the earth with a receiver? After that bombshell, we have an ATtiny85 emulating an 8080, a primer on how to embed magnets in 3D prints, definitive proof that more than one cassette mechanism is still being manufactured, and a look at what makes home automation enthusiasts tick.

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 in DRM-free MP3 and play it in space.

Episode 373 Show Notes:

News:

• No news is good news.  No Mailbag, on the other hand, is no fun!  Write or mail in a question to mailbag@hackaday.com.

What’s That Sound:

• Jenny came in with a sound this week. Have a guess at it!

Interesting Hacks of the Week:

• • Spy Tech: The GPS Numbers Station
    • New address for GNSS data and products – GFZ GNSS Observatory
    • Investigation into September 2020 GPS SVN 74 Performance Anomaly
  • Secret Radio Stations By The Numbers
    • Numbers Station Simulator, Right In Your Browser
  • An Unlikely Host For An 8080 Emulator
    • Because You Can: Linux On An Arduino Uno
  • Ways To Embed Magnets In 3D Prints And Not Ruin Printers
  • As It Turns Out, There’s More Than One Cassette Mechanism Being Made After All
    • Know Audio: Mixtapes, Tape Loops, And Razor Blades
  • Vintage Turntable Gets Brain Transplant And Home Assistant Integration
  • Connecting Your Car To Home Assistant
  • Print Your Own Robby The Robot
    • 3D Printing Computer Space

Quick Hacks:

• • • Elliot’s Picks:
      • The Winners Of The 2025 Obfuscated C Code Contest
      • If You Want To Hack Me, Come In Through The Speaker
      • Pico-Driven Ultrasound Enables Scaled Acoustic Model Of Home Stereo
      • Optimizing Pancakes From Chemical Principles
    • Jenny’s Picks:
      • Re-Enable All Compute Units On The PS5-like BC-250 Cryptomining Card
      • Less Than 10 Years? Commonwealth Fusion Systems Applies To Plug Into Grid In 2030s
      • A New Life For A Rare Console

Can’t-Miss Articles:

• • • Questions Remain About Tense Moment Aboard ISS
    • NASA Announces Artemis III Crew And Ambitious Goals
    • 10 Years Ago: EVA 23 – How A High Visibility Close Call Cut Short a Spacewalk – NASA
    • Remember When Flash Drives Were Going To Make Your PC Faster?

We don’t need to tell you: lasers are awesome. Those tiny red beams aren’t just for frustrating cats, but can do real work, be a source of infinite beauty, or constitute a science project in its own right — and you can win a $150 DigiKey gift certificate simply by writing your project up on Hackaday.io. The contest runs until July 23rd.

Of course, red lasers are only the beginning. If you have enough energy to move electrons into higher orbitals, you can make nearly anything lase. RGB setups can be breathtaking. Powerful IR and UV lasers are real tools. And the DIY side of lasering combines physics and electronics, with a spicy side of danger that needs to be contained.

We love laser builds of all sorts, and we’d like to see yours! Create a new Hackaday.io project that features what you’re working on, and we’ll pick our three favorites for a $150 gift certificate courtesy of this contest’s sponsor, DigiKey.

Honorable Mention Categories:

• Lightshow: A laser on its own makes a beam, but there’s so much more to a laser show than just a dot on the wall. If you’ve made your own projector, an RGB setup, or even something super simple with a spinning mirror, show it off here. We’re looking to see laser light beauty, and the machines that make it possible.

• DIY: This category is for the laser DIYers out there. If you made your own laser or laser support equipment, be it a TEA laser from scratch, or just a constant current driver to run a diode you salvaged from a projector, we want to see it. Have you resurrected an esoteric old device? Mixed up your own dyes? This category is all about the laser.

• With Remaining Eye: Lasers are not all fun and games; they can also do real work. If you’ve built a power laser project, or any functional device that relies on a laser to get the job done, it’s eligible here. Laser cutters, safety setups, data transfer over the light beam?  Any laser project that’s not about just looking good fits in here.

If you like to play with the coherent beams, head on over to Hackaday.io and detail your project — and don’t forget to enter it into the contest via the pulldown menu on the left side. If you win, you’ll have $150 to spend on more lasers. (We see you, with our remaining eye.)

The 2026 installment of Hackaday Europe was last weekend, and I’m still basking in the warm glow of hanging out with such an inspiring group of hackers. It’s hard to emphasize how important it is, maybe especially for those of us on the inside of Hackaday, to get to nerd out together like that. While we do our best to present your stories on our pages, there is just no substitute for getting to talk about projects, hacks, and dreams in real life.

While we can’t bring you all of the side-conversations that took place, we did manage to get the talks recorded, and we’ll be writing them up shortly. We have some bad news on that front, though: due to a technical limitation with the setup that the university had in place, we only got the audio and slide feeds, and not the camera that should have been filming the presenters. Still, we have a record of most everything that went down on the main stage, so stay tuned.

We know that not everyone can make it out to either Supercon or Hackaday Europe, but we heartily recommend keeping your eyes out for local hacker events near you. This weekend, there’s Open Hardware Summit in Berlin, for instance. If you’re near NYC, there’s HOPE coming up in August. If your tastes run more toward retrocomupting, there might be a Vintage Computer Festival chapter near you. Heck, consider looking into some of the more mainstream events as well, if that’s what is in your neighborhood.

It’s definitely more of an effort to get out to an event in the physical world, but the connections you make with fellow hackers are absolutely worth it. Any events that we should know about?

With Hackaday Europe no more than two days away, we want to help you wrap up all of the last loose ends. And that means last-minute changes in the workshop schedule, details on the Friday night pre-party, and more! Some tickets for the event itself, the workshops, and the pre-party (reservations required) are still available right here.

Pre-Party, Friday May 15th

Kick off the weekend with us at the official Hackaday Europe pre-party at Soqquadro Restaurant, Piazza Era 7, 23900 Lecco, Italy. Enjoy the Italian aperitivi on the gorgeous Lago di Lecco waterfront. Your ticket includes two drinks and an array of delicious snacks. It’s the Italian way to pregame the weekend ahead. Bring a hack, or just relax and hang out. Your choice. Either way, make sure you pre-register. (On the preregistration page, scroll all the way down past the workshops.)

Workshops

Unfortunately, the Let’s Mesh workshop has been canceled, but the good news, thanks to our incredible sponsors, we’ve added two great new workshops to the lineup. On Saturday, May 16th, we’ll have Tiny Tapeout, When Code Needs a Body, and Fault Injection 101. Sunday features EchoGlow: Arduino UNO Q Workshop with the brand-new Arduino Q devices, from 11:00 AM – 2:00 PM.

Tickets and full descriptions are available at registration.

Lightning Talks

On Sunday afternoon, we’ll dedicate some time to Lightning Talks. These are short, seven-minute talks, with or without slides, on whatever interests you at the moment. If you’ve got hacks or deep thoughts to share with us, you’ll never find a more receptive audience. Register now! Talk slots are FIFO.

Thanks, and See You Soon!

If you’ve never attended a Hackaday event before, we’re excited to see you. Half the fun is the crowd that convenes. If you want to bring along a hack to informally show-and-tell, it’s a great icebreaker. You won’t have to bring food or drinks – we’ve got that covered all weekend.

If you’re an old Hackaday hand, we’re stoked to see you again! A first at Hackaday Europe is going to be whatever large fraction of our SAO collection fits into carry-on luggage, and a sweet-looking SAO wall made by Hackaday Superfriend [Thomas Flummer]. If you have an SAO that you’d like to add to our pile, bring it along! It’s about time for us to do a photo gallery and write-up of everything we’ve got.

And we can’t leave without thanking our broad array of sponsors who make Hackaday Europe possible:

• element14 Community
• Makera
• Espressif
• Arduino
• iFixit
• Edge Impulse
• FibreSeek
• Tiny Tapeout
• And as always, Supplyframe!

We got asked a great question in the mailbag segment on the Podcast this week: are there hacks that we have read about on Hackaday that we use in our everyday life? The answer was absolutely yes, and I loved Tom’s take it often goes the other way – he sees a hack, tests it out, and then writes it up.

But I started looking around the office and I found more examples of projects that were absolutely inspired by projects I had seen on Hackaday, yet weren’t the same. I made a DIY mechanical keyboard because I saw someone else do it. There are a few home-made battery packs that I probably wouldn’t have attempted without having read about someone doing the same thing. I riffed on [Ted Yapo]’s Tritiled project, making a slightly inferior, but workable knockoff, and they’ve been glowing for many years now.

That got me to thinking about reproducing a project versus taking inspiration from it, and though I enjoy both, I’m find myself most often in the “inspiration” mode. I just can’t leave well enough alone, even when I’m fundamentally copying someone. NIH syndrome? Expediency? Probably both, and sometimes with a dose of hubris or feature creep.

Looking back at [Ted]’s TritiLED, though, I found some great examples in both the rebuild and redesign modes on Hackaday.io. [schlion]’s Making Ted Yapo’s TritiLED couldn’t be a clearer example of the former, and it’s great to look over his shoulder and appreciate all the lessons he learned along the way. [Stephan Walter]’s Yet another ultra low power LED is inspired by [Christoph Tack]’s Ultra low power LED, which is in turn inspired by [Ted]’s project, like a conceptual grandchild.

In a way, I look at this like with music: sometimes you play the notes the way they were written down, and sometimes you riff on someone else’s theme. Both are equally valid, and both owe a debt to the upstream source. Is Hackaday the hackers’ jazz club? And which of these modes do you find yourself working in most?

For this challenge, we asked you to show off your hacks that power themselves sustainably from the environment around them. After all, nobody likes wires, and changing batteries is just a hassle. What’s better than an autonomous gizmo? Nothing.

Because this is Hackaday, we expected to see some finished-looking projects, some absolutely zany concepts, and basically everything in-between, and you did not disappoint! So without further ado, let’s have a look at the 2026 Green Powered Challenge winners, each of whom will be going on a $150 shopping spree at DigiKey, our contest’s sponsor.

LightInk Solar Watch

LightInk is a beautiful wristwatch, and e-ink is a natural companion to the small power budget that you get with a wrist-mounted solar panel. But don’t be fooled by its good looks! The real beauty of this hack is the way that [Daniel Ansorregui] crammed the screen-updating routine into the wakeup stub in the RTC peripheral. This means that the ESP32 doesn’t have to access the SPI flash every time it wakes up, saving precious milliseconds of wake time, and cutting average power in half. This is a trick you’ll want to know even if you don’t need a sexy e-ink wristwatch. (Which you do.)

Supercapacitor Solar IoT

[Nelectra]’s “Heliotrax” solar supercapacitor charger stores up the sun’s power in low-maintenance supercapacitors until it’s time to wake up your device. But supercaps have an output voltage that depends dramatically on their state of charge, so [Nelectra] added a high-efficiency and low-leakage boost converter to get a nice constant voltage out. Depending on your current needs, it can charge up in the sun and run for a few dark days without any problems. It’s a one-stop shop for solar-powered IoT devices, and it should make a whole range of projects easier to realize.

powerTimer

[Juan Flores]’s powerTimer is another module that enables your small off-grid hacks. In this case, it’s a simple latching electronic switch, designed for ultra-low quiescent power. Maybe your project has a microcontroller with a good sleep mode, but the peripherals are leaky hogs? Put the powerTimer in the middle and get your whole system’s power budget down without much extra thought. And if you don’t want to wake the microcontroller, it’s got a low-power RTC on board that can handle periodic wakeups. It’s a sweet, simple design that solves a real problem, and our judges loved that.

Honorable Mentions

• Solar: We knew there would be some great solar-powered projects here, and [Jake Wachlin]’s Ultra Low Power Feather Development Board is a great example. He pairs a low-power accelerometer and barometer with a power-sipping microcontroller to almost achieve ambient-room-lighting capability. [Jake] says you have to put it directly under a light, or in indirect sunlight. But if you have full sun at your disposal, [Arnov Sharma]’s SolMate is a lovely DIY solar power bank that we’d love to bring to the park with us.
• Anything But PV: OK, enough solar. [Ethan]’s Gravity-Powered Digital Clock is exactly the sort of out-of-the-box idea we were hoping to see. He pairs a Casio F91W with an insane gear train, a homebrew electrical generator, and a dumbbell to gather up all of the gravity that makes it work. Or should do so. The gear train ended up having so many stages that it wouldn’t turn under its own magnified friction, and the project doesn’t quite spin. But we love the idea of a wind-up electrical clock, and we hope [Ethan] doesn’t give up!
• Least Power: [caspar]’s Harvesting NFC Energy to Transmit Commands includes a stock Pi Pico dev board and some AA batteries, so you might be thinking “where is the low power element?” It’s the NFC wakeup circuit that reads in some data and writes it directly to the Pico’s EEPROM, before it wakes the chip up, which then reads the command out of EEPROM and does whatever it does under normal battery power, and then shuts itself down again. We love the idea of surreptitious NFC-powered data insertion while the microcontroller is still sleeping.
• Most Power: We initially expected this honorable mention to go to an over-sized solar install, but in the end [alnwlsn]’s Practical Power Cycling won over our judges with an unbeatable display of human determination: over five years, [alnwlsn] has generated 38 kWh on his generator bike, has powered a 3D printer through a Benchy, and even toasted a piece of toast. Maybe the real power here is the human spirit? Check out [alnwlsn]’s great build logs and diary.

Thanks to All!

Much thanks to everyone who entered into this challenge. We had more great entries than we have space to feature, so be sure to check them all out on Hackaday.io. And of course, thanks again to DigiKey for sponsoring the contest, and for providing our three finalists with the parts they need!