Look! It’s A Knob! It’s A Jack! It’s Euroknob!

April 28, 2025 by 23 Comments

Are your Eurorack modules too crowded? Sick of your patch cables making it hard to twiddle your knobs? Then you might be very interested in the new Euroknob, the knob that sports a hidden patch cable jack.

Honestly, when we first saw the Euroknob demo board, we thought [Mitxela] had gone a little off the rails. It looks like nothing more than a PCB-mount potentiometer or perhaps an encoder with a knob attached. Twist the knob and a row of LEDs on the board light up in sequence. Nice, but not exactly what we’re used to seeing from him. But then he popped the knob off the board, revealing that what we thought was the pot body is actually a 3.5-mm audio jack, and that the knob was attached to a mating plug that acts as an axle.

The kicker is that underneath the audio jack is an AS5600 magnetic encoder, and hidden in a slot milled in the tip of the audio jack is a tiny magnet. Pop the knob into the jack, give it a twist, and you’ve got manual control of your module. Take the knob out, plug in a patch cable, and you can let a control voltage from another module do the job. Genius!

To make it all work mechanically, [Mitxela] had to sandwich a spacer board on top of the main PCB. The spacer has a large cutout to make room for the sensor chip so the magnet can rotate without hitting anything. He also added a CH32V003 to run the encoder and drive the LEDs to provide feedback for the knob-jack. The video below has a brief demo.

This is just a proof of concept, to be sure, but it’s still pretty slick. Almost as slick as [Mitxela]’s recent fluid-motion simulation pendant, or his dual-wielding soldering irons.

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Kaleidoscopico Shows Off Pi Pico’s Capabilities

April 27, 2025 by 14 Comments

In the early days of computing, and well into the era where home computers were common but not particularly powerful, programming these machines was a delicate balance of managing hardware with getting the most out of the software. Memory had to be monitored closely, clock cycles taken into account, and even video outputs had to be careful not to overwhelm the processor. This can seem foreign in the modern world where double-digit gigabytes of memory is not only common, it’s expected, but if you want to hone your programming skills there’s no better way to do it than with the limitations imposed by something like a retro computer or a Raspberry Pi Pico.

This project is called Kaleidoscopio, built by [Linus Åkesson] aka [lft] and goes deep into the hardware of the Pi Pico in order to squeeze as much out of the small, inexpensive platform as possible. The demo is written with 17,000 lines of assembly using the RISC-V instruction set. The microcontroller has two cores on it, with one core acting as the computer’s chipset and the other acts as the CPU, rendering the effects. The platform has no dedicated audio or video components, so everything here is done in software using this setup to act as a PC from the 80s might. In this case, [lft] is taking inspiration from the Amiga platform, his favorite of that era.

The only hardware involved in this project apart from the Pi Pico itself are a few resistors, an audio jack, and a VGA port, further demonstrating that the software is the workhorse in this build. It’s impressive not only for wringing out as much as possible from the platform but for using the arguably weaker RISC-V cores instead of the ARM cores, as the Pi Pico includes both. [lft] goes into every detail on the project’s page as well, for those who are still captivated by the era of computer programming where every bit mattered. For more computing demos like this, take a look at this one which is based on [lft]’s retrocomputer of choice, the Amiga.

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Design Constraints Bring Lockbox To Life

April 27, 2025 by 1 Comment

One of the most paradoxical aspects of creating art is the fact that constraints, whether arbitrary or real, and whether in space, time, materials, or rules, often cause creativity to flourish rather than to wither. Picasso’s blue period, Gadsby by Ernest Vincent Wright, Tetris, and even the Volkswagen Beetle are all famous examples of constraint-driven artistic brilliance. Similarly, in the world of electronics we can always reach for a microcontroller but this project from [Peter] has the constraint of only using passive components, and it is all the better for it.

The project is a lockbox, a small container that reveals a small keypad and the associated locking circuitry when opened. When the correct combination of push buttons is pressed, the box unlocks the hidden drawer. This works by setting a series of hidden switches in a certain way to program the combination. These switches are connected through various diodes to a series of relays, so that each correct press of a button activates the next relay. When the final correct button is pushed, power is applied to a solenoid which unlocks the drawer. An incorrect button push will disable a relay providing power to the rest of the relays, resetting the system back to the start.

The project uses a lot of clever tricks to do all of this without using a single microcontroller, including using capacitors that carefully provide timing to the relays to make them behave properly rather than all energizing at the same time. The woodworking is also notable as well, with the circuit components highlighted when the lid is opened (but importantly, hiding the combination switches). Using relays for logic is not a novel concept, though; they can be used for all kinds of complex tasks including replacing transistors in single-board computers.

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Hackaday Links: April 27, 2025

April 27, 2025 by 13 Comments

Looks like the Simpsons had it right again, now that an Australian radio station has been caught using an AI-generated DJ for their midday slot. Station CADA, a Sydney-based broadcaster that’s part of the Australian Radio Network, revealed that “Workdays with Thy” isn’t actually hosted by a person; rather, “Thy” is a generative AI text-to-speech system that has been on the air since November. An actual employee of the ARN finance department was used for Thy’s voice model and her headshot, which adds a bit to the creepy factor.

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An array of current or next-generation boosters powered by methalox engines.

How Methane Took Over The Booster World

April 27, 2025 by 41 Comments

Go back a generation of development, and excepting the shuttle-derived systems, all liquid rockets used RP-1 (aka kerosene) for their first stage. Now it seems everybody and their dog wants to fuel their rockets with methane. What happened? [Eager Space] was eager to explain in recent video, which you’ll find embedded below.

Space X Starship firing its many Raptor engines.
Space X Starship firing its many Raptor engines. The raptor pioneered the new generation of methalox. (Image: Space X)

At first glance, it’s a bit of a wash: the density and specific impulses of kerolox (kerosene-oxygen) and metholox (methane-oxygen) rockets are very similar. So there’s no immediate performance improvement or volumetric disadvantage, like you would see with hydrogen fuel. Instead it is a series of small factors that all add up to a meaningful design benefit when engineering the whole system.

Methane also has the advantage of being a gas when it warms up, and rocket engines tend to be warm. So the injectors don’t have to worry about atomizing a thick liquid, and mixing fuel and oxidizer inside the engine does tend to be easier. [Eager Space] calls RP-1 “a soup”, while methane’s simpler combustion chemistry makes the simulation of these engines quicker and easier as well.

There are other factors as well, like the fact that methane is much closer in temperature to LOX, and does cost quite a bit less than RP-1, but you’ll need to watch the whole video to see how they all stack up.

We write about rocketry fairly often on Hackaday, seeing projects with both liquid-fueled and solid-fueled engines. We’ve even highlighted at least one methalox rocket, way back in 2019. Our thanks to space-loving reader [Stephen Walters] for the tip. Building a rocket of your own? Let us know about it with the tip line.

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Quick And Easy Digital Stethoscope Keeps Tabs On Cat

April 27, 2025 by 7 Comments

For all their education, medical practitioners sometimes forget that what’s old hat to them is new territory for their patients. [David Revoy] learned that when a recent visit to the veterinarian resulted in the need to monitor his cat’s pulse rate at home, a task that he found difficult enough that he hacked together this digital cat stethoscope.

Never fear; [David] makes it clear that his fur-baby [Geuloush] is fine, although the gel needed for an echocardiogram likely left the cat permanently miffed. With a normal feline heart rate in the 140s, [David] found it hard to get an accurate pulse by palpation, so he bought a cheap stethoscope and a basic lavalier USB microphone. Getting them together was as easy as cutting the silicone tubing from the stethoscope head and sticking the microphone into it.

The tricky part, of course, would be getting [Geuloush] to cooperate. That took some doing, but soon enough [David] had a clean recording to visualize in an audio editor. From there it’s just a simple matter of counting up the peaks and figuring out the beats per second. It probably wouldn’t be too hard to build a small counter using a microcontroller so he doesn’t have to count on the cat napping near his PC, but in our experience, keyboards are pretty good cat attractants.

This is one of those nice, quick hacks whose simplicity belies their impact. It’s certainly not as fancy as some of the smart stethoscopes we’ve seen, but it doesn’t need to be.

Thanks to [Spooner] for the tip.

VESC Mods Made Via Vibe Coding

April 27, 2025 by 19 Comments

[David Bloomfield] wanted to make some tweaks to an embedded system, but didn’t quite have the requisite skills. He decided to see if vibe coding could help.

[David]’s goal was simple. To take the VESC Telemetry Display created by [Lukas Janky] and add some tweaks of his own. He wanted to add more colors to the display, while changing the format of the displayed data and tweaking how it gets saved to EEPROM. The only problem was that [David] wasn’t experienced in coding at all, let alone for embedded systems like the Arduino Nano. His solution? Hand over the reins to a large language model. [David] used Gemini 2.5 Pro to make the changes, and by and large, got the tweaks made that he was looking for.

There are risks here, of course. If you’re working on an embedded system, whatever you’re doing could have real world consequences. Meanwhile, if you’re relying on the AI to generate the code and you don’t fully understand it yourself… well, the possibilities are obvious. It pays to know what you’re doing at the end of the day. In this case, it’s hard to imagine much going wrong with a simple telemetry display, but it bears considering the risks whatever you’re doing.

We’ve talked about the advent of vibe coding before, too, with [Jenny List] exploring this nascent phenomenon. Expect it to remain a topic of controversy in coding circles for some time.

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