A man's hands are shown holding a black device. A white knob is in the center of the device, and above the knob in a central protrusion from the rest of the device is a small, circular LCD device.

Simplifying The SmartKnob

January 10, 2026 by Aaron Beckendorf 1 Comment

A knob can make a surprisingly versatile interface, particularly if it’s the SmartKnob, which builds a knob around a BLDC motor for programmable haptic response. It can rotate freely or with a set resistance, spring back to a fixed point when released, stick at detent points, and completely change its behavior as the interface demands. For people inexperienced in electronic assembly, though, smartknobs can be difficult to assemble. That’s why [Kokensha Tech] designed a simpler version, while at the same time letting it use a wider range of BLDC motors.

In addition to a motor, the original design used a magnetic encoder to detect position and a strain gauge to detect pressure on the knob. A circular LCD on the knob itself provided visual feedback, but it also required the motor to have a hollow center shaft. The LCD control wires running through the shaft proved tricky to assemble. [Kokensha Tech] moved the display out of the knob and onto a separate breakout board, which plugs into the controller board. This greatly broadens the range of compatible motors, since they no longer need a hollow shaft.

The motor now fits on a separate carrier board, which makes it easier to swap out different motors. The carrier board has mounting holes sized for a wide variety of motors, and four different types of motor connectors. [Kokensha Tech] also redesigned the rest of the PCB for easier soldering, while avoiding components with narrow pin spacing whenever possible. The original design used a LILYGO T-micro32 Plus MCU. The ESP32 is both cheaper and easier to solder, so it was a no-brainer to swap it in.

We’ve covered the original SmartKnob before, including a more in-depth look at its design. We’ve also seen another project use BLDCs and field-oriented control to make haptic knobs.

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Multi-material Parts The Easy Way

January 10, 2026 by Al Williams 4 Comments

You have a part that needs different colors or different material properties — with a multi-color 3D printer, no problem. You can also laboriously switch filaments on a single-color printer. But [anonymous kiwi] points out a different way, which is surprisingly obvious once you think about it. You simply add a previously made part to another one.

If you’ve ever experimented with adding a nut or a magnet into a print in the middle, the idea is exactly the same: you print one piece and then print a second piece, pausing in the middle to insert the completed first piece. The video example shows TPU robot wheels with PLA hubs. Of course, the same idea could apply to using different colors or even multiple materials or parts. You could imagine a hub with a steel nut embedded in it, then further being embedded in a TPU wheel, for example.

With multi-material printers becoming more commonplace, this technique might seem antiquated. But even if you have one of such a printer, this technique could save time and reduce waste. Not every part would work out this cleanly, but it is something to remember for the times when it does.

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For The Fun Of It

January 10, 2026 by Elliot Williams 10 Comments

I was off at the Chaos Communication Congress last weekend, and one of the big attractions for one who is nerdily inclined is seeing all of the personal projects that everyone brings along with them. Inevitably, someone would ask me what my favorite is. Maybe it’s my decision paralysis, maybe it’s being forced to pick a favorite child on the spot, or maybe it’s just that I’m not walking around ranking them, but that question always left me drawing a blank.

But after a week of thinking about it, I’m pretty sure I know why: I don’t actually care what I think of other peoples’ projects! I’m simply stoked to talk to everyone who brought anything, and bathe in the success and failure, hearing about the challenges that they saw coming, and then the new challenges they met along the way. I want to know what the hacker thinks of their project, what their intention was, and how their story went. I’m just a spectator, so I collected stories.

The overwhelming, entirely non-surprising result of listening to a couple hundred hackers talk about their projects? They’re all doing it for the fun of it. Simply for the grins. And that held equally well for the supremely planned-out and technical projects as well as their simpler I-bought-these-surplus-on-eBay-one-night relatives. “We were sitting around and thought, wouldn’t it be fun…” was the start of nearly every story.

That’s what I absolutely love about our community: that people are hacking because it makes them happy, and that the amazing variety of projects suggests an endless possibility for hacker happiness. It’s hard to come away from an event like that without being energized. Some of that comes from the sharing of ideas and brainstorming and hanging out with like-minded folks, but what I find most important is simply the celebration of the joy of the project for its own sake.

Happy hacking!

An LDO schematic and some notes about their features

Texas Instruments Explain Low-Dropout Linear Voltage Regulators

January 10, 2026 by John Elliot V 5 Comments

Today in power electronics, the folks over at Texas Instruments have put together a video covering low-dropout (LDO) linear regulators.

For a hacker, power is pretty fundamental, so it behooves us to know a little bit about what our options are when it comes time to regulate power to our projects. In this video [Alex Hanson] from Texas Instruments runs us through the linear voltage regulators known as low-dropout regulators (LDOs). It turns out that LDOs are often a poor choice for voltage regulation because they are inefficient when compared to switching regulator alternatives and can be more expensive too.

So when might you use an LDO? In very low power situations where heat and efficiency doesn’t matter very much. LDOs operate best when the input voltage is very near the output voltage and when current demands are low (roughly speaking less than ~50 mA is okay, ~500 mA is maximum, and some applications will support 1 to 3 A, although not with great efficiency and in this case thermal emissions — or magic smoke! — will become an issue).

What LDOs bring to the table is relatively clean and low-noise voltage as well as low dropout voltage (the minimum difference between the input and output voltage needed for regulation), which is their defining feature. What’s more with an appropriate output capacitor they can react quickly to load changes and they usually emit minimal EMI. LDOs are not about efficiency, they are about quality, simplicity, and control.

You might like to read more about when linear regulators might be the right choice or what your other options are.

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Yamato-1: The World’s First Ship With Magnetohydrodynamic Propulsion

January 10, 2026 by Maya Posch 23 Comments

Although the humble propeller and its derivatives still form the primary propulsion method for ships, this doesn’t mean that alternative methods haven’t been tried. One of the more fascinating ones is the magnetohydrodynamic drive (MHDD), which uses the Lorentz force to propel a watercraft through the water. The somewhat conductive seawater is thus the working medium, with no moving parts required.

The end of the MHD thruster from the Yamato 1. It has six smaller green tubes surrounding a central circle. All of these pieces are coming through a grey metal fixture that is a circular shape. Small labels are affixed with Japanese writing on them. It is inside a sky blue metal frame. — The end of the MHD thruster from the *Yamato-1*.

Although simple in nature, only the Japanese Yamato-1 full-scale prototype ever carried humans in 1992. As covered in a recent video by [Sails and Salvos], the prototype spent most of its time languishing at the Kobe Maritime Museum, until it was scrapped in 2016.

There are two types of MHDD, based around either conduction – involving electrodes – or induction, which uses a magnetic field. The thrusters used by the Yamato-1 used the latter type of MHDD, involving liquid helium-cooled, super-conducting coils. The seawater with its ions from the dissolved salts responds to this field by accelerating according to the well-known right-hand rule, thus providing thrust.

The main flaw with an MHDD as used by the Yamato-1 is that it’s not very efficient, with a working efficiency of about 15%, and a top speed of about 15 km/h (8 knots). Although research in MHDDs hasn’t ceased yet, the elemental problem of seawater not really being that great as the fluid without e.g. adding more ions to it has meant that ships like the Yamato-1 are likely to remain an oddity like the Lun-class ekranoplan ground effect vehicle.

For as futuristic as this technology sounds, it’s suprisingly straightforward to build a magnetohydrodynamic drive of your own in the kitchen sink. Continue reading “Yamato-1: The World’s First Ship With Magnetohydrodynamic Propulsion” →

BASIC Programming With No Strings Attached

January 9, 2026 by John Elliot V 18 Comments

Today in programming language hacks we have string art rendered in BASIC. String art — also known as pin and thread art, or filography — is an art form where images are invoked by thread woven between pins on the border of an image. In this case the thread and the pins are virtual and there is a simple 67 line BASIC program which generates and renders them.

Of course BASIC, the Beginner’s All-purpose Symbolic Instruction Code, isn’t just one thing and was a bit of a moving target over the years. Invented in 1964 at Dartmouth College by John Kemeny and Thomas Kurtz it turned into a family of languages as a dynamic array of implementations added, removed, and changed implementation details as the future unrolled.

We remember GW-BASIC and QuickBASIC, but the landscape was much broader than that. Implementations of QuickBASIC came with a “compiler”, qb45.exe, which worked by bundling the BASIC script as p-code into an executable along with the runtime binary, which we used back in the day to make “real applications”, not mere scripts.

Thanks to [Keith Olson] for writing in to let us know about this one. If you’re interested in seeing what the state of the art in string art is, be sure to check out String Art Build Uses CNC To Make Stringy Art and CNC Router Frame Repurposed For Colorful String Art Bot. The best string art is in the real world, not software!

Math Breakthrough Helps Your Feng Shui

January 9, 2026 by Al Williams 28 Comments

In 1966, a mathematician named [Leo Moser] proposed what sounds like a simple problem: What’s the largest shape you can move through a 1-meter corridor with a right-angle corner? Now, Korean mathematics whiz [Baek Jin-eon] claims to have solved the problem, nearly 60 years later.

The trick is, apparently, the shape of the sofa. By 1968, [John Hammerley] introduced a shape that did better than a rectangle, and by 1992, [Joseph Gerver] proposed something shaped like a phone handset, which remains the largest anyone had found, at 2.2195 square meters.

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