A round, 3D-printed motor housing is shown, with one flattened side holding a fan mount. A circular plate is mounted above the face of the housing, and a cord runs around it and pulleys on the side of the housing.

Tying Up Loose Ends On A Rope-based Robot Actuator

January 5, 2026 by 9 Comments

One of the perennial challenges of building robots is minimizing the size and weight of drive systems while preserving power. One established way to do this, at least on robots with joints, is to fit each joint with a quasi-direct-drive motor integrating a brushless motor and gearbox in one device. [The 5439 Workshop] wanted to take this approach with his own robot project, but since commercial drives were beyond his budget, he designed his own powerful, printable actuator.

The motor reducing mechanism was the biggest challenge: most quasi-direct drives use a planetary gearbox, but this would have been difficult to 3D-print without either serious backlash or limited torque. A cycloidal drive was an option, but previous printable cycloidal drives seemed to have low efficiency, and they didn’t want to work with a strain-wave gearing. Instead, he decided to use a rope drive (this seems to be another name for a kind of Capstan drive), which doesn’t require particularly strong materials or high precision. These normally use a rope wound around two side-by-side drums, which are difficult to integrate into a compact actuator, but he solved the issue by putting the drums in-line with the motor, with two pairs of pulleys guiding the rope between them in a “C” shaped path.

The actual motor is a hand-wound stator inside a 3D-printed rotor with magnets epoxied into it. The printed rotor proved problematic when the attraction between the rotor and magnets caused it to flex and scrape against the housing, and it eventually had to be reinforced with some thin metal sheets. After fixing this, it reached five Newton-meters of torque at one amp and nine Newton-meters at five amps. The diminishing returns seem to be because the 3D-printed pulley wheels broke under higher torque, which should be easy to fix in the future.

This looks like a promising design, but if you don’t need the output shaft inline with the motors, it’s probably easier to build a simple Capstan drive, the mathematics of which we’ve covered before. Both makers we’ve previously seen build Capstan drives used them to make robot dogs, which says something for their speed and responsiveness.

Putting The M In A UNI-T MSO

January 5, 2026 by 14 Comments

[Kerry Wong] points out that the Uni-T MSO oscilloscopes have a logic analyzer built in — that’s the MSO, or Mixed Signal Oscilloscope, part — but you have to add the probes. He shows you how it works in a recent video below.

He’s looked at the scope’s analog capabilities before and was not unimpressed. The probes aren’t inexpensive, but they do unlock the mixed signal capabilities of the instrument.

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Commodore Disk Drive Becomes General Purpose Computer

January 5, 2026 by 35 Comments

The Commodore 1541 was built to do one job—to save and load data from 5.25″ diskettes. [Commodore History] decided to see whether the drive could be put to other purposes, though. Namely, operating as a standalone computer in its own right!

It might sound silly, but there’s a very obvious inspiration behind this hack. It’s all because the Commodore 1541 disk drive contains a MOS 6502 CPU, along with some RAM, ROM, and other necessary supporting hardware. As you might remember, that’s the very same CPU that powers the Commodore 64 itself, along with a wide range of other 1980s machines. With a bit of work, that CPU can indeed be made to act like a general purpose computer instead of a single-purpose disk controller.

[Commodore History] compares the 1541 to the Commodore VIC-20, noting that the disk drive has a very similar configuration, but less than half the RAM. The video then explains how the drive can be reconfigured to run like the even-simpler MOS Technology KIM-1 — a very primitive but well-known 8-bit machine. What’s wild is that this can be achieved with no hardware modifications. It’s not just a thought exercise, either. We get a full “Hello World!” example running in both BASIC and machine code to demonstrate that it really works.

Code is on GitHub for the curious. We’ve featured hacks with the chunky Commodore 1541 before, too.

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Hands On WIth The Raspberry Pi Compute Module Zero

January 5, 2026 by 34 Comments

We are all familiar enough by now with the succession of boards that have come from Raspberry Pi in Cambridge over the years, and when a new one comes out we’ve got a pretty good idea what to expect. The “classic” Pi model B+ form factor has been copied widely by other manufacturers as has their current Compute Module. If you buy the real Raspberry Pi you know you’ll get a solid board with exceptionally good software support.

Every now and then though, they surprise us, with a board that follows a completely different path, which brings us to the one on our bench today. The Compute Module Zero packs the same quad-core RP3 system-on-chip (SoC) and Wi-Fi module as the Pi Zero 2 W with 512 MB of SDRAM onto a tiny 39 mm by 33 mm postage-stamp module. It’s a Pi, but not as you know it, so what is it useful for? Continue reading “Hands On WIth The Raspberry Pi Compute Module Zero” →

Illustration of Chladni's technique for producing his figures, from John Tyndall's Sound (1869)

Popular Science Experiments In Sound During The 19th-Century

January 5, 2026 by 13 Comments

Check one, two; check one, two; is this thing on? Over on The Public Domain Review [Lucas Thompson] takes us for a spin through sound, as it was in Britain around and through the 1800s.

The article begins by introducing the Father of Acoustics, German physicist Ernst Chladni. After placing grains of sand on a thin metal plate and drawing a violin bow along one edge Chladni figures appear, making manifest that which previously could only be heard, that is, sound waves.

It’s fun to think that it wasn’t so long ago that the physics of sound was avant-garde. Middle class Victorian society was encouraged to reproduce cutting edge experiments with equipment in their own homes, participating in a popular science which was at the same time part entertainment and part instruction, for young and old alike. Throughout the rest of his article [Lucas] lists a number of popular science books from the period and talks a little about what was to be found within.

See the video below the break for a demonstration of Chladni figures from The Royal Institution. Of course the present state of the art regarding sonics is well advanced as compared with that of the 19th century. If you’re interested to know more check out Building A Wall-Mounted Sound Visualizer and Seeing Sound For Under $200.

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2025: As The Hardware World Turns

January 5, 2026 by 29 Comments

If you’re reading this, that means you’ve successfully made it through 2025! Allow us to be the first to congratulate you — that’s another twelve months of skills learned, projects started, and hacks….hacked. The average Hackaday reader has a thirst for knowledge and an insatiable appetite for new challenges, so we know you’re already eager to take on everything 2026 has to offer.

But before we step too far into the unknown, we’ve found that it helps to take a moment and reflect on where we’ve been. You know how the saying goes: those that don’t learn from history are doomed to repeat it. That whole impending doom bit obviously has a negative connotation, but we like to think the axiom applies for both the lows and highs in life. Sure you should avoid making the same mistake twice, but why not have another go at the stuff that worked? In fact, why not try to make it even better this time?

As such, it’s become a Hackaday tradition to rewind the clock and take a look at some of the most noteworthy stories and trends of the previous year, as seen from our rather unique viewpoint in the maker and hacker world. With a little luck, reviewing the lessons of 2025 can help us prosper in 2026 and beyond.

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GitHub Disables Rockchip’s Linux MPP Repository After DMCA Request

January 5, 2026 by 64 Comments

Recently GitHub disabled the Rockchip Linux MPP repository, following a DMCA takedown request from the FFmpeg team. As of writing the affected repository remains unavailable. At the core of this issue is the Rockchip MPP framework, which provides hardware-accelerated video operations on Rockchip SoCs. Much of the code for this was lifted verbatim from FFmpeg, with the allegation being that this occurred with the removal of the original copyright notices and authors. The Rockchip MPP framework was further re-licensed from LGPL 2.1 to the Apache license.

Most egregious of all is perhaps that the FFmpeg team privately contacted Rockchip about this nearly two years ago, with clearly no action taken since. Thus FFmpeg demands that Rockchip either undoes these actions that violate the LGPL, or remove all infringing files.

This news and further context is also covered by [Brodie Robertson] in a video. What’s interesting is that Rockchip in public communications and in GitHub issues are clearly aware of this license issue, but seem to defer dealing with it until some undefined point in the future. Clearly that was the wrong choice by Rockchip, though it remains a major question what will happen next. [Brodie] speculates that Rockchip will keep ignoring the issue, but is hopeful that he’ll be proven wrong.

Unfortunately, these sort of long-standing license violations aren’t uncommon in the open source world.

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