A photo of an RPi and a note about the first lecture.

The Latest Projects From Cornell’s ECE 4760/5730

August 30, 2025 by John Elliot V 13 Comments

ECE 4760/5730 is the Digital Systems Design Using Microcontrollers course at Cornell University taught by [Hunter Adams]. The list of projects for spring this year includes forty write-ups — if you haven’t got time to read the whole lot you can pick a random project between 1 and 40 with: shuf -i 1-40 -n 1 and let the cards fall where they may. Or if you’re made of time you could spend a few days watching the full playlist of 119 projects, embedded below.

We won’t pick favorites from this semester’s list of projects, but having skimmed through the forty reports we can tell you that the creativity and acumen of the students really shines through. If the name [Hunter Adams] looks familiar that might be because we’ve featured his work here on Hackaday before. Earlier this year we saw his Love Letter To Embedded Systems.

While on the subject, [Hunter] also wanted us to know that he has updated his lectures, which are here: Raspberry Pi Pico Lectures 2025. Particularly these have expanded to include a bunch of Pico W content (making Bluetooth servers, connecting to WiFi, UDP communication, etc.), and some fun lower-level stuff (the RP2040 boot sequence, how to write a bootloader), and some interesting algorithms (FFT’s, physics modeling, etc.).

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The Qweremin Is A QWERTY Theremin With A C-64 Heart

August 30, 2025 by Tyler August 5 Comments

While we have nothing against other 1980s 8-bit machines, the Commodore 64 has always been something special. A case in point: another new instrument using the C-64 and its beloved SID chip. Not just new to retrocomputing, either, but new entirely. [Linus Åkesson] has invented the QWERTY Theremin, and there’s a Commodore at its core.

If this project sounds vaguely familiar, it’s because it’s based off of the C-64 Theremin [Linus] built a couple of years back. According to [Linus], there were a few issues with the instrument. A real thereminist told him there were issues with the volume response; his own experience taught him that theremins are very, very hard to play for the uninitiated.

This model fixes both problems: first, the volume circuit now includes a pair of digital-analog-converters (DACs) connected to the Commodore’s user port, allowing smooth and responsive volume control.In this case the DAC is being used solely for volume control: SID provides the analog reference voltage, while the 12-bit digital input served as volume control. That proved noisy, however, thanks to the DC bias voltage of the audio output being scaled by the DAC even when the SID was silent. A second DAC was the answer, providing a signal to cancel out the scaled bias voltage. That in and of itself is a clever hack.

The biggest change is that this instrument no longer plays like a theremin. Pitch has been taken out of the 555-based antenna circuit entirely; while vertical distance from the spoon-antenna still controls volume as in a regular theremin and the last version, the horizontal distance from the second antenna (still a clamp) now controls vibrato. Pitch is now controlled by the QWERTY keyboard. That’s a much easier arrangement for [Linus] — this isn’t his first chiptune QWERTY instrument, after all.

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Does It Make Sense To Upgrade A Prusa MK4S To A Core One?

August 30, 2025 by Maya Posch 6 Comments

One of the interesting things about Prusa’s FDM 3D printers is the availability of official upgrade kits, which allow you to combine bits off an older machine with those of the target machine to ideally save some money and not have an old machine gathering dust after the upgrade. While for a bedslinger-to-bedslinger upgrade this can make a lot of sense, the bedslinger to CoreXY Core One upgrade path is a bit more drastic. Recently the [Aurora Tech] channel had a look at which upgrade path makes the most sense, and in which scenario.

A big part of the comparison is the time and money spent compared to the print result, as you have effectively four options. Either you stick with the MK4S, get the DIY Core One (~8 hours of assembly time), get the pre-assembled Core One (more $$), or get the upgrade kit (also ~8 hours). There’s also the fifth option of getting the enclosure for the MK4S, but it costs about as much as the upgrade kit, so that doesn’t make a lot of logical sense.

In terms of print quality, it’s undeniable that the CoreXY motion system provides better results, with less ringing and better quality with tall prints, but unless you’re printing more than basic PLA and PETG, or care a lot about the faster print speeds of the CoreXY machine with large prints, the fully enclosed Core One is a bit overkill and sticking with the bedslinger may be the better choice.

The long and short of it is that you have look at each option and consider what works best for your needs and your wallet.

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Silent No More: Open-Source Fix For Mic Mishaps

August 30, 2025 by Matt Varian 12 Comments

“Sorry, my mic was muted…” With the rise of video calls, we’ve all found ourselves rushing to mute or unmute our mics in the midst of a call. This open-source Mute Button, sent in by [blackdevice], aims to take out the uncertainty and make toggling your mic easy.

It’s centered around a small PIC32MM microcontroller that handles the USB communications, controls the three built-in RGB LEDs, and reads the inputs from the encoder mounted to the center of this small device. The button knob combo is small enough to easily move around your desk, yet large enough to toggle without fuss when it’s your turn to talk.

To utilize all the functions of the button, you’ll need to install the Python-based driver on your machine. Doing so will let you not only toggle your microphone and volume, but it will also allow the button to light up to get your attention should you be trying to talk with the mic muted.

Although small, it’s also quite rugged, knowing it will spend its life being treated much like a game of Whac-A-Mole—slapped whenever needed. The case is designed to be 3D printed by any FDM printer, with the top knob section printed in translucent material to make the notification light clearly visible.

All of the design files, firmware, and parts list are available over on [blackdevices]’s GitHub page, and they are open-source, allowing you to tweak the design to fit your unique needs. Thank you for sending in this well-documented project, [blackdevices]; we look forward to seeing future work. If you like this type of thing, be sure to check out some of our other cool featured desk gadgets.

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A wrench is shown lying on a machinist’s mat. The end of the wrench holds a ratcheting wheel, on top of which are six independent metal blocks arranged into a hexagon.

Building A Shifting Ratchet Wrench

August 30, 2025 by Aaron Beckendorf 13 Comments

Convenient though they may be, [Trevor Faber] found some serious shortcomings in shifting spanners: their worm gears are slow to adjust and prone to jamming, they don’t apply even force to all faces of a bolt head, and without a ratchet, they’re rather slow. To overcome these limitations, he designed his own adjustable ratchet wrench.

The adjustment mechanism is based on a pair of plates with opposing slots; the wrench faces are mounted on pins which fit into these slots, and one plate rotates relative to the other, the faces slide inwards or outwards. A significant advantage of this design is that, since one plate is attached to the wrench’s handle, some of the torque applied to the wrench tightens its grip on the bolt. To let the wrench loosen as well as tighten bolts, [Trevor] simply mirrored the mechanism on the other side of the wrench. Manufacturing proved to be quite a challenge: laser cutting wasn’t precise enough for critical parts, and CNC control interpolation resulted in some rough curves which caused the mechanism to bind, but after numerous iterations, [Trevor] finally got a working tool.

To use the wrench, you twist an outer ring to open the jaws, place them over the bolt, then let them snap shut. One nice touch is that you can close this wrench over a bolt, let go of it, and do something else without the wrench falling off the bolt. Recessed bolts were a bit of an issue, but a chamfer ought to improve this. It probably won’t be replacing your socket set, but it looks like it could make the odd job more enjoyable.

If you prefer a more conventional shifting wrench, you can make a miniature out of an M20 nut. It’s also possible to make a shifting Allen wrench.

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Octos background with hackaday website pulled up

Open Source Interactive Wallpapers For Windows

August 30, 2025 by Ian Bos 19 Comments

It’s late at night, and you’re avoiding work that was supposed to be done yesterday. You could open an application on your desktop to keep your attention, or what about the desktop itself? [Underpig1] has you covered with Octos. Octos is an open-source application created to allow interactive wallpapers based on HTML, CSS, or JS for Windows 10 and 11.

There are many wallpaper applications made to spruce up your desktop, but Octos stands out to us here at Hackaday from the nature of being open source. What comes along with the project is a detailed API to reference when creating your own wallpaper. Additionally, this allows for detailed and efficient visualization techniques that would otherwise be difficult to display, perfect for procrastination.

Included demos range from an interactive solar system to Conway’s Game of Life. Customization options allow for basic manipulation of the backdrops in the application itself, but we’re sure you could allow for some fun options with enough tinkering.

If you want to try Octos out for yourself, it’s incredibly easy. Octos can be found on the Microsoft Store, and additional backdrops can be added within the application. Open-source applications allow for incredibly easy additions to your personal device, but it’s not always that way. Kindle has been a prime example of a fairly locked down system; however, that never stops a clever hacker!

Thanks to [Joshua Throm] for the tip!

FPGA Brings UNIX V1 To The DEC J-11

August 30, 2025 by Bryan Cockfield 13 Comments

If you’ve never used a PDP-11 before it’s probably because you simply weren’t around in the 70s and 80s. Although they started as expensive machines only in research labs and industry, they eventually became much more accessible. They’re a bit of a landmark in computing history, too, being largely responsible for the development of things like UNIX and the C programming language. [ryomuk] is using an FPGA in combination with an original DEC J-11 to bring us a new take on this machine. (Google Translate from Japanese)

The FPGA used in this build is a Tang Nano 20k, notable for its relatively low cost. The FPGA emulates the memory system and UART of a PDP-11 system down to the instruction set, while the original, unmodified DEC chip is left to its own devices. After some initial testing [ryomuk] built a PC11 paper tape emulator to ensure the system was working which runs a version of BASIC from the era. The next thing up was to emulate some disk drives and co-processors so that the machine can run the first version of UNIX.

[ryomuk] also developed a PCB for the DEC microprocessor and the FPGA to sit on together, and it includes all of the jumpers and wiring needed to allow the computer to run UNIX, as well as handling other miscellaneous tasks like power. It’s an interesting build that gets to the heart of the early days of computer science. PDP-11 computers did eventually get smaller and more accessible, and if you want to build a modern version this build fits a complete system into an ATX case.

Thanks to [RetepV] for the tip!