Micro:Bit Gets Pseudo-Polyphonic Sound With Neat Hack

November 18, 2025 by No comments

The Micro:bit is a fun microcontroller development platform, designed specifically for educational use. Out of the box, it’s got a pretty basic sound output feature that can play a single note at a time. However, if you’re willing to get a bit tricky, you can do some pseudo-polyphonic stuff as [microbit-noob] explains.

The trick to polyphony in a monophonic world? Rapidly alternating between the different notes you want to be playing at the same time. Do this fast enough and it feels like they’re playing together rather than seperately. [microbit-noob] demonstrates how to implement this with a simple function coded for the Micro:bit. Otherwise, it uses the completely stock sound hardware. However, the IR receiver is added to the device in order to allow a simple remote control to be used to command the notes desired, along with some extra tactile buttons to add further control.

Is it chiptune? Well, it’s a chip, playing a tune, so yes. Even if it is through a tiny speaker stuck to the PCB. In any case, if you’re trying to get some better bleeps and bloops out of the Micro:bit, this is a great place to start. If you’ve got other hacks for Britain’s educational little board, let us know on the tipsline!

Photo of [DENKI OTAKU] with his test circuit and oscilloscope

Exploring The Performance Gains Of Four-Pin MOSFETs

November 17, 2025 by 2 Comments

Over on YouTube [DENKI OTAKU] runs us through how a 4-pin MOSFET works and what the extra Kelvin source pin does.

A typical MOSFET might come in a 3-pin TO-247 package, but there are 4-pin variants which include an extra pin for the Kelvin source, also known as source sense. These 4-pin packages are known as TO-247-4. The fourth pin provides an additional source for gate current return which can in turn lessen the effect of parasitic inductance on the gate-source when switching current, particularly at high speed.

In the video [DENKI OTAKU] uses his custom made testing board to investigate the performance characteristics of some 4-pin TO-247-4 MOSFETs versus their 3-pin TO-247 equivalents. Spoiler alert: the TO-247-4 MOSFETs have better performance characteristics. The video takes a close look at the results on the oscilloscope. The downside is that as the switching speed increases the ringing in the Vds waveform increases, too. If you’re switching to a 4-pin MOSFET from a 3-pin MOSFET in your design you will need to be aware of this Vds overshoot and make accommodations for it.

If you’d like to go deeper with MOSFET technology check out Introduction To MOSFET Switching Losses and MOSFETs — The Hidden Gate.

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Writing Type-Safe Generics In C

November 17, 2025 by 5 Comments

The fun part about a programming language like C is that although the language doesn’t directly support many features including object-oriented programming and generics, there’s nothing that’s keeping you from implementing said features in C. This extends to something like type-safe generics in C, as [Raph] demonstrates in a blog post.

After running through the various ways that generics are also being implemented using methods including basic preprocessor macros and void pointers, the demonstrated method is introduced. While not necessarily a new one, the advantage with this method is that is type-safe. Much like C++ templates, these generics are evaluated at compile time, with the preprocessor handling both the type checking and filling in of the right template snippets.

While somewhat verbose, it can be condensed into a single header file, doesn’t rely on the void type or pointers and can be deduplicated by the linker, preventing bloat. If generics is what you are looking for in your C project, this might be a conceivable solution.

Binary Clock Also Monitors Weather

November 17, 2025 by 1 Comment

There are two things most of us want to know on a daily basis—the weather, and what time it is. [Guitarman9119] built a single device that can provide both pieces of information with a pleasingly nerdy aesthetic.

The heart of the build is a Raspberry Pi Pico W, which is proudly displayed on the front panel of the device. It’s responsible for driving the array of LEDs that display the time in hours, minutes, and seconds in binary format. The Pi Pico W uses its wireless connection to query the WorldTime API and an IP geolocation server. This provides the local date and time, and the location is then used to query the OpenWeather service for current weather information. The weather information is thankfully not displayed in binary format, because that would be straining to read. Instead, it’s displayed in human-readable format on a small OLED display.

There’s something about the way this is built—the discrete LEDs, that weird blue color that seemed to disappear by 1984—that gives this a wonderfully old school charm. You could imagine it turning up in a college lab full of old blinkenlights gear. Video after the break.

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Building A Smart Speaker Outside The Corporate Cloud

November 17, 2025 by 12 Comments

If you’re not worried about corporate surveillance bots scraping your shopping list and manipulating you through marketing, you can buy any number of off-the-shelf smart speakers for your home. Alternatively, you can roll your own like [arpy8] did, and keep your life a little more private.

The build is based around an ESP32 microcontroller. It connects to the ‘net via its inbuilt Wi-Fi connection, and listens out for your voice with an INMP441 omnidirectional microphone module. The audio data is trucked off to a backend server running a Whisper speech-to-text model. The text is then passed to Google’s Gemini 2.5 Flash large language model. The response generated is passed to the Piper Neural Voice text-to-speech engine, sent back to the ESP32, and spat out via the device’s DAC output and a speaker attached to an LM386 amplifier. Basically, anything you could ask Gemini, you can do with this device.

By virtue of using a commercial large language model, it’s not perfectly private by any means. Still, it’s at least a little farther removed than using a smart speaker that’s directly logged in to your Amazon/Google/Hulu/Beanstikk account. Files are on Github for those eager to dive into the code. We’ve seen some other fun builds along these lines before, too. Video after the break.

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Meet The Shape That Cannot Pass Through Itself

November 17, 2025 by 10 Comments

Can a shape pass through itself? That is to say, if one had two identical solids, would it be possible to orient one such that a hole could be cut through it, allowing the other to pass through without breaking the first into separate pieces? It turns out that the answer is yes, at least for certain shapes. Recently, two friends, [Sergey Yurkevich] and [Jakob Steininger], found the first shape proven not to have this property.

A 3D-printed representation of a cube passing through itself [image: Wikipedia]
Back in the late 1600s, Prince Rupert of the Rhine proved it was possible to accomplish this feat with two identical cubes. One can tilt a cube just so, and the other cube can fit through a tunnel bored through it. A representation is shown here.

Later, researchers showed this was also true of more complex shapes. This ability to pass unbroken through a copy of oneself became known as Rupert’s Property. Sometimes it’s an amazingly tight fit, but it seems to always work.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Cipher-Capable Typewriter

November 17, 2025 by 8 Comments

I must confess that my mouth froze in an O when I saw [Jeff]’s Typeframe PX-88 Portable Computing System, and I continue to stare in slack-jawed wonder as I find the words to share it with you. Let me give it a shot.

[Jeff] tells us that he designed Typeframe for his spouse to use as a writer deck. That’s good spousing, if you ask me. Amazingly, this is [Jeff]’s first project of this type and scope, and somehow it’s an elegant, yet easy build that’s quite well documented to boot. Whatever Typeframe’s design may borrow, it seems to give back in spades.

The Typeframe PX-88 Portable Computing System.
Image by [Jeff] via Typeframe.net
Use Typeframe for what you will — cyberdeck, writer deck, travel PC — this baby can handle whatever you throw at it. And of course, it’s open source from front to back.

This Raspberry Pi 4B-based productivity machine has all sorts of neat features. The touch screen flips upward at an angle, so you don’t have to hunch over it or carry a mouse around. Want to sit back a bit while you work? The aesthetically spot-on keyboard is detachable. Yeah.

If that’s not enough to get you interested, Typeframe is designed for simple construction with minimal soldering, and the sliding panels make maintenance a breeze.

A little more about that keyboard — this is Keebin’, after all. It’s an MK Point 65, which boasts hot-swap sockets under those DSA Dolch keycaps. See? Minimal soldering. In fact, the only things you have to solder to make the Typeframe your own are the power switch and the status light. Incredible.

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