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

Keebin’ With Kristina: The One With The 200% Typewriter

February 19, 2024 by 3 Comments

Image by [jefmer] via Hackaday.IO
You know, the really sad truth about cyberdecks and cyberdeck-adjacent builds is that many of them just end up on the shelf, collecting dust while waiting for the dystopian future. Well, not this one. No, [jefmer] says their Portable Pi sees daily use, and even comes along on the go.

Since [jefmer] is “temperamentally unsuited to 3D printing”, the Pi 4B and its accessories are nestled in a rugged, splash-proof case under some acrylic sheets. One of those accessories, the keyboard, is a KPrepublic BM40 with Gateron Yellows. In order to get used to the number and symbols layer, [jefmer] laid down some great-looking labels above the keyboard.

Although the build started with an SD card for storage, [jefmer] has since upgraded to a 120 GB SSD. This required a beefy battery pack, but the difference is that it gets around four hours of power versus five hours when using an SD card.

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Not A FrogPad But Close

February 19, 2024 by 7 Comments

While you might think one-handed keyboards are a niche item, if you have reduced function in one hand or you only have one hand, they are pretty important. [Kian] was getting ready for surgery that would put his left arm out of commission for a while, which spurred the construction of a one-handed keyboard inspired by FrogPad.

There was a time when creating a new keyboard would have been a significant task. These days, it is reasonably easy and [Kian] simply repurposed an existing kit for a split keyboard. Using just half the board was easy since it is made in two parts already.

There have been many attempts at building effective one-handed input devices over the years, and the circa 2002 FrogPad is one of the better devices. Like most one-handed keyboards, it uses layers. The top layer has the most common keystrokes to minimize the number of layer changes required to type common text.

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Printable Keyboard Dock Puts Steam Deck To Work

February 19, 2024 by 7 Comments

Whether or not you’re into playing video games, you have to admit, that the Steam Deck is a pretty interesting piece of hardware. We’ve seen hackers jump through all sorts of uncomfortable hoops to get Linux running on their mobile devices in the past. The fact that you can pick up a fairly powerful x86 handheld computer right now for a reasonable amount of money is certainly exciting. The Linux steam deck gets even more enticing when you consider the software support it enjoys thanks to its large and vibrant user community. No wonder we’ve started to see them dotting the workbenches during Hackaday Supercon.

If there’s a downside, it’s that the Steam Deck was very clearly designed to be a handheld gaming system, not a portable computer. Sure you can plug in an external monitor and keyboard, but things can quickly become ungainly. This is why a printable dock from [a8ksh4] caught our eye.

It’s officially designed to let you mate the Steam Deck with the Corne keyboard, a split ergonomic design that’s graced these pages a few times in the past. [A8ksh4] has included links for all the hardware you’ll need outside the printed parts, from the hinges and keyboard PCBs, all the way to the keycaps and stainless steel screws. If you’re looking for a turnkey experience, this is it.

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Double Fed Induction Motors: Clever Motor Control Through Frequency

February 18, 2024 by 27 Comments

Somewhere in most engineering educations, there’s a class on induction motors. Students learn about shaded-pole motors, two-phase and three-phase motors, squirrel cage motors, and DC-excited motors. It’s a pre-requisite for then learning about motor controllers and so-called brushless DC motors. [Jim Pytel] takes this a step further in a series of videos, in which he introduces the doubly fed induction motor. If a conventional three-phase motor can have its coils in either rotor or stator, here’s a motor with both. The special tricks with this motor come in feeding both rotor and stator with separate frequencies, at which point their interactions have useful effects on the motor speed.

There are two videos, both of which we’ve put below the break. Understanding the complex interaction of the two sets of magnetic fields is enough to make anyone’s brain hurt, but the interesting part for us is that the motor can run faster than either of the two drive frequencies.

Sadly we’re not aware of any easily available motors using this configuration, so we don’t think it will be possible to easily experiment. But if you want to amaze your friends with an in-depth knowledge of motors, take a look at the videos below.

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Low-Cost Saliva-based Biosensor For Cancer Detection

February 18, 2024 by 12 Comments

More and more biomarkers that can help in the early diagnosis of diseases like cancer are being discovered every year, but often the effective application relies on having diagnostic methods that are both affordable and as least invasive as possible. This is definitely true in the case of breast cancers, where the standard diagnostic method after seeing something ‘odd’ on a scan is to perform a biopsy so that a tissue sample can be tested in a laboratory. What [Hsiao-Hsuan Wan] and colleagues demonstrate in a recently published research article in the Journal of Vacuum Science & Technology B is a way to use saliva on disposable test strips to detect the presence of cancer-related biomarkers. Best of all, the system could be very affordable.

The two biomarkers tested in this experiment are HER2 (in 10 – 30% of breast cancer cases) and CA 15-3, both of which are indicative of a variety of cancers, including breast cancers. According to the researchers, the levels of these biomarkers in saliva can be correlated to those in blood serum. Where other biosensors may include the read-out circuitry – making those disposable and expensive – here the disposable part is the test strips which are plated with electrodes.

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Hackaday Links: February 18, 2024

February 18, 2024 by 17 Comments

So it turns out that walking around with $4,000 worth of hardware on your head isn’t quite the peak technology experience that some people thought it would be. We’re talking about the recently released Apple Vision Pro headset, which early adopters are lining up in droves to return. Complaints run the gamut from totally foreseeable episodes of motion sickness to neck pain from supporting the heavy headset. Any eyeglass wearer can certainly attest to even lightweight frames and lenses becoming a burden by the end of the day. We can’t imagine what it would be like to wear a headset like that all day. Ergonomic woes aside, some people are feeling buyer’s remorse thanks to a lack of apps that do anything to justify the hefty price tag. The evidence for a wave of returns is mostly gleaned from social media posts, so it has to be taken with a grain of salt. We wouldn’t expect Apple to be too forthcoming with official return figures, though, so the ultimate proof of uptake will probably be how often you spot one in the wild. Apart from a few cities and only for the next few weeks, we suspect sightings will be few and far between.

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No Inductors Needed For This Simple, Clean Twin-Tee Oscillator

February 18, 2024 by 11 Comments

If there’s one thing that amateur radio operators are passionate about, it’s the search for the perfect sine wave. Oscillators without any harmonics are an important part of spectrum hygiene, and while building a perfect oscillator with no distortion is a practical impossibility, this twin-tee audio frequency oscillator gets pretty close.

As [Alan Wolke (W2AEW)] explains, a twin-tee oscillator is quite simple in concept, and pretty simple to build too. It uses a twin-tee filter, which is just a low-pass RC filter in parallel with a high-pass RC filter. No inductors are required, which helps with low-frequency designs like this, which would call for bulky coils. His component value selections form an impressively sharp 1.6-kHz notch filter about 40 dB deep. He then plugs the notch filter into the feedback loop of an MCP6002 op-amp, which creates a high-impedance path at anything other than the notch filter frequency. The resulting sine wave is a thing of beauty, showing very little distortion on an FFT plot. Even on the total harmonic distortion meter, the oscillator performs, with a THD of only 0.125%.

This video is part of [Alan]’s “Circuit Fun” series, which we’ve really been enjoying. The way he breaks complex topics into simple steps that are easy to understand and then strings them all together has been quite valuable. We’ve covered tons of his stuff, everything from the basics of diodes to time-domain reflectometry.

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