Mysterious Files PH

Everybody loves aquariums. There’s something soothing about watching the lil’ critters inside them swimming, crawling and wriggling about. But at the same time few people are up to the task of ensuring that said critters stay alive and happy in said aquarium. This is where small robots may be able to steal some fishy jobs, like a modern take on the gaudy fake aquariums of the 1990s. Cue [CPSDrone]’s mini-drone aquarium with mostly maintenance-free robotic fish.

These pose a few interesting engineering challenges, such as the replacing of feeding fish by having them scuttle back to their charging station like an aquatic Roomba, and giving them some level of intelligence to the point that they at least appear to be doing something fish-like.

Rather than give each robot fish full autonomy, they are instead controlled by a central system. This then raised the problem of radio frequency communication while underwater. The theory was that 433 MHz transceivers would still work for something the size of an aquarium before attenuation spoils things, which a quick test confirmed to be true.

This enabled the construction of a small microcontroller-carrying submarine as a proof of concept before diving into the final version, involving resin 3D printed enclosures that are made water-tight using rubber O-ring seals and UV-cured resin. All that was left now was to add the big control system, which takes up much of the rest of the video.

Sadly they didn’t implement the boids algorithm, as this is pretty good at creating realistic life-like motion, as show with this demonstration by [Ben Eater]. This algorithm is pretty simple, with each ‘creature’ obeying rules on coherence, separation and alignment, creating a pattern that can be observed among schools of fish as well as flocks of birds. Due to its simplicity you could conceivably even omit the central control system and just give each ‘fish’ enough sensors to keep track of its buddies.

The phenomenon of cable-shaped indents in the plastic cases of retro systems is one that’s probably painfully familiar to many a collector of such systems. Although in these situations neither side got hot enough to cause any melting – especially while disconnected in storage – it still has that same melted appearance. The real cause here is not heat, but plasticizer migration, as detailed in a recent video by [Run Stop Restored] over on YouTube.

Plasticizers are an additive to many plastics that aim to make it more flexible (‘plastic’), as well as improve other characteristics of the base material, with PVC in particular relying on plasticizers to give it its desired properties for applications where PVC has to be flexible. Here the flexible cable insulation of these devices generally uses PVC, which over time can migrate to other polymers when brought into close contact for extended periods of time.

The – usually ABS – enclosures of e.g. Commodore tape drives as in this video demonstration thus get correspondingly inundated with the same type of plasticizers that ABS is also highly susceptible to. Since in storage the cables tend to be wrapped – tightly – around the device they’re attached to, this results in a solid contact which thus enables this gradual process to work its magic, whether it’s a Commodore datasette or a power supply brick.

Correspondingly the PVC insulation becomes brittle as it loses its plasticizer, with the process sped up by higher environmental temperatures. To prevent this, never wrap a PVC cable around a device, and keep it physically separated from susceptible plastics like ABS as much as reasonably possible. Along with a cool environment this should prevent plasticizer migration from ruining what used to be a pristine case.

This problem is particularly significant for retro gear from the 1980s and thereabouts, before phthalate-free plasticizer alternatives were developed, along with other changes such as more stable formulations that prevent this migration process. Adding a coating can also help, especially for protecting older gear, but flexible PVC in particular should be viewed with suspicion and treated carefully.

Every experienced machinist knows the value of taking regular measurements. If one works carefully and checks dimensions frequently, it’s possible to make a part much more precise than could be made by relying on the machine’s accuracy alone. In a similar vein, it’s possible to make a measuring device out of comparatively crude parts, as long as their behavior is well understood. Related to both principles is [BubsBuilds]’s displacement sensor, which uses a 3D printed frame but reaches precision better than two micrometers.

Admittedly the printed parts aren’t the source of the sensor’s precision, that comes from an opto-interrupter. This design has a central stylus, one end of which contacts the object under measurement. The other end flattens to a knife-edge blade, which fits between the diodes of the opto-interrupter. As the stylus point is pressed in, the blade blocks off more light from reaching the photodiode, creating an output signal proportional to displacement. To keep the stylus from twisting or moving side-to-side, two flat, circular flexures hold the stylus in the center of a cylindrical housing.

[Bubs] printed several flexure variations to see how well they resisted and permitted various torques and forces, and a symmetrical flexure design proved best for his purposes. Once the sensor was assembled, he tested it against the measurements recorded by a laser confocal displacement sensor. This design was an update from a previous version, and it improved in a few regards: the non-linearity had decreased, and the repeatability was now better than two microns, though the range had been halved. Significantly, though, it’s now much easier to mount, making this an actually practical tool.

If, however, this doesn’t fit your needs, there are many other ways to build a linear displacement sensor, ranging from capacitive to magnetostrictive. On the manual side of things, we’ve also covered a comparison of calipers.

A central problem with the arguably overhyped field of quantum computing remains the difficulty in objectively ascertaining performance and new developments, as much here relies on indirect measurements. Such is especially the case with topological quantum computing, with its use of Majorana fermions. For a few years now Microsoft’s quantum computing department (Azure Quantum) has made claims here of major progress, which have subsequently repeatedly been shot down in peer review. Their most recent attempt at said progress in topological quantum computing now got a blistering response (PDF) by Henry F. Legg in an article in Nature.

We previously reported on Microsoft’s attempts here in early 2025, when they claimed the detection of the crucial Majorana Zero Mode (MZM), before it faced the criticisms of peer review, including by Legg, which included academically vicious language by some researchers, including terms like ‘essentially fraudulent’.

This raises the awkward question of whether Microsoft’s quantum researchers are just too eager to confirm a discovery, or whether a more benign reason exists.

Majorana Versus Dirac

In traditional quantum computing generally Dirac fermions are used as the qubits for quantum computations, but so far this approach has been fraught with complications and challenges, with decoherence and noise intrusion making long-running computations extremely hard and necessitating the need to run computations multiple times for error-correction algorithms to have a shot at divining a plausible result.

This is where topological quantum computing comes into play, as although it imposes some limitations on its feature set, it would be much more resilient to outside influences. Some confusion here may exist with the referencing of Majorana particles, as fermions come in Dirac, Majorana and Weyl flavors. What is referenced here is actually a Majorana anyon, a quasiparticle that just happens to have the same property as Majorana fermions of being its own antiparticle.

By combining these anyons with braid theory using the intertwining of the anyon world lines it becomes possible to perform operations, which theoretically can be used to create a topological quantum computer.

Essentially, this swaps the very fickle, trapped quantum particles for significantly more stable braided Majorana anyons, which – if confirmed – could herald a significant breakthrough in the world of quantum computing.

Is It Majorana Shaped?

Even if you have created a device that theoretically should create Majorana fermions, the next challenge is to confirm that this is in fact the case. This, roughly speaking, is the challenging point where Microsoft’s attempts the past years have repeatedly ending up beaching themselves. As mentioned earlier, the evidence here is determined indirectly rather than through simple direct measurements or experiments.

When the first semiconductor transistor was demonstrated at Bell Laboratories in 1947 in the form of the world’s first point-contact transistor, it came after many years of theorizing and failed attempts starting in at least the 1920s.

Here the evidence of a working transistor was impossible to ignore, as it obviously worked as an amplifier of current, with even the simple current- and voltage-measuring devices of the era sufficing to establish the simple truth. Subsequently this design was commercialized before eventually being replaced with the bipolar junction transistor and a flurry of other devices that followed once the basic principles had been demonstrated.

In the case of quantum processors, whether traditional or topological, there is no obvious way to replicate such a basic demonstration at this point in time. Even the far more basic case of quantum annealing in the form of D-Wave’s commercial offerings is mired in controversy whether there is any ‘quantum advantage’ to be found here. This is territory where even mighty IBM has seen its quantum advantage claims trolled and outperformed by researchers using a lowly Commodore 64.

Where it concerns Majorana anyons and evidence of MZM, you can of course try to build a finished device that demonstrates a clear quantum advantage, or you can build a more limited device where you deduce the existence of these fundamental elements based on what remain mostly theoretical assumptions.

For its most recent attempt at proving that they had succeeded at creating these anyons and with it topological superconductors, Microsoft’s team used a new procedure they called the Topological Gap Protocol (TGP), which purportedly was able to perform a parity readout from their manufactured devices and use this to prove that they had really achieved their goal this time.

Broadside Peer Review

Consequently, Legg’s most recent critique comes as response to Microsoft Azure Quantum’s paper in Nature which got published as a result of that new approach. In this paper it’s claimed that this time they really did detect topological qubits in this improved test setup with TGP, based on – again – indirect measurements and analysis of recorded data. In Legg’s critique it is this analysis of the measurements that’s being attacked as having been performed incorrectly.

The main issue that he identifies is a selective interpretation of the measurements, focusing on the data that supports the experiment’s assumptions, in what would essentially be confirmation bias. There’s also the argument that Microsoft’s researchers made a number of mistakes in their Python code, where they use the array index rather than its value. After adjusting for said basic Python errors, Legg then got entirely different results based on the same measurements.

As noted by Legg, you can get very similar data signatures from sources like quantum dots. Along with the somewhat fundamental data processing issues, this obviously puts into question just how close the Microsoft team was to actually having created these topological qubits.

Microsoft Strikes Back

Of course, Microsoft’s team got in their reply (paywalled) after taking that broadside salvo. Their main arguments seem to be that TGP has no role in interpreting the RF results – being just a tune-up procedure – that form the basis of the original conclusions, nor do they recognize the issues with TGP that Legg indicated as being valid.

Another point is that Legg offers no alternative physical model that is capable of reproducing the capacitance signal or the RTS phenomenology, and thus the response basically seems to boil down to a curt ‘nuh uh’.

They did acknowledge an off-by-one pixel bug in the TGP processing, but insist that it is only a minor issue.

Effectively, the criticism is rejected, with the original 2025 paper maintained as being valid. This would mean that these topological qubits were truly detected, and with this knowledge a functional topological quantum processor could be constructed and integrated into a larger system.

The Science Continues

As much as academics and science in general can often appear to resemble a shooting gallery where the parties involved are happy to do some sniping, ultimately the scientific method has to prevail. This means the publishing of results, of experimental setups and methods with sufficient details that other researchers can attempt to reproduce the results from fundamentals.

If the Microsoft researchers are correct, then this might be a point-contact transistor moment within the world of quantum computing, which would naturally quickly be confirmed by other teams who would create their own devices and run their own tests, making it a historical fact.

Of course, just in the past few years we saw the Korean LK-99 room temperature superconductor and the controversial EmDrive meet a dismal end at the uncaring hands of peer review, while cold fusion is clinging on in a continuous state of limbo, even as it’s now called ‘low-energy nuclear reactions’.

Perhaps the best part of science is that even if nothing comes out of a research direction, it still offers a fascinating opportunity to learn more about physics, mathematics and so much more. Just in the course of writing this article I had to expand my knowledge of some subjects and refresh it on others. Ultimately this makes even something as controversial as topological quantum computing such a delightful topic to occasionally dive into.

The NOISFERATU is an open source generative textural sound synthesizer, or as creator [Robert Heel] puts it, “a sound designer’s dream and audiophile’s worst nightmare”.

NOISEFERATU offers 45 different sound algorithms grouped into five banks produce a dazzling range of evolving soundscapes and patterns that resist repetition or settling, each influenced and shaped — the word controlled does not quite apply — by a volume slider and a few hardware knobs.

So what does it actually sound like? Check out the video embedded below to give it a listen, it’s pretty trippy.

Hardware-wise NOISEFERATU is centered around the Seeed Studio XIAO SAMD21 microcontroller, takes power over USB-C, and has a headphone jack for sound output. We love the artwork on the dual-sided front panel, too.

DIY synthesizers based on logic chips have a long and proud history, and seeing the different directions people can go by incorporating microcontrollers is always a delight.

If NOISEFERATU’s experimental sound and noise sounds up your alley, the design files and code on GitHub have everything one should need to build one. Kits are for sale direct from the designer, as well.

For as popular as the piano is in music studios, homes, and schools, it almost defies logic. Compared to a guitar, harmonica, or drum set, pianos are incredibly complex machines that can have somewhere on the order of 8,000 moving parts in a case that can easily weigh hundreds of pounds and which often responds quite poorly to seasonal changes in temperature and humidity. But for putting up with all of these downsides, musicians are rewarded with an instrument that uniquely responds to touch, style, and emotion. A big reason for that is that mechanical complexity, and [Super Valid Designs] is attempting to bring that design to a drum set.

Compared to the complex machinery that connects the movement of a piano’s key to its hammer striking a string, a kick drum pedal is much simpler. It can only bounce off of the drum or get “buried” where the beater remains pressed up against the drum after hitting it. [Super Valid Designs] wanted something with a bit more finesse and control, so he first 3D printed a mechanism that throws the beater towards the drum head and then disconnects it mechanically from the pedal, so that it rebounds even if the pedal stays depressed. The next steps were more difficult, which involved making sure the mechanism reset itself in a repeatable way, without making too much noise of its own. This involved trying out a few different ideas and printing a massive amount of subtly different linkages, but in the end he’s left with a machine that nearly replicates all of the parts of a piano’s escapement,

The end goal of this project wasn’t simply to reproduce piano mechanisms on a drum set, though. [Super Valid Designs] hopes to make a kick drum that’s much smaller than those found in traditional kits, and since smaller drums respond poorly when the beater remains on or near the drum after striking it, a mechanism like this will dramatically improve the performance of the smaller drum and help reduce the requirement for perfect technique. And, maybe in 50 years or so, these types of escapements will take over the drumming world just like the piano escapement took over keyboards after its invention in the 1700s. Some simpler piano actions have been built before, but the complexity seems to be a requirement for all of the tasks they need to do whether its for a piano or a drum.

Perhaps the hardest thing for amateur astronomers just starting out is finding the things you want to look at. Prolific maker [mircemk] has submitted a quick-and-easy star-hopper device that will help guide your binoculars with laser-like precision using things you likely already have on hand: a smartphone, a mounting plate, and a green laser pointer.

The smartphone is running AstroHopper, an astronomy app that uses GPS and inertial navigation to know exactly where your phone is pointing, and offer an image of the sky on the screen. There are many others of this ilk, and there’s no reason [mircemk]’s trick won’t work with your favorite. The trick is decidedly simple: the smartphone is mounted to a flat plate, in line with a green laser pointer. Careful placement aligns the axis of the phone and the laser, and the mounting plate is set up to fit a tripod.

Using it is simple: with a labelled view of the sky displayed on the screen, one lines up the phone/laser combo with the desired object, and activates the laser pointer. [micremk] has wired in an on-off switch for this purpose and a large external battery, rather than relying on the stock pushbutton. Since the axis of the laser pointer and the phone are aligned, a green line launches out into the heavens for you to follow with your binoculars. Once you locate that green dot, you can turn off the laser. Yes, the computer has helped you find the object, but your muscles are doing the slewing and that will make it much more likely you start to learn the sky yourself rather than relying on electronic magic.

This is probably the simplest hack we’ve yet seen in the Frikkin’ Lasers Challenge, and yet also one of the most practical. If you enjoy playing with radiation that’s spontaneously emitted, there’s still time to get your entry together — the contest runs until July 23, 2026.