Built-In Batteries: A Daft Idea With An Uncertain Future

October 23, 2025 by Maya Posch 60 Comments

Having a gadget’s battery nestled snugly within the bowels of a device has certain advantages. It finally solves the ‘no batteries included’ problem, and there is no more juggling of AA or AAA cells, nor their respective chargers. Instead each device is paired to that one battery that is happily charged using a standardized USB connector, and suddenly everything is well in the world.

Everything, except for the devices that cannot be used while charging, wireless devices that are suddenly dragging along a wire while charging and which may have charging ports in irrational locations, as well as devices that would work quite well if it wasn’t for that snugly embedded battery that’s now dead, dying, or on fire.

Marrying devices with batteries in this manner effectively means tallying up all the disadvantages of the battery chemistries and their chargers, adding them to the device’s feature list, and limiting their effective lifespan in the process. It also prevents the rapid swapping with fresh batteries, which is why everyone is now lugging chunky powerbanks around instead of spare batteries, and hogging outlets with USB chargers. And the task of finding a replacement for non-standardized pouch cell batteries can prove to be hard or impossible.

Looking at the ‘convenience’ argument from this way makes one wonder whether it is all just marketing that we’re being sold. Especially in light of the looming 2027 EU regulation on internal batteries that is likely to wipe out the existence of built-in batteries with an orbital legal strike. Are we about to say ‘good riddance’ to a terrible idea?

Continue reading “Built-In Batteries: A Daft Idea With An Uncertain Future” →

UK’s MAST Upgrade Tokamak Stabilizes Plasma With Edge Magnetic Fields

October 22, 2025 by Maya Posch 16 Comments

Although nuclear fusion is exceedingly easy to achieve, as evidenced by desktop fusors, the real challenges begin to pop up whenever you try to sustain a plasma for extended periods of time, never mind trying to generate net energy output. Plasma instability was the reason why 1950s UK saw its nuclear fusion hopes dashed when Z-pinch fusion reactors failed to create a stable plasma, but now it seems that another UK fusion reactor is one step closer to addressing plasma instability, with the MAST Upgrade tokamak demonstrating the suppressing of ELMs.

ELMs, or edge localized modes, are instabilities that occur at the edge of the plasma. A type of magnetohydrodynamic instability, ELMs were first encountered after the switch to high-confinement mode (H-mode) to address instability issues encountered in the L-mode operating regime of previous tokamaks. These ELMs cause damage on the inside of the reactor vessel with these disturbances ablating the plasma-facing material.

One of the solutions proposed for ELMs are resonant magnetic perturbations (RMPs) using externally applied magnetic fields, with the South-Korean KSTAR tokamak already suppressing Type I ELMs using this method in 2011. Where the KSTAR and MAST Upgrade tokamaks differ is that the latter is a spherical tokamak, different from the more typical toroidal tokamak. As the name suggests, a spherical tokamak creates a sphere-like plasma rather than a doughnut-shape, with potential efficiency improvements.

All of this means that the MAST Upgrade tokamak can continue its testing campaign, as tokamaks around the globe keep trying to hit targets like the Greenwald Density Limit and other obstacles that stand in the way of sustained net energy production. Meanwhile stellarators seem to be surpassing one milestone after another, with the German Wendelstein 7-X being the current flagship project.

Top image: Inside MAST Upgrade, showing the magnetic field coils used to control ELMs. Credit: United Kingdom Atomic Energy Authority

The Lambda Papers: When LISP Got Turned Into A Microprocessor

October 20, 2025 by Maya Posch 17 Comments

The physical layout of the SCHEME-78 LISP-based microprocessor by Steele and Sussman. (Source: ACM, Vol 23, Issue 11, 1980)

During the AI research boom of the 1970s, the LISP language – from LISt Processor – saw a major surge in use and development, including many dialects being developed. One of these dialects was Scheme, developed by [Guy L. Steele] and [Gerald Jay Sussman], who wrote a number of articles that were published by the Massachusetts Institute of Technology (MIT) AI Lab as part of the AI Memos. This subset, called the Lambda Papers, cover the ideas from both men about lambda calculus, its application with LISP and ultimately the 1980 paper on the design of a LISP-based microprocessor.

Scheme is notable here because it influenced the development of what would be standardized in 1994 as Common Lisp, which is what can be called ‘modern Lisp’. The idea of creating dedicated LISP machines was not a new one, driven by the processing requirements of AI systems. The mismatch between the S-expressions of LISP and the typical way that assembly uses the CPUs of the era led to the development of CPUs with dedicated hardware support for LISP.

The design described by [Steele] and [Sussman] in their 1980 paper, as featured in the Communications of the ACM, features an instruction set architecture (ISA) that matches the LISP language more closely. As described, it is effectively a hardware-based LISP interpreter, implemented in a VLSI chip, called the SCHEME-78. By moving as much as possible into hardware, obviously performance is much improved. This is somewhat like how today’s AI boom is based around dedicated vector processors that excel at inference, unlike generic CPUs.

During the 1980s LISP machines began to integrate more and more hardware features, with the Symbolics and LMI systems featuring heavily. Later these systems also began to be marketed towards non-AI uses like 3D modelling and computer graphics. As however funding for AI research dried up and commodity hardware began to outpace specialized processors, so too did these systems vanish.

Top image: Symbolics 3620 and LMI Lambda Lisp machines (Credit: Jason Riedy)

High Performance Motor Control With FOC From The Ground Up

October 20, 2025 by Maya Posch 23 Comments

Testing the FOC-based motor controller. (Credit: Excessive Overkill, YouTube)

Vector Control, also known as Field Oriented Control or FOC is an AC motor control scheme that enables fine-grained control over a connected motor, through the precise control of its phases. In a recent video [Excessive Overkill] goes through the basics and then the finer details of how FOC works, as well as how to implement it. These controllers generally uses a proportional integral (PI) loop, capable of measuring and integrating the position of the connected motor, thus allowing for precise adjustments of the applied vector.

If this controller looks familiar, it is because we featured it previously in the context of reviving old industrial robotic arms. Whether you are driving the big motors on an industrial robot, or a much smaller permanent magnet AC (PMAC) motor, FOV is very likely the control mechanism that you want to use for the best results. Of note is that most BLDC motors are actually also PMACs with ESC to provide a DC interface.

Continue reading “High Performance Motor Control With FOC From The Ground Up” →

The MSL10 Mechanosensor Makes Venus Flytrap Plants Touchy

October 19, 2025 by Maya Posch 2 Comments

Carnivorous plants are a fascinating part of the natural world, especially species like the Venus flytrap (Dionaea muscipula) that rely on what is effectively a spring-loaded trap to ensnare unsuspecting prey. As also seen with species like the waterwheel plant (Aldrovanda vesiculosa), species like sundews are a lot more chill with movement in the order of seconds, excluding D. glanduligera which displays a similar sub-second response as the Venus flytrap. Over the years there has been much speculation about the exact mechanism that enables such a fast response, with [Hiraku Suda] and colleagues offering an explanation, via a recently published paper in Nature Communications.

The calcium response in a Venus flytrap with the DmMSL10 knockout variant. The ant is allowed to just waddle around. (Credit: Hiraku Suda et al., Nature Comm, 2025)

The sensory hairs that line the Venus flytrap’s leaves are finely tuned to respond to certain kind of stimuli using calcium threshold signals. This is something which was previously known already, but the exact mechanism still proved to be elusive.

This new study shows that a mechanosensor called DmMSL10 lies at the core of the touchiness of these plants by breeding a version where this particular stretch-activated chloride ion (Cl^–) channel is absent.

While the mechanical action of the sensor hair triggers the release of calcium ions in both the wild- and knockout dmmsl10 variant, the action potential generation rate was much lower in the latter, while the former continued to generate action potentials even after major stimulation had ceased. This demonstrates that DmMSL10 is essential for the processing of slight stimulation of the sensor hairs and thus prey detection.

A subsequent experiment with some ants being allowed to wander around on the leaves of the wild- and knockout type plants further served to demonstrate the point, with the wild type catching the first ant to waddle onto the leaf, while the knockout type leaf didn’t even twitch as four successive ants failed to propagate the calcium signal sufficiently to close the leaf.

With this knowledge we now have a likely mechanism for how D. muscipula and friends are able to generate the long range calcium signals that ultimately allow them to snack on these tasty protein-and-nitrogen packets on legs. Further research is likely to illuminate how exactly these mechanisms were evolved in parallel with similar mechanisms in animals.

Site Of Secret 1950s Cold War Iceworm Project Rediscovered

October 17, 2025 by Maya Posch 9 Comments

The overall theme of the early part of the Cold War was that of subterfuge — with scientific missions often providing excellent cover for placing missiles right on the USSR’s doorstep. Recently NASA rediscovered Camp Century, while testing a airplane-based synthetic aperture radar instrument (UAVSAR) over Greenland. Although established on the surface in 1959 as a polar research site, and actually producing good science from e.g. ice core samples, beneath this benign surface was the secretive Project Iceworm.

By 1967 the base was forced to be abandoned due to shifting ice caps, which would eventually bury the site under over 30 meters of ice. Before that, the scientists would test out the PM-2A small modular reactor. It not only provided 2 MW of electrical power and heat to the base, but was itself subjected to various experiments. Alongside this public face, Project Iceworm sought to set up a network of mobile nuclear missile launch sites for Minuteman missiles. These would be located below the ice sheet, capable of surviving a first strike scenario by the USSR. A lack of Danish permission, among other complications, led to the project eventually being abandoned.

It was this base that popped up during the NASA scan of the ice bed. Although it was thought that the crushed remains would be safely entombed, it’s estimated that by the year 2100 global warming will have led to the site being exposed again, including the thousands of liters of diesel and tons of hazardous waste that were left behind back in 1967. The positive news here is probably that with this SAR instrument we can keep much better tabs on the condition of the site as the ice cap continues to grind it into a fine paste.

Top image: Camp Century in happier times. (Source: US Army, Wikimedia)

How Bad Can A Cheap Knockoff ADS1115 ADC Be?

October 15, 2025 by Maya Posch 29 Comments

Although the saying of caveat emptor rings loudly in the mind of any purveyor of electronic components, the lure of Very Cheap Stuff is almost impossible to resist. Sure, that $0.60 Ti ADS1115 ADC on LCSC feels like it almost has to be a knock-off since the same part on Digikey is $4 a pop, and that’s when you buy a pack of 1,000. Yet what if it’s a really good knockoff that provides similar performance for a fraction of the price, such as with those cheap ADC boards you can get from Amazon? Cue [James Bowman] letting curiosity getting the better of him and ordering a stash of four boards presumably equipped with at least some kind of cheapo knockoff part, mostly on account of getting all boards for a mere $2.97.

The goal was of course to subject these four purported ADS1115s to some testing and comparison with the listed performance in the Ti datasheet. Telling was that each of the ADCs on the boards showed different characteristics, noticeably with the Data Rate. This is supposed to be ±10% of the nominal, so 7.2 – 8.8 times per second in 8 samples per second mode, but three boards lagged at 6.5 – 7 SPS and the fourth did an astounding 300 SPS, which would give you pretty noisy results.

Using a calibrated 2.5 voltage source the accuracy of the measurements were also validated, which showed them to be too low by 12 mV. The good news was that a linear correction on the MCU can correct for this, but it shows that despite these parts being ADS1115 compatible and having features like the PGA working, you’re definitely getting dinged on performance and accuracy.

[James] said that he’s going to run the same tests on an ADS1115 board obtained from Adafruit, which likely will have the genuine part. We would also love to see someone test the $0.60 version from LCSC to see whether they can match the datasheet. Either way, if you are eyeing this ADC for your own projects, it pays to consider whether the compromises and potential broken-ness of the knockoffs are worth it over coughing up a bit more cash. As they say, caveat emptor.