Even though the very concept of an ‘unpickable lock’ is as plausible as making water not be wet, this doesn’t take away from the intellectual thrill of devising solutions to picking attacks and subsequently circumventing those solutions. Case in point the ‘unpickable’ traveling key lock that [Works by Design] recently featured and sent a few copies off to lock pickers such as [Lock Noob] who gave picking it a shake.

Many of the details and reasoning behind [Works by Design]’s lock design can be found in the original video, with [Lock Noob] going over the basic summary before getting to work trying to pick it.

Rather than trying to bump the tumbler lock mechanism or another indirect approach, the focus is here on an impressioning attack. Although in this traveling key mechanism the physical key is moved inside the lock, the pins of the tumbler lock will leave impressions on the brass blanks when the lock is gently forced to rotate, indicating that there’s still too much material there.

The approach here is thus to slowly file away these sections, with interestingly the plastic pin that [Works by Design] had added to dodge impressioning attacks not being too much of an issue. Thus after over an hour of turning-filing-turning-filing ad nauseam, the lock mechanism rotated, confirming that it had been defeated.

In the subsequent teardown of the lock it can be seen that a plastic pin is indeed rather fragile, with part of its top having been torn off. After replacing this damaged plastic pin with a fresh one, a foil-based impressioning attack is attempted by putting aluminium foil over a skeleton key, but this didn’t quite work out as the pins come in sideways and thus do not leave a useful impression.

Theoretically the pins would press down onto the soft foil, creating an almost immediate impression of the required key. Perhaps that leaving a solid side on the blank would make it work, but this is an approach that would have to be refined.

Either way, it shows that ‘unpickable’ depends on your definition, as ‘1+ hour of filing with knowledge of bitting depths’ would be considered ‘unpickable’ by some. At least it’s not as dramatic as a 2020 [Stuff Made Here] ‘unpickable lock’ hack that we covered, before it got shredded by the [LockPickingLawyer] with resulting list of potential fixes of multiple easy exploits before even having to resort to impressioning.

Considering that traveling key designs generally require at least a tedious impressioning attack, with potential ways to address this in a more substantial way, a redesign featuring these changes would be rather interesting to see picked. If it can defeat the average lockpicking enthusiast including those practicing the legal profession, it’s probably as close to ‘unpickable’ as can be before the bolt cutters and angle grinders are used against any vulnerable parts that aren’t the lock itself.

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Electrostatic discharge machining (EDM) may be slower than alternatives like laser cutting, water jets, or a milling machine, but for some applications there’s no alternative: it can cut through any conductive material, no matter how hard, and it leaves no mechanical or thermal stress in the workpiece. Best of all, they’re relatively accessible for a resourceful hacker, such as [Inofid], who recently built the second iteration of his desktop wire EDM.

The EDM’s motion system comes from a cheap desktop CNC router, which had a water tank mounted in its workspace and had the spindle replaced with a wire-management mechanism. The wire-management mechanism needs to continuously wind a tensioned brass wire from one spool through the cutting zone onto another spool. The tensioning system uses two motors: one to pull the wire through, and one to maintain tension by slightly counteracting it, with a tension sensor and Ardunio to maintain the proper tension. If it detects that the wire has broken, it can stop the CNC controller. To keep the wire from breaking or short-circuiting with the workpiece, a current monitor counts sparks between the wire and workpiece and uses this to predict whether the wire is getting too close to the metal, in which case it slows down the movement.

As a first test, [Inofid] cut through a five by three centimeters-thick block of aluminium, taking two hours but producing a clean cut. To speed up the next cut, [Inofid] added a pump and filter to remove sludge from the cutting area. The next cut was an aluminium gear, and then a meshing steel gear, which took about ten hours but turned out well.

EDMs of various kinds appear here from time to time, particularly since the popularization of 3D printers. We’ve even seen one built into a lathe.

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Thanks to [Keith Olson] for the tip!

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It shouldn’t be any surprise that NFC and similar RFID implementations are capable of providing power to a receiver, since this is after all how RFID tags can work without a battery. The question is more whether you can do more with NFC than just briefly power some low-power circuitry to spit out some data. This is the topic of a recent [Denki Otaku] video.

Although both Qi and NFC use electromagnetic induction, they differ in the frequency and correspondingly the maximum power that they can deliver to a receiver. For NFC this is around a Watt, with the used NFC module supporting up to 250 mW, which already sets the rough scope of what one can expect from an NFC-powered device. That said, an NFC transmitter and receiver can be significantly smaller than those for Qi due to the much higher frequency.

An additional benefit of NFC is that it offers more freedom to the user in its protocol in terms of user data, which is useful for applications where you don’t just want to power a device. In the video an MCU and IMU are powered along with an OLED display, which demonstrates wireless charging as well as data transfer of the IMU data to a second MCU.

The benefits of NFC over Qi would thus be the smaller antenna size, and depending on the used NFC implementation also charging and data transfer at the same time.

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If you’ve been paying any attention to the renewable energy space, you’ll know that generation isn’t really the problem anymore. Solar panels are cheap, and wind turbines are everywhere. The problem is matching generation with demand—sometimes there’s too much wind and sun, and sometimes there’s not enough. Ideally, you could store that energy somewhere, and deploy it when you need it.

The answer everyone keeps reaching for is lithium-ion batteries, and they work just fine. However, there’s a competing technology that’s been quietly scaling up in the background—the vanadium flow battery. It has some unique advantages that could see it rise to prominence in the world of large-scale grid storage.

The Juice That Stores Juice

Flow batteries are chemically simple, but mechanically complicated. They use pumps to flow electrolyte from massive tanks through cell stacks to generate electricity. This means they are very easy to scale in capacity – just add bigger tanks, and you’ve got a bigger battery. Credit: Kavin Teenakul, CC BY-SA 4.0
Flow batteries are beautiful in their simplicity, storing charge in huge tanks full of liquid electrolyte rather than in gel-like materials sandwiched between solid electrodes as per a regular battery. Specifically, two big tanks of vanadium ions, typically dissolved in sulfuric acid. By pumping the electrolyte through a cell stack where the electrochemical reaction happens, you generate electricity. Getting more power is as simple as adding more cell stacks, while increasing the battery’s capacity is as simple as getting bigger tanks full of more electrolyte. The two variables are almost entirely decoupled, which is an extremely elegant property for a grid-scale storage system. It makes right-sizing the system a cinch, it’s simply a matter of scale. These batteries also have the property of surviving tens of thousands of charge cycles without damage, and lifespans measured in decades.

The chemistry itself works out quite tidily. Both the positive and negative electrolyte use vanadium, just in different oxidation states. The positive side hosts VO₂⁺ and VO²⁺ ions, while the negative side works with V²⁺ and V³⁺ ions. These solutions are pumped through a cell, either side of a permeable membrane that allows proton exchange. When the battery is being discharged, electrons leave the anode electrolyte and are transferred through the external load to the cathode electrolyte; this is balanced by the transfer of protons across the membrane. During charging, the opposite occurs.

A neat side-benefit of this is that because the battery uses the same element on both sides of the membrane, cross-contamination between the two tanks — an inevitable consequence of some ions sneaking through the membrane over thousands of cycles — doesn’t actually kill the battery. The electrolyte merely needs to be rebalanced and normal operation can resume. This single-element trick also means the electrolyte has a very long service life. It doesn’t degrade in the way an electrolyte in a regular battery might. A well-maintained vanadium flow battery can run for ten to twenty years with minimal capacity loss, and at end of life, that vanadium electrolyte still has value. It can be sold, recycled, or reprocessed as needed. Meanwhile, the electrodes in the cell stack and the pumps and machinery that moves the electrolyte around can be serviced or replaced as needed. It’s a very different scenario compared to lithium-ion cells, where recycling the raw materials involves great mechanical and chemical complexity.

There is a complexity gain versus traditional batteries, in that moving all the electrolyte around requires mechanical pumps that in turn draw power to operate. These batteries are also not particularly compact, nor efficient in terms of energy-to-volume ratio. However, these problems are offset with the ease of scaling and maintaining them.

Deployment

An aerial view of a flow battery installed by Rongke Power in Hami, in northwest China. Credit: Rongke Power
In the real world, vanadium flow batteries are starting to hit the big time. The largest example in the world is a Chinese project, consisting of a 200 MW battery in Jimusaer, with a total capacity of 1000 MWh, built by Rongke Power. The second largest installation, installed in the city of Ushi in 2024, has a capacity of 700 MWh and can discharge 175 MW to the grid, and was constructed by the same firm. These batteries are comparable in power output to the Victorian Big Battery, a lithium ion installation that outputs 300 MW at peak, but far larger in capacity, as the Australian installation tops out at just 450 MWh by comparison. These installs build upon a previous effort to install a 100 MW battery in Dalian with 400 MWh capacity, along with smaller projects in Shenyang and Zongkyang that operate at sub-10MW levels. The batteries are intended to be used to support grid stability in their local grids. They also have grid-forming capabilities, which means that the flow battery can be used to do a black start, helping to bring traditional thermal generation units online in the event of a total grid collapse.

Australia has also been leaping to adopt vanadium flow battery technology, too. The country is well known for having a huge install base of rooftop solar, which has created a difficult-to-control grid at times. The abundance of sunlight and solar generation during the day has lead to huge peaks where power prices at times turn negative, and the goal is to add storage so that this power can be stored for more effective use over longer time periods.
The vanadium flow battery installation in Port Pirie, South Australia, operated by Yadlamalka Energy. Credit: Yadlamalka Energy
In South Australia, a small project has proven the viability of vanadium flow batteries in local conditions. The Co-Located Vanadium Flow Battery Storage and Solar project in Neuroodla was installed by Yadlamalka Energy, and combined photovoltaic generation and storage into a single site. The project’s goal was to demonstrate the value of vanadium flow batteries for providing both simple energy storage and frequency control services to the grid. It’s a relatively small installation, of just 2MW output and 8MWh capacity, paired with 6MWp of solar panels on site. The build was located adjacent to the Neuroodla substation for easy connection to the grid. The project faced some challenges in terms of power derating during the hottest local conditions, and with some limitations on power deployment and energy trading based on the inverter capabilities at the site. Ultimately, though, the project was able to generate serious revenue even with its limited capacity, thanks in part to energy price volatility in the local market as solar peaks and troughs occurred on a regular basis.

Over in Western Australia, sights are being set much higher. The state government has put out an expression of interest for a 50 MW, 500MWh vanadium flow battery to be installed in Kalgoorlie. The project is backed by $150 million in government funding, and hopes to offer a mighty 10-hour discharge capability to the grid. The project hopes to be up and running by 2029, relying on locally-produced vanadium to fill the tanks.

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Every now and then in our travels we come upon a project with such an obvious need that it’s almost a surprise nobody has thought of doing it before. So it is with [Elehobica]’s project, an audio recorder for S/PDIF audio streams. It’s the device you could have used, years ago!

S/PDIF, or its optical fiber cousin TOSLINK, is the digital output you’ll find on the back of Hi-Fi equipment, it’s a serial encoding of an uncompressed digital audio data stream dating from the era when CDs were new. Its relative simplicity may be what’s given it longevity — it’s easy to implement so it plugs into pretty much everything.

Perhaps back in the day it might have been a pain for an 8-bit microprocessor to handle, but in 2026 it’s no bother for a Raspberry Pi Pico. The project is a small PCB with the Pico, a few interface components, and an SD card socket, and it sends what it hears on the input to the card as WAV files. We particularly like its smart sample rate and bit depth detection, and the way it cuts up tracks based on periods of silence. If you work with SPD/IF, this is going to be a useful tool.

Perhaps it could even be fed with a laser!

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