Author: Aaron Beckendorf

182 Articles

A laptop is shown set up on a desk next to a spectrum analyser, an SDR, and two antennas. The antennas are aimed toward assorted electronics, including headphones and a phone handset.

Reviving TEMPEST Attacks With An Injected Signal

September 20, 2026 by No comments

TEMPEST attacks are often the most effective way to break air-gapped security: rather than directly accessing a computer, the attacker records the system’s unintended radio emissions and uses them to reconstruct its internal operations. This kind of attack was much more effective in the days of noisy, high-voltage CRT displays, and has gradually become less effective as electronics migrate to quieter, less powerful components. A group of researchers, however, has found that even modern electronics can become effective TEMPEST transmitters when irradiated with an RF signal.

The RF a device emits depends on the unintentional antennas in its internal structure. These are difficult to eliminate, and it’s usually not worth the effort; they’re usually small enough that they only effectively radiate at much higher frequencies than the electronics carry. The researchers’ technique, called InjectEave, radiated these electronics with a radio frequency tuned to their internal antennas, injecting that frequency into the circuit. Nonlinear electronic components, such as amplifiers, then mix the injected frequency with the internal signal, creating RF sidebands. This mixed signal then radiates out of the device and can be picked up and demodulated to recover the device’s internal signal.

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A black robotic hand is shown walking across a granite floor, using its fingers as legs.

Teaching A Robot Hand To Walk

September 19, 2026 by 19 Comments

Although it wasn’t apparently designed with this in mind, it seems particularly fortuitous that this walking robotic hand was released in time for Halloween. Designed by researchers from ETH Zurich, the slightly unsettling disembodied hand can use its fingers as legs to traverse terrain, push small objects around, and operate a keyboard.

The researchers started from commercially-available robot hand, equipped it with a battery and Raspberry Pi Zero 2 W, and developed neural net-based software to control it. The hand has twenty joints, four per finger, and the neural net iteratively outputs the next joint state, based on previous movements, the state of the hand, and the hand’s current goal. To train the net, the researchers built a simulated model, then used this for reinforcement learning; this yielded a faster walking speed than an adapted quadrupedal motion model did.

The hand was trained to move in a straight line, turn, recover from a fall, and press the keys of a keyboard (since it doesn’t have a camera, though, it can’t operate a keyboard by itself). The fall recovery is impressive to watch: in 21 out of 25 tests, it was able to right itself within twenty seconds. Due to the hand’s geometry, it drifts to the right while walking, so a constant correction needed to be applied. It did, however, manage to successfully cross fourteen varying surfaces, ranging in roughness from a rubber mat to gravel and grass. It even managed to push light objects toward goals.

The authors envision this kind of autonomous hand enabling greater freedom for a larger robot, such as a robot arm: if it needs to reach something farther away, the hand simply detaches and walks over. Regardless of the use to which they put in, such a project is already within reach of hackers; we’ve seen a few robotic hand projects here over the years.

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An angular, 3D-printed base holds two icosahedra with numerals on their faces. Each icosahedron has a zig-zagging path running through it, showing red gears inside.

Keeping Time On Tumbling Icosahedra

September 13, 2026 by 10 Comments

Clocks are almost the ideal devices to inspire creativity in hackers — they have a simple, well-defined task, but there’s an almost unlimited number of ways to carry it out. [ekaggrat singh kalsi]’s OVODYO is a particularly intriguing approach, tumbling a pair of icosahedral counters to display the current time.

Each 3D-printed icosahedron has numerals sunk through each of its twelve sides, and is raised above the base of the clock on a brass support shaft. An inner drive shaft runs through the center of the support shaft and drives a set of beveled gears. These spin the outer shells around two axes, periodically cycling through all twelve faces. The pattern in which an icosahedron rotates means that only set of numerals appears upright at a time, making it easier to distinguish the time.

A split path around the icosahedra both lets them rotate around the support shaft and shows off the internal gearing. On the control side, an ATmega8 drives a pair of stepper motors with drv8833 motor drivers, using a hall effect sensor to detect each indicator’s position. Since the minutes dial only gives the time in five-minute intervals, it also drives an LED strip to indicate the exact minute.

[ekaggrat] has a long history of creative clock designs, from this dynamic chain-link sculpture to a hair-tie clock or a mechanical seven-segment display.

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On the left side of the image, a mannequin holds a blade of grass in its mouth. A trail of dust follows a blurred green trail past the piece of grass. A man in the background is pointing a wooden device toward the mannequin.

Whip-Cracking Machine Reliably Breaks The Sound Barrier

September 13, 2026 by 9 Comments

We tend to think of breaking the sound barrier as a comparatively modern accomplishment, but on a smaller scale, cattle herders have been breaking it for centuries: the cracking sound of the tip of a bullwhip snapping comes from a small-scale sonic boom. Reliably getting a crack out of a whip takes skill and practice, though, which is why [Craig Turner] built a whip-cracking machine.

The first step was to build the whip itself, which was surprisingly complicated. Bullwhips taper down toward the end of the whip. As the whip uncurls during a crack, momentum passes down the whip; since the whip becomes continually narrower and lighter, conservation of momentum means that different stretches of the whip must move progressively faster. To get this effect, [Craig] joined together a series of increasingly thin and light ropes. The heavy end of the whip terminated in an eyelet connected to a length of elastic shock cord. Stretching the whip back on the shock cord and releasing it whipped it around, resulting in a fairly reliable crack.

For greater convenience, [Craig] built this into a launcher mechanism, with the elastic cord wrapped around the end of the launcher, an electrical-conduit guide for the whip, and a spring-loaded trigger mechanism to release it. This worked even better than expected, getting a reliable crack every time. The tip of the whip could slice leaves, tear open aluminium cans, put out candle flames, knock the cap off a bottle without tipping it over, and reliably hit small targets on the first shot.

As [Craig] mentioned, this setup would make it much easier to study the cracking effect with a schlieren imaging setup.

A white background is shown, with a grey metal plate at the base of the image. On the plate are three tiny green Benchy models. Above the Benchies is a glass cylinder. Below one of the Benchy models, text says "250 µm".

Printing Micron-Scale Benchies With Resin And Turmeric

September 6, 2026 by 16 Comments

Resin 3D printing has opened up a whole new scale of resolution for hackers, but the technology can go still finer; commercial micro-SLA and two-photon polymerization printers can print items with sub-micron feature sizes, but the machines are well out of reach for hackers. There’s more than one way to get such high resolution, though, as [Diffraction Limited] demonstrated with his micron-scale resin printer.

The printer builds on [Diffraction Limited]’s previous micro-manipulator and fiber-coupled laser. The micro-manipulator holds the end of the optical fiber just in front of the build plate, which is coated with resin. A 405-nm laser shines through the fiber, curing the resin in a narrow cone in front of the fiber’s core, which the micro-manipulator can trace in a pattern to build up objects, much like an FDM printer. Since the fiber’s inner core is only three microns across, the cured resin shears cleanly away from it when the fiber moves. Since the principle is so similar to an FDM printer, a standard slicer could be used to generate the tool paths.

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A grid of images shows pictures emerging from patches of random noise. To the left, images are more random, while to the right they become more recognizable.

Running Generative AI On An RP2350

September 5, 2026 by 22 Comments

Driven by a desire for privacy, customization, and lower costs, there’s growing interest in AI models which can be run on local hardware. Few of them go as far as [Tim], though, who built an image generation diffusion model which can run on an RP2350 microcontroller.

As might be expected, its capabilities are limited. The resolution is 128×128, it only generates images of human faces, and it takes about twenty seconds per image – still impressive for such limited hardware. It runs on a Waveshare RP2350 development board, and it can output the generated image over USB or display it with the aid of a VGA adapter board.

The generative model doesn’t directly create an image. Rather, it generates a distribution in a latent space, which a variational auto-encoder’s decoder component translates into an image. The auto-encoder was trained in two parts: an encoder which transforms an image into a latent-space distribution, and a decoder to transform that distribution back to an image; once this was trained, only the decoder was used.

The generative portion of the model uses a latent flow diffusion transformer; this takes in noise to start with, then iteratively predicts changes which bring it toward the desired image. It can also take in a output class, which guides the generator’s direction (toward a smiling face, for example). [Tim] trained two models, one larger and one faster, and quantized the weights for both to 8-bit integers. Both models, along with the inference program, then fit into 4 MB of flash memory.

For such a small model, the results are remarkably good; they don’t look quite natural, but they’re quite recognizable. For more on how diffusion image generators work, check out our article on Stable Diffusion.

A small rocket is shown launching into the sky, with a trail of smoke leading into the mount of a black pipe. Four large plastic pieces are falling away from below the rocket.

Tube Launch Boosts Rocket’s Performance

September 3, 2026 by 18 Comments

If you want improve a model rocket’s performance, all the common options come with serious trade-offs: you could increase the motor’s size, which raises safety issues, or you could cut down on weight, which limits the possible payload. [Con Hathy] was therefore intrigued by the design of the Arcas sounding rockets, which with the aid of a gas-fed launch tube could reach an altitude of 100 km. Even in models without a gas generator, a launch tube apparently boosted performance, an effect which [Con] was able to replicate in a much smaller model rocket.

In theory, as the rocket engine fires, it should pressurize the tube behind the rocket, providing an extra boost out of the tube. To test this, [Con] 3D printed a test rocket, launched it both from a standard rail and from a tube, and compared the results. During tube launches, a printed sabot fit around the rocket and formed a seal with the launch tube. The results were surprising: the tube-launched rocket actually performed substantially worse than a rail launch. After building a simulation, [Con] found that, as the rocket moves down the tube, the volume of tube it needs to back-fill with gas increases faster than the engine puts out exhaust; it was pulling a slight vacuum behind it, slowing itself down.

To solve this, [Con] decreased the diameter of the launch tube. To let the rocket fit into the tube, he also modified it to use pop-out stabilizer fins which wrap around the rocket while in the tube. The sabot was also shrunk, and had foam added to improve the seal between it and the rocket. For this second test, [Con] also connected a pressure sensor to the base of the launch tube. The results on the second launch were much better: according to an altimeter, it managed to fly 72% higher. Based on the pressure sensor’s data, a longer tube could have squeezed out still more performance, but this still demonstrated the principle quite well.

We’ve seen a tube-launched rocket before, though not with such a performance focus.

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