2026-01-14 20:00:34
Getting a significant energy return from tokamak-based nuclear fusion reactors depends for a large part on plasma density, but increasing said density is tricky, as beyond a certain point the plasma transitions back from the much more stable high-confinement mode (H-mode) into L-mode. Recently Chinese researchers have reported that they managed to increase the plasma density in the EAST tokamak beyond the previously known upper Greenwald Density Limit (GDL), as this phenomenon is known.
We covered these details with nuclear fusion reactors in great detail last year, noting the importance of plasma edge stability, as this causes tokamak wall erosion as well as loss of energy. The EAST tokamak (HT-7U) is a superconducting tokamak that was upgraded and resumed operations in 2014, featuring a 1.85 meter major radius and 7.5 MW heating power. As a tokamak the issue of plasma and edge stability are major concerns, even in H-mode, requiring constant intervention.
In the recent EAST findings, the real news appears to be more confirmation of the plasma-wall self-organization (PWSO) theory that postulates that one of the causes behind plasma wall (edge) instability is due to the interaction between plasma dynamics and wall conditions through impurity radiation. By using electron cyclotron resonance heating (ECRH) and/or pre-filled gas pressure this impurity level might be reduced, enabling higher densities and thus exceeding the empirical GDL.
What’s interesting is that the paper also compares EAST and the Wendelstein 7-X (W7-X) stellarator, making the argument that tokamaks can operate in a way that’s more similar to stellarators, though W7-X is of course gifted with the same advantages as every current stellarator, such as no real GDL or the necessity of dealing with H- or L-mode. It’s therefore not surprising that W7-X is so far the most efficient fusion reactor to achieve the highest triple product.
2026-01-14 17:00:06
Drawing tablets have been a favorite computer of artists since its inception in the 1980s. If you have ever used a drawing tablet of this nature, you may have wondered, how it works, and if you can make one. Well, wonder no longer as [Yukidama] has demonstrated an open source electromagnetic resonance (EMR) drawing tablet build!
The principle of simple EMR tablets is quite straight forward. A coil in the tablet oscillates from around 400 kHz to 600 kHz. This induces a current inside a coil within the pen at its resonant frequency. This in turn, results in a voltage spike within the tablet around the pen’s resonant frequency. For pressure sensing, a simple circuit within the pen can shift its resonant frequency, which likewise is picked up within the tablet. The tablet’s input buttons work in similar ways!
But this is merely one dimensional. To sample two dimensions, two arrays of coils are needed. One to sample the horizontal axis, and one the vertical. The driver circuit simply sweeps over the array and samples every coil at any arbitrary speed the driver can achieve.
Finally, [Yukidama] made a last demo by refining the driver board, designed to drive a flexible circuit containing the coils. This then sits behind the screen of a Panasonic RZ series laptop, turning the device into a rather effective drawing tablet!
If tablets aren’t your style, check out this drawing pen.
Thanks [anfractuosity] for the tip!
2026-01-14 14:00:36
[The 8-Bit Guy] tells us how 8-bit Atari computers work.
The first Atari came out in 1977, it was originally called the Atari Video Computer System. It was followed two years later, in 1979, by the Atari 400 and Atari 800. The Atari 800 had a music synthesizer, bit-mapped graphics, and sprites which compared favorably to the capabilities of the other systems of the day, known as the Trinity of 1977, being the Apple II, Commodore PET, and TRS-80. [The 8-Bit Guy] says the only real competition in terms of features came from the TI-99/4 which was released around the same time.
The main way to load software into the early Atari 400 and 800 computers was to plug in cartridges. The Atari 400 supported one cartridge and the Atari 800 supported two. The built-in keyboards were pretty terrible by today’s standards, but as [The 8-Bit Guy] points out there wasn’t really any expectations around keyboards back in the late 1970s because everything was new and not many precedents had been set.
[The 8-Bit Guy] goes into the hardware that was used, how the video system works, how the audio system works, and what peripheral hardware was supported, including cassette drives and floppy disk drives. He covers briefly all ten of the 8-bit systems from Atari starting in 1979 through 1992.
If you’re interested in Atari nostalgia you might like to read Electromechanical Atari Is A Steampunk Meccano Masterpiece or Randomly Generating Atari Games.
2026-01-14 11:00:03
Everyone knows that the path of least resistance is the path that will always be taken, be it by water, electricity or the feet of humans. This is where the PCB presented by [ElectrArc240] on YouTube is rather confusing, as it demonstrates two similarly sized traces, one of which is much shorter than the other, yet the current opts to travel via the much longer trace. If you were to measure this PCB between each path, the shorter path has the lowest resistance at 0.44 Ω while the longer path is 1.44 Ω. Did the laws of physics break down here?
Of course, this is just a trick question, as the effective resistance for an electrical circuit isn’t just about ohmic resistance. Instead the relevant phrasing here is ‘path of least impedance‘, which is excellently demonstrated here using this PCB. Note that its return path sneaks on the back side along the same path as the long path on the front. To this is added a 1 MHz high current source that demonstrates the impact of alternating current, with reactance combining with the resistance.
Although for direct current it’s fair to say that impedance is the equivalent of resistance, once the inductance of a trace has to be taken into account – as in the case of AC and high-frequency signaling – the much higher inductance of the short path means that now the long path is actually the shortest.
When you are doing some impedance matching in your favorite EDA software while implementing an Ethernet RMII link or similar, this is basically part of the process, with higher frequencies requiring ever more stringent mechanisms to keep both sides happy. At some point any stray signals from nearby traces and components become a factor, never mind the properties of the PCB material.
2026-01-14 08:00:49
Windsurfing has experienced a major decline in popularity in the last few decades as the sport’s culture failed to cater to beginners at the same time that experienced riders largely shifted to kiteboarding. While it’s sad to see a once-popular and enjoyable sport loose its mass market appeal, it does present a unique opportunity for others as there’s cheap windsurfing gear all over the online classifieds now. [Dane] recently found that some of these old boards are uniquely suited to be modified into electric surfboards.
The key design element of certain windsurfers that makes this possible is the centerboard, a fin mounted on the windsurfer extending down into the water that resists the lateral force of the sail, keeping the board moving forward instead of sideways. [Dane] used this strengthened area of the board to mount a submerged electric motor, with all of the control electronics and a battery on the top of the board. The motor controller did need a way to expel excess heat while being in a sealed waterproof enclosure, but with a hole cut in the case and a heat sink installed on top of it, this was a problem quickly solved.
The operator control consists of a few buttons which correspond to pre-selected speeds on the motor. There’s no separate control input for steering, though; in order to turn this contraption the operator has to lean the board. With some practice it’s possible to stand up on this like any other electric surfboard and scoot around [Dane]’s local lake. For the extreme budget version of this project be sure to check out [Ben Gravy]’s model which involves duct taping two cheap surfboards together instead.
2026-01-14 05:00:48
With more and more kitchen utilities gaining touch screens and capable microcontrollers it’d be inconceivable that they do not get put to other uses as well. To this end [Aaron Christophel] is back with another briefly Doom-less device in the form of the Krups Cook4Me pressure cooking pot with its rather sizeable touch screen and proclaimed smarts in addition to WiFi and an associated smartphone app.
Inside is an ESP32 module for the WiFi side, with the brains of the whole operation being a Renesas R7S721031VC SoC with a single 400 MHz Cortex-A9. This is backed by 128 MB of Flash and 128 MB of RAM. The lower touch interface is handled by a separate Microchip PIC MCU to apparently enable for low standby power usage until woken up by touch.
The developers were nice enough to make it easy to dump the firmware on the SoC via SWD, allowing for convenient reverse-engineering and porting of Doom. With the touch screen used as the human input device it was actually quite playable, and considering the fairly beefy SoC, Doom runs like a dream. Sadly, due to the rarity of this device, [Aaron] is not releasing project files for it.
As for why a simple cooking pot needs all of this hardware, the answer is probably along the lines of ‘because we can’.
