Balancing A Turbine Rotor To 1 Milligram With A DIY Dynamic Balancer

January 25, 2026 by Maya Posch 19 Comments

Although jet engines are theoretically quite simple devices, in reality they tread a fine line between working as intended and vaporizing into a cloud of lethal shrapnel. The main reason for this is the high rotational speed of the rotors, with any imbalance due to poor manufacturing or damage leading to undesirable outcomes. It’s for this reason that [AlfMart CNC Garage] on YouTube decided to spend some quality time building a balancer for his DIY RC turbine project and making sure it can prevent such a disaster scenario.

In the previous part of the series the turbine disc was machined out of inconel alloy, as the part will be subjected to significant heat as well when operating. To make sure that the disc is perfectly balanced, a dynamic balancing machine is required. The design that was settled on after a few failed attempts uses an ADXL335 accelerometer and Hall sensor hooked up to an ESP32, which is said to measure imbalance down to ~1 mg at 4,000 RPM.

A big part of the dynamic balancing machine is the isolation of external vibrations using a bearing-supported free-floating structure. With that taken care of, this made measuring the vibrations caused by an imbalanced rotor much easier to distinguish. The ESP32 is here basically just to read out the sensors and output the waveforms to a connected PC via serial, with the real work being a slow and methodical data interpretation and balancing by hand.

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Inside A Sketchy Mains Voltage Touch Control Dimmer

January 25, 2026 by Maya Posch 6 Comments

In [Big Clive]’s recent grab bag of tat ordered from Chinese commerce platforms, there were two touch light control boxes that can turn any ungrounded conductive surface into a mains load dimmer control. Of course, the primary reason for the purchase was a teardown, and a teardown we got.

These unassuming little boxes are built around the Tontek TT6061A, listed as a ‘touch dimmer’, which uses a triac to control the output current. There are four levels, ranging from off to full brightness, before the next touch event turns the output off again.

With the output off, [Clive] measured 0.7 W power usage. After popping open the plastic enclosure, the circuitry turned out to largely follow the recommended application circuit from the datasheet — as can be seen in the above screenshot — with apparently a few cost optimizations, in the form of omitted diodes and a capacitor.

The problem with these devices is that they are only really suitable for dimming low-power resistive loads like incandescent lights, with LED lights likely requiring the unpopulated capacitor spot on the PCB to be populated to tweak the chip’s triac timing, among other changes. There are also the slight issues with no real concern with them radiating EMI, and the exciting possibility of getting shocked at mains voltage without at least a class-Y capacitor installed.

Perhaps using a capacitive touch controller instead that works through plastic, for example, isn’t such a crazy alternative here, especially since they’re not really much more expensive and less likely to shock you. Want to create your own triac designs? We have just the post to get you started.

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Isolated AC/DC Power Supply And Testing Station For 230 V Devices

January 24, 2026 by Maya Posch 23 Comments

When you’re testing or debugging some mains-powered gear, plugging it directly into the outlet can often be an exciting proposition. If such excitement is not really your thing, you can opt for an isolation transformer and other types of safeties. In the case of [Michał Słomkowski], he opted to take a few steps further by modding a vintage East-German isolating variac with a broken amp meter into an isolated AC/DC power supply and testing station.

The core is formed by the isolated variable transformer, to which a configurable DC output section, a current limiter and digital voltage and current read-outs were added. This enables a variable AC output of 0 – 330 VAC and 0 – 450 VDC on their respective terminals, with the incandescent light bulb providing an optional current limiter.

In its final configuration [Michał] has been using the device for the past four years now for a range of tasks, including the simulating of various undesirable mains power conditions, varying the speed of an old Soviet-era drill, powering vacuum tube devices, capacitor reforming and of course running 100-120 VAC devices from e.g. the US.

As far as feature set goes, we have to admit that it is an impressive device, indeed. Although some parts of it are clearly playing it fast and loose with best practices, with [Michał] admitting to not being an electrician, it was clearly engineered well enough to survive a few years of use, something which cannot be said for even professional laboratory equipment these days.

Polymer Skins That Change Color And Texture When Exposed To Water

January 23, 2026 by Maya Posch 1 Comment

Researchers at Stanford University recently came up with an interesting way (Phys.org summary) to create patterns and colors that emerge when a polymer is exposed to water. Although the paper itself is sadly paywalled with no preprint available, it’s fairly easily summarized and illustrated with details from the Supplementary Data section. The polymer used is poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), which when exposed to an electron beam (electron-beam lithography) undergoes certain changes that become apparent when said water is added.

The polymer is hygroscopic, but the electron beam modifies the extent to which a specific area swells up, thus making it possible to create patterns that depend on the amount of electron beam exposure. In order to ‘colorize’ the polymer, complex cavities are created that modify the angular distribution of light, as illustrated in the top image from the Supplemental Data docx file.

By varying the concentration of IPA versus water, the intermediate swelling states can be controlled. Although this sounds pretty advanced, if you look at the supplementary videos that are already sped up a lot, you can see that it is a very slow process. Compared to an octopus and kin whose ability to alter their own skin texture and coloring is legendary and directly controlled by their nervous system, this isn’t quite in the same ballpark yet, even if it’s pretty cool to watch.

Vacuum Fluorescent Displays Explained

January 23, 2026 by Maya Posch 11 Comments

After having been sent a vacuum fluorescent display (VFD) based clock for a review, [Anthony Francis-Jones] took the opportunity to explain how these types of displays work.

Although VFDs are generally praised for their very pleasant appearance, they’re also relatively low-power compared to the similar cathode ray tubes. The tungsten wire cathode with its oxide coating produces the electrons whenever the relatively low supply voltage is applied, with a positively charged grid between it and the phosphors on the anode side inducing the accelerating force.

Although a few different digit control configurations exist, all VFDs follow this basic layout. The reason why they’re also called ‘cold cathode’ displays is because the cathode doesn’t heat up nearly as hot as those of a typical vacuum tube, at a mere 650 °C. Since this temperature is confined to the very fine cathode mesh, this is not noticeable outside of the glass envelope.

While LCDs and OLED displays have basically eradicated the VFD market, these phosphor-based displays still readily beat out LCDs when it comes to viewing angles, lack of polarization filter, brightness and low temperature performance, as LC displays become extremely sluggish in cold weather. Perhaps their biggest flaw is the need for a vacuum to work, inside very much breakable glass, as this is usually how VFDs die.

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Converting A Nebra Cryptocurrency Miner To A Meshcore Repeater

January 22, 2026 by Maya Posch 6 Comments

After the swivel by Helium Inc. towards simply running distributed WiFi hotspots after for years pushing LoRaWAN nodes, much of the associated hardware became effectively obsolete. This led to quite a few of these Nebra LoRa Miners getting sold off, with the [Buy it Fix it] channel being one of those who sought to give these chunks of IP-67-rated computing hardware a new life.

Originally designed to be part of the Helium Network Token (HNT) cryptocurrency mining operation, with users getting rewarded by having these devices operating, they contain fairly off-the-shelf hardware. As can be glanced from e.g. the Sparkfun product page, it’s basically a Raspberry Pi Compute Module 3+ on a breakout board with a RAK 2287 LoRa module. The idea in the video was to convert it into a Meshcore repeater, which ought to be fairly straightforward, one might think.

Unfortunately the unit came with a dead eMMC chip on the compute module, the LoRa module wasn’t compatible with Meshcore, and the Nebra breakout board only covers the first 24 pins of the standard RPi header on its pin header.

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PlayStation 3 Emulator RPCS3 Can Play Nearly Three-Quarters Of All PS3 Games

January 22, 2026 by Maya Posch 6 Comments

Although already having entered the territory of ‘retro gaming’, the Sony PlayStation 3 remains a notoriously hard to emulate game console. Much of this is to blame on its unique PowerPC-based Cell processor architecture, which uses a highly parallel approach across its asymmetric multi-core die that is very hard to map to more standard architectures like those in today’s x86 and ARM CPUs. This makes it even more amazing that the RPCS3 emulator team has now crossed the 70% ‘playable’ threshold on their compatibility list.

This doesn’t mean that you can fire up these games on any purported ‘gaming system’, as the system requirements are pretty steep. If you want any kind of enjoyable performance the recommended PC specifications feature an Intel 10th generation 6-core CPU, 16 GB of dual-channel RAM and a NVIDIA RTX 2000 or AMD RX 5000 series GPU or better.

It should be noted here also that the ‘playable’ tag in the compatibility list means that the game can be completed without game breaking glitches. Performance remains an issue, with very creative optimizations through e.g. the abuse of x86 SIMD instructions remaining the topic of research by the emulator developers. Yet as original PS3 hardware gradually becomes less available, the importance of projects like RPCS3 will become more clear.

Header: Evan-Amos, Public domain.