Mysterious Files PH

[Igor] of [My Tech Fun] set out to discover what differences, if any, can be found between parts printed in PC-ABS filament on an industrial 3D printer, and those from prosumer-grade machines and filament. His video is full of his usual attention to detail as he compares a test suite of parts printed at home in Polymaker PC-ABS with those from a Stratasys Fortus 450mc using proprietary PC-ABS filament.

PC-ABS is a filament that strives to deliver the benefits of both polycarbonate and ABS. It’s durable and has fantastic impact resistance, but it costs a bit more than either PC or ABS and requires a heated chamber.

[Igor] has previously compared industrial ABS with comsumer ABS, but what made him curious about PC-ABS in particular was the large difference in print temperatures between Polymaker PC-ABS, and Stratasys’s own proprietary PC-ABS.

[Igor] prints Polymaker filament at 280º C in a 60-65º C  chamber, whereas the Stratasys filament prints at 325º C with a chamber temperature of 95º C. That’s quite a difference. The industrial printer has over double the print time, to boot. Would test objects printed from the industrial filament, on an industrial machine, be noticeably different from those printed at home?

To find out, [Igor] orders a test suite of parts from a company with a Stratasys Fortus 450mc (who was also kind enough to take a short video of the machine in action) and prints his own on both a Prusa Core One L, and a Bambu Labs H2D. He then proceeds to compare them in a variety of ways while testing them to destruction.

What’s the bottom line? The industrial prints have better dimensional accuracy, but the home prints have the edge in appearance. When it comes to performance the differences are mostly minor, and not always in the industrial system’s favor. Broadly speaking, PC-ABS from the home workshop compares very favorably from an expensive industrial system and proprietary filament, at a fraction of the price. See it for yourself in the video, embedded just below.

Before LEGO train sets moved to battery-powered locomotives with plastic rails, all of them worked pretty much like any other train set of the era. This meant metal rails that the locomotive’s wheels would use to pick up power from and a central controller that would inject said power and also regulate the train’s speed and direction. The LEGO 2868b Electric Train Speed Regulator is one such example, and [Nonsense Wars] recently had one under the knife to repair it.

The single PCB inside is quite straightforward, with the 9-12 VAC supply input from an external power adapter, and a variable voltage regulator that sees its target voltage switched by a bank of resistors.

It are these resistors that the big yellow control switches between when you operate it, changing the output voltage and also output polarity you cross the midway point. Effectively this means that there is just one non-passive component on the PCB, in the form of the TO-220 package strapped to the big heatsink.

In this particular unit it was found to be a Fairchild KA317, which is for all intents and purposes here the same as an LM317T. One quick swap later and this controller was back in business like it was 1995.

Compared to the engineering crammed into a modern “smart brick”, things really have come quite a ways in the world of LEGO.

As a certified RC airplane fan, the [RCMakerLab] on YouTube found themselves looking at one of those nifty mini air blowers that provide an alternative to a compressor and canned air for dusting and other high-volume, high-pressure air-related tasks.

Inside these quite affordable units is a ducted fan (EDF) that can produce fairly high levels of airflow to get to every last dust bunny hiding on a PCB or inside a keyboard, raising the question of whether you could use these to fly a model airplane with.

As can be seen in the torn down unit, there isn’t a lot to these air blowers, with the ESC bolted onto the EDF and only the speed regulator and on/off switch being external controls. This would make it very easy to integrate into an airplane, but leaves the question of whether it can generate enough thrust to make it worth the effort.

Using a custom rig, it was shown to generate up to 110 grams of thrust with a current of 16.5 A, which would at least go a long way to carrying its own battery pack. In order to create an airplane with it, probably two of these motors are needed. There’s also the potential of reducing weight by changing the ESC and such, making reusing these little EDFs from any discarded or broken mini air blowers at least worth a shot.

At the very least, it seems like it has a better shot of working than a plane powered by an electric leaf blower.

As easy as the Sun is to observe, it’s simultaneously very hard to study due to how extreme the conditions are, even on the surface of a rather unassuming star. One of these study topics is the interaction between the Sun’s plasma and magnetic field, as this drives much of the dynamism of the Sun’s surface layer (i.e., the photosphere). Recent observations by the 4-meter solar telescope in Hawaii have now led to interesting new findings, as detailed in a paper in Nature by [David Kuridze] et al.

Despite popular portrayal, this photosphere is not a boiling liquid, but rather pockets of plasma at various temperatures. The plasma moves within the magnetic field and convective movements that create the ‘boiling’ pattern, which gives the illusion of a boiling liquid surface.

Within this photosphere, [Kuridze] et al. were able to observe Kelvin-Helmholtz instabilities, which are fluid instabilities caused by velocity shearing in either a continuous fluid or due to a velocity difference between two fluids. This is also observed in clouds in Earth’s atmosphere, where they cause the billowing effect, somewhat similar to watching a boiling liquid.

In a MURaM simulation (see heading image), these findings were confirmed, showing how these instabilities drive the transport of plasma in the Sun’s photosphere.

Once upon a time, you had the option of waking up to a bell, a harsh buzzer, or whatever happened to be on the radio that morning. Now that it’s the 21st century, we’ve gotten used to being able to set our alarms to whatever sound or song we want, but what if you don’t just want to wake up to sound? Enter [Impossible_Agent1436] a.k.a. [brunokeymolen]’s Video Alarm Clock that will wake you up to whatever clip you want, as long as it fits on the 720 pixel square display.

That display is a pre-built Waveshare module powered by an ESP32-P4, which looks like a handy bit of kit aside from being out of stock at the moment. The dev board makes this almost entirely a software project– the only hardware [bruno] had to come up with was the 3D-printed stand to hold it on his bedside. That’s not a slight to [bruno]; it was a good choice in the spirit of “work smarter, not harder”. Sometimes you want to reinvent the wheel, and sometimes you just want an alarm clock.

The module’s RTC means it keeps good time, and the built-in SD card reader means you can load up a whole library of clips to wake up to. The only caveat is that those files have to be AVI containers holding 720×720 MJPEG video with PCM stereo audio at 44.1 kHz, and you’re limited to old FAT filename rules: eight characters, and none of them special.

This is an easier project and a better idea than the exploding capacitor alarm clock, but there’s no arguing which would get us out of bed faster. If you miss the old days of clock radios, you can always bring them back with the right microcontroller.

Story via reddit.

The earliest all-electronic computers used vacuum tubes, and most of us will know about machines such as ENIAC or Colossus. Vast machines that required the budget of a country at war to build, andfill very large rooms. It’s very pleasing then to see that a useful vacuum tube computer can be made which has neither of these requirements, as with this example from [Mike] that uses former eastern bloc double-triodes.

It’s an 8-bit design following a von Neumann architecture with 16 instructions, whose operational block diagram would be instantly recognisable to anyone used to working with a 1970s-era 8-bit microcomputer. It follows a NOR-based design in the same manner as the famous NASA machines from the Apollo programme, and as we understand from the description it uses more modern parts for its I/O circuitry. Physically it’s a surprisingly compact wall-mounted unit, and it has an accompanying ex-British Rail flip-digit display as well as a control panel for a simple airship simulator game. There’s a website with full details, if you are interested.

We like this machine, a lot. It may not be the largest computer we’ve seen and it certainly isn’t the first one with vacuum tubes, but it’s a very impressive achievement to have created it. If tubes in computing interest you meanwhile, we took a trip to see the daddy of them all.

Should [Mike] enter this into the Retrocomputing Challenge? We think so.

Sometimes you find gold in unexpected places. In this case, it’s from a video about the CH-53 helicopter. The CH-53 Sea Stallion first entered service in 1966. It’s a huge helicopter, capable of lifting immense amounts of weight. All that weight hangs from 6 (or 7 on some models) rotor blades.  The problem was detecting problems with the blades before they grew into a catastrophic failure.

Much like a fixed-wing aircraft wing, the CH-53 rotor blades are designed with a spar as the main structural member.  On early designs, the spar was extruded aluminum. The CH-53D and other variants moved to cold-formed titanium.

All of these blades shared the same problem – detecting tiny cracks in the metal before they grow into blade failure. Detecting cracks turned out to be rather easy. The blades are sealed and pressurized with nitrogen gas. Cracks allow the gas to leak out. A barber pole pressure indicator on the blades allows mechanics to tell at a glance if everything is ok.

That’s all fine and good on the ground, but if a blade begins cracking in the air, the pilots want to know about it immediately. What was needed was something akin to the tire pressure monitoring system on modern cars. A pressure sensor that would turn on a light in the cockpit.  Modern automotive TPMS systems use wireless sensors inside the tire. In the early 60’s though, electronic components were not reliable enough to survive rotating on a helicopter blade. Wiring the sensors through the spinning rotor head using slip rings would be incredibly complex. Expecting wireless electronic components to survive life in a rotorhead would be even more problematic.

The solution turned out to be simple: Throw a little ionizing radiation into the mix. Called IBIS, short for Inflight Blade Monitoring System keeps the CH-53 safe. The magic happens in the same pressure indicator we mentioned earlier. Rather than just a shift from a green to a barber pole indication, the IBIS module also exposes a tiny amount of radioactive Strontium-90.  The Strontium is a beta emitter, meaning its radiation can be detected by a Geiger counter inside the helicopter.  It’s also relatively safe for humans as long as they don’t eat or breathe it in. No batteries, no electronics on the rotor blade. It’s a simple mechanical solution to a difficult problem.

The solution is so elegant it’s still being used today. The newest versions of the CH-53 of fiber optics to detect faults in the newest all-composite blades. The older variants? They’re still going with the nuclear option.