Kritik sah

When the temperature climbs, it’s an eternal problem: how to stay cool. An exciting field of materials science lies in radiative cooling materials, things which reflect so much incoming heat that they can cool down from their own radiation rather than heating up in the sun. It’s something [NightHawkInLight] has been working on over a series, and he’s dropped a very long video we’ve placed below. It’s ostensibly about spinning radiative cooling fibers, but in fact provides a huge quantity of background as well as a bonus explanation of cotton candy machines. These materials achieve their reflectivity by creating a surface full of microscopic bubbles. It’s the same process that makes snow so white and reflective, and in this case it’s achieved by dissolving a polymer in a mixture of two solvents. The lower boiling point solvent evaporates first leaving the polymer full of microscopic bubbles of the higher boiling point solvent, and once these evaporate they leave behind the tiny voids...

Here in the United States, we’re lagging behind the rest of the world when it comes to shiny new passenger rail, despite being leaders in previous centuries. The Federal Railroad Administration (FRA) has just released a story map of how the US could close the gap (a little). The Corridor Identification and Development (CID) Program is a way for FRA to provide both funding and technical assistance as corridor sponsors (mostly state Departments of Transportation) evaluate either new intercity service or expansion of existing services. While it isn’t a guarantee of anything, it is a step in the right direction to rebuilding passenger rail capacity in the US. Some cities would be getting rail service back for the first time in decades, and perhaps even more exciting is that several of the routes being studied are for high speed rail “primarily or solely on new trackage.” As any railfan can tell you, vintage rails aren’t the best for trains going fast (sorry, Acela ). With recent polli...

Car camping gets you out in the great outdoors, but sometimes it’s nice to bring a few comforts from home. [Ed’s Garage] has taken a module from a salvaged EV and turned it into a handy portable power station . With 2.3 kWh of storage from the single Spark EV module , the battery pack can power [Ed]’s hotplate, lights, fridge, and other electric accessories while camping away from shore power. The inverter he selected can provide up to 1500W of AC power and his 12V converter can do 150W. Several USB ports and a wireless charging pad adorn the outside next to the waterproof AC ports. He even printed a small magnetic flashlight to reuse the light from the inverter which uses an 18650 cell that can be charged from the big battery in a charger built into the exterior of the pack. The battery management system (BMS) has a Bluetooth module allowing for remote monitoring of state of charge and setting the maximum and minimum charge points for the pack. The whole thing comes in at 73 pounds...

Angry Birds , flash mobs, Russell Brand, fidget spinners. All of these were virtually unavoidable in the previous decade, and yet, like so many popular trends, have now largely faded into obscurity. But in a recent announcement, the developers of LightBurn have brought back a relic of the past that we thought was all but buried along with Harambe — popular software not supporting Linux . But this isn’t a case of the developers not wanting to bring their software to Linux. LightBurn, the defacto tool for controlling hobbyist laser cutters and engravers, was already multi-platform. Looking forward, however, the developers claim that too much of their time is spent supporting and packaging the software for Linux relative to the size of the user base. In an announcement email sent out to users , they reached even deeper into the mid-2000s bag of excuses, and cited the number of Linux distributions as a further challenge: The segmentation of Linux distributions complicates these burdens...

Subway cars have a tough life. Moving people through a city efficiently underground every day and night takes a toll on the hardware. To keep things running efficiently, NYC rebuilds its cars every six years. The enormous job of refurbing a subway car back to factory spec happens in one of two yards, either in Brooklyn or Manhattan. The cars are pulled off their 16,000 lb trucks, and treated to an overhaul of their “doors, windows, signage, seats, floor tiles and HVAC.” The trucks are inspected and wheels can be reground to true at the six year mark; they get all new wheels every 12. Once everything is repaired, the shiny and like-new components are inspected and reassembled to go back out on the line. While it’s no small job, the overhaul shops can process over 1,000 cars in a year to keep things running smoothly. Before the overhaul program was introduced in the 1980s, NYC subway cars typically experienced failures every 16,000 miles, but between the scheduled maintenance and othe...

Hydroforming is a very effective way to turn a ductile metal like aluminium or stainless steel into a specific shape, either using a die or by creating a closed envelope in which the hydraulic fluid is injected. While trying to think of ways to create a hydroformed airplane without spending big bucks on having it done professionally – or learning to weld sheet metal together with waterproof welds along the seams – [Adrian Perez] decided that using plain aluminium foil as found in the average kitchen might be a good way to get his feet wet here. When stuck together with double-sided tape, the foil is both strong and light enough to be inflated like a party balloon and still fly better than a lead balloon (which do fly, albeit poorly). The basic design for the initial Luma glider that he assembled is based around a Kline-Fogleman (KA) airfoil . This type of airfoil is mostly characterized by the simplicity of construction, having been devised in the 1960s for paper airplanes. It uses...

Various decades have their musical signature, like the excessive use of synthesizers and hairspray in the 1980s pop music scene. Likewise, the early 2010s was marked by a fairly extreme use of autotune, a technology that allows sounds, especially vocals, to be shifted to precise pitches regardless of the pitch of the original source. In this dark era, a wide swath of instruments and voices on the charts were auto-tuned at some point, although we don’t remember this iconic instrument ever being featured among the annals of pitch-shifted pop music . The auto-tuned kazoo created by [Guy Dupont] does its pitch corrections on-the-fly thanks to a built-in ESP-32-S3 microcontroller which, through a microphone inside the kazoo, listens for note of the musician’s hum and corrects it to the closest correctly pitched note. Once it identifies the note it outputs a kazoo-like pitch-corrected note from a small speaker, also hidden inside the instrument. It does this fast enough for live performanc...

Cathode-ray tube (CRT) televisions may no longer be in production, but its last bastion came in the form of extremely cheap little Chinese portable sets with a black-and-white tube. They’re now useless for broadcast TV, so can often be had for next-to-nothing. [Action Retro] has a video showing a Mac Classic clone using one , and with a built-in Raspberry Pi and a copy of RiscOS it almost makes a usable computer. The video below the break is a little heavy on the 3D printer sponsor and the Mac case comes from a Thingiverse project, but it’s well executed and we’re grateful for being introduced to that original project . We’d have gone for a period-correct beige filament rather than the glow-in-the-dark green one used here. We’re guessing that more than one reader will have a few of those TVs around the place, such is their ubiquity. Is it worth making this as a novelty item? It depends upon your viewpoint, but we can’t help liking the result even if perhaps it’s not for us. If RiscO...

Hurricanes can cause widespread destruction, so early forecasting of their strength is important to protect people and their homes. The US National Oceanic and Atmospheric Administration (NOAA) is using saildrones to get better data from inside these monster storms. Rising ocean temperatures due to climate change are causing hurricanes to intensify more rapidly than in the past, although modeling these changes is still a difficult task. People on shore need to know if they’re in store for a tropical storm or a high strength hurricane to know what precautions to take. Evacuating an area is expensive and disruptive, so it’s understandable that people want to know if it’s necessary. Starting with five units in 2021, the fleet has gradually increased in size to twelve last summer. These 23ft (7m), 33ft (10m), or 65ft (20m) long vessels are propelled by wing sails and power their radio and telemetry systems with a combination of solar and battery power. No fossil fueled vessel can match...

The ps command is extremely useful when you want to get some quick information on active system processes (hence the name), especially followed by piping it into grep and kin for some filtering. One gotcha is of course that ps doesn’t run in the current shell process, but is forked off into its own process, so what if everything goes wrong and you absolutely need to run ps aux on a system that is completely and utterly out of fresh process IDs to hand out? In that scenario, you fortunately can write a shell script that does the same, but all within the same shell, as [Isabella Bosia] did , with a Bash shell script. The how and why is mostly covered in the shell script itself, using detailed comments. Initially the hope was to just read out and parse the contents of /proc/<pid>/status , but that doesn’t have details like CPU%. The result is a bit more parsing to get the desired result, as well as a significant amount of cussing in the comments. Even if it’s not entirely prac...

When it comes to writing, sometimes a computer or smartphone is just too distracting to keep on task. [vagabondvivant] found this to be the case and rolled their own distraction-free writing tool, the Foliodeck . With the increasing availability of parts for cyberdecks, it’s not too surprising to see we’re seeing the emergence of the writerdeck. Typically designed to be a no frills word processing device, they are designed to help their creators focus on writing and not be subject to the myriad notifications present trying to work with a more general computing device or smartphone. In this case, [vagabondvivant] took a classy looking planner folio and removed its paper management components to leave a fabric and leather shell. The heart of the assembly is a HiSense A5 eink smartphone magnetically attached to a piece of MDF cut to mate the phone to the planner shell. A 10Ah powerbank slots into the MDF below the keyboard which is also magnetically attached, and the whole thing zips u...

There are a handful of gadgets that do one thing so well that they become cult classics long after the company that made them has moved on or closed up shop. [This Does Not Compute] takes us through the history of the AlphaSmart word processor which started as an educational tool, but finds itself in many a writer’s bag today. The original AlphaSmart bears more than a passing resemblance to its Apple contemporaries since the company was founded by two Apple engineers. The Cupertino company didn’t see the value in the concept, but didn’t lean on any non-competes to keep the pair from pursuing the idea on their own time either. What resulted was a dead simple word processor that could be had for 1/5 of what a new computer typically cost in the era, which was particularly attractive for the target market of schools. After several successful years, the pressure of PDAs and then smartphones from one side and cheaper laptops from the other meant school districts no longer wanted single-pu...

The BiVACOR THA hooked up with the CTO Dianiel Timms in the background. (Credit: BiVACOR) Outside of the brain, the heart is probably the organ that you miss the most when it ceases to function correctly. Unfortunately, as we cannot grow custom replacement hearts yet, we have to keep heart patients alive long enough for them to receive a donor heart. Yet despite the heart being essentially a blood pump, engineering even a short-term artificial replacement has been a struggle for many decades. A new contender has now arrived in the BiVACOR TAH (total artificial heart), which just had the first prototype implanted in a human patient. Unlike the typical membrane-based pumps, the BiVACOR TAH is a rotary pump that uses an impeller-based design with magnetic levitation replacing bearings and theoretically minimizing damage to the blood. This design should also mean a significant flowrate, enough even for an exercising adult. Naturally, this TAH is only being tested as a bridge-to-tran...

There’s an old saying in the amateur radio community that when it comes to antennas all you need is a piece of wet string. This may be a little fanciful, but it’s certainly true that an effective antenna can be made with surprisingly little in the way of conductor. It’s something [Evan Pratten VZ3ZZA] demonstrates amply with a description of the antenna he took camping in a Canadian provincial park . Most of us would try some form of dipole on our adventures, but the antenna he’s using caught our eye as it’s described as an end-fed half-wave, but it has both a half-wave and quarter-wave element. Made from speaker cable or in this case thin mains cable for lamps, it’s obviously far from a perfect match and requires an ATU, but it generates an impressive array of FT4 contacts on a pretty meagre power level. We particularly like his in-plain-sight test run in the parking lot of a supermarket. We frequently talk about the diversity of pursuits in amateur radio aside from that of the che...

What is this dystopia coming to when one of the world’s largest tech companies can’t find a way to sufficiently monetize a nearly endless stream of personal data coming from its army of high-tech privacy-invading robots? To the surprise of almost nobody, Amazon is rolling out a paid tier to their Alexa service in an attempt to backfill the $25 billion hole the smart devices helped dig over the last few years. The business model was supposed to be simple: insinuate an always-on listening device into customers’ lives to make it as easy as possible for them to instantly gratify their need for the widgets and whatsits that Amazon is uniquely poised to deliver, collecting as much metadata along the way as possible; multiple revenue streams — what could go wrong? Apparently a lot, because the only thing people didn’t do with Alexa was order stuff. Now Amazon is reportedly seeking an additional $10 a month for the improved AI version of Alexa, which will be on top of the ever-expanding Amaz...

Small robots can be found at all levels from STEM toys for kids all the way through to complex hacker projects. Somewhere along that line between easy enough for anyone to build and interesting enough for hackers lies the PlayCar , from [ComfySpace]. It’s a small build-it-yourself tracked robot that’s controlled from your smartphone via an app. At the PlayCar’s heart is a Raspberry Pi Zero 2W, and surrounding it are a set of inexpensive off the shelf modules for power and motor control. The juice meanwhile comes from a set of AA batteries, and the motors are geared DC units. Having acquired all the components, the 3D printable parts can then be downloaded from Printables , and the ComfySpace app can be downloaded for either Apple or Android platforms. It’s clear that ComfySpace is a start-up targeting the education sector, and we wish them every success. The approach of making an open platform is one we like, as it has the potential to create a community feeding back designs and ad...

If you have a late-model laptop, you’ve probably seen how the chargers magnetically snap into place. In theory, this should be easy to recreate for your own purposes. But why reinvent the wheel when [DarthKaker] has already done the work for you — assuming you only need two conductors. The 3D-printed shells take the usual round magnets. Obviously, the north pole on one part should point to the south pole on the other part. In addition, if polarity matters, you should also have each housing contain one north-facing and one south-facing magnet so that the connectors will only mate one way. It appears the project uses wires soldered or spot welded to the magnets. Heating magnets sometimes has bad effects, so we might try something different. For example, you could solder the wires to thin washers affixed to the magnets with epoxy, perhaps. Or use the magnets for alignment and make a different arrangement for the contacts, although that would take a different shell design. We have tal...

We all love a nice strip or grid of addressable LEDs. It can add flair or an artistic touch to many projects, and it can make gaming computers look extra 1337. However, providing enough current to a long strip of addressable LEDs can sometimes be difficult. Often a separate voltage rail is needed to supply enough juice. At the same time, continually sending out data to animate them can often use 100% of the microcontroller’s CPU power, especially if the serial bus is being bit-banged. A crash or badly timed interrupt can leave the system in a weird state and sometimes with the LEDs not displaying the correct colours. Or you might just want to enter a power-saving mode from time to time on your main MCU? Well, the BAPPR is designed to address all of these problems. [TheMariday] created the BAPPR and made it fully open-source. It’s a switch-mode power supply that can accept anywhere from 7 V to 17 V and converts it into a strong 5 V rail for typical addressable LEDs. It also has a “sm...

MIDI as a standard has opened up a huge world to any musician willing to use a computer to generate or enhance their playing and recording. Since the 80s, it has it has revolutionized the way music is produced and performed, allowing for seamless integration of digital instruments, automation of complex sequences, and unprecedented control over everything from production to editing. It has also resulted in a number of musical instruments that probably wouldn’t be possible without electronic help, like this MIDI instrument which might be the world’s smallest. Fitting into a cubic inch of space, the tiny instrument’s volume is mostly taken up by the MIDI connector itself which was perhaps an acceptable size by 1980s standards but seems rather bulky today. A two-layer PCB split into three sections sandwiches the connector in place and boasts an ATtiny85 microcontroller and all the associated electronics needed to implement MIDI. Small threaded screws hold the platform together and provi...

Admittedly it’s a bit of a niche application, but if you need lots of flat 3D printed objects, one way to go about it is to print them in a stack and separate them somehow. An old(er) solution is to use a non-extruding “ironing” step between each layer, which makes them easier to pull apart. But another trick is to use the fact that PLA and PETG don’t stick well to each other to your advantage. And thus is born multi-material stack printing . (Video, embedded below the break.) [Jonathan] wants to print out multiples of his fun Multiboard mounting system backplates, and these are the ideal candidate for stack printing: they’re thin, but otherwise take up the entire build plate. As you’d expect, the main trick is to print thin layers of PETG between the PLA plate layers that you do want. He demonstrates that you can then simply pull them apart. There are some tricks, though. First is to make two pillars in addition to the plates, which apparently convinces the slicer to not flatten ...

It sometimes seems as though computing power in your pocket is a relatively new phenomenon, but in fact there have been ultraportable computers since the 8-bit era. They started to become useful around the end of the 1980s though as enterprising manufacturers started cramming full-fat PC XTs into pocket form factors. Of these the one to own was the Poqet PC, a slim clamshell design that would run for ages on a pair of AA cells . If you have one today you’d be lucky if its display ribbon cable is without faults though, and [Robert’s Retro] is here with a fix previously thought impossible . A large proportion of the video below the break is devoted to dismantling the unit, no easy task. The cable once exposed is found to have delaminated completely, and he takes us through the delicate task of attaching a modern equivalent. We particularly like the way in which the cable’s own springiness is used to retract it. The result has a white cable rather than the original black, but that’s a s...

Artificial Neural Networks (ANNs) are commonly used for machine vision purposes, where they are tasked with object recognition. This is accomplished by taking a multi-layer network and using a training data set to configure the weights associated with each ‘neuron’. Due to the complexity of these ANNs for non-trivial data sets, it’s often hard to make head or tails of what the network is actually matching in a given (non-training data) input. In a March 2024 study ( preprint ) by [A. Radhakrishnan] and colleagues in Science an approach is provided to elucidate and diagnose this mystery somewhat, by using what they call the average gradient outer product (AGOP). Defined as the uncentered covariance matrix of the ANN’s input-output gradients averaged over the training dataset, this property can provide information on the data set’s features used for predictions. This turns out to be strongly correlated with repetitive information, such as the presence of eyes in recognizing whether li...

An object of desire back in the mid-1990s might have been Apple’s QuickTake camera. In a form factor not unlike a monocular it packed a 640×480 digital camera, the images from which could be downloaded to a computer via a serial cable. A quarter century later it’s a great retro camera for the enthusiast, but both the serial ports and the operating systems needed to run its software have passed into history. Time for the junk pile? Not at all, for [Crazylegstoo] has produced a new piece of software for 2024 that works for both QuickTake 100 and 150 cameras with USB serial ports on modern operating systems. Called JQuickTake, it’s a Java app which has the advantage of building on that early Java promise of running cross platform so can be had for Mac or Windows. It allows retrieval of both metadata and images from the camera, but sadly it doesn’t display any of the images. It also doesn’t work with the QuickTake 200. Happily though, there are instructions for building a serial cable, ...