Kritik sah

We’ve seen a few H-bridge circuits around these parts before, and here’s another application. This time we have an Old Train Station Clock which has been refurbished after being picked up for cheap at the flea market. These are big analog clocks which used to be common at railway stations around the world. This build uses an ESP32 C3-mini microcontroller (PDF) in combination with an A4988 Microstepping Motor Driver (PDF). The logic is handled with MicroPython code. The A4988 provides two H-bridge circuits, one for each of two stepper motors, only one of which is used in this build. The controller for this clock needs to send an alternating positive then negative DC pulse every minute to register that a minute has passed so the clock can update its hour hand and minute hand as appropriate. The ESP32 and the A4988 H-bridge cooperate to make that happen. The wifi on the ESP32 C3-mini is put to good use by facilitating the fetching of the current time from the internet. On an hourly...

If you’re a regular reader of Hackaday, you may have noticed a certain fondness for Meshtastic devices, and the LoRa protocol more generally. LoRa is a great, low-power radio communications standards, but sometimes the antennas you get with the modules can leave you wanting more. That’s why [Chris Prioli] at the Gloucester County Amateur Radio Club in the great state of New Jersey have got a Yagi antenna for North America’s 915 MHz LoRa band. Right out the gate, their article links to one of ours , where [tastes_the_code] builds a Yagi antenna for the European 868 MHz LoRa. Like [tastes_the_code], the radio club found [Chris]’s antenna gives much better reception than what came with the LoRa module. Looking out their window, instead of two Metastatic nodes with a stock antenna, one club member is now connecting to two hundred . A simulation of the radiation pattern. Looks like a Yagi, alright. Now, the Yagi is directional, so you only get that boost pointed down the axis of the a...

Humans have lots of basic requirements that need to be met in order to stay alive. Food is a necessary one, though it’s possible to go without for great stretches of time. Water is more important, with survival becoming difficult beyond a few days in its absence. Most of all, though, we crave oxygen. Without an air supply, death arrives in mere minutes. The importance of oxygen is why airway management is such a key part of emergency medicine. It can be particularly challenging in cases where there is significant trauma to the head, neck, or surrounding areas. In these cases, new research suggests there may be an alternative route to oxygenating the body— through the rear . When Nothing Else Works Promising rials have been run with mammal subjects, while human testing is at an early stage. Credit: research paper Most of us are familiar with the usual route of human respiration. We take in air through the mouth and nose, and it passes through the windpipe and into the lungs, whe...

The worst thing about the getting people together is when everyone starts fighting over their favourite map projection– maybe you like the Watterman Butterfly, but your cousin really digs Gall-Peters, and that one Uncle who insists on defending Mercator after a couple of beers. Over on Instructables [madkins9] has an answer to that problem that will still let you play a rousing game of Risk– which will surely not drag on into the night and cause further drama– skip the projection, and put the game on a globe.  The pieces are from a 1960s version. The abstract tokens have a certain charm the modern ones lack. Most globes, being cardboard, aren’t amenable to having game pieces cling to them. [madkins9] thus fabricates a steel globe from a pair of pre-purchased hemispheres. Magnets firmly affixed to the bases of all game pieces allow them to stick firmly to the spherical play surface. In a “learn from my mistakes” moment, [madkins] suggests that if you use two pre-made hemisphere...

[Andrew Menadue] wrote in to let us know about the TULIP-DevBoard and TULIP-Module being developed on GitHub. TULIP is short for “The Ultimate Intelligent Peripheral” and it’s an everything expansion board for the HP-41 line of handheld calculators sold by HP from 1979 to 1990. These particular calculators support Reverse Polish notation which seems to be one of those things, like the Dvorak keyboard, where once you get used to it you can never go back. In doing the research for this article we came across the fan site hpcalc.org which has been online since 1997, although the Way Back Machine can only go back to late 1998 . Still, we were impressed. It’s fun that the site still looks very much like it did 28 years ago! The TULIP4041 is based around the RP2350 microcontroller which you might know as the heart of a Raspberry Pi Pico 2 board. The video below the break is a talk about the present and future of the TULIP project, and the slides are here: TULIP4041 – The Next Chapter...

With two cores at 240 MHz and about 8.5 MB of non-banked RAM if you’re using the right ESP32-S3 version, this MCU seems at least in terms of specifications to be quite the mini PC. Obviously this means that it should be capable of self-hosting its compiler, which is exactly what [Valentyn Danylchuk] did with the xcc700 C compiler project. Targeting the Xtensa Lx7 ISA of the ESP32-S3, this is a minimal C compiler that outputs relocatable ELF binaries. These binaries can subsequently be run with for example the ESP-IDF-based elf_loader component . Obviously, this is best done on an ESP32 platform that has PSRAM, unless your binary fits within the few hundred kB that’s left after all the housekeeping and communication stacks are loaded. The xcc700 compiler is currently very minimalistic, omitting more complex loop types as well as long and floating point types, for starters. There’s no optimization of the final code either, but considering that it’s 700 lines of code just for a PoC, t...

People say they don’t make em’ like they used to, and while this isn’t always the case, it’s certainly true that old vices rarely die with time. This doesn’t mean they can’t use a refresh. [Marius Hornberger] recently backed that up when he decided to restore an old vice that had seen better days . Customized axial bearing assembly When refreshing old tools, you’ll almost always start the same: cleaning up all the layers of grease and ruined paint. The stories that each layer could tell will never be known, but new ones will be made with the care put into it by [Marius]. Bearings for the tightening mechanism had become worn down past saving, requiring new replacements. However, simply swapping them with carbon copies would be no fun. [Marius] decided to completely rethink the clamping mechanism, allowing for much smoother use. To do this was simple, just machine down new axial bearings, design and print a bearing cage, machine the main rod itself, and finally make a casing. It’s...

Some synthesizer sounds are just catchy, but some of them are genre-defining. We think you could make that case for the Roland JP-8000 patch “Sandstorm”, which you’ve heard if you listened to any trance from the 90’s, but especially the song that was named after it. “Sandstorm” is powered by the Roland Supersaw, and synth nerds have argued for a decade about how it’s made. The JP-8000 is a digital synthesizer, though, so it’s just code, run through custom DSP chips. If you could reverse engineer these chips, make a virtual machine, and send them the right program, you could get the sound 100% right. Think MAME but for synthesizers. That brings us to [giulioz]’s talk at the 39th Chaos Communication Congress, where he dives deep into the custom DSP chip at the heart of the JP-8000 . He and his crew had approached older digital synths by decapping and mapping out the logic, as you often do in video game emulation. Here, getting the connections right turned out to be simply too daun...

Sorting algorithms are a common exercise for new programmers, and for good reason: they introduce many programming fundamentals at once, including loops and conditionals, arrays and lists, comparisons, algorithmic complexity, and the tradeoff between correctness and performance. As a fun Christmas project, [Scripsi] set out to implement twelve different sorting algorithms over twelve days, using Christmas lights as the sorting medium . The lights in use here are strings of WS2812 addressable LED strips, with the program set up to assign random hue values to each of the lights in the string. From there, an RP2040-based platform will step through the array of lights and implement the day’s sorting algorithm of choice. When operating on an element in the array the saturation is turned all the way up, helping to show exactly what it’s doing at any specific time. When the sorting algorithm has finished, the microcontroller randomizes the lights and starts the process all over again. For ...

The astute among you may remember an earlier version of this Russian beauty, the Lapa , which I featured last year around this time. Creator [lemosbor] claims that the worry was less about visual beauty and more about ergonomics. Way more. Well then, let this serve rather nicely as a textbook definition of that old form-follows-function principle. The lovely Lapa. See, [lemosbor] believes that the keyboard must adapt to the hands and not the other way around. The main goals were to minimize hand and finger movement as well as the visual attention required of the keyboard itself. No, there were never going to be any screens or RGB, and there likely never will be. But I refuse to sidestep the obvious beauty in this keyboard, which from the side resembles a stylish and expensive pair of slightly-heeled shoes that were tailored to the contours of the human hand. And let’s not forget those handmade, oval keycaps, which again are a product of form-follows-function. Underneath those k...

In almost every measurable way, a lossless digital audio file is superior to any analog media. This doesn’t mean that analog audio isn’t valuable though; plenty of people appreciate the compression, ambiance, and other side-effects of listening to a vinyl record or a cassette tape despite the technical limitations. To combine the audio technology of the modern world with these pleasant effects of old analog media, [Julius] built a cassette-based media streamer . The music playback device takes input from a Bluetooth stream of some sort, converts the digital stream to analog, combines the stereo signal into a mono signal, and then records it to a cassette tape. The tape is then looped through to a playback device which outputs the sound to a single speaker. This has the effect of functioning as a tape delay device, and [Julius] did add input and output jacks to use it as such, but in its default state it has the effect of taking modern streaming through a real analog device and adding...

Over on YouTube [Lockdown Electronics] reviews an old bit of kit known as the Silicon Controlled Rectifier (SCR) . Invented in the 1950s the SCR is a type of thyristor and they were popular back in the 1970s. They are often replaced these days by the TRIAC and the MOSFET but you might still find some old schematics that call for them and you can still buy them. The SCR is a three terminal electronic switch which latches on. You apply a signal at the gate which allows the other two pins, the anode and cathode, to conduct; and they continue to do so until power is removed. The silicon inside the device is comprised of three semiconductor junctions, as: PNPN. The P on the left is the anode, the N on the right is the cathode, and the P in the right middle is the gate. In the video [Lockdown Electronics] runs us through how to use them and compares them with a TRIAC. Unfortunately the lighting is a bit off for the demo of the SCR with AC power. To finish the video [Lockdown Electron...

To make aerated concrete, add a foam-forming agent and stir in a significant amount of air. This serves to make the concrete significantly lighter, better insulating, and more resilient to fire. Making it can however be a bit of an issue, often requiring ingredients that aren’t purchased at the average DIY store. This is where [NightHawkInLight]’s method seems rather promising , requiring effectively only xanthan gum and dishwashing detergent. For the small-scale demonstration, 15 grams of the thickening agent xanthan gum is mixed with enough alcohol to create a slurry. To this 60 mL of the detergent and 1 liter of water is added and mixed until the xanthan gum has absorbed all the moisture, which takes about 5-10 minutes. This mixture is then added to Portland cement with two parts cement to one part xanthan gum/detergent mixture and mixed for a while. Of importance here is that this mixture will keep expanding in volume while mixing, so you have to have to keep an eye on the amoun...

These days, it can be hard to remain competitive in online shooters without spending your entire life dedicated to the sport. This leads some to explore the world of competitive aids. (AKA: cheating.) A great example is [Nick], who built a mechanical aimbot to help in this regard. [Nick’s] build moves a mousepad underneath the mouse opposite to the desired movement direction, in order to simulate the mouse movements required to aim at targets in game. This is achieved with the aid of a XDraw A4 pen plotter, which served as a cheap prebuilt X-Y motion platform. The plotter responds to simple serial commands, which makes it easy to control. The X-Y gantry was mounted underneath the desk so the mousepad sits seamlessly on top of the desk, sliding neatly on low-friction mouse skate stickers. With the mousepad control system built, it was then necessary to figure out how to turn it into an aimbot. [Nick] already had a machine vision tool to detect enemies in shooting game, so it was mere...

At the Houston Museum of Natural Science they recently made a disturbing discovery: their Foucault pendulum had stopped swinging for the first time since its installation in the 1970s. (Video, embedded below.) While some might take this as yet another sign of the end times, here it is simply a sign that the electromagnetic system that kicks the pendulum developed a fault and will need to be fixed. Their explainer video of this Herzstein Foucault pendulum is also worth watching, as it explains both the underlying physics and this particular pendulum’s construction. Every 48 hours the 81.6 kg heavy pendulum completes a full rotation, like clockwork, with pins along the circumference being tipped over one by one as the pendulum precesses. Overview of the Foucault pendulum system, with the electromagnets that sustain the movement on top. (Credit: Houston Museum of Natural Science) Invented by [Léon Foucault] in 1851 as an experimental demonstration of Earth’s rotation using a swi...

There are five general senses: touch for feels, taste for food, smell for avoiding trash, hearing for sounds, and, of course, eyesight for visualizing the very waves making up that sound. [PlasmatronX] drives that last point home with his camera for sound waves , that’s even able to capture constructive and destructive interference. (Video, embedded below.) You may have heard of Schlieren imaging , which is usually used to capture the movement of air currents caused by heat sources. [PlasmatronX] sets up a concave mirror to amplify the refraction of different densities of air, only unlike traditional Schlieren setups, he’s after the different densities of air caused by the pressure waves that we interpret as sound. To capture the sound waves, you could have a camera with the shutter speed to match, but cameras with that ability run quite a premium. The route taken by [Plasma] uses a cleverly synced audio and optical capture system. Even this wasn’t easy, though. Audio circuits have...