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A Tiny Chemistry Lab

8 Noviembre 2024 at 21:00

While advances in modern technology have allowed average people access to tremendous computing power as well as novel tools like 3D printers and laser cutters for a bare minimum cost, around here we tend to overlook some of the areas that have taken advantage of these trends as well. Specifically in the area of chemistry, the accessibility of these things have opened up a wide range of possibilities for those immersed in this world, and [Marb’s Lab] shows us how to build a glucose-detection lab in an incredibly small form factor.

The key to the build is a set of three laser-cut acrylic sheets, which when sandwiched together provide a path for the fluid to flow as well as a chamber that will be monitored by electronic optical sensors. The fluid is pumped through the circuit by a custom-built syringe pump driven by a linear actuator, and when the chamber is filled the reaction can begin. In this case, if the fluid contains glucose it will turn blue, which is detected by the microcontroller’s sensors. The color value is then displayed on a small screen mounted to the PCB, allowing the experimenter to take quick readings.

Chemistry labs like this aren’t limited to one specific reaction, though. The acrylic plates are straightforward to laser cut, so other forms can be made quickly. [Marb’s Lab] also made the syringe pump a standalone system, so it can be quickly moved or duplicated for use in other experiments as well. If you want to take your chemistry lab to the extreme, you can even build your own mass spectrometer.

Using AI To Help With Assembly

8 Noviembre 2024 at 03:00

Although generative AI and large language models have been pushed as direct replacements for certain kinds of workers, plenty of businesses actually doing this have found that using this new technology can cause more problems than it solves when it is given free reign over tasks. While this might not be true indefinitely, the real use case for these tools right now is as a kind of assistant to certain kinds of work. For this they can be incredibly powerful as [Ricardo] demonstrates here, using Amazon Q to help with game development on the Commodore 64.

The first step here was to generate code that would show a sprite moving across the screen. The AI first generated code in all caps, as was the style at the time of the C64, but in [Ricardo]’s development environment this caused some major problems, so the code was converted to lowercase. A more impressive conversion was done in the next steps, as the program needed to take advantage of the optimizations found in the Assembly language. With the code converted to 6502 Assembly that can run on the virtual Commodore, [Ricardo] was eventually able to show four sprites moving across the screen after several iterations with the AI, as well as change the style of the sprites to arbitrary designs.

Although the post is a bit over-optimistic on Amazon Q as a tool specifically for developers, it might have some benefits over other generative AIs especially if it’s capable at the chore of programming in Assembly language. We’d love to hear anyone with real-world experience with this and whether it is truly worth the extra cost over something like Copilot or GPT 4. For any of these generative AI models, though, it’s probably worth trying them out while they’re in their early stages. Keep in mind that there’s a lot more than programming that can be done with some of them as well.

Disposable Vape Batteries Power eBike

7 Noviembre 2024 at 21:00

There are a lot of things that get landfilled that have some marginal value, but generally if there’s not a huge amount of money to be made recycling things they won’t get recycled. It might not be surprising to most that this is true of almost all plastic, a substantial portion of glass, and even a lot of paper and metals, but what might come as a shock is that plenty of rechargeable lithium batteries are included in this list as well. It’s cheaper to build lithium batteries into one-time-use items like disposable vape pens and just throw them out after one (or less than one) charge cycle, but if you have some spare time these batteries are plenty useful.

[Chris Doel] found over a hundred disposable vape pens after a local music festival and collected them all to build into a battery powerful enough for an ebike. Granted, this involves a lot of work disassembling each vape which is full of some fairly toxic compounds and which also generally tend to have some sensitive electronics, but once each pen was disassembled the real work of building a battery gets going. He starts with testing each cell and charging them to the same voltage, grouping cells with similar internal resistances. From there he assembles them into a 48V pack with a battery management system and custom 3D printed cell holders to accommodate the wide range of cell sizes. A 3D printed enclosure with charge/discharge ports, a power switch, and a status display round out the build.

With the battery bank completed he straps it to his existing ebike and hits the trails, easily traveling 20 miles with barely any pedal input. These cells are only rated for 300 charge-discharge cycles which is on par for plenty of similar 18650 cells, making this an impressive build for essentially free materials minus the costs of filament, a few parts, and the sweat equity that went into sourcing the cells. If you want to take an ebike to the next level of low-cost, we’d recommend pairing this battery with the drivetrain from the Spin Cycle.\

Thanks to [Anton] for the tip!

https://www.youtube.com/watch?v=VcVp9T8f_W4

The Most Inexpensive Apple Computer Possible

7 Noviembre 2024 at 12:00

If Apple has a reputation for anything other than decent hardware and excellent industrial design, it’s for selling its products at extremely inflated prices. But there are some alternatives if you want the Apple experience on the cheap. Buying their hardware a few years out of date of course is one way to avoid the bulk of the depreciation, but at the extreme end is this working Mac clone that cost just $14.

This build relies on the fact that modern microcontrollers absolutely blow away the computing power available to the average consumer in the 1980s. To emulate the Macintosh 128K, this build uses nothing more powerful than a Raspberry Pi Pico. There’s a little bit more to it than that, though, since this build also replicates the feel of the screen of the era as well. Using a “hat” for the Pi Pico from [Ron’s Computer Videos] lets the Pico’s remaining system resources send the video signal from the emulated Mac out over VGA, meaning that monitors from the late 80s and on can be used with ease. There’s an option for micro SD card storage as well, allowing the retro Mac to have an incredible amount of storage compared to the original.

The emulation of the 80s-era Mac is available on a separate GitHub page for anyone wanting to take a look at that. A VGA monitor is not strictly required, but we do feel that displaying retro computer graphics on 4K OLEDs leaves a little something out of the experience of older machines like this, even if they are emulated. Although this Macintosh replica with a modern e-ink display does an excellent job of recreating the original monochrome displays of early Macs as well.

Open-Source Robot Transforms

5 Noviembre 2024 at 19:30

Besides Pokémon, there might have been no greater media franchise for a child of the 90s than the Transformers, mysterious robots fighting an intergalactic war but which can inexplicably change into various Earth-based object, like trucks and airplanes. It led to a number of toys which can also change shapes from fighting robots into various ordinary objects as well. And, perhaps in a way of life imitating art, plenty of real-life robots have features one might think were inspired by this franchise like this transforming quadruped robot.

Called the CYOBot, the robot has four articulating arms with a wheel at the end of each. The arms can be placed in a wide array of positions for different operating characteristics, allowing the robot to move in an incredibly diverse way. It’s based on a previous version called the CYOCrawler, using similar articulating arms but with no wheels. The build centers around an ESP32-S3 microcontroller, giving it plenty of compute power for things like machine learning, as well as wireless capabilities for control or access to more computing power.

Both robots are open source and modular as well, allowing a range of people to use and add on to the platform. Another perk here is that most parts are common or 3d printed, making it a fairly low barrier to entry for a platform with so many different configurations and options for expansion and development. If you prefer robots without wheels, though, we’d always recommend looking at Strandbeests for inspiration.

Few Things Are Cheaper than This Antenna

1 Noviembre 2024 at 02:00

As far as hobbies go, ham radio tends to be on the more expensive side. A dual-band mobile radio can easily run $600, and a high-end HF base station with the capability of more than 100 watts will easily be in the thousands of dollars. But, like most things, there’s an aspect to the hobby that can be incredibly inexpensive and accessible to newcomers. Crystal radios, for example, can be built largely from stuff most of us would have in our parts drawers, CW QRP radios don’t need much more than that, and sometimes even the highest-performing antennas are little more than two lengths of wire.

For this specific antenna, [W3CT] is putting together an inverted-V which is a type of dipole antenna. Rather than each of the dipole’s legs being straight, the center is suspended at some point relatively high above ground with the two ends closer to the earth. Dipoles, including inverted-Vs, are resonant antennas, meaning that they don’t need any tuning between them and the radio so the only thing needed to match the antenna to the feed line is a coax-to-banana adapter. From there it’s as simple as attaching the two measured lengths of wire for the target band and hoisting the center of the antenna up somehow. In [W3CT]’s case he’s using a mast which would break the $8 budget, but a tree or building will do just as well.

The video on the construction of this antenna goes into great detail, so if you haven’t built a dipole yet or you’re just getting started on your ham radio journey, it’s a great place to get started. From there we’d recommend checking out an off-center-fed dipole which lets a dipole operate efficiently on multiple bands instead of just one, and for more general ham radio advice without breaking the bank we’d always recommend the $50 Ham series.

Pi Pico Lays Down the Groove

30 Octubre 2024 at 23:00

From the 60s to perhaps the mid-00s, the path to musical stardom was essentially straight with very few forks. As a teenager you’d round up a drummer and a few guitar players and start jamming out of a garage, hoping to build to bigger and bigger venues. Few people made it for plenty of reasons, not least of which was because putting together a band like this is expensive. It wasn’t until capable electronic devices became mainstream and accepted in popular culture in the last decade or two that a few different paths for success finally opened up, and this groovebox shows just how much music can be created this way with a few straightforward electronic tools.

The groovebox is based on a Raspberry Pi Pico 2 and includes enough storage for 16 tracks with a sequencer for each track, along with a set of 16 scenes. Audio plays through PCM5102A DAC module, with a 160×128 TFT display and a touch-sensitive pad for user inputs. It’s not just a device for looping stored audio, though. There’s also a drum machine built in which can record and loop beats with varying sounds and pitches, as well as a sample slicer and a pattern generator and also as the ability to copy and paste clips.

There are a few limitations to using a device this small though. Because of memory size it outputs a 22 kHz mono signal, and its on-board storage is not particularly large either, but it does have an SD card slot for expansion. But it’s hard to beat the bang-for-the-buck qualities of a device like this, regardless, not to mention the portability. Especially when compared with the cost of multiple guitars, a drum set and a bunch of other analog equipment, it’s easy to see how musicians wielding these instruments have risen in popularity recently. This 12-button MIDI instrument could expand one’s digital musical capabilities even further.

Custom Fan Controller For Otherwise Fanless PCs

29 Octubre 2024 at 20:00

Most of us using desktop computers, and plenty of us on laptops, have some sort of fan or pump installed in our computer to remove heat and keep our machines running at the most optimum temperature. That’s generally a good thing for performance, but comes with a noise pollution cost. It’s possible to build fanless computers, though, which are passively cooled by using larger heat sinks with greater thermal mass, or by building more efficient computers, or both. But sometimes even fanless designs can benefit from some forced air, so [Sasa] built this system for cooling fanless systems with fans.

The main advantage of a system like this is that the fans on an otherwise fanless system remain off when not absolutely necessary, keeping ambient noise levels to a minimum. [Sasa] does have a few computers with fans, and this system helps there as well. Each fan module is WiFi-enabled, allowing for control of each fan on the system to be set up and controlled from a web page. It also can control 5V and 12V fans automatically with no user input, and can run from any USB power source, so it’s not necessary to find a USB-PD-compatible source just to run a small fan.

Like his previous project, this version is built to easily integrate with scripting and other third-party software, making it fairly straightforward to configure in a home automation setup or with any other system that is monitoring a temperature. It doesn’t have to be limited to a computer, either; [Sasa] runs one inside a server cabinet that monitors the ambient temperature in the cabinet, but it could be put to use anywhere else a fan is needed. Perhaps even a hydroponic setup.

Custom Drone Software Searches, Rescues

25 Octubre 2024 at 05:00

When a new technology first arrives in people’s hands, it often takes a bit of time before the full capabilities of that technology are realized. In much the same way that many early Internet users simply used it to replace snail mail, or early smartphones were used as more convenient methods for messaging and calling than their flip-phone cousins, autonomous drones also took a little bit of time before their capabilities became fully realized. While some initially used them as a drop-in replacement for things like aerial photography, a group of mountain rescue volunteers in the United Kingdom realized that they could be put to work in more efficient ways suited to their unique abilities and have been behind a bit of a revolution in the search-and-rescue community.

The first search-and-rescue groups using drones to help in their efforts generally used them to search in the same way a helicopter would have been used in the past, only with less expense. But the effort involved is still the same; a human still needed to do the searching themselves. The group in the UK devised an improved system to take the human effort out of the equation by sending a drone to fly autonomously over piece of mountainous terrain and take images of the ground in such a way that any one thing would be present in many individual images. From there, the drone would fly back to its base station where an operator could download the images and run them through a computer program which would analyse the images and look for outliers in the colors of the individual pixels. Generally, humans tend to stand out against their backgrounds in ways that computers are good at spotting while humans themselves might not notice at all, and in the group’s first efforts to locate a missing person they were able to locate them almost immediately using this technology.

Although the system is built on a mapping system somewhat unique to the UK, the group has not attempted to commercialize the system. MR Maps, the software underpinning this new feature, has been free to use for anyone who wants to use it. And for those just starting out in this field, it’s also worth pointing out that location services offered by modern technologies in rugged terrain like this can often be misleading, and won’t be as straightforward of a solution to the problem as one might think.

A Modern PC With a Retro OS

23 Octubre 2024 at 02:00

Despite the rise of ARM processors in more and more computers from embedded systems to daily driver PCs, the x86 architecture maintains a stronghold in the computing space that won’t be going away anytime soon. One of the main drivers of this is its beachhead in industrial systems; the x86 architecture is backwards-compatible farther back than many of us have been alive and in situations where machines need to run for years with minimum downtime it’s good to know you can grab any x86 system off the shelf and it’ll largely work. This is also true for gaming, so if you’re like [Yeo Kheng Meng] and want to run games like DOOM natively on modern hardware it’s certainly possible, although there are a few catches.

This build goes into the design of a modern AMD Ryzen 5 desktop computer, with all of the components selected specifically for their use running software more than three decades old now. [Yeo Kheng Meng] is targeting DOS 6.22 as his operating system of choice, meaning that modern EFI motherboards won’t necessarily work. He’s turned to business class products as a solution for many of these issues, as motherboards targeting business and industrial customers often contain more support for antiquated hardware like PS/2 and parallel ports while still having modern amenities like DDR5 memory slots. PS/2 ports additionally are an indicator that the motherboard will supports older non-EFI boot modes (BIOS) and can potentially run DOS natively. Everything here can also run modern operating systems, since he isn’t building this system only to run DOS and retro games.

Beyond the motherboard choice, he’s also using a Soundblaster card for audio which is a design choice generally relegated to history, but still used in modern gaming by a dedicated group. There’s also a floppy drive running via a USB header adapter cable. Of course, there are a few problems running DOS and other era-appropriate software natively on such incomprehensibly fast hardware (by early 90s standards). Some video games were hard coded to the processor clock of the x86 process of the era, so increasing the clock speed orders of magnitude results in several playability issues. In emulators it’s easier to provide an artificially slow clock speed, but on real hardware this isn’t always possible. But [Yeo Kheng Meng] has done a lot to get this modern computer running older software like this. Another take we’ve seen for retro gaming on original hardware is this system which uses a brand-new 486 processor meant for use in industrial settings as well.

Libre Space Foundation Aims to Improve Satellite Tech

22 Octubre 2024 at 11:00

There’s no shortage of movies, TV shows, and books that show a dystopian future with corporations run amok in outer space with little or no effective oversight. Dune, The Expanse, and The Dispossessed spring to mind as predicting different aspects of this idea, but there are plenty of other warnings throughout sci-fi depicting this potential future. One possible way of preventing this outcome is by ensuring that space is as open-sourced as possible and one group, the Libre Space Foundation (LSF), is working towards this end. Their latest is a project with Ondsel to develop and model a satellite deploying mechanism using almost entirely open source software.

The LSF had already designed the PICOBUS satellite launcher system that flew to space in 2022 and deployed a number of CubeSats, but the group needed more information about how the system would perform. They turned to Ondsel to help develop a multi-body dynamics (MBD) solver, managing simulations with mass-spring-damper models. The satellite launcher includes a large constant-force spring that pushes the CubeSats out of the device once the door is opened, and the model can now simulate their paths in space without gravity. The team will launch their next set of satellites sometime next year on an RFA-ONE rocket.

The LSF maintains a huge database of their open source space projects, including this one, on their GitLab page. Although it might seem like small potatoes now, the adoption of open source software and hardware by space-fairing entities can help further the democratization of low Earth orbit.

Thanks to [johnad] for the tip!

Pac-Man Ghost Helps With Air Quality Sensing

22 Octubre 2024 at 05:00

In the past, building construction methods generally didn’t worry much about air quality. There were enough gaps around windows, doors, siding, and flooring that a house could naturally “breathe” and do a decent enough job of making sure the occupants didn’t suffocate. Modern buildings, on the other hand, are extremely concerned with efficiency and go to great lengths to ensure that no air leaks in or out. This can be a problem for occupants though and generally requires some sort of mechanical ventilation, but to be on the safe side and keep an eye on it a CO2 sensor like this unique Pac-Man-inspired monitor can be helpful.

Although there are some ways to approximate indoor air quality with inexpensive sensors, [Tobias] decided on a dedicated CO2 sensor for accuracy and effectiveness, despite its relatively large cost of around $30. An ESP32 handles the data from the sensor and then outputs the results to an array of LEDs hidden inside a ghost modeled after the ones from the classic arcade game Pac-Man. There are 17 WS2812B LEDs in total installed on a custom PCB, with everything held together in the custom 3D printed ghost-shaped case. The LEDs change from green to red as the air quality gets worse, although a few preserve the ghost’s white eyes even as the colors change.

For anyone looking to recreate this project and keep an eye on their own air quality, [Tobias] has made everything from the code, the PCB, and the 3D printer files open source, and has used accessible hardware in the build as well. Although the CO2 sensors can indeed be pricey, there are a few less expensive ways of keeping an eye on indoor air quality. Some of these methods attempt to approximate CO2 levels indirectly, but current consensus is that there’s no real substitute for taking this measurement directly if that’s the metric targeted for your own air quality.

The Design Process For A Tiny Robot Brain

21 Octubre 2024 at 05:00

As things get smaller, we can fit more processing power into devices like robots to allow them to do more things or interact with their environment in new ways. If not, we can at least build them for less cost. But the design process can get exponentially more complicated when miniaturizing things. [Carl] wanted to build the smallest 9-axis robotic microcontroller with as many features as possible, and went through a number of design iterations to finally get to this extremely small robotics platform.

Although there are smaller wireless-enabled microcontrollers, [Carl] based this project around the popular ESP32 platform to allow it to be usable by a wider range of people. With that module taking up most of the top side of the PCB, he turned to the bottom to add the rest of the components for the platform. The first thing to add was a power management circuit, and after one iteration he settled on a circuit which can provide the board power from a battery or a USB cable, while also managing the battery’s charge. As for sensors, it has a light sensor and an optional 9-axis motion sensor, allowing for gesture sensing, proximity detection, and motion tracking.

Of course there were some compromises in this design to minimize the footprint, like placing the antenna near the USB-C charger and sacrificing some processing power compared to other development boards like the STM-32. But for the size and cost of components it’s hard to get so many features in such a small package. [Carl] is using it to build some pretty tiny robots so it suits his needs perfectly. In fact, it’s hard to find anything smaller that isn’t a bristlebot.

A Parts Bin MIDI Controller in 24 Hours

20 Octubre 2024 at 14:00

Part of the reason MIDI has hung on as a standard in the musical world for so long is that it is incredibly versatile. Sure, standard instruments like pianos and drums can be interfaced with a computer fairly easily using this standard, but essentially anything can be converted to a MIDI instrument with the right wiring and a little bit of coding. [Jeremy] needed to build a MIDI controller in a single day, and with just a few off-the-shelf parts he was able to piece together a musical instrument from his parts bin.

The build is housed in an off-brand protective case from a favorite American discount tool store, but the more unique part of the project is the choice to use arcade buttons as the instrument’s inputs. [Jeremy] tied eight of these buttons to an Arduino Uno to provide a full octave’s worth of notes, and before you jump to the comments to explain that there are 12 notes in an octave, he also added a button to the side of the case to bend any note when pressed simultaneously. An emergency stop button serves as a master on/off switch and a MIDI dongle on the other side serves as the interface point to a computer.

After a slight bit of debugging, the interface is up and running within [Jeremy]’s required 24-hour window. He’s eventually planning to use it to control a custom MIDI-enabled drum kit, but for now it was fun to play around with it in some other ways. He’s also posted the project code on a GitHub page. And, if this looks a bit familiar, this was not [Jeremy]’s first MIDI project. He was also the creator of one of the smallest MIDI interfaces we’ve ever seen.

Self-Portaging Canoe is Part Bicycle

19 Octubre 2024 at 08:00

Normally when making a long voyage in a canoe, an adventurer would paddle the vessel as far as possible and then “portage”, or carry, the canoe over the short sections of land separating the bodies of water. Portaging is a lot of work, though, since canoes generally aren’t particularly light or designed for traveling over land. To solve this problem, [Ben] is modifying his home-built canoe with some interesting parts to make it into an amphibious vehicle which can much more easily traverse land.

The wheels for the amphibious craft come from BMX bicycles, which have much smaller wheels as well as more robust frames when compared to more traditional bicycles. The rear of the canoe was modified to use a go-kart axle with two driven wheels. An additional set of cranks mounted outboard drive a custom-built paddle to propel the boat when traveling on water. The frame borrows heavily from recumbent bicycle design and includes a similarly comfortable seat, with steering handled by a wheel at the front when traveling on land and a rudder at the rear when traveling over water.

[Ben] intends to take this unique vehicle on a cross-country trip across Scotland, with the first part of the adventure on water via the Caledonian Canal and the return trip on land via the Great Glen Way. Hopefully, there’s no actual portaging required for his trip as the bike components add a tremendous amount of weight to the boat. [Ben] he even added a sail that could theoretically be used in either mode. We’ll be keeping watch for his next videos showing his adventure, and in the meantime daydreaming about other unique bikes that let you travel where bikes normally can’t.

Thanks to [Risu no Kairu] for the tip!

Using the 555 for Everything

14 Octubre 2024 at 11:00

The 555 timer is one of the most versatile integrated circuits available. It can generate PWM signals, tones, and single-shot pulses. You can even put one in a bi-stable mode similar to a flip flop. All of these modes are available by only changing a few components outside of the IC itself. It’s also dirt cheap, so it finds its way into all kinds of applications its original inventors never imagined. There’s a bit of a trope around here as well that you ought not to use a microcontroller when one of these will do, and while it’s a bit of a played-out comment, it’s often more true than it seems. This video shows a few uncommon ways of using these circuits instead of putting a microcontroller to work.

After a brief overview of the internals of the hallowed 555, [Doctor Volt] walks us through some of its uses, starting with applications for digital inputs, including a debounce circuit and a toggle switch. From there, he moves on to demonstrating a circuit that can protect batteries from deep discharge, and a small change to that circuit can turn the 555 into a resetting fuse that can protect against short circuit events. Finally, the PWM capabilities of this small integrated circuit are put to work as an audio amplifier, although perhaps not one that would pass muster for the most devout audiophiles among us.

Even though it’s possible to offload a lot of the capabilities of a 555 onto a microcontroller, there’s certainly an opportunity to offload some things to the 555, even if your project still needs a microcontroller. However, offloading tasks like debounce or input latching to hardware rather than spending microcontroller cycles or pins can make a project more robust, both from reliability and software points of view. For some other useful circuits, some of which have been forgotten in the modern microcontroller age, it’s worth taking a look at some of these antique circuit books as well. While we are sure the 555 designers hoped it would be a big hit, no one imagined this giant one.

Quake in 276 KB of RAM

5 Octubre 2024 at 23:00

Porting the original DOOM to various pieces of esoteric hardware is a rite of passage in some software circles. But in the modern world, we can get better performance than the 386 processor required to run the 1993 shooter for the cost of a dinner at a nice restaurant — with plenty of other embedded systems blowing these original minimum system requirements out of the water.

For a much tougher challenge, a group from Silicon Labs decided to port DOOM‘s successor, Quake, to the Arduino Nano Matter Board platform instead even though this platform has some pretty significant limitations for a game as advanced as Quake.

To begin work on the memory problem, the group began with a port of Quake originally designed for Windows, allowing them to use a modern Windows machine to whittle down the memory usage before moving over to hardware. They do have a flash memory module available as well, but there’s a speed penalty with this type of memory. To improve speed they did what any true gamer would do with their system: overclock the processor. This got them to around 10 frames per second, which is playable, but not particularly enjoyable. The further optimizations to improve the FPS required a much deeper dive which included generating lookup tables instead of relying on computation, optimizing some of the original C programming, coding some functions in assembly, and only refreshing certain sections of the screen when needed.

On a technical level, Quake was a dramatic improvement over DOOM, allowing for things like real-time 3D rendering, polygonal models instead of sprites, and much more intricate level design. As a result, ports of this game tend to rely on much more powerful processors than DOOM ports and this team shows real mastery of their hardware to pull off a build with a system with these limitations. Other Quake ports we’ve seen like this one running on an iPod Classic require a similar level of knowledge of the code and the ability to use assembly language to make optimizations.

Thanks to [Nicola] for the tip!

Reverse Time Back to the Days of RPN

26 Septiembre 2024 at 20:00

While Texas Instruments maintains dominance in the calculator market (especially graphing calculators), there was a time when this wasn’t the case. HP famously built the first portable scientific calculator, the HP-35, although its reverse-Polish notation (RPN) might be a bit of a head-scratcher to those of us who came up in the TI world of the last three or four decades. Part of the reason TI is so dominant now is because they were the first to popularize infix notation, making the math on the calculator look much more like the math written on the page, especially when compared to the RPN used by HP calculators. But if you want to step into a time machine and see what that world was like without having to find a working HP-35, take a look at [Jeroen]’s DIY RPN calculator.

Since the calculator is going to be RPN-based, it needs to have a classic feel. For that, mechanical keyboard keys are used for the calculator buttons with a custom case to hold it all together. It uses two rows of seven-segment displays to show the current operation and the results. Programming the Arduino Nano to work as an RPN calculator involved a few tricks, though. [Jeroen] wanted a backspace button, but this disrupts the way that the Arduino handles the input and shows it on the display but it turns out there’s an Arudino library which solves some of these common problems with RPN builds like this.

One of the main reasons that RPN exists at all is that it is much easier for the processor in the calculator to understand the operations, even if it makes it a little bit harder for the human. This is because early calculators made much more overt use of a stack for performing operations in a similar way to Assembly language. Rather than learning Assembly, an RPN build like this can be a great introduction to this concept. If you want to get into the weeds of Assembly programming this is a great place to go to get started.

Digital Audio Workstation In A Box

24 Septiembre 2024 at 05:00

Although it’s still possible to grab a couple of friends, guitars, and a set of drums and start making analog music like it’s 1992 and there are vacant garages everywhere yearning for the sounds of power chords, the music scene almost demands the use of a computer now. There are a lot of benefits, largely that it dramatically lowers the barrier to entry since it greatly reduces the need for expensive analog instruments. It’s possible to get by with an impressively small computer and only a handful of other components too, as [BAussems] demonstrates with this tiny digital audio workstation (DAW).

The DAW is housed inside a small wooden box and is centered around a Behringer JT-4000 which does most of the heavy lifting in this project. It’s a synthesizer designed to be as small as possible, but [BAussems] has a few other things to add to this build to round out its musical capabilities. A digital reverb effects pedal was disassembled to reduce size and added to the DAW beneath the synthesizer. At its most basic level this DAW can be used with nothing but these components and a pair of headphones, but it’s also possible to add a smartphone to act as a sequencer and a stereo as well.

For a portable on-the-go rig, this digital audio workstation checks a lot of the boxes needed including MIDI and integration with a computer. It’s excellent inspiration for anyone else who needs a setup like this but doesn’t have access, space, or funds for a more traditional laptop- or desktop-centered version. For some other small on-the-go musical instruments we recently saw a MIDI-enabled keyboard not much larger than a credit card.

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