Big Time Character LCD Clock

While the SSD1306 OLED has somewhat become the go-to display for up-to-date projects, the good old character displays with their Hitachi HD44780 controller don’t seem to be disappearing just yet either. And why would they, especially if you want to show just text, having a built-in font has certainly its perk compared to worrying about integrating your own characters — which you can still do on top as well. Or perhaps you can combine both worlds, which is what [oldmaninSC] did with his digital clock that takes an entire 16×2 LCD to show each single digit.

The whole clock uses 16 individual, upright rotated 16×2 LCDs that are arranged in two rows of eight LCDs each, turning the entire construct sort of into a giant 8×2 display itself. For some additional information such as the date, there’s also a smaller font available that uses only half the height, allowing up to four total rows of information. To communicate with each LCD via I2C, two TCA9548A I2C multiplexers are connected to an Arduino, along with an RTC to keep track of the time and date itself.

As the TCA9548A has three pins dedicated to define its own address, the entire clock could be scaled up to a total of 64 LCDs — so how about a 16×4 display made out of 16×4 displays? Sure, adding smooth scrolling might become a bit tricky at some point, but imagine playing Tetris on that one!

source https://hackaday.com/2020/12/28/big-time-character-lcd-clock/

Rheoscopic Holiday Ornaments

We had to look it up on Wikipedia – “Rheoscopic fluid means ‘current showing’ fluid. Such fluids are effective in visualizing dynamic currents in fluids, such as convection and laminar flow. They have microscopic crystalline platelets such as mica, metallic flakes, or fish scales, in suspension in a fluid such as water or glycol stearate.” And so it seems [Will Donaldson] has figured out a great way to Animate Christmas Ornaments using Rheoscopic Fluid, just in time for the holiday season.

Making the fluid is pretty simple, and uses just a few readily available materials – distilled water, rheoscopic fluid concentrate and your choice of food colouring. The hardware is dead simple too – clear, spherical baubles with lids and core-less DC motors such as used in mini and nano drones, to agitate the fluid. You can use cell phone vibration motors too, but [Will]’s experimentation suggests that the level of agitation is not a lot.

Rheoscopic 03To make a bauble, you fill it with the fluid, hot glue the motor to the lid, close the lid such that the motor and its agitator are dunked in the fluid, and dab a generous amount of hot melt glue to seal it all shut. Then, hook it up to a suitable power supply and get enchanted by the mesmerising movements of the rheoscopic fluid in the bauble. The agitator is just a plain ol’ drone propeller forced in to a shape that is narrow enough to be pushed through the neck of the bauble. It’s a seasonal ornament, so don’t expect the motors to last long being submerged in the rheoscopic fluid. [Will]’s contraptions have not yet failed after a couple of days, and it may be safe to estimate that the motors may last about a week or two at most. Of course, YMMV depending on if you used distilled water or plain tap water and other factors.

As [Will] suggests, if you prefer slower swirls, or random agitation, then it’s best to hook up a micro-controller and motor driver for fancy effects. At this point, it may be tempting to think of embedding LED’s inside the baubles, but doing so reduces the rheoscopic effect since it relies on reflecting light shining on it from the outside. The video embedded after the break has all the build details.

It’s a great way to teach some science to the kids during the holidays and maybe even get them to help with the project. And don’t assume this is just a cheap Christmas trick. Artist Paul Matisse has invented an art device/technique based on rheoscopic fluids which he calls “Kalliroscope©”. He patented it in 1968, and has sold Kalliroscope artworks throughout the world since then. From his website “A Kalliroscope is a device for viewing fluid currents. Kalliroscopes are both works of art and intuitively educational displays of the scientific principles of fluid dynamics. They are glass and steel constructions containing a current-visualizing fluid.” We’re not sure how priceless those works of art are, but it’s safe to assume you need deep pockets to buy one. So go ahead, turn your Christmas Tree in to a work of Art !

source https://hackaday.com/2020/12/27/rheoscopic-holiday-ornaments/

Rheoscopic Holiday Ornaments

We had to look it up on Wikipedia – “Rheoscopic fluid means ‘current showing’ fluid. Such fluids are effective in visualizing dynamic currents in fluids, such as convection and laminar flow. They have microscopic crystalline platelets such as mica, metallic flakes, or fish scales, in suspension in a fluid such as water or glycol stearate.” And so it seems [Will Donaldson] has figured out a great way to Animate Christmas Ornaments using Rheoscopic Fluid, just in time for the holiday season.

Making the fluid is pretty simple, and uses just a few readily available materials – distilled water, rheoscopic fluid concentrate and your choice of food colouring. The hardware is dead simple too – clear, spherical baubles with lids and core-less DC motors such as used in mini and nano drones, to agitate the fluid. You can use cell phone vibration motors too, but [Will]’s experimentation suggests that the level of agitation is not a lot.

Rheoscopic 03To make a bauble, you fill it with the fluid, hot glue the motor to the lid, close the lid such that the motor and its agitator are dunked in the fluid, and dab a generous amount of hot melt glue to seal it all shut. Then, hook it up to a suitable power supply and get enchanted by the mesmerising movements of the rheoscopic fluid in the bauble. The agitator is just a plain ol’ drone propeller forced in to a shape that is narrow enough to be pushed through the neck of the bauble. It’s a seasonal ornament, so don’t expect the motors to last long being submerged in the rheoscopic fluid. [Will]’s contraptions have not yet failed after a couple of days, and it may be safe to estimate that the motors may last about a week or two at most. Of course, YMMV depending on if you used distilled water or plain tap water and other factors.

As [Will] suggests, if you prefer slower swirls, or random agitation, then it’s best to hook up a micro-controller and motor driver for fancy effects. At this point, it may be tempting to think of embedding LED’s inside the baubles, but doing so reduces the rheoscopic effect since it relies on reflecting light shining on it from the outside. The video embedded after the break has all the build details.

It’s a great way to teach some science to the kids during the holidays and maybe even get them to help with the project. And don’t assume this is just a cheap Christmas trick. Artist Paul Matisse has invented an art device/technique based on rheoscopic fluids which he calls “Kalliroscope©”. He patented it in 1968, and has sold Kalliroscope artworks throughout the world since then. From his website “A Kalliroscope is a device for viewing fluid currents. Kalliroscopes are both works of art and intuitively educational displays of the scientific principles of fluid dynamics. They are glass and steel constructions containing a current-visualizing fluid.” We’re not sure how priceless those works of art are, but it’s safe to assume you need deep pockets to buy one. So go ahead, turn your Christmas Tree in to a work of Art !

source https://hackaday.com/2020/12/27/rheoscopic-holiday-ornaments/

Rheoscopic Holiday Ornaments

We had to look it up on Wikipedia – “Rheoscopic fluid means ‘current showing’ fluid. Such fluids are effective in visualizing dynamic currents in fluids, such as convection and laminar flow. They have microscopic crystalline platelets such as mica, metallic flakes, or fish scales, in suspension in a fluid such as water or glycol stearate.” And so it seems [Will Donaldson] has figured out a great way to Animate Christmas Ornaments using Rheoscopic Fluid, just in time for the holiday season.

Making the fluid is pretty simple, and uses just a few readily available materials – distilled water, rheoscopic fluid concentrate and your choice of food colouring. The hardware is dead simple too – clear, spherical baubles with lids and core-less DC motors such as used in mini and nano drones, to agitate the fluid. You can use cell phone vibration motors too, but [Will]’s experimentation suggests that the level of agitation is not a lot.

Rheoscopic 03To make a bauble, you fill it with the fluid, hot glue the motor to the lid, close the lid such that the motor and its agitator are dunked in the fluid, and dab a generous amount of hot melt glue to seal it all shut. Then, hook it up to a suitable power supply and get enchanted by the mesmerising movements of the rheoscopic fluid in the bauble. The agitator is just a plain ol’ drone propeller forced in to a shape that is narrow enough to be pushed through the neck of the bauble. It’s a seasonal ornament, so don’t expect the motors to last long being submerged in the rheoscopic fluid. [Will]’s contraptions have not yet failed after a couple of days, and it may be safe to estimate that the motors may last about a week or two at most. Of course, YMMV depending on if you used distilled water or plain tap water and other factors.

As [Will] suggests, if you prefer slower swirls, or random agitation, then it’s best to hook up a micro-controller and motor driver for fancy effects. At this point, it may be tempting to think of embedding LED’s inside the baubles, but doing so reduces the rheoscopic effect since it relies on reflecting light shining on it from the outside. The video embedded after the break has all the build details.

It’s a great way to teach some science to the kids during the holidays and maybe even get them to help with the project. And don’t assume this is just a cheap Christmas trick. Artist Paul Matisse has invented an art device/technique based on rheoscopic fluids which he calls “Kalliroscope©”. He patented it in 1968, and has sold Kalliroscope artworks throughout the world since then. From his website “A Kalliroscope is a device for viewing fluid currents. Kalliroscopes are both works of art and intuitively educational displays of the scientific principles of fluid dynamics. They are glass and steel constructions containing a current-visualizing fluid.” We’re not sure how priceless those works of art are, but it’s safe to assume you need deep pockets to buy one. So go ahead, turn your Christmas Tree in to a work of Art !

source https://hackaday.com/2020/12/27/rheoscopic-holiday-ornaments/

Hackaday Links: December 27, 2020

We’re always pleased to see one of our community’s projects succeed, and we celebrate that success in whatever what it comes. But seeing a company launched to commercialize an idea that started as a Hackaday.io project and a Hackaday Prize entry is especially gratifying. So we were pleased as punch to see that MAKESafe Tools has managed to bring the idea of add-on machine tool braking to market. We’d love to add this to several tools in our shop. Honestly, of all the terrifying ways machine tools can slice, dice, and shred human flesh asunder, we always considered the lowly bench grinder fairly low-risk — and then we had a chance to “Shake Hands with Danger.”

Another great thing about the Hackaday community is the way we all try to keep each other up to speed on changes and news that affects even our smallest niches. Just last week Tom Nardi covered a project using the venerable TI eZ430-Chronos smartwatch as a makeshift medical alert bracelet for a family member. It’s a great application for the proto-smartwatch, but one eagle-eyed commenter helpfully pointed out that TI is shutting down their processors wiki in just a couple of weeks. The banner at the top of each page warns that the wiki is not read-only and that any files needed should be downloaded by January 15. Also helpfully, subsequent comments include instructions to download the entire wiki and a torrent link to the archive. It’s always sad to see a platform lose support, especially one that has gained a nice following, but it’s heartening to see the community pull together to continue to support each other like this.

We came across an interesting article this week that’s was a fascinating glimpse into how economic forces shape  and drive technological process, and vice versa. It turns out that some of the hottest real estate commodities these days are the plots of land occupied by AM radio stations serving metropolitan markets. It’s no secret that terrestrial radio in general, and AM radio in particular, are growing increasingly moribund, and the infrastructure needed to keep them on the air is getting harder and harder to justify. Chief among these are the large tracts of land devoted to antenna farms, which are often located in suburban and exurban areas near major cities. They’re tempting targets for developers looking to plunk down the physical infrastructure needed to support “New Economy” players like Amazon, which continue to build vast automated warehouses in areas that are handy to large customer bases. It’s a bit sad to watch a once mighty industry unravel and be sold off like this, but such is the nature of progress.

And finally, you may recall a Links article mention a few weeks back about a teardown of a super-sized IBM processor module. A quarter-million dollar relic of the 1990s, the huge System/390 module was an engineering masterpiece that met an unfortunate end at the hands of EEVblog’s Dave Jones. As a follow-up, Dave teamed up with fellow YouTuber CPU Galaxy to take a less-destructive tour of the module using X-ray analysis. The level of engineering needed for a 64-layer ceramic backplane is astonishing, and Dave’s play-by-play is pretty entertaining too. As a bonus, CPU Galaxy has some really interesting stuff; his place is basically a museum of vintage tech, and he just earned a new sub.

source https://hackaday.com/2020/12/27/hackaday-links-december-27-2020/

Put a Hardened Edge on Mild Steel with Just a Drill Bit. Sort of.

People have been working metal for so long that the list of tips and tricks is now nearly infinite. So it’s always a joy to pick up a new trick, especially one as simple as putting a hardened edge on mild steel using a drill bit as a filler rod.

This tip comes to us by way of [Jody], aka “The Weldmonger” on YouTube. Subscribing to his channel is a sure way to keep your welding ego in check; you may be good, but [Jody] is better, and he’s willing to share as much of his experience in video format as possible. For this tip, he starts with a cheap chipping hammer, the universal welder’s tool that helps remove the glass-like slag that forms during shielded-metal arc welding, or what’s commonly known as stick welding. The mild steel of the hammer makes it hard to keep an edge, so [Jody] pulled out his TIG welder and laid down a bead on the cutting edge using an old drill bit as a fill rod. The video below shows the process in all its simplicity.

The tool steel of the drill bit is far harder than the mild steel of the hammer, but still soft enough to take an edge, and the resulting tool is much improved. We’ve seen something similar to this before, when hard-facing filler rod was built up on the edge of a mild steel slug to make a cutter for internal weld seams. We liked that hack, but knowing the same thing can be done with something we’ve all likely got in abundance in the shop is a neat trick. Thanks, [Jody]!

source https://hackaday.com/2020/12/27/put-a-hardened-edge-on-mild-steel-with-just-a-drill-bit-sort-of/

Custom Powerbank In Compact Form Factor

The wide availability and power density of 18650 lithium-ion cells have made them a good option for everything from electric cars to flashlights. [Theo] needed a new power source for his FPV drone goggles, so he designed his own power bank with a very compact charge controller.The narrow PCB slips in between the cells

While [Theo] could charge the batteries with an RC battery charger, he preferred the convenience of one with a standard 5V micro USB input, and wanted battery level indication to avoid having the FPV goggles die unexpectedly mid-flight. When four 18650 cells are held in a cube arrangement, a 8x8x65 mm gap is formed between the cells. In this space [Theo] was able to fit a custom PCB with a micro USB jack, 1.3 mm power jack, BQ25606 charge controller, TPS61085 boost converter, and ATtiny MCU with LED for battery level feedback. The charge controller also allows 5V devices to be charged via USB, while the boost converter outputs 9V via the 1.3mm jack for [Theo]’s FPV goggles. Everything fits inside a nice compact 3D printed enclosure.

The project was not without hiccups. After ordering and building the PCB he discovered some minor PCB layout mistakes, and realized the boost converted could only output 600mA at 9V, which was not enough for his more power-hungry googles. He plans to fix this in the next version.

We’ve seen custom power banks in quite a few shapes and sizes, including one that runs on power tool batteries (which probably also have 18650s inside) and one that has just about every output you could want, including AC and wireless QI charging.

source https://hackaday.com/2020/12/27/custom-powerbank-in-compact-form-factor/

Custom Powerbank In Compact Form Factor

The wide availability and power density of 18650 lithium-ion cells have made them a good option for everything from electric cars to flashlights. [Theo] needed a new power source for his FPV drone goggles, so he designed his own power bank with a very compact charge controller.The narrow PCB slips in between the cells

While [Theo] could charge the batteries with an RC battery charger, he preferred the convenience of one with a standard 5V micro USB input, and wanted battery level indication to avoid having the FPV goggles die unexpectedly mid-flight. When four 18650 cells are held in a cube arrangement, a 8x8x65 mm gap is formed between the cells. In this space [Theo] was able to fit a custom PCB with a micro USB jack, 1.3 mm power jack, BQ25606 charge controller, TPS61085 boost converter, and ATtiny MCU with LED for battery level feedback. The charge controller also allows 5V devices to be charged via USB, while the boost converter outputs 9V via the 1.3mm jack for [Theo]’s FPV goggles. Everything fits inside a nice compact 3D printed enclosure.

The project was not without hiccups. After ordering and building the PCB he discovered some minor PCB layout mistakes, and realized the boost converted could only output 600mA at 9V, which was not enough for his more power-hungry googles. He plans to fix this in the next version.

We’ve seen custom power banks in quite a few shapes and sizes, including one that runs on power tool batteries (which probably also have 18650s inside) and one that has just about every output you could want, including AC and wireless QI charging.

source https://hackaday.com/2020/12/27/custom-powerbank-in-compact-form-factor/

A Tracker For Radio Sondes

Radiosondes – the telemetry packages carried aloft by sounding balloons for atmospheric weather data measurements – are regularly used by weather bureaus around the world to collect data, and there are quite a number of launches daily. Most of them are in Europe, but they also happen at many locations in North and South America, Japan, and Australia. The balloons burst when they reach a high enough altitude, the radiosonde falls back, and most often there is no effort made to recover them since they are deemed “expendable”. So it’s Finders Keepers, and rich pickings for any hacker who is fortunate enough to grab the fallen radiosondes. For successful recovery, you need to first be able to track those radiosondes, and that’s why leet guy [Robert Stefanowicz aka p1337] built his Weather ballon tracker (sic) project.

The hardware is all off-the-shelf, packaged in a pretty cool 3D printed package designed to make it look like the hand held radio that it is. At its heart is the ESP32 based TTGO T-BEAM V1.0 which has almost everything needed for this project. Add an OLED display, 18650 Li-Po cells, antenna and connectors and you can put it all together in an evening over your favourite beverage.

[DL9RDZ] wrote the software which runs on the T-Beam, available at the RDZ-Sonde repo on Github, that allows hunting these balloons. Setup is straightforward, and you need to fiddle with just a couple of well-explained config parameters. Once connected to your WiFi, config and settings can be accessed via convenient web URL’s and the single user action button on the TTGO offers quick access to different functional modes. At the moment, the software is written to decode signals from the widely used Vaisala RS41, Graw DFM06 and Graw DFM09 radiosondes. This LINK provides details for some of the popular radiosonde models.

Once you’re done building this piece of hunting gear, you’ll need some additional help finding out when and where the launches are taking place. If you’re in Europe, you luck out – there is a live radiosonde tracker map, thanks to the great work done by [Michał Lewiński – SQ6KXY]. If you live else where and know of similar resources, let us know in the comments. As a side note, Wikipedia tells us there are about 1300 launch sites worldwide and twice a day missions, so there’s quite a number of fallen pieces of hardware lying around just waiting to be picked up. At the very least, each will have a GPS module and temperature and humidity sensors that you can recover.

So, what do you do with the recovered radiosondes ? Here’s a tip on a “Fallen Radiosonde reborn as active L-band antenna“. And If you’d like to get the skinny on radiosondes, check out “Radiosondes: getting data from upstairs

Thanks for the tip, [Alex aka MD23F3].

source https://hackaday.com/2020/12/27/a-tracker-for-radio-sondes/

3D Printed Server Case Holds 14 Raspberry Pis

If you ever need to cluster up to 14 Raspberry Pis and an equal number of 2.5 inch hard drives, you might want to look at the Raspberry Pi Server Mark III case from [Ivan Kuleshov]. The original Mark I design came from Thingiverse, but the Mark III is a complete redesign.

The redesign allows for more boards along with a reduction in the number of parts. That takes less plastic and less time to print. The design is also modular, so there should be new components in the future.

In addition to the 3D printed parts and the electronics, you also need five fans and some miscellaneous hardware and cables. The setup is made to accommodate a power over Ethernet HAT, but apparently you can also get it to work without it. You also need a power supply for the fans, so we aren’t sure the Ethernet power matters that much. We have to wonder what [Ivan]’s up to with all these computers and hard drives in a rack mount.

The 10 STL files and some other data is in one downloadable ZIP file. Of course, some of these you print multiple times, so expect to keep your printer busy for awhile.

With 14 boards, you’ll be well on your way to Raspberry Pi clustering, but you’ll still have a ways to go to match Oracle. But it is plenty compared to some builds we’ve seen.

source https://hackaday.com/2020/12/26/3d-printed-server-case-holds-14-raspberry-pis/

Analyzing the “Source Code” of the COVID-19 Vaccine

Computer programs are written in code, which comes in many forms. At the lowest level, there’s machine code and assembly, while higher-level languages like C and Python aim to be more human-readable. However, the natural world has source code too, in the form of DNA and RNA strings that contain the code for the building blocks of life. [Bert] decided to take a look at the mRNA source code of Tozinameran, the COVID-19 vaccine developed by BioNTech and Pfizer.

The analysis is simple enough for the general reader, while nonetheless explaining some highly complex concepts at the cutting edge of biology. From codon substitutions for efficiency and the Ψ-base substitution to avoid the vaccine being destroyed by the immune system, to the complex initialisation string required at the start of the RNA sequence, [Bert] clearly explains the clever coding hacks that made the vaccine possible. Particularly interesting to note is the Prolase substitution, a technique developed in 2017. This allows the production of coronavirus spike proteins in isolation of the whole virus, in order to safely prime the immune system.

It’s a great primer and we can imagine it might inspire some to delve further into the rich world of genetics and biology. We’ve featured other cutting edge stories on COVID-19 too; [Dan Maloney] took a look at how CRISPR techniques are helping with the testing effort. If there’s one thing the 2020 pandemic has shown, it’s humanity’s ability to rapidly develop new technology in the face of a crisis.

source https://hackaday.com/2020/12/26/analyzing-the-source-code-of-the-covid-19-vaccine/

Squeezing Every Bit from an ATMega

While the ATMega328 is “mega” for a microcontroller, it’s still a fairly limited platform. It has plenty of I/O and working memory for most tasks, but this Battleship game that [thorlancaster328] has put together really stretches the capabilities of this tiny chip. Normally a Battleship game wouldn’t be that complicated, but this one has audio, an LED display, and can also play a fine rendition of Nyan Cat to boot, which really puts the Atmel chip through its paces.

The audio is played through a 512-byte buffer and an interrupt triggers the microcontroller when to fill the buffer while it works on the other processes. The 12×12 LED display is also fed through a shift register triggered by the same interrupt as the audio, and since the build uses so many shift registers the microcontroller can actually output four separate displays (two players, each with a dispaly for shots and one for ships). It will also eventually support a player-vs-computer mode for the battleship game, and also has a mode where it plays Nyan cat just to demonstrate its own capabilities.

We’re pretty impressed with the amount of work this small microcontroller is doing, largely thanks to code optimization from its creator [thorlancaster328]. If there’s enough interest he also says he will provide the source code too. Until then, be sure to check out this other way of pushing a small microcontroller to its limits.

Thanks to [Thinkerer] for the tip!

source https://hackaday.com/2020/12/26/squeezing-every-bit-from-an-atmega/

Fox Hunting with Software-Defined Radio

Fox hunting, or direction finding, is a favorite pastime in the ham radio community where radio operators attempt to triangulate the position of a radio transmission. While it may have required a large amount of expensive equipment in the past, like most ham radio operations the advent of software-defined radio (SDR) has helped revolutionize this aspect of the hobby as well. [Aaron] shows us how to make use of SDR for direction finding using his custom SDR-based Linux distribution called DragonOS.

We have mentioned DragonOS before, but every iteration seems to add new features. This time it includes implementation of a software package called DF-Aggregator. The software (from [ckoval7]), along with the rest of DragonOS, is loaded onto a set of (typically at least three) networked Raspberry Pis. The networked computers can communicate information about the radio waves they receive, and make direction finding another capable feature found in this distribution.

[Aaron] has a few videos showing the process of setting this up and using it, and all of the software is available for attempting something like this on your own. While the future of ham radio as a hobby does remain in doubt, projects like this which bring classic ham activities to the SDR realm really go a long way to reviving it.

source https://hackaday.com/2020/12/26/fox-hunting-with-software-defined-radio/

Indoor Antennas Worthy of 007

Many ham radio operators now live where installing an outdoor antenna is all but impossible. It seems that homeowner’s associations are on the lookout for the non-conformity of the dreaded ham radio antenna. [Peter] can sympathize, and has a solution based on lessons of spycraft from the cold war.

[Peter] points out that spies like the [Krogers] needed to report British Navy secrets like the plans for a nuclear boomer sub to Russia but didn’t want to attract the attention of their neighbors. In this case, the transmitter itself was so well-hidden that it took MI5 nine days to find the first of them. Clearly, then, there wasn’t a giant antenna on the roof. If there had been, the authorities could simply follow the feedline to find the radio. A concealed spy antenna might be just the ticket for a deed-restricted ham radio station.

The antenna the [Kroger’s] used was a 22-meter wire in the attic of their home. Keep in mind, the old tube transmitters were less finicky about SWR and by adjusting the loading circuits, you could transmit into almost anything. Paradoxically, older houses work better with indoor antennas because they lack things like solar cell panels, radiant barriers, and metallic insulation.

Like many people, [Peter] likes loop antennas for indoor use. He also shows other types of indoor antennas. They probably won’t do as much good as a proper outdoor antenna, but you can make quite a few contacts with some skill, some luck, and good propagation. [Peter] has some period spy radios, which are always interesting to see. By today’s standards, they aren’t especially small, but for their day they are positively tiny. Video after the break.

If you think spy radios were small then, you should see what you can do now. Then again, some of the most famous cold war spy radios didn’t have any obvious antenna or even required power.

source https://hackaday.com/2020/12/26/indoor-antennas-worthy-of-007/

Legged Robots Put On Wheels And Skate Away

We don’t know how much time passed between the invention of the wheel and someone putting wheels on their feet, but we expect that was a great moment of discovery: combining the ability to roll off at speed and our leg’s ability to quickly adapt to changing terrain. Now that we have a wide assortment of recreational wheeled footwear, what’s next? How about teaching robots to skate, too? An IEEE Spectrum interview with [Marko Bjelonic] of ETH Zürich describes progress by one of many research teams working on the problem.

For many of us, the first robot we saw rolling on powered wheels at the end of actively articulated legs was when footage of the Boston Dynamics ‘Handle’ project surfaced a few years ago. Rolling up and down a wide variety of terrain and performing an occasional jump, its athleticism caused quite a stir in robotics circles. But when Handle was introduced as a commercial product, its job was… stacking boxes in a warehouse? That was disappointing. Warehouse floors are quite flat, leaving Handle’s agility under-utilized.

Boston Dynamic has typically been pretty tight-lipped on details of their robotics development, so we may never know the full story behind Handle. But what they have definitely accomplished is getting a lot more people thinking about the control problems involved. Even for humans, we face a nontrivial learning curve paved with bruised and occasionally broken body parts, and that’s even before we start applying power to the wheels. So there are plenty of problems to solve, generating a steady stream of research papers describing how robots might master this mode of locomotion.

TachikomaAdding to the excitement is the fact this is becoming an area where reality is catching up to fiction, as wheeled-legged robots have been imagined in forms like Tachikoma of Ghost in the Shell. While those fictional robots have inspired projects ranging from LEGO creations to 28-servo beasts, their wheel and leg motions have not been autonomously coordinated as they are in this generation of research robots.

As control algorithms mature in robot research labs around the world, we’re confident we’ll see wheeled-legged robots finding applications in other fields. This concept is far too cool to be left stacking boxes in a warehouse.

source https://hackaday.com/2020/12/26/legged-robots-put-on-wheels-and-skate-away/

Casting Skateboard Wheels with a 3D Printed Mold

We’ll admit that most of the Hackaday staff wouldn’t get too far on a skateboard, but that doesn’t mean we can’t appreciate the impressive DIY wheels that [Chris McCann] has managed to cast using 3D printed molds. From unique color combinations to experimental materials, the process certainly opens up some interesting possibilities for those looking to truly customize their rides. Though it’s worth noting there’s a certain element of risk involved; should a set of homemade wheels fail at speed, it could go rather poorly for the rider.

Both the STL and STEP files for the mold have been released under the Creative Commons Attribution 4.0 license, meaning anyone with a 3D printer can follow along at home. Unfortunately, it’s not quite as simple as clicking print and coming back to a usable mold. Because of the layer lines inherent to FDM 3D printing, the inside of the mold needs to be thoroughly sanded and polished. [Chris] mentions that printing the mold in ABS and using vapor smoothing might be a workable alternative to elbow grease and PLA, but he hasn’t personally tried it yet.

Castskate DetailOnce you’ve got the three part mold printed, smoothed, and coated with an appropriate release agent like petroleum jelly, it’s time to make some wheels. The core of each wheel is actually 3D printed from PETG, which should give it pretty reasonable impact resistance. If you have access to a lathe, producing aluminum cores shouldn’t be too difficult either. With the core loaded into the mold, urethane resin is poured in through the top until all the empty space is filled.

But you’re not done yet. All those little air bubbles in the resin need to be dealt with before it cures. [Chris] puts his filled molds into a pressure chamber, though he mentions that vacuum degassing might also be a possibility depending on the urethane mixture used. After everything is solidified, the mold can easily be taken apart to reveal the newly cast wheel.

While there’s often some trial and error involved, 3D printing and resin casting are an undeniably powerful combination. If you can master the techniques involved, you can produce some very impressive parts that otherwise would be exceptionally difficult to produce on a hacker’s budget. Especially when you’re ready to start casting molten metal.

source https://hackaday.com/2020/12/26/casting-skateboard-wheels-with-a-3d-printed-mold/

No Doorknobs Needed for This Nitrogen Laser Build

Sometimes the decision to tackle a project or not can boil down to sourcing parts. Not everything is as close as a Digi-Key or Mouser order, and relying on the availability of surplus parts from eBay or other such markets can be difficult. Knowing if and when a substitute will work for an exotic part can sometimes be a project all on its own.

Building lasers is a great example of this, and [Les Wright] recently looked at substitutes for hard-to-find “doorknob” capacitors for his transversely excited atmospheric lasers. We took at his homebrew TEA lasers recently, which rely on a high voltage supply and very rapid switching to get nitrogen gas to lase. His design uses surplus doorknob caps, big chunky parts rated for very high voltages but also with very low parasitic inductance, which makes them perfect for the triggering circuit.

[Les] tried to substitute cheaper and easier-to-find ceramic power caps with radial wire leads rather than threaded lugs. With a nominal 40-kV rating, one would expect these chunky blue caps to tolerate the 17-kV power supply, but as he suspected, the distance between the leads was short enough to result in flashover arcing. Turning down the pressure in the spark gap chamber helped reduce the flashover and prove that these caps won’t spoil the carefully engineered inductive properties of the trigger. Check out the video below for more details.

Thanks to [Les] for following up on this and making sure everyone can replicate his designs. That’s one of the things we love about this community — true hackers always try to find a way around problems, even when it’s just finding alternates for unobtanium parts.

source https://hackaday.com/2020/12/26/no-doorknobs-needed-for-this-nitrogen-laser-build/

Webcam Heart Rate Monitor Brings Photoplethysmography to Your PC

It seems like within the last ten years, every other gadget to be released has some sort of heart rate monitoring capability. Most modern smartwatches can report your BPMs, and we’ve even seen some headphones with the same ability hitting the market. Most of these devices use an optical measurement method in which skin is illuminated (usually by an LED) and a sensor records changes in skin color and light absorption. This method is called Photoplethysmography (PPG), and has even been implemented (in a simple form) in smartphone apps in which the data is generated by video of your finger covering the phone camera.

The basic theory of operation here has its roots in an experiment you probably undertook as a child. Did you ever hold a flashlight up to your hand to see the light, filtered red by your blood, shine through? That’s exactly what’s happening here. One key detail that is hard to perceive when a flashlight is illuminating your entire hand, however, is that deoxygenated blood is darker in color than oxygenated blood. By observing the frequency of the light-dark color change, we can back out the heart rate.

This is exactly how [Andy Kong] approached two methods of measuring heart rate from a webcam.

Method 1: The Cover-Up

The first detection scheme [Andy] tried is what he refers to as the “phone flashlight trick”. Essentially, you cover the webcam lens entirely with your finger. Ambient light shines through your skin and produces a video stream that looks like a dark red rectangle. Though it may be imperceptible to us, the color changes ever-so-slightly as your heart beats. An FFT of the raw data gives us a heart rate that’s surprisingly accurate. [Andy] even has a live demo up that you can try for yourself (just remember to clean the smudges off your webcam afterwards).

Method 2: Remote Sensing

Now things are getting a bit more advanced. What if you don’t want to clean your webcam after each time you measure your heart rate? Well thankfully there’s a remote sensing option as well.

For this method, [Andy] is actually using OpenCV to measure the cyclical swelling and shrinking of blood vessels in your skin by measuring the color change in your face. It’s absolutely mind-blowing that this works, considering the resolution of a standard webcam. He found the most success by focusing on fleshy patches of skin right below the eyes, though he says others recommend taking a look at the forehead.

Every now and then we see something that works even though it really seems like it shouldn’t. How is a webcam sensitive enough to measure these minute changes in facial color? Why isn’t the signal uselessly noisy? This project is in good company with other neat heart rate measurement tricks we’ve seen. It’s amazing that this works at all, and even more incredible that it works so well.

source https://hackaday.com/2020/12/25/webcam-heart-rate-monitor-brings-photoplethysmography-to-your-pc/

Better Security, Harry Potter Style

We all know we shouldn’t use 1234 as our password. But we often don’t do the absolute best practice when it comes to passwords. After all, you should have some obscure strange password that is unique for every site. But we all have lots of passwords, so most of us use $pock2020 or something like that. If you know I’m a Star Trek fan, that wouldn’t be super hard to guess. [Phani] writes about a technique called Horcruxing — a term taken from the literary realm of Harry Potter that allowed Voldemort to preserve life by splitting it into multiple parts, all of which were required to bring an end to his villany. [Phani’s] process promises to offer better security than using a single password, without the problems associated with having hundreds of random passwords.

Most people these days use some form of password manager. That’s great because the manager can create 48 character passwords of random words or symbols and even you don’t know the password. Of course, you do know the master password or, at least, you better. So if anyone ever compromised that password, they’d have all your passwords at their fingers. Horcruxing makes sure that the password manager doesn’t know the entire password, just the hard parts of it.

Here’s how it works. Suppose you decide your personal horcrux string will be HamNCheese. That’s easy to remember and spell. It isn’t a great password all by itself. However, the idea is to never store that string in your password manager. Instead, you store a unique prefix and you have to add the horcrux.

If the password manager, for example, creates a password of 4337feeb90210, then you’d set the actual password to be 4337feeb90210HamNCheese. This means you’d have to set the password manager to not auto-submit the login form, of course. Once it filled in its part, you’ll have to add the extra string. Now if someone compromises your password manager, it doesn’t help them unless they also know your horcrux which, obviously, you should keep super secret.

This doesn’t help if someone phishes your password from you or otherwise intercepts it using, say, a keystroke logger. But it does seem like it has some value of preventing your password database from being a useful target. You’ll probably have to figure the best way to configure not only to prevent automatic submission but also to stop the password manager from helpfully trying to update your password every time you enter the horcrux, but that’s a small thing.

[Phani] doesn’t mention it, but it reminded us of the problem with security questions, too. It is reasonably easy to research people and find things like their mother’s maiden name or where they went to high school. The best solution is to have a made-up identity that you use to answer those questions. So your mother’s maiden name might be Pfffft and your older brother’s middle name might be MiddleName. The problem, of course, is keeping all that straight. Maybe you can store it in your password manager.

We’ve talked about odd ways to generate passwords before. If you can not lose a hardware device, that’s another solution.

source https://hackaday.com/2020/12/25/better-security-harry-potter-style/

Ten Robot Mechanisms For Your Design Toolbox

The convergence of mechanics and electronics in robotics brings with it a lot of challenges. Thanks to 3D printing and low cost components, it’s possible to quickly and easily experiment with a variety of robotics mechanism for various use cases. [Paul Gould] has been doing exactly this, and is giving us a taste of ten designs he will be open sourcing in the near future. Video after the break.

Three of the designs are capstan mechanisms, with different motors and layouts, tested for [Paul]’s latest quadruped robot. Capstan mechanisms are a few centuries old, and were originally used on sailing ships to give the required mechanical advantage to tension large sails and hoist cargo.

Two of the mechanisms employ GUS Simpson Drives, which use a combination of belts and a rolling joint. These were inspired by the LIMS2-AMBIDEX developed at the University of Korea. The ever-popular cycloidal gearbox also makes and appearance in the form of a high torque dual disk linked, two stage, NEMA17 driven gearbox.

[Paul] also built a room sized skycam-like claw robot for his daughter, suspended by four ball chain strings reeled in by four brushless motors with ESP32 powered motor controllers. We are looking forward to having a close look at these designs when [Paul] releases them, and to see how his quadruped robot will turn out.

[Thanks TTN for the tip!]

source https://hackaday.com/2020/12/25/ten-robot-mechanisms-for-your-design-toolbox/

Is This The World’s Smallest Nintendo 64?

A niche activity in console fandom is the shrinking of full-size consoles to smaller formats, taking what could once only be played on the family TV into portable formats that fit in the pocket. In a particularly impressive example of the art, [GmanModz] has made what he claims is the world’s smallest portable Nintendo 64. What makes it particularly noteworthy is that he’s done it not with an emulator or a custom PCB, instead there is a real Nintendo 64 motherboard in there having undergone a significant quantity of trimming.

The video below the break goes into detail on the state of the art in these mods, and shows how he has eschewed the latest tech and instead restricted himself to only using commercially available breakout PCBs and off the shelf modules. The N64 board trimmed down particularly aggressively, requiring a lot of fine magnet wire soldering for the various PCBs replacing the parts removed. The cartridge slot is brought out to the back of the board at a right angle, jutting out from the rear of the 3D printed case above a space for an 18650 cell and allowing an original game cartridge to be played. There is a microcontroller to facilitate a few compromises on lesser uses of the Nintendo control pads, but the result is a fully playable mini handheld console. He does admit that “The battery life sucks, it’s uncomfortable to hold […] But hey — it fits in my pocket. Does your N64?” We can’t fault him on that.

This isn’t the first portable N64 we’ve seen, but will it hold the title of smallest for long? Only time will tell.

Thanks [Matthew Carlson] for the tip.

source https://hackaday.com/2020/12/25/is-this-the-worlds-smallest-nintendo-64/

Tank Track Skateboard

As electric skateboards kits and components become more commonly available, you really need to do something different to make your custom board stand out. [Emiel] [The Practical Engineer] has managed to do this by building a half-track skateboard. (Video, embedded below.)

Except for the front trucks, fasteners and bearings, all the mechanical components on the board were custom-made. The sturdy rear chassis and the track sections were machined from aluminum plate, and the wheels and track linkages were machined from POM/Delrin. The large carbon fiber deck and the polyurethane pads on the tracks were custom molded, which [Emiel] covered in detail in separate videos, also below. Two beefy brushless motors drive the tracks and are powered by LiPos in enclosed in the sheet metal electronics box. The final product looks very well-built and refined, especially considering most of the work happened in a tiny 2 m x 3 m workshop.

It looks like the board handles gravel paths well, but we would really like to see how it performs on soft surfaces like sand, where even off-road skateboards can struggle. It struggled a bit with low RPM torque, so a slight gearing change is in this board’s future.

Everything is cooler with tank tracks. If you’re willing to live with plastic tracks, 3D printing is a viable option, as demonstrated by [rctestflight]’s tracked rover and [Ivan Miranda]’s tank  skateboard.

source https://hackaday.com/2020/12/25/tank-track-skateboard/

Control Theory Spellcasting Banishes the 3D Printing Ghosts

It seems as though we still can’t hit the ceiling on better control schemes for 3D Printers. Input Shaping is the latest technique to land on our radar, a form of resonance compensation that all but eliminates the ghosting (aka: vertical ringing) artifacts we see on the walls of printed parts. While the technique has been around for decades, only recently did [Dmitry Butyugin] both apply it to 3D printer control and merge their hard work into the open source firmware package Klipper. Once tuned, the results are simply astonishing–especially since this scheme can augment the print quality of even the most budget printer.

Input Shaping Demo Luke
A Split A/B Test with and without Klipper’s Input Shaping feature courtesy of [@LukesLaboratory]

Assuming your 3D printer isn’t infinitely stiff, when your nozzle moves from point to point or changes direction, it vibrates in response to having its speed altered. The result is that the nozzle wobbles along the ideal path it’s trying to track. The result is ghosting, an aesthetic blemish that looks like vertical waves on the sides of your printed part.

Input Shaping is a feed-forward controls technique for cancelling the mechanical vibrations that create ghosting. The idea is that, if we wanted to move the machine from point to point, we send it two impulses. The first impulse kicks the machine into moving and the second impulse follows up at a precise time to cancel the vibrations we would see when the machine comes to a stop. Albeit, moving any machine by sending it two impulses is pretty crude, so we take these impulses, adjust their amplitudes so that they sum to 1, and convolve them with a control input signal that we’d actually like to send it. The result is that the resonance cancellation part of the signal seamlessly “mixes” into the control input signal, and the machine moves from point to point with significantly less vibration at the end of the travel move. For more info on the maths behind this process, have a look at the first four pages of this paper from [Singh and Singhose].

The only hiccup is that you need to do some up-front system characterization of your 3D Printer running Klipper before you can take advantage of this technique. Thankfully the Klipper update comes with a set of step-by-step instructions for characterizing your machine up-front. After a couple test prints to measure the periodicity of your ringing, you can simply apply your measurement results to your config file, and you’re set.

Input Shaping is a prime example of “just wrap a computer around it!“–fixing hardware by characterizing and cancelling unwanted behaviors with software. If you’re hungry for more clever, characterized hardware control schemes, look no further than this Anti-Cogging algorithm for BLDC Motors. And for a video walkthrough of the Klipper implementation, have a look at [eddietheengineer]’s breakdown after the break.

Does your 3D Printer run Klipper? We’d love to see some of your Input Shaping results in the comments.

source https://hackaday.com/2020/12/24/control-theory-spellcasting-banishes-the-3d-printing-ghosts/

Control Theory Spellcasting Banishes the 3D Printing Ghosts

It seems as though we still can’t hit the ceiling on better control schemes for 3D Printers. Input Shaping is the latest technique to land on our radar, a form of resonance compensation that all but eliminates the ghosting (aka: vertical ringing) artifacts we see on the walls of printed parts. While the technique has been around for decades, only recently did [Dmitry Butyugin] both apply it to 3D printer control and merge their hard work into the open source firmware package Klipper. Once tuned, the results are simply astonishing–especially since this scheme can augment the print quality of even the most budget printer.

Input Shaping Demo Luke
A Split A/B Test with and without Klipper’s Input Shaping feature courtesy of [@LukesLaboratory]

Assuming your 3D printer isn’t infinitely stiff, when your nozzle moves from point to point or changes direction, it vibrates in response to having its speed altered. The result is that the nozzle wobbles along the ideal path it’s trying to track. The result is ghosting, an aesthetic blemish that looks like vertical waves on the sides of your printed part.

Input Shaping is a feed-forward controls technique for cancelling the mechanical vibrations that create ghosting. The idea is that, if we wanted to move the machine from point to point, we send it two impulses. The first impulse kicks the machine into moving and the second impulse follows up at a precise time to cancel the vibrations we would see when the machine comes to a stop. Albeit, moving any machine by sending it two impulses is pretty crude, so we take these impulses, adjust their amplitudes so that they sum to 1, and convolve them with a control input signal that we’d actually like to send it. The result is that the resonance cancellation part of the signal seamlessly “mixes” into the control input signal, and the machine moves from point to point with significantly less vibration at the end of the travel move. For more info on the maths behind this process, have a look at the first four pages of this paper from [Singh and Singhose].

The only hiccup is that you need to do some up-front system characterization of your 3D Printer running Klipper before you can take advantage of this technique. Thankfully the Klipper update comes with a set of step-by-step instructions for characterizing your machine up-front. After a couple test prints to measure the periodicity of your ringing, you can simply apply your measurement results to your config file, and you’re set.

Input Shaping is a prime example of “just wrap a computer around it!“–fixing hardware by characterizing and cancelling unwanted behaviors with software. If you’re hungry for more clever, characterized hardware control schemes, look no further than this Anti-Cogging algorithm for BLDC Motors. And for a video walkthrough of the Klipper implementation, have a look at [eddietheengineer]’s breakdown after the break.

Does your 3D Printer run Klipper? We’d love to see some of your Input Shaping results in the comments.

source https://hackaday.com/2020/12/24/control-theory-spellcasting-banishes-the-3d-printing-ghosts/

Fully Backlit AlphaSmart NEO2 Lights Up the Night

The AlphaSmart NEO and NEO2 are great little word processors for distraction-free writing anywhere you want to go, but they lack the backlight of the later Dana model. Well, [starboyk] has done what many thought impossible and added a backlight to a NEO2. Experience gained from a ton of console mods and repairs led to the question of whether the NEO2’s LCD is similar to a Game Boy’s.

[starboyk] started with a fresh NEO2 from ebay, then swapped out the reflective polarizer for a translucent polarizer and added a trio of LED backlights meant for the original Game Boy across the back of the screen. The best part is that the backlight has its own power switch and a brightness control pot. It sounds easy enough, but this mod is not for the faint of heart as it sounds like a really tight fit in the end. Apparently we only need 500 orders to get a custom backlight manufactured, but barring that does anyone know of a backlight that’s 157mm x 44mm?

You can always stick with the mod where you power the USB-A port and use a USB reading light like I did with my NEO.

source https://hackaday.com/2020/12/24/fully-backlit-alphasmart-neo2-lights-up-the-night/