Solving Grounding Issues On Switch Audio

Grounding of electrical systems is an often forgotten yet important design consideration. Issues with proper grounding can be complicated, confusing, and downright frustrating to solve. So much so that engineers can spend their entire careers specializing in grounding and bonding. [Bsilvereagle] was running into just this sort of frustrating problem while attempting to send audio from a Nintendo Switch into a PC, and documented some of the ways he attempted to fix a common problem known as a ground loop.

Ground loops occur when there are multiple paths to ground, especially in wires carrying signals. The low impedance path creates oscillations and ringing which is especially problematic for audio. When sending the Switch audio into a computer a loop like this formed. [Bsilvereagle] set about solving the issue using an isolating transformer. It took a few revisions, but eventually they settled on a circuit which improved sound quality tremendously. With that out of the way, the task of mixing the Switch audio with sources from other devices could finally proceed unimpeded.

As an investigation into a nuisance problem, this project goes into quite a bit of depth about ground loops and carrying signals over various transforming devices. It’s a great read if you’ve ever been stumped by a mysterious noise in a project. If you’ve never heard of a ground loop before, take a look at this guide to we featured a few years ago.

Tube Tumbler Provides The Perfect Culture

We’ve all had to shake jars of nail polish, model paint, or cell cultures. Mixing paint is easy – but bacteria and cells need to be agitated for hours.  Happily, laboratory tube tumblers automate this for us. The swishing action is handled with rotation. The vials are mounted at angles around a wheel. The angular offset means the tubes are inclined as they rise, and declined as they fall. This causes the liquid in the tube to slosh from one side to the other as the wheel rotates.  [Sebastian S. Cocioba] aka [ATinyGreenCell] released his plans through Tinkercad and GitHub, and with a name like Sir Tumbalot, we know he must be cultured indeed.

Grab your monocles. Version 2 features a driven wheel lined with magnets to attach tube adapters, and he’s modeled 50mL and twin 15mL tube holders. The attachment points look like a simple beveled rectangle with a magnet pocket, so if you’re feeling vigorous for vials, you can whip up custom sockets and tumble any darn thing. A Trinamic StealthChop chip on a custom PCB controls the pancake stepper, and the whole shebang should cost less than $50USD. We’re wondering what other purposes this modular design could have, like the smallest rock tumbler or resin print rinser.

Making lab equipment is phenomenal for saving money for things that just spin up to a biotech lab.

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Hackaday Links: March 27, 2022

Remember that time back in 2021 when a huge container ship blocked the Suez Canal and disrupted world shipping for a week? Well, something a little like that is playing out again, this time in the Chesapeake Bay outside of the Port of Baltimore, where the MV Ever Forward ran aground over a week ago as it was headed out to sea. Luckily, the mammoth container ship isn’t in quite as narrow a space as her canal-occluding sister ship Ever Given was last year, so traffic isn’t nearly as impacted. But the recovery operation is causing a stir, and refloating a ship that was drawing 13 meters when it strayed from the shipping channel into a muddy-bottomed area that’s only about 6 meters deep is going to be quite a feat of marine engineering. Merchant Marine YouTuber Chief MAKOi has a good rundown of what’s going on, and what will be required to get the ship moving again.

With the pace of deep-space exploration increasing dramatically of late, and with a full slate of missions planned for the future, it was good news to hear that NASA added another antenna to its Deep Space Network. The huge dish antenna, dubbed DSS-53, is the fourteenth dish in the DSN network, which spans three sites: Goldstone in California; outside of Canberra in Australia; and in Madrid, where the new dish was installed. The 34-meter dish will add 8% more capacity to the network; that may not sound like much, but with the DSN currently supporting 40 missions and with close to that number of missions planned, every little bit counts. We find the DSN fascinating, enough so that we did an article on the system a few years ago. We also love the insider’s scoop on DSN operations that @Richard Stephenson, one of the Canberra operators, provides.

Does anybody know what’s up with Benchy? We got a tip the other day that the trusty benchmarking tugboat model has gone missing from several sites. It sure looks like Sketchfab and Thingiverse have deleted their Benchy files, while other sites still seem to allow access. We poked around a bit but couldn’t get a clear picture of what’s going on, if anything. If anyone has information, let us know in the comments. We sure hope this isn’t some kind of intellectual property thing, where you’re going to have to cough up money to print a Benchy.

Speaking of IP protections, if you’ve ever wondered how far a company will go to enforce its position, look no further than Andrew Zonenberg’s “teardown” of an anti-counterfeiting label that Hewlett Packard uses on their ink cartridges. There’s a dizzying array of technologies embedded inside what appears to be a simple label. In addition to the standard stuff, like the little cuts that make it difficult to peel a tag off one item and place it on another — commonly used to thwart “price swapping” retail thefts — there’s an almost holographic area of the label. Zooming in with a microscope, the color-shifting image appears to be made from tiny hexagonal cells that almost look like the pixels in an e-ink display. Zooming in even further, the pixels offer an even bigger (smaller) surprise. Take a look, and marvel at the effort involved in making sure you pay top dollar for printer ink.

And finally, we got a tip a couple of weeks ago on a video about jerry cans. If that sounds boring, stop reading right now — this one won’t reach you. But if you’re even marginally interested in engineering design and military history, make sure you watch this video. What is now known to the US military as “Can, Gasoline, Military 5-Gallon (S/S by MIL-C-53109)” and colloquially known as the NATO jerry can, started life as the Wehrmacht-Einheitskanister, a 20-liter jug whose design addresses a long list of specifications, from the amount of liquid it could contain to how the cans would be carried. The original could serve as a master class in good design, and some of the jugs that were built in the 1940s are still in service and actively sought by collectors of militaria. Cheap knockoffs are out there, of course, but after watching this video, we’ve developed a taste for jerry cans that only the original will sate.

A 3D-printed Portal Turret

3D Printed Portal Turret Moves And Talks Like The Real Thing

Thanks to its innovative gameplay and quirky humor, Portal became an instant hit when it was released in 2007. Characters became cultural icons, quotes became memes and the game became a classic along with its 2011 sequel. Even today, more than a decade later, we regularly see hackers applying their skills in recreating some of the game’s elements. One beautiful example is [Joran de Raaff]’s physical rendition of a Portal Turret.

A 3D CAD drawing of a Portal Turret
Inside the Turret it’s full of moving parts.

[Joran] decided to use his 3D printer to create a Turret that can move and speak exactly as it does in the game. The result, as you can see in the video embedded below, was a triumph. We’re making a note here, “huge success”. The outer shell is a beautiful shiny white, an effect achieved through patient sanding, priming, and spraying with high-gloss paint. The internals are even more impressive with servos, microswitches, and a whole array of 3D-printed gears, cams, and levers.

A motion sensor activates the Turret whenever a human moves nearby. It will then open its wings and fire its guns while playing the corresponding sounds from the game. Its brains are formed by a Wemos D1 which drives the various LEDs and servos, while an MP3 player board holds a library of sound bites and plays them through a speaker hidden inside the Turret’s shell.

After posting his creation on YouTube [Joran] got many requests for the 3D files, so he made them available and wrote a comprehensive build guide. This should enable anyone with a 3D printer to build this neat gun, without getting too much science done. If this model is too small for you, then perhaps this life-sized model is more to your liking. If you prefer your Turret small and cute, check out this plushie version.

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3D Printed Forge For Recycling

If you own a CNC and have kept tabs on metal prices these past few years (honestly months), you might shed a small tear as you watch chips fly off your work and into the trash. With a sigh, these flecks and pieces are consigned to be the cost of machining a part. Thankfully, the fine folks at [ActionBox] have been working on a 3d printed plaster forge for recycling their metal scraps.

The team ordered some graphite crucibles of a few sizes from a large online bookstore and started 3D printing some molds for crucible holders. They started with a smaller version to try the method. While the walls were too thin in that initial version, the approach was proven. With slightly thicker walls, the medium-sized version worked much better. The goal of the forge was to smelt copper as they had a lot of thick copper wire lying around. Armed with several propane torches, they started melting aluminum and brass, which worked reasonably well. However, the melting point of copper continued to elude them (1984°F or 1085°C).  To counter this, the [ActionBox] team bought some new torches that provided significantly higher BTU output, while still fitting the holes in the mold. This did the trick!

The mold to accommodate the large crucible was massive and printed in four sections. The team did melt copper successfully and had four ingots to show off. We want to stress how dangerous molten copper and other metals are, particularly regarding things you might not realize have moisture soaked up inside. Proper PPE is essential to use these things without getting hurt. [ActionBox] has some helpful pointers in that area, but they admit they are relatively new to forging and casting themselves. Perhaps version two can incorporate a flip lid for added safety.

Video after the break.
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ESP32 composite library with LVGL demo. (Credit: aquaticus)

Generating Composite Video On ESP32 With LVGL GUI

RCA connector mounted to ESP32 board. (Credit: aquaticus)
RCA connector mounted to ESP32 board. (Credit: aquaticus)

Just because a microcontroller doesn’t have a dedicated video peripheral doesn’t mean it cannot output a video signal. This is demonstrated once again, this time on the ESP32 by [aquaticus] with a library that generates PAL/SECAM and NTSC composite signals. As a finishing touch on the hardware side, [aqaticus] added an RCA jack is an optional extra. The composite signal itself is generated on GPIO 25, with the selection from a wide number of PAL and NTSC resolutions.

In addition, LVGL support is integrated: this is an open-source library that provides a cross-platform way to provide graphical UIs for embedded platforms. Using this combination any ESP32 can generate a fully graphical UI on a monochrome or color display to add some extra flair and functionality to an ESP32 project.

Currently, this library does not support color output, but hopefully this will be added in the future. Even so, together with simple VGA output using a DAC, this library provides yet another way to add analog video output to ubiquitous MCUs like the ESP32. Even if these MCUs are not going to be decoding any video formats at a reasonable speed, adding a UI that’s more user-friendly than an HD44780-based display and a few buttons can really elevate the user experience.

Chris playing his tiny pinball machine

Tiny Pinball Is As Cute As Pi

Pinball machines are large, complex, and heavy boxes of joy and delight. However, when you don’t have the money or space for one, you have to make your own mini Raspberry Pi-powered one.

With access to a local makerspace and a bit of extra free time, [Chris Dalke] had plans to capture the flavor of a full-scale pinball machine in a small package. Laser-cut Baltic birch forms the enclosure, and a screen makes up the playing field rather than a physical ball. An Arduino Uno handles the three buttons, the four LED matrixes, and a solenoid for haptic feedback, communicating

with the Pi via serial. Unfortunately, even with a relatively decent

volume inside, it is still a tight squeeze.

Rather than use an off-the-shelf pinball game, [Chris] wrote his own in C using raylib and raygui, two handy libraries that can be included in the project quickly. SQLLite3 writes high scores out to disk. All in all, an inspiring project that has a very high level of polish.

If you’re looking for a tiny pinball machine but want more of the classic pinball feel, why not look at this scale pinball machine?

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