Mysterious Files PH

Measuring electric currents is an essential element of many electrical systems, but doing so in a way that is as nonintrusive as possible is not an easy problem to solve. Due to this we got a wide variety of current sensors to choose from for any given application, with [ElectrArc240] running us through these variants in a recent video.

The fairly low-tech, cheap and quite reliable method of using a shunt resistor is first demonstrated. This sees a lot of use in fairly low-voltage and low-current applications, with for example videocards using it to limit the amount of power the GPU can use, a feature that modders will happily bypass. Here simply the voltage drop across a known resistance value is measured, from which the current can be derived.

Of course, you got higher voltage and higher current applications too, as well as direct- and alternating current, with the latter especially allowing for easy current measurements simply from the electromagnetic field, or flux. Anyone who has used a clamp meter can attest to that such contact-free current sensing works, even for DC applications.

Beyond the basic transformer type you got many variants including Hall-Effect, TMR and fluxgate sensors, as well as the fiber-optic current sensor that uses an interferometer to measure the phase-change induced by the magnetic field – the Faraday effect – to the transmitted electromagnetic radiation. These more exotic types will improve resolution, at the cost of a rapidly increasing void in your project budget.

These various sensor types and their construction are demonstrated and discussed in the video, including when you’d want to use a specific type, and what the potential gotchas are with each type. Even if for many applications a simple shunt resistor suffices, it’s a good idea to know these different types, as well as their underlying theory of operation.

The Philips CD-i was not popular upon its launch in 1991, and is barely acknowledged today. In the opinion of [MattKC], it had a particularly poor selection of controllers, too, and it’s often hard to find used examples anyway. To rectify this situation, he whipped up an adapter to let him use Sega Genesis controllers instead.

The benefit of the Genesis controller is that it uses DB-9 connectors that are readily available, and it’s got a simple pinout that is compatible with the Atari joystick port, too. It makes interfacing the controllers supremely easy. Converting the controllers required using a Arduino Pro Micro to read the Genesis pad and translate it into something suitable for the CD-i.

On the Sega controller side, the microcontroller just has to strobe one pin while reading the state of others to determine what all the buttons are doing. The CD-i, however, expects a serial data stream from the original Philips controllers. Thus, the microcontroller is set up to poll the Genesis controller, and then translate this into the serial commands for the CD-i. It gets a little complicated, because the CD-i wasn’t really built for game controllers, but mouse-like inputs instead. But it’s not too hard to get things working once you understand what the weird Philips console is looking for.

There aren’t really any good games on the CD-i, so this isn’t a project that the retro gaming masses will be flocking to. Still, if you have a CD-i and you want to hook up some controllers on the cheap, this might come in handy. Alternatively, you could also try the BlueRetro project.

We don’t generally think of 3D printing and knitting in the same sentence. One uses threads and fine motor control, while the other requires great knowledge of pressing buttons and plastics. That said, they both entail stacking material over and over until a finished product emerges. So why not blend the two crafts together? [Joram de Haas] decided to work on just that in the form of FilaLoom.

This isn’t the first time we have seen additional elements embedded into 3D printed parts here on Hackaday. However, this particular implementation has some extra features which allow the embedded structures to grow larger than most examples prior. Instead of placing any implements directly into a structure by hand, all thread is placed by a tool head not so different from tool-changer printers. Using both the 3D printing tool head and the thread tool, some truly interesting properties can emerge from the finished product. If you aren’t interested in the weird webbing properties themselves, you surely could appreciate the possibilities demonstrated by the 3D knits.

You might not have a specific use case for thread printing, but why not check out some other fancy 3D printing techniques? Here’s a group of various design techniques that will certainly make you think twice in your next design!

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Thanks [Sam Smith] for the tip!

Broadcast radio isn’t as popular as it once was, its popularity suffering in turn due to technologies like MP3 players and music streaming services. If you don’t fancy either of those, you might like to listen to some internet radio stations, using a rig like the one [CodersCafeTech] built.

It’s a simple desktop radio set, but instead of tuning in to AM or FM broadcast bands, it has an antenna for 2.4 GHz instead. That’s because inside this radio is an ESP32-S3 development board, which is equipped with onboard WiFi hardware that lets it connect to the internet. It’s hooked up to a 1.3-inch OLED display over I2C, which acts as a user interface in concert with a rotary encoder. Sound is handled with a MAX98357 I2S audio amplifier, hooked up to a small 3 W speaker. Once programmed appropriately, all the unit needs is a WiFi SSID and password, and the URL for the internet radio station you’d like to listen to.

We’ve featured a few internet radio builds over the years, as well as a rather fun build that saw a Macintosh SE/30 hooked up to Spotify. If you’re tinkering with something along those lines, don’t hesitate to let us know on the tipsline!

If you have developed in Pascal or Delphi in the past decades, you’re probably familiar with the Lazarus IDE that provides an interface to the Free Pascal Compiler (FPC), much like Delphi’s IDE. For users of Lazarus IDE there’s now an exciting new development, with the announcement that FPC and Lazarus now support dynamic packages.

The upshot of this is that you no longer need to rebuild the IDE if you want to add components, controls and Lazarus extensions. In addition you can use this same dynamic package feature in your own Pascal applications this way.

Naturally this is a great improvement, and it’s good to see more improvements to such a venerable programming language. Not only is it still being used today for just about anything, including web development, but there is a good case to be made for using Pascal today as it’s no longer the language it was half a decade ago.

We’d also be remiss to not mention the legacy of [Niklaus Wirth], who not only created Pascal, but was also instrumental in the development of Object Pascal together with Apple. This effort ultimately led to everything from Turbo Pascal to Delphi, FPC and so much more, making it a heartening sight to see this legacy being kept alive today.

When most radio enthusiasts start trying to pick up signals from satellites, they might put together a quick-and-dirty Yagi antenna and try to catch a repeater as is passes overhead, or they might grab a small unused dish from a satellite TV service and point it up at a weather satellite by hand to try to decode some of the data coming down. But [Cranktown City] had a different approach. He found an eight-foot dish online and built a massive articulating base station out of it as his first exploration into the world of satellites.

The first problem that needs to be solved with a dish of this size is its mounting location. This installation uses a large post and concrete foundation with a custom-fabricated metal base at the bottom. The metal base houses all of the electronics not just for receiving signals from the dish, but also for orienting it properly. That includes a large metal gear driven by a wheelchair motor to control its azimuth and a linear actuator to take care of its elevation. Getting the large dish onto the frame was its own ordeal, complicated by the fact that it’s not uniform in its shape and has to be mounted in a specific orientation.

With everything assembled, the circularly-polarized antenna installed, and the computers up and running, the dish is able to track satellites across the sky and download data from things like GOES weather satellites. [Cranktown City] also built in a system that detects wind and points the dish vertically when it goes above a certain speed. This level of effort is impressive, and absolutely not required to listen in on plenty of sattelite activity out in the sky, but this installation will certainly give [Cranktown City] a lot of mileage and possibly even work for some radio astronomy.

One could make a joke about how an astronaut walking on the lunar surface is rather akin to a cat walking on the carpet in the living room, but out in space the resulting triboelectric discharge can do a lot more damage than just some stinging fingers and a bemused looking cat.

The problem that NASA and other space agencies are dealing with is that the charge that builds up on a lunar-walking astronaut is very hard to equalize with something like a lunar lander. For this reason they have now set up the Lunar Grounding Challenge to consult the public whilst dangling $150,000 of rewards in front of anyone ready to pounce with a good idea.

Here on Earth we got many ways in which we can get rid of such an unwanted charge, with dry winter weather demonstrating quite effectively why humidity is a crucial factor here. With no real atmosphere on the Moon, each astronaut thus becomes a walking capacitor, which is worsened when said astronaut ventures outside of the sunlit areas and then returns to the slightly positively charged lander.

The challenge here is thus to equalize the astronaut and lander, with a design specification of a -100 kV or higher astronaut and about 100 V lander. A resulting current should not exceed 1 mA, ideally less than 0.2 mA to remain below human perception levels. If an arc exists it should not contact the suit or astronaut.

Of course, the most low-tech solution would be to use a resistor to limit the current, but at those voltage ranges it would take an awful long time to bleed off, in an environment that’s basically a perfect insulator as space will never be cold. It definitely seems like a fun challenge to sink one’s fangs into.