M1 Development Board From Scraps

May 18, 2024 by Bryan Cockfield 1 Comment

Apple is fairly notorious for building devices that are difficult to repair, but with the right tools it’s often not completely impossible to circumvent some of their barriers. As they say, every lock has a key. [dosdude1] has wanted a specific M1 development board for a while now and has been slowly piecing together everything he needs to cobble one together, and finally got this unit running despite many roadblocks put in his way by Apple.

The development kit is a Developer Transition Kit or “DTK” meant for developers during Apple’s transition from Intel chips to their own in-house ARM-based M1 platform. This particular version is in a Mac Mini form factor but it has a few hurdles to clear before it powers on. First, the board was cut in a critical location that shorted out many of the PCB layers, so this had to be carefully filed down to remove the shorts. It was also missing a few tiny surface mount components and a NAND chip, but these were scavenged from other scrapped parts and assembled into a fully working machine.

There are a number of other non-physical problems to solve here as well, too. Apple coded their NAND chips to work with specific WiFi modules so if these aren’t programmed to work together the computer will get stuck in a boot loop. But with that and a few other details out of the way [dosdude1] finally has his DTK up and running in a 2018 Mac Mini chassis, right down to the working power LEDs. We’ve seen all kinds of PCB damage before (although not often quite this intricate) and even PCBs repaired that were snapped in half.

Thanks to [CodeAsm] for the tip!

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Hack Your Own Adventure Story With Yarn Spinner

May 18, 2024 by Al Williams 1 Comment

We are big fans of programmed texts for education. You know, the kind where you answer a question and go to a new page based on your answer. But they can also be entertaining “choose your own adventure” stories. You might say, “You are standing in front of an oak door, two meters high, with an iron handle. Do you a) open it? b) knock on it? c) ignore it?” Then, based on your answer, you go to a different part of the story. These are tough to write, but you can get some help using Yarn Spinner and the Yarn scripting language.

The original purpose of Yarn is to produce conversations for games. There’s a tutorial for that. The difference is to produce a book, you get a choose your own adventure PDF at the end. For the tutorial, you can try to read the text on the left-hand side of the editor or just press Test (at the top) and let it “read” the tutorial to you, which is a little more fluid.

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How Italians Got Their Power

May 18, 2024 by Jenny List 11 Comments

We take for granted that electrical power standards are generally unified across countries and territories. Europe for instance has a standard at 230 volts AC, with a wide enough voltage acceptance band to accommodate places still running at 220 or 240 volts. Even the sockets maintain a level of compatibility across territories, with a few notable exceptions.

It was not always this way though, and to illustrate this we have [Sam], who’s provided us with a potted history of mains power in Italy. The complex twists and turns of power delivery in that country reflect the diversity of the power industry in the late 19th and early 20th century as the technology spread across the continent.

Starting with a table showing the impressive range of voltages found across the country from differing power countries, it delves into the taxation of power in Italy which led to two entirely different plug standards, and their 110/220 volt system. Nationalization may have ironed out some of the kinks and unified 220 volts across the country, but the two plugs remain.

Altogether it’s a fascinating read, and one which brings to mind that where this is being written you could still find a few years ago some houses with three sizes of the archaic British round-pin socket. Interested in the diversity of plugs? We have a link for that.

Students’ Leaf Blower Suppressor To Hit Retail

May 18, 2024 by Tom Nardi 26 Comments

Electric leaf blowers are already far quieter than their gas-powered peers, but they still aren’t the kind of thing you’d like to hear first-thing on a Saturday morning. Looking to improve on the situation, a group of students from Johns Hopkins University have successfully designed a 3D printed add-on that manages to significantly reduce the noise generated by a modern electric leaf blower without compromising the amount of air it’s able to move. The device has proven to be so successful in tests that Stanley Black & Decker is looking to put a commercial version of the device on store shelves within the next two years.

The team says the first part of the problem was identifying where the noise was actually coming from. After taking an example leaf blower apart and studying all of its moving components, they determined that most of the noise produced wasn’t mechanical at all — what you’re actually hearing is the complex cacophony of high-speed air rushing out of the nozzle. With this knowledge in hand, they isolated the frequencies which were the harshest to the human ear and focused on canceling them out.

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About Right

May 18, 2024 by Elliot Williams 2 Comments

I really enjoyed reading Anne Ogborn’s piece on making simple DIY measurement devices for physical quantities like force, power, and torque. It is full of food for thought, if you’re building something small with motors and need to figure out how to spec them out.

Aside from a few good examples, what I really took home from this piece is how easy it can be to take approximate measurements. Take the push stick, which is a spring-loaded plunger in a transparent barrel. You use it to measure force by, well, squeezing the spring and reading off how far it deflects. That’s obvious, but the real trick is in calibration by pushing it into a weighing scale and marking divisions on the barrel. That quickly and easily turns “it’s pressing this hard” into an actual numerical force measurement.

The accuracy and precision of the push stick are limited by the quality of your scale and the fineness of the pen tip that you use to mark the barrel. But when you’re just looking to choose among two servo motors, this kind of seat-of-the-pants measure is more than enough to buy the right part. Almost any actual measurement is better than a wild-ass guess, so don’t hold yourself to outrageous standards or think that improvised quantitative measurement devices aren’t going to get the job done.

Al Williams quoted a teacher of his as saying that the soul of metrology is “taking something you know and using it to find something you don’t know”, and that sums up this piece nicely. But it’s also almost a hacker manifesto: “take something you can do and use it to do something that you can’t (yet)”.

Got any good measurement hacks you’d like to share?

Flexures Keep This Printed Displacement Sensor In Line

May 18, 2024 by Dan Maloney 4 Comments

When the job at hand is measuring something with micron-range precision, thoughts generally turn to a tool with a Mitutoyo or Starrett nameplate. But with a clever design and a little electronics know-how, it turns out you can 3D print a displacement sensor for measuring in the micron range for only about $10.

While the tool that [BubsBuilds] came up with isn’t as compact as a dial indicator and probably won’t win any industrial design awards, that doesn’t detract from its usefulness. And unlike a dial indicator — at least the analog type — this sensor outputs an easily digitized signal. That comes courtesy of a simple opto-interrupter sensor, which measures the position of a fine blade within its field of view. The blade is attached to a flexure that constrains its movement to a single plane; the other end of the flexure has a steel ball acting as a stylus. In use, any displacement of the stylus results in more or less light being received by the phototransistor in the opto-interrupter; the greater the deflection, the less light and the lower the current through the transistor. In addition to the sensor itself, [Bub] printed a calibration jig that allows precision gauge blocks or simple feeler gauges to be inserted in front of the stylus. The voltage across the emitter resistor for these known displacements is then used to create a calibration curve.

[Bub] says he’s getting 5-micron repeatability with careful calibration and multiple measurements of each gauge block, which seems pretty impressive to us. If you don’t need the digital output, this compliant mechanism dial indicator might be helpful too. Continue reading “Flexures Keep This Printed Displacement Sensor In Line” →

NetBSD Bans AI-Generated Code From Commits

May 18, 2024 by Maya Posch 30 Comments

A recent change was announced to the NetBSD commit guidelines which amends these to state that code which was generated by Large Language Models (LLMs) or similar technologies, such as ChatGPT, Microsoft’s Copilot or Meta’s Code Llama is presumed to be tainted code. This amendment was to the existing section about tainted code, which originally referred to any code that was not written directly by the person committing the code, and was due to licensing concerns. The obvious reason behind this is that otherwise code may be copied into the NetBSD codebase which may have been licensed under an incompatible (or proprietary) license.

In the case of LLM-based code generators like the above-mentioned, the problem stems from the fact that they are trained on millions of lines of code from all over the internet, which are naturally released under a wide variety of licenses. Invariably, some of that code will be covered by a license that’s not acceptable for the NetBSD codebase. Although the guideline mentions that these auto-generated code commits may still be admissible, they require written permission from core developers, and presumably an in-depth audit of the code’s heritage. This should leave non-trivial commits that got churned out by ChatGPT and kin out in the cold.

The debate about the validity of works produced by current-gen “artificial intelligence” software is only just beginning, but there’s little question that NetBSD has made the right call here. From a legal and software engineering perspective this policy makes perfect sense, as LLM-generated code simply doesn’t meet the project’s standards. That said, code produced by humans brings with it a whole different set of potential problems.