Best Ways To Make PCB Breakaway Tabs, Revealed

April 9, 2022 by Donald Papp 20 Comments

Most of us are familiar with the concept of producing PCBs in a panel, and snapping them apart afterwards. V-grooves that go most of the way through a PCB are one way to go about this, but a line of perforations along which to snap a tab is another. But what’s the best size and spacing of holes to use? Sparkfun’s [Nick Poole] spent some $400 on PCBs to get some solid answers by snapping each of them apart, and judging the results.

The nice thing about creating a perforation line (or “mouse bites”) is that drill hits are a very normal thing in PCB production, which makes creating this kind of breakaway tab a very straightforward and flexible method. However, it can be tricky to get results that are just right. Too sturdy, and breaking apart is a hassle. Too weak, and the board may break or twist before its time. On top of that, edges must also break cleanly. We’ve covered panelizing PCBs in this way before, but this is the first time we’ve seen someone seriously look into how to create optimal breakaway tabs.

Placing holes tangent to the board edge (as shown above) isn’t the prettiest, but keeps PCB edges free from protrusions. This is best for boards that are rail-mounted, or have tight enclosures.

Data on designing mouse bites was sparse and a bit inconsistent, so [Nick] decided to figure it out empirically and share the results. The full details are available in Building a Better Mousebite (PDF download) but the essence of the recommendations are: 0.015″ unplated holes, spaced 0.025″ apart (center-to-center), tabs a maximum of 0.118″ wide (so as to be compatible with depanelizing tools), and holes that extend into the corners of the breakaway tab to avoid sharp edges. Holes should be placed slightly differently depending on whether one wishes to optimize the cosmetic appearance versus the physical smoothness of the board edge, but those numbers are the core of the guidelines.

To fine tune, [Nick] suggests increasing the spacing between holes to add strength, or just adding additional tabs. What about thickness of PCB? [Nick] tested boards both 0.8 mm and 1.6 mm thick, and while different amounts of torque were needed to snap the boards apart, things still worked as expected regardless of PCB thickness.

When it comes down to it, the best numbers will ultimately be the ones that your process or fab house can most efficiently handle, but [Nick]’s numbers should not steer anyone wrong, and it’s fantastic to see this kind of work go into refining such a common PCB feature.

Enjoy This Animatronic Eyeball’s Smooth Moves

April 8, 2022 by Donald Papp 10 Comments

[Enza3D] shows off a surprisingly compact articulated animatronic eyeball that can be intuitively controlled with a Wii nunchuk controller. The design uses 3D printed parts and some tiny servos, and all of the necessary electronics can be easily purchased online. The mechanical design of the eye is very impressive, and [Enza3D] walks through several different versions of the design, the end result of which is a tidy little assembly that would fit nicely into masks, costumes, or other projects.

A Wii nunchuk is ideal for manual control of such a device, thanks to its ergonomic design and ease of interface (the nunchuk communicates over I²C, which is easily within the reach of even most modest of microcontrollers.) Of course, since driving servos is also almost trivial nowadays, it doesn’t look like working this into an automated project would pose much of a challenge.

The eyeball looks great, but if you want to try for yourself, accessing the design files and code will set you back $10 which might look attractive if an eye like this is the missing link for a project.

On the other hand, enjoying the video (embedded below) and getting ideas from [Enza3D]’s design notes will only cost you a few minutes.

Continue reading “Enjoy This Animatronic Eyeball’s Smooth Moves” →

Turn Timing Diagrams Into ASCII Art, For Friendlier Pasting

April 4, 2022 by Donald Papp 21 Comments

We all use text-based fields at one time or another, and being limited to ASCII only can end up being a limitation. That’s what led [Luke Wren] to create asciiwave, a fantastic tool that turns WaveDrom timing diagrams into ASCII art. Unlike images, ASCII timing diagrams are suitable for pasting into comment fields, change logs, or anywhere else that accepts text only. [Update: As the author kindly shared in the comments below, this tool’s original niche is pasting into HDL (e.g. Verilog) source code comments, where it has a special kind of usefulness.]

WaveDrom itself is a nifty JavaScript tool that we have covered before. It accepts timing diagrams expressed as JSON data, and renders nicely-readable digital timing diagrams as images directly inside one’s browser.

As cool and useful as that is, images can’t be pasted into text fields. That’s where asciiwave comes in. It reads the exact same format that WaveDrom uses, but generates an ASCII-art timing diagram instead. So if you’ve found WaveDrom useful, but wish you could generate ASCII versions, here’s your solution.

Is Your Device Actually USB 3.0, Or Is The Connector Just Blue?

April 3, 2022 by Donald Papp 66 Comments

Discount (or even grey market) electronics can be economical ways to get a job done, but one usually pays in other ways. [Majenko] ran into this when a need to capture some HDMI video output ended up with rather less than was expected.

Faced with two similar choices of discount HDMI capture device, [Majenko] opted for the fancier-looking USB 3.0 version over the cheaper USB 2.0 version, reasoning that the higher bandwidth available to a USB 3.0 version would avoiding the kind of compression necessary to shove high resolution HDMI video over a more limited USB 2.0 connection.

The device worked fine, but [Majenko] quickly noticed compression artifacts, and interrogating the “USB 3.0” device with lsusb -t revealed it was not running at the expected speeds. A peek at the connector itself revealed a sad truth: the device wasn’t USB 3.0 at all — it didn’t even have the right number of pins!

A normal USB 3.0 connector is blue inside, and has both sets of pins for backward compatibility (five in the rear, four in the front) like the one shown here.

A USB 3.0 connection requires five conductors, and the connectors are blue in color. Backward compatibility is typically provided by including four additional conductors, as shown in the image here. The connector on [Majenko]’s “USB 3.0” HDMI capture device clearly shows it is not USB 3.0, it’s just colored blue.

Most of us are willing to deal with the occasional glitch or dud in exchange for low prices, but when something isn’t (and never could be) what it is sold as, that’s something else. [Majenko] certainly knows that as well as anyone, having picked apart a defective power bank module to uncover a pretty serious flaw.

Who Needs Yeast When You Have Lab Equipment?

March 26, 2022 by Donald Papp 32 Comments

This particular story on researchers successfully making yeast-free pizza dough has been making the rounds. As usual with stories written from a scientific angle, it’s worth digging into the details for some interesting bits. We took a look at the actual research paper and there are a few curious details worth sharing. Turns out that this isn’t the first method for yeast-free baking that has been developed, but it is the first method to combine leavening and baking together for a result on par with traditional bread-making processes.

Some different results from varying the amount of pressure released during the baking process.

Basically, a dough consisting of water, flour, and salt go into a hot autoclave (the header image shows a piece of dough as seen through the viewing window.) The autoclave pressurizes, forcing gasses into the dough in a process similar to carbonating beverages. Pressure is then released in a controlled fashion while the dough bakes and solidifies, and careful tuning of this process is what controls how the bread turns out.

With the right heat and pressure curve, researchers created a pizza whose crust was not only pleasing and tasty, but with a quality comparable to traditional methods.

How this idea came about is interesting in itself. One of the researchers developed a new method for thermosetting polyurethane, and realized that bread and polyurethane have something in common: they both require a foaming (proofing in the case of bread) and curing (baking in the case of bread) process. Performing the two processes concurrently with the correct balance yields the best product: optimized thermal insulation in the case of polyurethane, and a tasty and texturally-pleasing result in the case of pizza dough. After that, it was just a matter of experimentation to find the right balance.

The pressures (up to 6 bar) and temperatures (145° Celsius) involved are even pretty mild, relatively speaking, which could bode well for home-based pizza experimenters.

AI-Generated Sleep Podcast Urges You To Imagine Pleasant Nonsense

March 26, 2022 by Donald Papp 12 Comments

[Stavros Korokithakis] finds the experience of falling asleep to fairy tales soothing, and this has resulted in a fascinating project that indulges this desire by using machine learning to generate mildly incoherent fairy tales and read them aloud. The result is a fantastic sort of automated, machine-generated audible sleep aid. Even the logo is machine-generated!

The Deep Dreams Podcast is entirely machine-generated, including the logo.

The project leverages the natural language generation abilities of OpenAI’s GPT-3 to create fairytale-style content that is just coherent enough to sound natural, but not quite coherent enough to make a sensible plotline. The quasi-lucid, dreamlike result is perfect for urging listeners to imagine pleasant nonsense (thanks to Nathan W Pyle for that term) as they drift off to sleep.

We especially loved reading about the methods and challenges [Stavros] encountered while creating this project. For example, he talks about how there is more to a good-sounding narration than just pointing a text-to-speech engine at a wall of text and mashing “GO”. A good episode has things like strategic pauses, background music, and audio fades. That’s where pydub — a Python library for manipulating audio — came in handy. As for the speech, text-to-speech quality is beyond what it was even just a few years ago (and certainly leaps beyond machine-generated speech in the 80s) but it still took some work to settle on a voice that best suited the content, and the project gradually saw improvement.

Deep Dreams Podcast has a GitLab repository if you want to see the code that drives it all, and you can go to the podcast itself to give it a listen.

Learn All About Writing A Published Technical Book, From Idea To Print

March 19, 2022 by Donald Papp 3 Comments

Ever wondered what, exactly, goes into creating a technical book? If you’d like to know the steps that bring a book from idea to publication, [Sara Robinson] tells all about it as she explains what went into co-authoring O’Reilly’s Machine Learning Design Patterns.

Her post was written in 2020, but don’t let that worry you, because her writeup isn’t about the book itself so much as it is about the whole book-writing process, and her experiences in going through it. (By the way, every O’Reilly book has a distinctive animal on the cover, and we learned from [Sara] that choosing the cover animal is a slightly mysterious process, and is not done by the authors.)

It turns out that there are quite a few steps that need to happen — like proposals and approvals — before the real writing even starts. The book writing itself is a process, and like most processes to which one is new, things start out slow and inefficient before they improve.

[Sara] also talks a bit about burnout, and her advice on dealing with it is as insightful as it is practical: begin by communicating honestly how you are feeling to the people involved.

Over the years I’ve learned that people will very rarely guess how you’re feeling and it’s almost always better to tell them […] I decided to tell my co-authors and my manager that I was burnt out. This went better than expected.

There is a lot of code in the book, and it has its own associated GitHub repository should you wish to check some of it out.

By the way, [Sara] celebrated publication by making a custom cake, which you can see near the bottom of her blog post. This comes as no surprise seeing as she has previously managed to combine machine learning with her love of making cakes!