Author: Al Williams

4504 Articles

Aircraft Compass Teardown

May 30, 2021 by 6 Comments

We didn’t know what a C-2400 LP was before we saw [David’s] video below, but it turned out to be pretty interesting. The device is an aircraft compass and after replacing it, he decided to take it apart for us. Turns out, that like a nautical compass, these devices need adjustment for all the metal around them. But while a ship’s compass has huge steel balls for that purpose, the tiny and lightweight aviation compass has to be a bit more parsimonious.

The little device that stands in for a binnacle’s compensators — often called Kelvin’s balls — is almost like a mechanical watch. Tiny gears and ratchets, all in brass. Apparently, the device is pretty reliable since the date on this one is 1966.

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Spell Checking Your Programming From The Linux Command Line

May 29, 2021 by 17 Comments

For most of us who didn’t do well in high school English class, spell checkers are a real game-changer. Sure, you can still swap a “to” and a “too,” but a spell checker will catch a lot of typos. But what about in your source code? You usually don’t spell check source code and even if you did, the rules are funny. After all, “my_proejct” is a perfectly fine variable name, but you probably meant “my_project.” That’s where a program called typos comes in. It aims to be a spell checker for source code that is fast enough and with a low enough false positive rate that you can run it against changed code and reject spelling problems.

Sure, if “my_proejct” is a one-time typo, the compiler or interpreter will probably catch it. But it won’t catch comments and it also won’t catch something you spell wrong consistently. For that you need something like typos.

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Build A New ZX81

May 28, 2021 by 17 Comments

[Retro Shack’s] ZX81 died, and while he tried to figure out the fix, he decided to build a new one. Of course, building a circa-1980-something computer from new parts is a bit daunting. Unless you start with an existing design that has it all ready to put together.

The PCB looks great and we like that the silkscreen shows acknowledgments of projects that helped the designer, [Alejandro Sebastian]. The case is, of course, 3D printed. At first, the power LED didn’t work, but voltages looked correct and the board powered up.

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Web Assembly, Music Synthesis, And The Beauty Of Math

May 28, 2021 by 9 Comments

The electronics hobby has changed a lot since the advent of the microprocessor. Before that — and with the lack of large-scale integrated circuits — projects in magazines tended to be either super simple or ultra complex. However, one popular type of project dealt with music synthesis. Fairly simple circuits could combine to make a complex synthesizer so it was sort of the best of both worlds. Nowadays, you are more likely to tackle a music synthesizer in software like [Tim] did when he created Abelton in Web Assembly and C++. Along the way, he learned a lot about the relationship between math and music.

[Tim] covers what he learned about the Nyquist theorem and how to keep synthesis data flowing in real time with buffers. However, there are some problems trying to do all this in a cross-browser context. The AudioWorklet class appears to have widespread support, though, and [Tim] managed to get that working.

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Finite Element Analysis Vs Real World

May 27, 2021 by 15 Comments

In advanced engineering circles, the finite element method — or, more commonly, finite element analysis — is a real staple. With the advent of more powerful home computers, though, even your home projects can benefit. The technique itself is very general, but you usually see it used for structural analysis. However, you might wonder how well it corresponds to reality. That is if analysis shows a segment of your part is weak (or strong) does that hold true when you actually build the part? [Fiveohno] wondered the same thing and decided to do some testing, which you can see in the video below.

Of course, like any simulation, the accuracy will only be as good as your data input and model. But if you work carefully, it should match up pretty well to the real world, so it is interesting to see the results of a real-world test. In fact, a video from Solidworks that shows a similar part points out — inadvertently — what not to do. For example, the force used in that analysis was too low and at a point where the part was at relatively low stress instead of at the maximum stress.

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Ptychography Shows Atoms At Amazing Resolution

May 25, 2021 by 34 Comments

Cornell University enhanced electron microscopy using a technique known as ptychography in 2018. At the time, it allowed an electron microscope to resolve things three times smaller than previously possible. But that wasn’t enough. The team has now doubled that resolution by improving on their previous work.

The team says that the images are so precise that the only blurring is due to the thermal motion of the atoms themselves. This could mean that you won’t see a further improvement in resolution in the future.

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Getting Started With Aluminum Extrusions

May 25, 2021 by 64 Comments

T-slot extrusions used to be somewhat mysterious, but today they are quite common thanks to their use in many 3D printers. However, it is one thing to assemble a kit with some extrusions and another thing to design your own creations with the material. If you ever had a Play-Doh Fun Factory as a kid, then you know about extrusions. You push some material out through a die to make a shape. Of course, aluminum extrusions aren’t made from modeling clay, but usually 6105-T5 aluminum. Oddly, there doesn’t seem to be an official standard, but it is so common that there’s usually not much variation between different vendors.

We use extrusions to create frames for 3D printers, laser cutters, and CNC machines. But you can use it anywhere you need a sturdy and versatile frame. There seems to be a lot of people using them, for example, to build custom fixtures inside vans. If you need a custom workbench, a light fixture, or even a picture frame, you can build anything you like using extrusions. Continue reading “Getting Started With Aluminum Extrusions” →