ChatGPT Powers A Different Kind Of Logic Analyzer

April 6, 2023 by 17 Comments

If you’re hoping that this AI-powered logic analyzer will help you quickly debug that wonky digital circuit on your bench with the magic of AI, we’re sorry to disappoint you. But if you’re in luck if you’re in the market for something to help you detect logical fallacies someone spouts in conversation. With the magic of AI, of course.

First, a quick review: logic fallacies are errors in reasoning that lead to the wrong conclusions from a set of observations. Enumerating the kinds of fallacies has become a bit of a cottage industry in this age of fake news and misinformation, to the extent that many of the common fallacies have catchy names like “Texas Sharpshooter” or “No True Scotsman”. Each fallacy has its own set of characteristics, and while it can be easy to pick some of them out, analyzing speech and finding them all is a tough job.

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Even Amstrad Spectrums Need Their Bugs Fixing

April 6, 2023 by 2 Comments

The history of the Sinclair ZX Spectrum is one that mirrors the fortunes of the British home computer industry, one of an early 8-bit boom followed by a sharp decline as manufacturers failed to capitalise on the next generation of 16-bit machines. The grey ZX Spectrum on [Keri Szafir]’s bench is one that encapsulates that decline perfectly, being one of the first models produced under the ownership of Amstrad after Sir Clive’s company foundered. Amstrad made many improvements to the Spectrum, but as she demonstrates, there are still some fixes needed.

The machine came her way because of a hum from the tape deck circuitry. The read amplifier was picking up electrical noise, and she fixed it without mods to the circuit but with the simple expedient of powering the analogue circuit from the tape motor switch so it only works when needed.

Beyond that, this machine demonstrates another ’80s innovation, the SCART/Peritel AV connector. These first appeared on early-80s French TV sets, but by the later half of the decade had made it to the UK where Amstrad included support for an adapter cable from the DIN socket on the back of their Spectrum.  Even then they didn’t get it quite right, and she modifies some links on the board to better support it.

Sinclair were famous for on-board bodges, and even in new ownership continued. There’s a reversed transistor and at least one bodged-on component, but of course, it wouldn’t be a Spectrum without bugs, would it!

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Printing Antennas On Circuit Boards

April 6, 2023 by 19 Comments

Yagi-Uda antennas, or simply “Yagis”, are directional antennas that focus radio waves to increase gain, meaning that the radio waves can travel further in that direction for a given transmitter power. Anyone might recognize an old TV antenna on a roof that uses this type of antenna, but they can be used to increase the gain of an antenna at any frequency. This one is designed to operate within the frequencies allotted to WiFi and as a result is so small that the entire antenna can be printed directly on a PCB.

The antenna consists of what is effectively a dipole antenna, sandwiched in between a reflector and three directors. The reflector and directors are passive elements in that they interact with the radio wave to focus it in a specific direction, but the only thing actually powered is the dipole in the middle. It looks almost like a short circuit at first but thanks to the high frequencies involved in this band, will still function like any other dipole antenna would. [IMSAI Guy], who created the video linked above which goes over these details also analyzed the performance of this antenna and found it to be fairly impressive as a WiFi antenna, but he did make a few changes to the board for some other minor improvements in performance.

The creator of these antennas, [WA5VJB] aka [Kent Britain] is an antenna builder based in Texas who has developed a few unique styles of antennas produced in non-traditional ways. Besides this small Yagi, there are other microwave antennas available for direction-finding, some wide-band antennas, and log-periodic antennas that look similar to Yagi antennas but are fundamentally different designs. But if you’re looking to simply extend your home’s WiFi range you might not need any of these, as Yagi antennas for home routers can be a lot simpler than you ever imagined.

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Supercon 2022: Chris Combs Reveals His Art-World Compatibility Layer

April 4, 2023 by 12 Comments

[Chris Combs] is a full time artist who loves using technology to create unique art projects and has been building blinky artwork since about a decade now. In his 2022 Supercon talk “Art-World Compatibility Layer: How to Hang and Sell Your Blinky Goodness as Art” (Slides, PDF), [Chris] takes us behind the scenes and shows us how to turn our blinky doodads in to coveted art works. There is a big difference between a project that just works, and a work of art, and it’s the attention to small details that differentiates the two.

Just like the field of engineering and technology, the art world has its own jargon and requires knowledge of essential skills that make it intimidating to newcomers. It’s not very easy to define what makes an artwork “art” or even “Art”, and sometimes it’s difficult to distinguish if you are looking at a child’s scrawls or a master’s brushstrokes. But there are a few distinguishing requirements that a piece of artwork, particularly one revolving around the use of technology, must meet.

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Tour A PCB Assembly Line From Your Armchair

April 2, 2023 by 15 Comments

Those of us who build our own electronics should have some idea of the process used to assemble modern surface-mount printed circuit boards. Whether we hand-solder, apply paste with a syringe, use a hotplate, or go the whole hog with stencil and oven, the process of putting components on boards and soldering them is fairly straightforward. It’s the same in an industrial setting, though perhaps fewer of us will have seen an industrial pick-and-place line in action. [Martina] looks at just such a line for us, giving a very accessible introduction to the machines and how they are used. Have a look, in the video below the break.

It’s particularly interesting as someone used to the home-made versions of these machines, to see the optical self-alignment and the multiple pick-and-place tools which are beyond the simpler pick-and-place machines you’ll find in a hackerspace. Multiple machines in a line are also beyond hackerspaces, so the revelation that the first machine is deliberately run slowly to avoid the line backing up is a valuable one.

At the end of the line is the reflow oven itself, through which the boards pass on a belt through carefully graded hot air zones. Certainly a step up from a toaster oven with an Arduino controller!

Sadly not all of us will be lucky enough to have such a line at our disposal, but pick-and-place projects come up here quite often. We did a teardown on the feeders from a Siemens machine a couple of years ago.

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See Satellites In Broad Daylight With This Sky-Mapping Dish Antenna

March 31, 2023 by 16 Comments

If you look up at the night sky in a dark enough place, with enough patience you’re almost sure to see a satellite cross the sky. It’s pretty cool to think you’re watching light reflect off a hunk of metal zipping around the Earth fast enough to never hit it. Unfortunately, it doesn’t work during the daylight hours, and you really only get to see satellites in low orbits.

Thankfully, there’s a trick that allows you to see satellites any time of day, even the ones in geosynchronous orbits — you just need to look using microwaves. That’s what [Gabe] at [saveitforparts] did with a repurposed portable satellite dish, the kind that people who really don’t like being without their satellite TV programming when they’re away from home buy and quickly sell when they realize that toting a satellite dish around is both expensive and embarrassing. They can be had for a song, and contain pretty much everything needed for satellite comms in one package: a small dish on a motorized altazimuth mount, a low-noise block amplifier (LNB), and a single-board computer that exposes a Linux shell.

After figuring out how to command the dish to specific coordinates and read the signal strength of the received transponder signals, [Gabe] was able to cobble together a Python program to automate the task. The data from these sweeps of the sky resulted in heat maps that showed a clear arc of geosynchronous satellites across the southern sky. It’s quite similar to something that [Justin] from Thought Emporium did a while back, albeit in a much more compact and portable package. The video below has full details.

[Gabe] also tried turning the dish away from the satellites and seeing what his house looks like bathed in microwaves reflected from the satellite constellation, which worked surprisingly well — well enough that we’ll be trawling the secondary market for one of these dishes; they look like a ton of fun.

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Digitizing Sound On An Unmodified Sinclair ZX81

March 25, 2023 by 26 Comments

Whatever the first computer you used to manipulate digital audio was, the chances are it came with dedicated sound hardware that could play, and probably record, digitized audio. Perhaps it might have been a Commodore Amiga, or maybe a PC with a Sound Blaster. If you happen to be [NICKMANN] though, you can lay claim to the honor of doing so on a machine with no such hardware, because he managed it on an unmodified Sinclair ZX81.

For those of you unfamiliar with the ZX, it embodied Clive Sinclair’s usual blend of inflated promises on minimal hardware and came with the very minimum required to generate a black-and-white TV picture from a Zilog Z80 microprocessor. All it had in the way of built-in expansion was a cassette interface, 1-bit read and write ports exposed as 3.5 mm jacks on its side. It’s these that in an impressive feat of hackery he managed to use as a 1-bit sampler with some Z80 assembler code, capturing a few seconds of exceptionally low quality audio in an ’81 with the plug-in 16k RAM upgrade.

From 2023 of course, it’s about as awful as audio sampling gets, but in 1980s terms it’s pulling off an almost impossible feat that when we tried it with a 1-bit PC speaker a few years later, we didn’t succeed at. We’re impressed.

The ’81 may be one of the simplest of the 8-bit crop, but in its day it set many a future software developer on their career path. It’s still a machine that appears here today, from time to time.