Day: May 10, 2020

Lowering The Boom On Yagi Element Isolation

May 10, 2020 by 19 Comments

Antenna design can be confusing, to say the least. There’s so much black magic that goes into antennas that newbies often look at designs and are left wondering exactly how the thing could ever work. Slight changes in length or the angle between two elements result in a vastly different resonant frequency or a significant change in the antenna’s impedance. It can drive one to distraction.

Particularly concerning are the frequent appearances of what seem to be dead shorts between the two conductors of a feedline, which [andrew mcneil] explored with a pair of WiFi Yagi antennas. These highly directional antennas have a driven element and a number of parasitic elements, specifically a reflector behind the driven element and one or more directors in front of it. Constructive and destructive interference based on the spacing of the elements and capacitive or inductive coupling based on their length determine the characteristics of the antenna. [Andrew]’s test antennas have their twelve directors either isolated from the boom or shorted together to the shield of the feedline. In side-by-side tests with a known signal source, both antennas performed exactly the same, meaning that if you choose to build a Yagi, you’ve got a lot of flexibility in what materials you choose and how you attach elements to the boom.

If you want to dive a little deeper into how the Yagi works, and to learn why it’s more properly known as the Yagi-Uda antenna, check out our story on their history and operational theory. And hats off to [andrew] for reminding us that antenna design is often an exercise in practicality; after all, an umbrella and some tin cans or even a rusty nail will do under the right circumstances.

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Clear Some Space And Build A Cosmo Clock

May 10, 2020 by 4 Comments

Like many of us, [Artistikk] is inspired by astronauts and space travel in general. To keep the inspiration coming, he made the Cosmo Clock — a sleek little clock that changes color whenever an astronaut is launched into space.

As awesome as space is, we’re inspired by the amount of Earth-saving reuse going on in this project. The actual time-telling is coming from a recycled wristwatch movement. [Artistikk] cut a bigger set of hands for it out of a plastic container, and used the lid from another container for the clock’s body.

The launch inquiries are handled by an ESP8266, which uses a Blynk app and some IFTTT magic to get notified whenever NASA yeets an astronaut into space. Then the ESP generates random RGB values and sends them to a single RGB LED. The clock body is small enough that a single LED is bright enough to light up all the parts that aren’t blacked out with thick paper. In case you’re wondering, the pattern around the edge isn’t random, it’s Morse code for ‘sky’, but you probably already knew that, right? Make a dash past the break to take the tour.

Clocks that wind up in space are much more complicated. Check out this tear-down of the clock from a late-90s Soyuz spacecraft.

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Hackaday Links: May 10, 2020

May 10, 2020 by 16 Comments

It’s a meme come true: DEF CON is canceled. Or at least canceled as the large, IRL conference that the hacker gathering has grown into. Rather than risk drawing people from all over the world and stuffing them into a Las Vegas convention hall in August, Dark Tangent has taken the prudent step of switching DEF CON 28 to a virtual meeting. If you’re interested in his reasoning behind the switch, check out his blog post on the decision. For more details on participating in DEF CON 28 in “Safe Mode”, see the FAQ.

Think that wearing a mask in public protects you from the surveillance state? Think again. Facial recognition software concern Rank One has announced new algorithms that only need to see your face from the mask up to make a match. It would seem to us that the limited number of mappable features in the periocular space would increase the error rate, and according to Rank One’s published data, that seems to be the case. But the relative error rate is still low, so expect to see this and similar periocular algorithms deployed widely. Your only defense may be to adopt the tactical shemagh as everyday wear. If only they made an N95 version.

The tech news this week was abuzz with descriptions of a new “non-fossil fuel jet engine” that could soon be powering aircraft devoid of paying passengers across our skies and perhaps directly into space using only battery power. Those reports were a bit overwrought since the experiment in question was a laboratory-scale setup using a magnetron that could have come from a smallish microwave to generate a plasma-air stream with 11 Newtons of thrust. That corresponds to an efficiency that beats that of current electric airplane engines, like those used on the Airbus E-Fan, if the extrapolation holds. So the technology is promising, but it still has a long way to go.

In what’s perhaps the longest beta in history, Inkscape 1.0 was officially released this week.

Something big — literally — is going on at Dalibor Farný’s Nixie tube factory. He dropped a video this week teasing the production of enormous Nixies for a large display installation. Each tube in the 11 by 11 tube display will be 150 mm in diameter, making them the largest Nixies ever made. Dalibor has already done much of the design work and has even started on the glasswork; the resulting tube looks a bit like the old iconoscope tubes from early TV cameras. We expect that scaling up a Nixie and producing 121 of them will present some interesting challenges, and we look forward to watching his progress.

If you’re part of a hackerspace, you should probably look at Vancouver Hackspace’s virtual tour. Not only does it show off what appears to be a great hackerspace, the video style is a great lesson in building up the excitement needed to recruit new members. There are also some great ideas in there about space layout and organization that you can leverage for your own hackerspace or even your home shop.

And finally, it’s Mother’s Day here in the US and almost 100 other countries, and circumstances may sadly keep many of us from being with Mom today. So here’s to the women who tolerated the often messy hobbies many of us pursued in our youths, who were always attentive audiences as we showed off our latest blinkenlights, and perhaps even inspired us to follow in their footsteps. Thanks, Mom!

No More Floppy Drives For This Agilent Scope

May 10, 2020 by 28 Comments

When [kiwih] picked up an Agilent 54621A scope, he was amused that it had a floppy disk. At one time, it was high-tech to use a disk to transfer scope data to your computer. Today, not so much. However, on the back was a serial port. Surely it was possible to read data from there. It is, and what results is a nice walkthrough of finding the port’s info and interfacing with it using Python.

Normally, you’d use the included BenchLinkXL software to grab data from the port, but that software is so old it would not run under Windows 10 or Wine. Searching didn’t turn up much on the serial port, but it did locate a manual for a similar Agilent scope. That manual wasn’t too helpful since it assumed you were connecting via a LAN or USB. However, it did make reference to an older model that was also similar and that was the key to finding a manual that did explain the serial port protocol.

The command set looks suspiciously like SCPI — Standard Commands for Programmable Instruments — which is a layer on top of the GPIB protocol. Many scopes speak that language, so that’s not surprising. That also means if you are in the mood to communicate with an SCPI scope, you might find the code useful, even if you don’t use a serial port or have this exact Agilent model.

SCPI has a lot of uses. For example, try talking to your scope. The cheap Rigol and similar scopes usually have SCPI and you can control and read them using the same kind of techniques.

512 Bytes Ought To Be Enough For Dinosaurs

May 10, 2020 by 9 Comments

It’s said that slow internet is worse than no internet at all, which is mainly a matter of continuously crushing all hope and sanity vs. finding peace in accepting a fate out of your control. Plus, you can easily pass the time of being catapulted back to the prehistoric ages by navigating a jumpy little creature from that same age through a field of cacti — at least if you’re using Chrome or Chromium. But neither a browser nor actually an operating system are really necessary for that, as [franeklubi] shows with a boot sector implementation of the same game.

Sure, the graphics aren’t quite on par, but compared to the original’s 3000+ lines of JavaScript, [franeklubi] managed to implement it in a few hundred lines of assembly, and was of course constrained by the 512 bytes of the boot sector itself (well, 510 plus the signature). This constraint causes a few limitations, like a slight lack of randomness in the obstacle arrangements, and a constant running speed, but it also makes it the perfect playground and starting point to delve into the world of nifty knacks and hacks, trying to squeeze every last byte.

If you want to give it a try for yourself, all you need is NASM and QEMU — and while you’re at it, why not have some Tetris along the way? We could also see this nicely combined with the real-world jumping version from a few weeks back, and turn it into a standalone arcade game. Bounce Crouch Revolution anyone?

Help Us Throw More Cycles At The Coronavirus Problem

May 10, 2020 by 45 Comments

The Hackaday community has answered the call and put their computers put to work folding proteins found in the coronavirus. Team_Hack-a-Day ranks #44 in the world so far this month, and I’ve seen us rank as high as #19 on 24-hour leaderboards.

Want to join the fight? Donate some of those computing cycles you’re not using to battling SARS‑CoV‑2. You’re probably not an epidemiologist or a vaccine researcher, but you can make their jobs easier by providing them with the data they need through the Folding@home Project.

As Dan Maloney explained in his excellent article on protein folding, understanding the incredibly complex folding behavior of the proteins in the virus will be key to finding treatments and possibly a vaccine. Folding@home connects countless computers via the internet and is now the largest supercomputer in the world, consisting of over 3.5 million CPUs and over half a million GPUs. The resulting data is freely available to researchers.

Let’s take a look at how easy it is to get up and running, how a GPU can supercharge a setup, and dip into the stats for Team_Hack-a-Day’s effort.

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Pulling A Crystal By Grinding It

May 10, 2020 by 29 Comments

If you own a radio transmitter, from a $10 Baofeng handheld to a $1000 fancy all-band transceiver, setting the frequency is simply a case of dialing in where you want to go. A phase-locked-loop frequency synthesizer or a software-defined radio will generate your frequency, and away you go. There was a time though when synthesizers were impossibly complex and radio amateurs were faced with a simple choice. Use an LC oscillator and put up with drifting in frequency, or use a crystal oscillator, and be restricted to only the frequencies of the crystals you had. [Mark Erdle, AE2EA] modified a 1950s broadcast AM broadcast transmitter for the 1.8MHz amateur band, and his friend [Andy Flowers, K0SM] thought it needed its crystal back for originality rather than the external frequency source [Mark] had provided. He documents the process of modifying a crystal oven and moving a crystal frequency in the video below the break.

A crystal oven is a unit containing the crystal itself alongside a thermostatic heater, and in this one, the crystal was a 1970s-vintage hermetically sealed HC6 device. He modified the oven to take a socket for older FT243 crystals because the quartz element can easily be accessed. [Andy] picked a crystal as close as he could find below the required frequency. He then ground it down with very fine grit on a glass plate, reducing its mass and thus its resonant frequency. We’re taken through the process of getting it close to frequency, but sadly don’t see the etching that he uses for the very last stage. At the end of the video, we see a QSO on the transmitter itself, which is something of an oddity in an age when AM on amateur bands has been supplanted by other modes for decades.

If you’re curious about the transmitter there’s a video thread following its restoration, and if the guts of older radio gear interests you then take a look at this aircraft receiver lovingly brought back to life.

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