Author: Dan Maloney

3283 Articles

It’s Numbers All The Way Down With This Tape Measure Number Station Antenna

September 6, 2023 by 12 Comments

For all their talk of cooperation and shared interests, the nations of the world put an awful lot of effort into spying on each other. All this espionage is an open secret, of course, but some of their activities are so mysterious that no one will confirm or deny that they’re doing it. We’re talking about numbers stations, the super secret shortwave radio stations that broadcast seemingly random strings of numbers for the purpose of… well, your guess is as good as ours.

If you want to try to figure out what’s going on for yourself, all you need is a pair of tape measures and a software defined radio (SDR), as [Tom Farnell] demonstrates. Tape measure antennas have a long and proud history in amateur radio and shortwave listening, being a long strip of conductive material rolled up in a convenient package. In this case, [Tom] wanted to receive some well-known numbers stations in the 20- to 30-meter band, and decided that a single 15-meter conductor would do the job. Unlike other tape measure antennas we’ve seen, [Tom] just harvested the blades from two 7.5-meter tape measures, connected them end-to-end, and threw the whole thing out the window in sort of a “sloper” configuration. The other end is connected to an RTL-SDR dongle and a smartphone running what appears to be SDRTouch, which lets him tune directly into the numbers stations.

Copying the transmissions is pretty simple, since they transmit either in voice or Morse; the latter can be automatically decoded on a laptop with suitable software. As for what the long strings of numbers mean, that’ll remain a mystery. If they mean anything at all; we like to think this whole thing is an elaborate plan to get other countries to waste time and resources intercepting truly random numbers that encode nothing meaningful. It would serve them right.

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Electro-Optical Control Of Lasers With A Licorice Twist

September 5, 2023 by 8 Comments

You’ve got to hand it to [Les Wright]; he really knows how to dig into optical arcana and present topics in an interesting way. Case in point: an electro-optical control cell that’s powered by ouzo.

OK, the bit about the Greek aperitif may be stretching things a bit, but the Kerr Cell that [Les] builds in the video below does depend on anethole, the essential component of aniseed extract, which lends its aromatic flavor to everything from licorice to Galliano and ouzo. As [Les] explains, the Kerr effect uses a high-voltage field to rapidly switch light passing through a medium on and off. The most common medium in Kerr cells is nitrobenzene, a “distressingly powerful organic solvent” with such fun side effects as toxicity, flammability, and carcinogenicity.

Luckily, [Les] found a suitable substitute in the form of anethole — a purified sample, not just an ouzo nip. The solution went into a plain glass cuvette equipped with a pair of aluminum electrodes, which got connected to one of the high-voltage supplies we’ve seen him build before for his nitrogen laser. A pair of polarizing filters go on either end of the cuvette, and are adjusted to blank out the light passing through it. Applying 45 kilovolts across the cell instantly turns the light back on. Watch it in action in the video below.

There’s a lot of room left for experimentation on this one, including purification of the anethole for potentially better results. We’d also be curious if plain ouzo would show some degree of Kerr effect. For science, of course.

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Clean Up Your Resin-Printing Rinse With Dialysis

September 5, 2023 by 64 Comments

There’s a lot to like about resin 3D printing. The detail, the smooth surface finish, the mechanical simplicity of the printer itself compared to an FDM printer. But there are downsides, too, not least of which is the toxic waste that resin printing generates. What’s one to do with all that resin-tainted alcohol left over from curing prints?

How about sending it through this homebrew filtering apparatus to make it ready for reuse? [Involute] likens this process to dialysis, and while we see the similarities, what’s going on here is a lot simpler than the process used to filter wastes from the blood in patients with failing kidneys — there are no semipermeable membranes used here. Not that the idea suffers from its simplicity, mind you; it just removes unpolymerized resin from the isopropyl alcohol rinse using the same photopolymerization process used during printing. Continue reading “Clean Up Your Resin-Printing Rinse With Dialysis” →

Hackaday Prize 2023: The Gearing Up Challenge Finalists

September 5, 2023 by 3 Comments

If there’s more to life than just a workshop full of tools, it’s probably a workshop full of tools that you’ve built yourself. At least that was the thinking behind the recently concluded “Gearing Up” challenge of the 2023 Hackaday Prize, which unsurprisingly generated quite a list of entries for our judges to review and whittle down to their top ten favorite tools, jigs, fixtures, and general labor-savers.

Having piqued the interest of our crack team of judges, these ten projects have not only earned a spot in the 2023 Hackaday Prize Finals, but they’ll also get a $500 cash prize to boot. But the heat is really on now; like all the finalists from the previous rounds, they’ve only got until October to get their projects as far along as they can before the final round. The grand prize is grand indeed — $50,000 in cash and a residency at the Supplyframe Design Lab in Pasadena!

We’re really getting down to the wire here, but it’s worth taking a little time out to look at some of the Gearing Up challenge winners, and what they came up with to make life in the shop a little easier. And don’t forget — the one who dies with the most tools wins!

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Growing Oxides On Silicon On The Road To DIY Semiconductors

September 3, 2023 by 18 Comments

Doing anything that requires measurements in nanometers is pretty difficult, and seems like it would require some pretty sophisticated equipment. But when the task at hand is growing oxide layers on silicon chips in preparation for making your own integrated circuits, it turns out that the old Mark 1 eyeball is all you need.

Alert readers may recall that [ProjectsInFlight] teased this process in his previous video, which covered the design and construction of a DIY tube furnace. In case you missed that, a tube furnace is basically a long, fused quartz tube wrapped in electrical heating elements and lots of insulation, which is designed to reach the very high temperatures needed when making integrated circuits. The tube furnace proved itself up to the task by creating a thin layer of silicon dioxide on a scrap of silicon wafer. Continue reading “Growing Oxides On Silicon On The Road To DIY Semiconductors” →

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Hackaday Links: September 3, 2023

September 3, 2023 by 16 Comments

Right-to-repair has been a hot-button topic lately, with everyone from consumers to farmers pretty much united behind the idea that owning an item should come with a plausible path to getting it fixed if it breaks, or more specifically, that you shouldn’t be subject to prosecution for trying to repair your widget. Not everyone likes right-to-repair, of course — plenty of big corporations want to keep you from getting up close and personal with their intellectual property. Strangely enough, their ranks are now apparently joined by the Church of Scientology, who through a media outfit in charge of the accumulated works of Church founder L. Ron Hubbard are arguing against exemptions to the Digital Millennium Copyright Act (DMCA) that make self-repair possible for certain classes of devices. They apparently want the exemption amended to not allow self-repair of any “software-powered devices that can only be purchased by someone with particular qualifications or training or that use software ‘governed by a license agreement negotiated and executed’ before purchase.

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Teaching A Mini-Tesla To Steer Itself

September 2, 2023 by 4 Comments

At the risk of stating the obvious, even when you’ve got unlimited resources and access to the best engineering minds, self-driving cars are hard. Building a multi-ton guided missile that can handle the chaotic environment of rush-hour traffic without killing someone is a challenge, to say the least. So if you’re looking to get into the autonomous car game, perhaps it’s best to start small.

If [Austin Blake]’s fun-sized Tesla go-kart looks familiar, it’s probably because we covered the Teskart back when he whipped up this little demon of an EV from a Radio Flyer toy. Adding self-driving to the kart is a natural next step, so [Austin] set off on a journey into machine learning to make it happen. Having settled on behavioral cloning, which trains a model to replicate a behavior by showing it examples of the behavior, he built a bolt-on frame to hold a steering servo made from an electric wheelchair motor, some drive electronics, and a webcam attached to a laptop. Ten or so human-piloted laps around a walking path at a park resulted in a 48,000-image training set, along with the steering wheel angle at each point.

The first go-around wasn’t so great, with the Teskart seemingly bent on going off the track. [Austin] retooled by adding two more webcams, to get a little parallax data and hopefully improve the training data. After a bug fix, the improved model really seemed to do the trick, with the Teskart pretty much keeping in its lane around the track, no matter how fast [Austin] pushed it. Check out the video below to see the Teskart in action.

It’s important to note that this isn’t even close to “Full Self-Driving.” The only thing being controlled is the steering angle; [Austin] is controlling the throttle himself and generally acting as the safety driver should the car veer off course, which it tends to do at one particular junction. But it’s a great first step, and we’re looking forward to further development.

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