The Battlefield That’s 5 KHz Wide

The airwaves are full of news from the battle in Ukraine, with TV and radio journalists providing coverage at all hours. But for those with a bit of patience there’s something else from the conflict that can be found with a radio receiver, the battle over 5 kHz of spectrum starting at 4625 kHz. This has for many years been the location on the dial for “the Buzzer“, a Russian military transmitter whose nickname describes its monotonous on/off buzzing transmission perfectly. As the current Ukrainian situation has taken shape it has become a minor battleground, and the Buzzer now shares its frequency with a variety of other stations broadcasting music, spectrograms, and other radio junk intended to disrupt it.

A spectrogram showing the wavy line of an air raid siren
The air raid siren produces a particularly distinctive spectrogram.

For the curious this can be watched unfolding on a spectrogram or through headphones by anyone within range who has an HF receiver, or for everyone else, with a WebSDR. In Western Europe it’s best listened to in hours of darkness, we suggest you consult the webSDR.org list to see which has the best signal. We’ve heard it on receivers in Poland, Russia, and the ever-reliable uTwente WebSDR in the Netherlands. Over the time we’ve been monitoring it we’ve heard overlaying speech, and music varying from the Soviet and American anthems through dance music and K-pop to 1960s British rock and of course Boney M’s Rasputin, with a few slightly macabre choices such as Final Countdown and an air raid siren. We’ve even heard TV intros from the Benny Hill Show, the A-Team and Mission Impossible, so whoever is doing this has a wide taste.

Alongside the music at about 4628kHz meanwhile we’ve watched a series of spectrogram messages scroll past in Ukrainian, Russian, and English, ranging from “Stop war” to lewd suggestions about the Russian President. It’s fair to say that none of these transmissions have obscured the Buzzer, but they have had the effect of significantly increasing the noise on the channel.

To have a listen yourself, point a receiver within range at the appropriate time of day towards 4625 kHz and select USB demodulation and a 5 kHz bandwidth. Meanwhile, for some background on the Cold War HF relics, have a read about numbers stations.

A purple 3D-printed case with an LCD screen on the front and Pikachu on top

Avoid Repetitive Strain Injury With Machine Learning – And Pikachu

The humble mouse has been an essential part of the desktop computing experience ever since the original Apple Macintosh popularized it in 1984. While mice enabled user-friendly GUIs, thus making computers accessible to more people than ever, they also caused a significant increase in repetitive strain injuries (RSI). Mainly caused by poor posture and stress, RSI can lead to pain, numbness and tingling sensations in the hand and arm, which the user might only notice when it’s too late.

Hoping to catch signs of RSI before it manifests itself, [kutluhan_aktar] built a device that allows him to track mouse fatigue. It does so through two sensors: one that measures galvanic skin response (GSR) and another that performs electromyography (EMG). Together, these two measurements should give an indication of the amount of muscle soreness. The sensor readout circuits are connected to a Wio Terminal, a small ARM Cortex-M4 development board with a 2.4″ LCD.

However, calculating muscle soreness is not as simple as just adding a few numbers together; in fact the link between the sensor data and the muscles’ state of health is complicated enough that [kutluhan] decided to train a TensorFlow artificial neural network (ANN), taking into account observed stress levels collected in real life. The network ran on the Wio while he used the mouse, pressing buttons to indicate the amount of stress he experienced. After a few rounds of training he ended up with a network that reached an accuracy of more than 80%.

[kutluhan] also designed a rather neat 3D printed enclosure to house the sensor readout boards as well as a battery to power the Wio Terminal. Naturally, the case was graced by a 3D rendition of Pikachu on top (get it? a mouse Pokémon that can paralyze its opponents!). We’ve seen [kutluhan]’s fondness for Pokémon-themed projects in his earlier Jigglypuff CO2 sensor.

Although the setup with multiple sensors doesn’t seem too practical for everyday use, the Mouse Fatigue Estimator might be a useful tool to train yourself to keep good posture and avoid stress while using a mouse. If you also use a keyboard (and who doesn’t?), make sure you’re using that correctly as well.

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Antique Beat Box Showcases 1950’s Engineering Prowess

Before you could just put a drum machine app on your phone, or fire up Garage Band, there were breakthroughs like the Roland 808 drum machine. But that’s not where it all started. In 1959 a company called Wurlitzer (known for things like juke boxes, pianos, and giant pipe organs) produced a new device that had musicians worried it would put drummers out of a job: The 1959 Wurlitzer Sideman. And in the video below the break, we have the joy of watching [LOOK MUM NO COMPUTER] open up, explain, and play one of these marvelous machines.

Can you spot the early circuit sculpture?

It’s noteworthy that in 1959, almost none of the advancements we take for granted had made it out of the laboratory. Transistors? Nope. Integrated Circuits? Definitely not. What does that leave us with? Vacuum tubes (Valves for those across the pond), resistors, capacitors, relays, and… motors? Yep. Motors.

The unit is artfully constructed, and we mean that quite literally- the build was clearly done with care and it is easy to see an early example of circuit sculpture around the 3 minute mark. Electromechanical mechanisms take on tasks that we’d probably use a 555 for these days, but for any of you working on mechanical projects, take note: Wurlitzer really knew what they were doing, and there are some excellent examples of mechanical and electrical engineering throughout this primordial beat box.

If you move to the beat of interesting drum machines, you might enjoy this Teensy based Open Source drum machine that you can build. No tubes required!

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Hands probing inside a case with tools

Hardware Hacking 101 Needs Matching Toolkit

One doesn’t always have the luxury of sipping tea comfortably while hacking a piece of hardware at a fully-equipped workbench, where every tool is within reach. To address this, [Zokol] shares an early look at a hardware hacking toolkit-in-progress, whose purpose is to make hacking sessions as productive as possible while keeping size and weight within reasonable limits. There isn’t a part list yet, but there are some good tips on creating your own.

A view of a wide variety of toolsTo put together an effective hardware hacking toolkit, one must carefully consider what kinds of tasks need to be performed, and in what order. Once a basic workflow is identified, one can put together a set of complementary hardware tools and resources to meet the expected needs. The goal is to have the tools to go as far as one can in a single session, and identify any specialized equipment that will be needed later. That way, follow-up sessions can be as effective as possible.

Since hardware hacking is all about inspecting (and possibly modifying the behavior of) electronic devices, [Zokol] observes that step one is always to begin with external interfaces. That means common cables and adapters should all be part of a hardware hacking toolkit, otherwise the session might end awfully early. The next step is to open the device, so common tools and ways to deal with things like adhesives are needed. After that, diagnostic tools like multimeters come into play, with tools becoming more specialized as investigation proceeds. It’s a very sensible way to approach the problem of what to bring (and not bring) in a hardware hacking toolkit, and we can’t wait to see what the final version looks like.

Hardware hacking sometimes involves hardware that can’t be opened without damaging it. The Google Stadia controller is one such piece of hardware, and [Zokol] addressed the problem of how to permanently disable the microphone by figuring out exactly where to drill a hole.

Row of white 3D printed shoes in different styles

CAD Up Some Shoes, But Don’t Start From Scratch

Nothing helps a project get off the ground better than a good set of resources, and that’s what led [DaveMakesStuff] to release his Digital Shoe Design Kit, which is a set of 3D models ready to customize into a basic running shoe.

This is exactly what is needed for people who are interested in designing a custom shoe, but perhaps not interested in modeling every element entirely from scratch. [DaveMakesStuff]’s resources allows one to mix outsoles, midsoles, uppers, and other basic shoe elements into a finished model, ready to be resized or even 3D printed if desired. The files are all in stl format, but resizing stl files is trivial, and more advanced editing is possible with mesh sculpting programs like Blender.

If the gears in your head are starting to turn and you are wondering whether it is feasible to 3D scan your feet for some experiments in DIY custom footwear, take a few minutes and read up on 3D scanning and what to expect from the process to hit the ground running.

Internal Combustion Torque Monster Has Great Impact

Once the domain of automotive repair shops and serious hobbyists with air compressors, the impact driver so famously used to remove and install wheel lug nuts and other Big Fasteners with just a squeeze of the trigger is more accessible than ever. Thanks to Lithium Ion batteries and powerful and compact brushless motors, you can now buy a reasonably powerful and torquey impact driver for a relatively low price- no air compressor needed! But what if you relish the thought of a noisy, unwieldy and unnecessarily loud torque monster? Then the video below the break by [Torque Test Channel] is just what you need!

Now, this is Hackaday, so we don’t have to go into detail about why a person might want to rip out the electric motor and adapt a 60cc 2 stroke engine in its place. Of course that’s the obvious choice. But [Torque Test Channel] isn’t just mucking about for the fun of it. No, they’re having their fun, experimenting with internal combustion engines in odd places before they are banned by 2024 in California. Now, we’re not sure if the ban includes these exact types of engines- but who needs details when you have an impact driver that can change semi tires like a NASCAR pit crew.

Looking like an overpowered weapon from a first person shoot’em up game, [Torque Test Channel]’s modified Milwaukee tests well after some modifications. Be sure to watch the video to see how it performs against an electric tool that’s even larger than itself. There are graphs, charts, and an explanation of what can be done to make even more power in the future. We’re looking forward to it!

What’s that you say? You don’t have a two stroke engine sitting around waiting to be swapped into ridiculous gadgets? Look no further than your local fridge compressor and be ready to burn some hours getting it running.

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Compressed Air Jumping Shoes Are Not For The Faint-Hearted

[Ian Charnas] has taken a short break from building things that might injure himself, by building something that could injure somebody else instead. (Video, embedded below) Well, hopefully not anyway. After working with YouTuber [Tyler Csatari] on a few ideas, [Tyler] was insistent on getting some power-assisted jumping shoes, so [Ian] set to work mounting some compressed-air powered pistons to a pair of walking shoes. With a large backpack housing the 200 PSI air cylinder, control valves and timers. The whole affair looks solidly constructed, if a little ungainly, but does seem to work surprisingly well.

After some initial calculations of how much force each piston could exert before risking leg injury, he found that whilst it did work, to an extent, the pressure required was beyond the capability of the compressor they had on hand. After a shopping trip, a bigger compressor was located, but that still needed a modification to get anywhere near its maximum 200 psi rating. The thing is, that modification was to bypass the regulator and the safety valve, and this is definitely something you don’t want to be making a habit of. Compressed air systems like this can hold quite a bit of an explosion potential if pushed beyond reasonable limits, and care needs to be taken to keep things within safe bounds.

Cost-wise, [Ian] does mention a figure of around $3,000 USD making it a bit of a pricey project, but hey a YouTuber’s paying the bill, so it must just be a drop in the ocean for them?

Just to illustrate how useful compressed air is as a method of storing energy, here’s a compressed-air powered helicopter, and a 3D printed wankel rotary engine, which must’ve been tough to dial in and get working!

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