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Hackaday Links: October 17, 2021

We found a couple of headlines this week that seemed pretty alarming at first, mentioning as they did both “Chinese grannies” and “stun guns.” Digging a little deeper, it appears that widespread elder abuse isn’t what this is about, although there certainly is an unsavory aspect to the story. Apparently, it’s pretty common in Chinese cities for large groups of people to get together for exercise, with “square dancing” being one popular form. This isn’t the “do-si-do and allemande right” square dancing that made high school gym class really awkward for a few days, but rather large groups of mostly older women busting moves to Chinese music in public spaces. It’s the music that’s bothering some people, enough so that they’re buying “stun guns” that can somehow turn off the dancing grannies’ music. None of the articles go into any detail on the device besides describing it as a flashlight-looking thing, and that it appears to do no permanent damage to the sound system. We’d love to know where to get one of these things — you know, for science. And really, it’s kind of sad that people are taking offense at senior citizens just looking for a bit of exercise and social contact.

A couple of weeks back, we mentioned TeachMePCB, a free online PCB design class designed to take you from zero to PCB designer. We’ve been working through the course material and enjoying it, but it strikes us that there’s a lot to keep track when you’re designing a PCB, especially if you’re new to the game. That’s where this very detailed PCB design checklist would come in handy. It takes you right from schematic review and breadboard testing of subassemblies right through to routing traces to avoid crosstalk and stray capacitance problems, and right on to panelization tips and even how to make sure assembly services get your build right. Reading through the list, you get the feeling that each item is something that tripped up the author (grosdode) at one time or another. So it’s a little like having someone with hard-won experience watching over your shoulder as you work, and that can’t really be a bad thing.

Our friend Jeroen Vleggaar over at Huygens Optics on YouTube posted a video the other day about building an entire Schmidt-Cassegrain reflecting telescope out of a single piece of glass. The video is mostly an interview with optical engineer Rik ter Horst, who took up the building of monolithic telescopes as a hobby. It turns out that one of his scopes will be flying to space aboard a cubesat in January. If you’re a fan of precision optics, you’ll want to check this out. Jeroen also teased that he’ll be building his own version of Rik’s monolithic telescope, so watch for an article on that soon.

Heads up — applications are now being accepted for the Open Hardware Summit’s Ada Lovelace Fellowships. This year there are up to ten fellowships offered, each of which includes a $500 travel stipend to attend the Open Hardware Summit in April. The fellowships seek to foster a more diverse community in open-source hardware; applications are being accepted until December 17th, so hurry.

And finally, if you’ve got some spare cycles, you might want to turn your Mark 1 eyeballs to the task of spotting walrus from space. The World Wildlife Federation (WWF) is crowdsourcing its walrus census efforts by training people to spot the well-armed marine mammals in satellite photos. Assessing population numbers and distribution is important to understanding their ecology, and walrus are cute and cuddly (no, they’re not), so getting people to count them makes sense. But this seems like a job for machine vision — there has to be a model trained to recognize walrus, right? Or maybe just something to count dark spots against a white background? Maybe someone can whip something up to make this job a bit easier and less subjective.

A DIY Stun Gun You Probably Shouldn’t Build

In these troubled times, when a trip to the grocery store could turn into a brawl over toilet paper, you might be inclined to build yourself a low-cost electroshock weapon. Or at least, that’s what [Alex Zidros] did. We don’t necessarily recommend you follow in his footsteps, and we’re certainly not advocating testing it on a loved one. We just bring you this information, you have to decide what you do with it.

This is what peer pressure looks like.

So what does it take to build an improvised stun gun? Not a whole lot, it turns out. As you might have guessed, the star of the show is a high voltage transformer which supposedly puts out 400 kV. Just looking at it (and the price) we’re going to go out on a limb and say the performance specs are way overrated, but in this case that might actually be a good thing.

Beyond the transformer, there’s a simple 9 V battery holder and electrodes made from the prongs of a hacked up travel adapter. To deliver the lightning, [Alex] is using a pink arcade button. Just because you might be fighting for your life doesn’t mean you can’t have a little fun, right? Everything is packed into a simple 3D printed enclosure, but you could easily replace that with any suitably sized box. Something made out of wood might be a good idea, considering.

If you’d like to see another person shocked by a cobbled together high-voltage weapon, and potentially even learn something in the process, check out the “tutorial” video [Mehdi Sadaghdar] did back in 2014. We did mention you definitely shouldn’t do this at home, right?

Stun Gun Vs 220v Mains Electricity

Those fearless Ukrainians are at it again! This time around they’re giving wall outlets some high voltage stun gun shocks and observing the results, as [Kreosan] decided to see what would happen when you use a stun gun on mains electrical sockets. Surprisingly, they are still alive and well, and creating more videos. .

Shocking a light switch blew up some light bulbs, while shocking an extension cord with a TV plugged in blew the TV up. It seems these guys never run out of appliances to fry, or totally insane experiments to try out that no one else would really have the stomach for.

Although their experiments are on the extreme side of things they do know what they are doing, as they are electrical professionals, So maybe sit this one out unless you too really know what you are doing and understand the risks. The video is below the break for your enjoyment.

We have featured some of their equally scary hacks in the past, like mains voltage EL wire and wirelessly charging your phone from high voltage overhead power lines.

Continue reading “Stun Gun Vs 220v Mains Electricity”

Trio Of Magnetrons Power A Microwave Rifle

Can you build a working EM weapon from three microwave ovens? Apparently, yes. Should you do so? Maybe not when the best safety gear you can muster is a metallized Mylar film fetish suit and a Hershey’s Kiss hat.

Proving that language need not be a barrier to perfect understanding of bad ideas, the video below tells you all you need to know, even without subtitles in the non-Russian language of your choice. [KREOSAN]’s build is obnoxiously obvious — three magnetrons mounted on a tin can “resonator” with a foil-covered waveguide at the business end. The magnetrons are tickled by a stun-gun that’s powered by a pack of 18650 batteries. The video shows some “experiments”, like lighting up unpowered CFL bulbs from about 15 meters away and releasing the Blue Smoke from the electrical system of a running motor scooter. Assuming they weren’t added in post, the artifacts in the video belie the gun’s lack of shielding for the operator. We doubt any of the ad hoc safety gear would provide any protection from the resulting microwaves, but we also doubt that it matters much when things have gotten this far.

We’re not too sure about this one — some of the zapping stunts look a little too conveniently explosive. It’s hard to tell the details without a translation, so maybe one of our Russian-speaking readers can pitch in on the comments. Although this isn’t [KRESOAN]’s first microwave rodeo, having melted a few lightbulbs with magnetrons before. Even seeing this we still consider EMP Weapons a figment of Hollywood’s imagination.

Continue reading “Trio Of Magnetrons Power A Microwave Rifle”

Mehdi wth his homemade taser

[Mehdi’s] Shocking Stun Gun Tutorial

[Mehdi Sadaghdar] never lets little things like fire, shocks, or singed fingers get in the way of his projects.  His latest is a tutorial on making a simple electroshock device. A stun weapon creates a very high voltage, and is used in law enforcement to temporarily disable a person. [Mehdi] stresses repeatedly to not use this on anyone. If you do, he won’t like you anymore. Of course, if you’ve seen any of his previous videos, you know he’ll shock himself and set something on fire before the project is complete.

To create his stunner, [Mehdi] used a car ignition to produce a high voltage. The igniton coil, which is a specialized transformer, allowed him to generate the >10000V output needed for the stunner. The coil has a 60:1 ratio and is powered by a 12V DC supply. Since a coil is a short at DC, the system only creates a high voltage pulse when power is disconnected. However, the pulse was too short to create a satisfying arc. [Mehdi] added a capacitor, creating an LC circuit that oscillates as the charge decays, creating a nicer spark. He then used an RC circuit and a relay to create a simple oscillating switch. For the finishing touch, he created a spark gap on the secondary of the transformer with two nails. In typical [Mehdi] fashion, he nearly fried his digital caliper in the process.

The end result is a nice spark that warms the cockles of [Mehdi’s] fibrillating heart. We commend him for being such a brave masochist in the name of science.  Check out his tutorial after the break!

Continue reading “[Mehdi’s] Shocking Stun Gun Tutorial”

Stun Baton

Shocking Idea: Prank Stun Baton

[Christopher] has put together a Prank Stun Baton to annoy his friends. It delivers a slight shock to the person on the business end of the device. Oddly, it’s powered solely by static electricity, there is no battery here and the resulting injury is no worse than touching a door knob after scooting your socks around on some shag carpet.

The design is super simple and is effectively just a rudimentary capacitor. The main housing is a PVC pipe that acts as a dielectric in the ‘cap’ system. Two separate pieces of tin foil are wrapped around the inside and outside of the PVC pipe. These layers of tin foil provide a conductive path up to the a couple of screws stuck in the end of the baton. A ping-pong ball and some foam act as an insulator between the PVC and the screws.

To charge the baton it only has to be brought close to a source of static electricity, a tube TV will do the trick. Rubbing it with a piece of wool will also work. When this is done an electrostatic field is stored in the PVC between the two pieces of tin foil, one side takes on a positive charge and the other a negative charge creating an electric potential between the two screws at the end of the baton. When something (with a low-enough resistance) shorts the screws, the stored energy on the positive screw tries to go to the negative screw, shocking the unsuspecting victim.

Need something a little more powerful? You may want to check out this other stun baton.

Forget Stopping Bullets – Vest Warms You While Stopping Taser

[Bruce Wayne] [Shenzhen] wanted a garment that would protect him from a jolt, while keeping him toasty in the cold weather. Well that’s not it at all, these are merely two of his projects using the same material in different ways.

We’re going to start with the infrared image on the right. This is a vest with chest and back pieces made of carbon tape totaling two meters of the material swirled on each side. Hook it to a power source and the carbon tape warms the wearer. Portability is something of an issue as each “element” takes 36 W of power (3A at 12V). Click through for advice on how to interface the tape with the power source.

Onto the main event… avoiding electrical shock when you get all up in the grill of that mall cop you’re hated for years. [Shenzhen’s] jacket is really just an ordinary long-sleeved coat. But he separated the lining at the bottom seam and used fusible material to hold the carbon tape in place. The carbon tape provides a better conductor than your skin, preventing the shock from stunning you as it was intended. This really is the thing of superheroes, or former editors who should have known better.