In our age of pervasive digital media, “pics or it didn’t happen” is a common enough cry that most of us will gladly snap a picture of pretty near anything to post online. So if you’re going to take a picture, it may as well be as stunning as these corona discharge photographs made with a homebrew Kirlian photography rig.
We know, Kirlian photography has a whole “woo-woo” vibe to it, associated as it has been with paranormal investigations and the like. But [Hyperspace Pirate] isn’t flogging any of that; in fact, he seems way more interested in the electronics of the setup than anything else. The idea with Kirlian photography is basically to capacitively couple a high-voltage charge across a dielectric, which induces an electrostatic discharge to a grounded object. The result is a beautiful purple discharge, thanks to atmospheric nitrogen, that outlines the object being photographed.
[Pirate]’s first attempt at a Kirlian rig used acrylic as a dielectric, which proved to be susceptible to melting. We found this surprising since we’ve seen [Jay Bowles] successfully use acrylic for his Kirlian setup. Version 2 used glass as a dielectric — right up until he tried to drill a fill port into the glass. (Important safety tip: don’t try to drill holes in tempered glass.) Version 3 used regular glass and a 3D-printed frame to make the Kirlian chamber; filled with saltwater and charged up with a homebrew Tesla coil, the corona discharge proved enough to char fingertips and ignite paper. It also gave some beautiful results, which can be seen starting at around the 7:40 mark in the video below.
We loved the photos, of course, but also appreciated the insights into the effects of inductance on the performance of this setup. And that first homebrew flyback transformer [Hyperspace Pirate] built was pretty cool, too.
Continue reading “Enjoy The Beauty Of Corona Discharge With This Kirlian Photography Setup” →
While it almost seems like an insane fever dream from an otherwise brilliant inventor, Nikola Tesla’s plan to harvest energy straight out of the atmosphere and essentially give it away is more reality than fiction. It’s usually prohibitively difficult get that energy out of the atmosphere for several obvious reasons, although it is still possible to do as [lasersaber] shows with his most recent atmospheric motor.
To help solve some of the logistical problems of harvesting electricity from the atmosphere, [lasersaber] is using a Van de Graaff generator as a stand-in for the high voltage gradient that can be found when suspending a long wire in the air. He has been experimenting with high-voltage motors like this for a while now and has refined his designs for corona discharge motors like these to be big enough and have enough torque to drive a drill bit. The motors have a conductive rotor with a series of discharge tubes on the stator, and exposing a metal point on the wiring (where the atmospheric wire would attach) to a sufficiently high voltage will cause rotation. In this case, it’s around 30,000 volts but with an extremely low current.
There are a number of videos documenting his latest build, including this follow-up video where he drills an arbitrarily large number of holes in various materials to demonstrate its effectiveness. Even though he is using a Van de Graaff generator in these builds, he does also show them working with a wire suspended by a drone as well for proof-of-concept. He’s also become somewhat of an expert on high-efficiency and low-power motors and has a number of other interesting builds based on these concepts.
Continue reading “Atmospheric High-Voltage Motor Makes Useful Power” →
As the coronavirus pandemic circles the world, a fact of daily life for millions of people has become the wearing of a face mask. Some people sport colorful fabric masks, but for many, this means the ubiquitous Chinese disposable mask. They have become the litter of our time, which as [blorgggg] notes is something that shouldn’t have to be the case. Their plastic can be recycled and made into other useful things, for example, ear savers similar to the ones many of us were 3D printing earlier in the year.
As you might imagine diving into a pile of used masks can be a little unhygienic, so the first step is to disinfect with alcohol. Then the various layers can be separated and the outer polypropylene ones collected and stacked between baking parchment to be melted on a skillet. The result is a polypropylene sheet that can be laser cut if it is thick enough, and from this are cut the ear savers. It’s not quite as neat a cut as the acrylic sheet we may be used to, but it’s adequate for the task.
While on the subject of masks, earlier in the year we presented a series in whose first part we dissected a selection.
[Serge Vaudenay] and [Martin Vuagnoux] released a video yesterday documenting a privacy-breaking flaw in the Apple/Google COVID-tracing framework, and they’re calling the attack “Little Thumb” after a French children’s story in which a child drops pebbles to be able to retrace his steps. But unlike Hänsel and Gretl with the breadcrumbs, the goal of a privacy preserving framework is to prevent periodic waypoints from allowing you to follow anyone’s phone around. (Video embedded below.)
The Apple/Google framework is, in theory, quite sound. For instance, the system broadcasts hashed, rolling IDs that prevent tracing an individual phone for more than fifteen minutes. And since Bluetooth LE has a unique numeric address for each phone, like a MAC address in other networks, they even thought of changing the Bluetooth address in lock-step to foil would-be trackers. And there’s no difference between theory and practice, in theory.
In practice, [Serge] and [Martin] found that a slight difference in timing between changing the Bluetooth
BD_ADDR and changing the COVID-tracing framework’s rolling proximity IDs can create what they are calling “pebbles”: an overlap where the rolling ID has updated but the Bluetooth ID hasn’t yet. Logging these allows one to associate rolling IDs over time. A large network of Bluetooth listeners could then trace people’s movements and possibly attach identities to chains of rolling IDs, breaking one of the framework’s privacy guarantees.
This timing issue only affects some phones, about half of the set that they tested. And of course, it’s only creating a problem for privacy within Bluetooth LE range. But for a system that’s otherwise so well thought out in principle, it’s a flaw that needs fixing.
Why didn’t the researchers submit a patch? They can’t. The Apple/Google code is mostly closed-source, in contrast to the open-source nature of most of the apps that are running on it. This remains troubling, precisely because the difference between the solid theory and the real practice lies exactly in those lines of uninspectable code, and leaves all apps that build upon them vulnerable without any recourse other than “trust us”. We encourage Apple and Google to make the entirety of their COVID framework code open. Bugs would then get found and fixed, faster.
Continue reading “COVID-tracing Framework Privacy Busted By Bluetooth” →
Terrestrial radio may be a dying medium, but there are still plenty of listeners out there. What would a commute to or from work be without a check of “Traffic on the Eights” to see if you need to alter your route, or an update of the scores from yesterday’s games? Getting that signal out to as many listeners as possible takes a lot of power, and this dangerous yet fascinating demo shows just how much power there is on some radio towers.
Coming to us by way of a reddit post, the short video clips show a crew working on a 15,000-Watt AM radio tower. They appear to be preparing to do tower maintenance, which means de-energizing the antenna. As the engineer explains, antennas for AM radio stations in the medium-wave band are generally the entire tower structure, as opposed to the towers for FM and TV stations, which generally just loft the antenna as high as possible above the landscape. The fun starts when the crew disconnects a jumper and an arc forms across the clamp and the antenna feed. The resulting ball of plasma acts like a speaker, letting us clearly hear the programming on the station. It’s like one of the plasma speakers we’ve seen before, albeit exceptionally more dangerous.
It’s an impressive display of the power coursing through broadcast towers, and a vivid reminder to not mess with them. Such warnings often go unheeded, sadly, with the young and foolish paying the price. There’s a reason they put fences up around radio towers, after all.
Continue reading “A Dangerous Demonstration Of The Power Of Radio” →
We know, we know – “Kirlian photography” is a term loaded with pseudoscientific baggage. Paranormal researchers have longed claimed that Kirlian photography can explore the mood or emotional state of a subject through the “aura”, an energy field said to surround and emanate from all living things. It’s straight-up nonsense, of course, but that doesn’t detract from the beauty of plasma aficionado [Jay Bowles]’ images produced by capacitive coupling and corona discharge.
Technically, what [Jay] is doing here is not quite Kirlian photography. The classic setup for “electrophotography” is a sandwich of photographic film, a glass plate, and a metal ground plate. An object with a high-voltage, high-frequency power supply attached is placed on top of the sandwich, and the resulting corona discharge exposes the film. [Jay]’s version is a thin chamber made of two pieces of solvent-welded acrylic and filled with water. A bolt between the acrylic panes conducts current from a Tesla coil – perhaps this one that we’ve featured before – into the water. When something is placed on the acrylic, a beautiful purple corona discharge streams out from the object.
It’s an eerie effect, and it’s easy to see how people can see an aura and attribute mystical properties to it. In the end, though, it’s not much different than touching a plasma globe, and just about as safe. Feeling a bit more destructive? Corona discharge is a great way to make art, both in wood and in acrylic.
Continue reading “Simple Acrylic Plates Make Kirlian Photography A Breeze” →
Small pinwheel type ion motors fall into the category of a fun science experiment or something neat to do with high voltage, but Hackaday’s own [Manuel Rodriguez-Achach] added a neat twist that incorporates neon lamps.
Normally you’d take a straight wire and make 90 degree bends at either end but pointing in opposite directions, balance it on a pole, and apply a high voltage with a moderate amount of current. The wire starts spinning around at the top of the pole, provided the ends of the wire are sharp enough or the wire has a small enough diameter. If your power supply has ample current available then in the dark you’ll even see a purplish glow, called a corona, at the tips of the wire.
[Manuel] made just such an ion motor but his power supply didn’t have the necessary current to produce a strong enough corona to be visible to his camera. So he very cleverly soldered neon lamps on the two ends of the wires. One leg of each lamp goes to the wire and the other end of the lamp acts as the sharp point left out in the air for emitting the ions.
The voltage needed across each lamp in order to ignite it is that between the high voltage power supply’s output and the potential of the surrounding air. That air may be initially at ground potential but he also bends the other output terminal of the power supply such that its tip is also up in the air. This way it sprays ions of the opposite polarity into the surrounding air.
Either way, the neon lamps light up and the wire spins around on the pole. Now, even without a visible corona, his ion motor makes an awesome display. Check it out in the video below.
For more about these ion motors, sometimes called electric whirls, check our article about all sorts of interesting non-electromagnetic motors.
Continue reading “Neon Lamps Light Up Dim Ion Motor” →