Ah, what fond memories we have of our misspent youth, walking around with a 9,000-volt electromagnetic pulse generator in our Levi’s 501s and zapping all the electronic devices nobody yet carried with them everywhere they went. Crazy days indeed.
We’re sure that’s not at all what [Rostislav Persion] had in mind when designing his portable EMP generator; given the different topologies and the careful measurement of results, we suspect his interest is strictly academic. There are three different designs presented, all centering around a battery-powered high-voltage power module, the Amazon listing of which optimistically lists as capable of a 400,000- to 700,000-volt output. Sadly, [Rostislav]’s unit was capable of a mere 9,000 volts, which luckily was enough to get some results.
Coupled to a spark gap, one of seven different coils — from one to 40 turns — and plus or minus some high-voltage capacitors in series or parallel, he tested each configuration’s ability to interfere with a simple pocket calculator. The best range for a reset and scramble of the calculator was only about 3″ (7.6 cm), although an LED hooked to a second coil could detect the EMP up to 16″ (41 cm) away. [Rostislav]’s finished EMP generators were housed in a number of different enclosures, one of which totally doesn’t resemble a pipe bomb and whose “RF Hazard” labels are sure not to arouse suspicions when brandished in public.
We suppose these experiments lay to rest the Hollywood hype about EMP generators, but then again, their range is pretty limited. You might want to rethink your bank heist plans if they center around one of these designs.
Arguably, the most tedious part of any Tesla coil build is winding the transformer. Getting that fine wire wound onto a suitable form, making everything neat, and making sure it’s electrically and mechanically sound can be tricky, and it’s a make-or-break proposition, both in terms of the function and the aesthetics of the final product. So this high-output printed circuit Tesla should take away some of that tedium and uncertainty.
Now, PCB coils are nothing new — we’ve seen plenty of examples used for everything from motors to speakers. We’ve even seen a few PCB Tesla coils, but as [Ray Ring] points out, these have mostly been lower-output coils that fail to bring the heat, as it were. His printed coil generates some pretty serious streamers — a foot long (30 cm) in some cases. The secondary of the coil has 6-mil traces spaced 6 mils apart, for a total of 240 turns. The primary is a single 240-mil trace on the other side of the board, and the whole thing is potted in a clear, two-part epoxy resin to prevent arcing. Driven by the non-resonant half-bridge driver living on the PCB below it, the coil can really pack a punch. A complete schematic and build info can be found in the link above, while the video below shows off just what it can do.
Have you ever seen something that’s so fascinating you’re sure there has to be some kind of practical application for it, but you just can’t figure out what? That’s how we feel when watching tiny ball bearings assemble themselves into alien-like structures under the influence of high voltage in the latest Plasma Channel video from [Jay Bowles].
Now to be clear, [Jay] isn’t trying to take credit for the idea. He explains that researchers at Stanford University first documented the phenomenon back in 2015, and that his goal was to recreate their initial results as a baseline and go from there. The process is pretty simple: put small metal ball bearings into a tray of oil, apply high voltage, and watch them self-assemble into “wires” that branch out in search of the ground terminal like a plant’s roots looking for water. With the encouragement of his 500,000 volt Van de Graaff generator, the ball bearings leaped into action and created structures just like in the Stanford study.
With the basic pieces now in place, [Jay] starts to push the envelope. He experiments with various oils to see how their viscosity impacts the ball’s ability to assemble, finding that olive oil seems to be the ideal candidate (at least of those he’s tried so far). He also switches up the size and shape of the tray, to try and find how far the balls can realistically stretch out on their own.
In the end we’re no closer to finding a practical application for this wild effect than the good folks at Stanford were back in 2015, but at least we got to watch the little fellows do their thing in glorious 4K and with the exceptional production value we’ve come to expect from Plasma Channel. That said, [Jay] does hint at his ongoing efforts to turn the structures into works of art by “freezing” them with clear resin, so keep your eyes out for that.
The Van de Graaff generator is a staple of science museums, to the point that even if the average person might not know its name, there’s an excellent chance they’ll be familiar with the “metal ball that makes your hair stand up” description. That’s partly because they’re a fairly safe way to show off high voltages, but also because they’re surprisingly cheap and easy to build.
In his latest Plasma Channel video [Jay Bowles] builds a large Van de Graaff generator that wouldn’t look out of place in a museum or university, which he estimates is producing up to 500,000 volts. It can easily throw impressive looking (and sounding) sparks 10 inches or more, and as you can see in the video below, is more than capable of pulling off those classic science museum tricks.
It’s really quite amazing to see just how little it takes to generate these kinds of voltages with a Van de Graaff. In fact there’s nothing inside that you’d immediately equate with high voltage, the only electronic component in the generator’s base beyond the battery pack is a motor speed controller. While everything else might look suspiciously like magic, our own [Steven Dufresne] wrote up a properly scientific explanation of how it all works.
In this particular case, the motor spins a nylon pulley in the base of the generator, which is connected to a Teflon pulley in the top by way of a neoprene rubber belt. Combs made from fine metal mesh placed close to the belt at the top and bottom allow the Van de Graaff to build up a static charge in the sphere. Incidentally, it sounds like sourcing the large metal sphere was the most difficult part of this whole build, as it took [Jay] several hours to modify the garden gazing ball to fit atop the acrylic tube that serves as the machine’s core.
Electric vehicles are becoming more and more common on the road, but when they’re parked in the driveway or garage there are still some kinks to work out when getting them charged up. Sure, there are plenty of charging stations on the market, but they all have different features, capabilities, and even ports, so to really make sure that full control is maintained over charging a car’s batteries it might be necessary to reach into the parts bin and pull out a trusty Arduino.
This project comes to us from [Sebastian] who needed this level of control over charging his Leaf, and who also has the skills to implement it from the large high voltage switching contactors to the software running its network connectivity and web app. This charging station has every available feature, too. It can tell the car to charge at different rates, and can restrict it to charging at different times (if energy is cheaper at night, for example). It is able to monitor the car’s charge state and other information over the communications bus to the vehicle, and even has a front-end web app for monitoring and controlling the device.
The project is based around an Arduino Nano 33 IoT with all of the code available on the project’s GitHub page. While we would advise using extreme caution when dealing with mains voltage and when interfacing with a high-ticket item like an EV, at first blush the build looks like it has crossed all its Ts and might even make a good prototype for a production unit in the future. If you don’t need all of the features that this charging station has, though, you can always hack the car itself to add some more advanced charging features.
[Cranktown City]’s build style is refreshingly informal, but there’s a lot going on with this build that’s worth looking at — although it’s perhaps best to ignore the sourcing of glass tubing by cutting the ends off of an old fluorescent tube; there’s no mention of what became of the mercury vapor or liquid therein, but we’ll just assume it was disposed of safely. We’ll further assume that stealing nitrogen for the lasing gas mix from car tires was just prank, but we did like the rough-and-ready volumetric method for estimating the gas mix.
The video below shows the whole process of building and testing the tube. Initial tests were disappointing, but with a lot of tweaking and the addition of a much bigger neon sign transformer to power the tube, the familiar bluish-purple plasma made an appearance. Further fiddling with the mirrors revealed the least little bit of laser output — nowhere near enough to start cutting, but certainly on the path to the ultimate goal of building a laser cutter.
We appreciate [Cranktown City]’s unique approach to his builds; you may recall his abuse-powered drill bit index that we recently covered. We’re interested to see where this laser build goes, and we’ll be sure to keep you posted.
We use electricity to move things with the help of motors and magnets all the time. But if you have enough voltage, you can move things with voltage alone. As [James] found out, though, it works best if your objects — ping pong balls, in his case — are conductive.
He wanted to add a Van de Graaff generator to add to his “great ball machine” which already has some cool ways to move ping pong balls. However, to get the electrostatic motion, [James] had to resort to spraying the balls with RF shielding spray.