Fuses are generally there to stop excessive electrical currents from damaging equipment or people’s soft, fleshy bodies when faults occur. However, some people like to blow them just for fun, and [Photonicinduction] is just one of those people. He recently decided to push the boat out, setting his mind to the task of popping a 5000 A fuse in his own back yard. (Video, embedded below.)
It’s not a job for the faint-hearted. The fuse is rated at 5,000 A — that’s the nominal rating for the currents at which it is intended to operate. Based on the datasheet, the part in question is capable of withstanding 30,000 A for up to five full seconds. To pop the fuse instantly takes something in the realm of 200,000 A.
To achieve this mighty current, a capacitor bank was built to dump a huge amount of energy through the fuse. Built out of ten individual capacitor units wired up in parallel, the total bank comes in at 10,000 μF, and is capable of delivering 200,000 A at 3000 V. (Just not for very long.) The bank was switched into circuit with the fuse via a pneumatic switch rated at just 12,000 A.
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.
For anyone that’s fiddled around with a magnifying glass, it’s pretty easy to understand how optical microscopes work. And as microscopes are just an elaboration on a simple hand lens, so too are electron microscopes an elaboration on the optical kind, with electrons and magnets standing in for light and lenses. But atomic force microscopes? Now those take a little effort to wrap your brain around.
Luckily for us, [Zachary Tong] over at the Breaking Taps YouTube channel recently got his hands on a remarkably compact atomic force microscope, which led to this video about how AFM works. Before diving into the commercial unit — but not before sharing some eye-candy shots of what it can do — [Zach] helpfully goes through AFM basics with what amounts to a macro version of the instrument.
His macro-AFM uses an old 3D-printer as an X-Y-Z gantry, with a probe head added to the printer’s extruder. The probe is simply a sharp stylus on the end of a springy armature, which is excited into up-and-down oscillation by a voice coil and a magnet. The probe rasters over a sample — he looked at his 3D-printed lattices — while bouncing up and down over the surface features. A current induced in the voice coil by the armature produces a signal that’s proportional to how far the probe traveled to reach the surface, allowing him to map the sample’s features.
The actual AFM does basically the same thing, albeit at a much finer scale. The probe is a MEMS device attached to — and dwarfed by — a piece of PCB. [Zach] used the device to image a range of samples, all of which revealed fascinating details about the nanoscale realm. The scans are beautiful, to be sure, but we really appreciated the clear and accessible explanation of AFM.
Ferris Bueller’s Day Off is a pop culture classic, and remains one of the standout teen films of the era. Notably, titular character Ferris was somewhat of a hacker himself, with the movie showcasing several contraptions the teenager used to get out of a day of school. Among them was the intercom, which [Aaron] faithfully recreated with modern technology.
For those who haven’t seen the film, the intercom was hooked up to a cassette player to feign a believable response to anyone that visited the house while Ferris was away. Rather than do things the old fashioned way, [Aaron] built his replica using an ESP32 fitted with a sound chip instead. When visitors ring the intercom, it plays back sound clips from the movie, while also signalling another ESP microcontroller inside [Aaron]’s house to let him know he has visitors.
The build is a charming tribute to the classic film, and all the more fun for [Aaron’s] efforts to make it look the part as well, choosing to build it inside a period-correct intercom housing. To avoid confusion for those who haven’t seen the film, however, he’s been careful to place a sign up to clarify the intercom is not as it seems.
The basic idea is a chessboard that a player can use in the typical way, moving the pieces on the board as normal. The opposing pieces are then moved automatically to reflect an opposing player’s moves as received from an online chess server.
The board outwardly appears normal, with little to suggest anything is amiss. Only the metallic gleam at the base of each piece gives the game away. Pieces are moved by a SCARA arm hidden inside the board, which uses a magnet to drag them around from position to position. It’s quite something to watch the pieces glide around as if by magic, even more so when one is dragged off the board in a combat situation.
As for the control system, an Arduino Nano 33 IoT handles online connectivity to fetch game data from the Lichess chess server, while an ESP32 is responsible for all the motors, and a regular Arduino Nano scans a matrix of Hall effect sensors responsible for locating pieces on the board.
The system allows for seamless play, detecting when pieces are moved by the player via the Hall effect sensors, and reporting back to the chess server online. Similarly, when the game state is updated, the SCARA arm steps in to move the relevant pieces reflecting the moves of the distant player.
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.
Looks and RGB LEDs are usually not a priority in tool batteries, but [Oleg Pevtsov] decided the battery for his DIY vacuum cleaner needed to be different. In the process, he learned some lessons in chemical etching, plating, machining, casting, and electronics. See the video after the break for the build compilation.
The core of the battery is just five 18650 cells in a 3D-printed holder with a BMS, but the real magic is in the external components. The outer body is a brass tube with the logo etched through the 0.6 mm wall. Getting the etching right took a few tries and a lot of frustration, but he eventually found success with a solution of sulfuric acid and nitric acid in a magnetically stirred container. For etch resist he sprayed lacquer on the outside and filled the inside with silicone. The inside was then coated with clear epoxy by allowing it to cure while spinning. The final touches were nickel plating, then gold plating, and a high polish.
The silver-plated connector on one end consists of a machined copper tip and ring, epoxied together for isolation. The tip has a multi-start external thread, allowing the female side of the connector to securely connect with a single twist. A set of RGB LEDs were added to the core to light up the battery from the inside. We have to hope the vacuum this is supposed to attach to is equally impressive.