[Glen Akins] had a WW2-era aircraft engine cowl flap indicator lying around (as you do) and thought it would make a jolly fine USB-attached indicator. The model in question is a General Electric model 8DJ4PBV DC Selsyn, which was intended for four-engined aircraft. For those not familiar with the purpose [Glen] explains in his detailed writeup, that piston-engine aircraft of that era were air-cooled, and during conditions of maximum engine power — such as during take-off — flaps on the side of the engine cowling could be opened to admit additional cooling airflow. These indicator dials were connected to a sender unit on each of the flap actuators, providing the pilots an indication of the flaps’ positions.Continue reading “Interfacing An Old Engine Cowl Flaps Indicator To USB”→
Any project that contains something called a “flux modulator” instantly commands our attention. And while we’re pretty sure that [Retsetman] didn’t invent it after hitting his head on the toilet, this magnetic gearbox is still really cool.
Where most gearboxes have, you know, gears, a magnetic gearbox works by coupling input and output shafts not with meshing teeth but via magnetic attraction. [Retsetman]’s version has three circular elements nested together on a common axis, and while not exactly a planetary gear in the traditional sense, he still uses planetary terminology to explain how it works. The inner sun gear is a rotor with four pairs of bar magnets on its outer circumference. An outer ring gear has ten pairs of magnets, making the ratio of “teeth” between the two gears 10:2. Between these two elements is the aforementioned flux modulator, roughly equivalent to the planet gears of a traditional gearbox, with twelve grub screws around its circumference. The screws serve to conduct magnetic flux between the magnets, dragging the rotating elements along for the ride.
This gearbox appears to be a refinement on [Retsetman]’s earlier design, and while he provides no build files that we can find, it shouldn’t be too hard to roll your own designs for the printed parts.
You’ve probably heard the term magnetic gradient before, but have you ever seen one? Now you can in [supermagnetman’s] video, below. The key is to use very fine (2 micron) iron filings and special silicone oil. The video is a good mix of whiteboard lectures and practical hands-on experimenting. Just watching him spin the iron filings in the bottle was entertaining. There’s sources in the video description for the oil and the filings if you want to replicate the demonstrations for a classroom or just for your own enjoyment.
It’s one thing to know the math behind magnetic fields. It’s another to be able to use them in practical applications. But a good understanding of the physical manifestation of the magnetic field coupled can help clarify the math and vice versa. There’s a lot of common sense explanations too. For example, the way the filings accelerate as they get closer to the magnet explains why the patterns form the way they do. Iron filings are a traditional way to “see” magnetic fields. Ask anyone who ever had a Wooly Willy.
Iron filings can be fun to play with, although we don’t think we’ve ever had any this fine. If you prefer your magnetic field visualizations to be higher-tech, we have the answer.
Most of the hacks we see around these parts have to do with taking existing components and cobbling them together in interesting new ways. It’s less often that we see existing components gutted and repurposed, but when it happens, like with this reimagined rotary encoder, it certainly grabs our attention.
You may recall [Chris G] from his recent laser-based Asteroids game. If not you should really check it out — the build was pretty sweet. One small problem with the build was in the controls, where the off-the-shelf rotary encoder he was using didn’t have nearly enough resolution for the job. Rather than choosing a commodity replacement part, [Chris] rolled his own from the mechanical parts of the original encoder, like the shaft and panel bushing, and an AS5048A sensor board. The magnetic angle sensor has 14 bits of resolution, and with a small neodymium ring magnet glued to the bottom of the original shaft, the modified encoder offers far greater resolution than the original contact-based encoder.
The sensor breakout board is just the right size for this job; all that [Chris] needed to do to get the two pieces together was to 3D-print a small adapter. We have to admit that when we first saw this on Hackaday.io, we failed to see what the hack was — the modified part looks pretty much like a run-of-the-mill encoder. The video below shows the design and build process with a little precision rock blasting.
[NotLikeALeafOnTheWind] has created many LED-based display projects, and shares his method for making attractive LED panel frames and mounts. At first glance it may look as though slapping a rectangle of aluminum extrusion around a display is all it takes, there is also the mounting and management of wiring, power supply, and possibly a Raspberry Pi to deal with. The process of building an attractive frame also has a few hidden gotchas that can be avoided with a bit of careful planning.
Magnetic feet on the LED panels makes mounting much easier and more flexible.
Here is one tip that will resonate with some readers: don’t rely on specified dimensions of parts; measure the actual parts yourself. There can be small differences between what a data sheet says to expect, and the dimensions of the actual part in one’s hands. It may not be much, but it can be the difference between an ideal fit, and something that looks like a bit of a hack job.
[NotLikeALeafOnTheWind] provides some basic frame layouts, and suggests using two- or three-channel extrusions to provide a flat bezel around the display edge if desired. Mounting the LED panel itself is done with magnetic feet and providing a length of steel bar to which the display can attach. This can provide a flush mount while avoiding the whole issue of screw-mounting the display panels themselves, or sliding them into channels. For mounting all the other hardware, a piece of DIN rail and some 3D-printed parts takes care of that.
The result looks slick and sturdy, and some of the tips are sure to be useful even if the whole process isn’t applied. We like the way the basic design scales and is flexible about the thickness and size of the LED panels themselves, making it a promising way to accommodate perfectly functional oddball panels that end up in the trash.
While the days of audio cassette tapes are long over for almost everyone, magnetic tape still enjoys extensive use in some other realms such as large-scale data backup. Those that are still using it to store their tunes are a special subset of audio enthusiasts. [Frank] still has a working tape deck, and enthusiasm for classic non-vinyl sound. His homage to audio tape? Building a working cassette made (almost) entirely of wood.
The cassette is modeled on the formerly popular Maxell XL-II and the first versions of this build were modeled in paper. Once the precise dimensions of the enclosure were determined, [Frank] got to work building the final version from wood in a decidedly 2D process. He used a plotter to cut layers out of a wood veneer and glued them together one-by-one. The impressive part of this build is that the tape reel bearings are also made from wood, using a small piece as a race that holds the reels without too much friction.
Once everything was pieced together and glued up, [Frank] had a perfect working cassette tape made entirely from wood with the exception of the magnetic tape and a few critical plastic parts that handle the tape directly. The build is an impressive piece of woodworking, not unlike the solid wood arcade cabinet from a few days ago.
If you have a pile of old VHS tapes collecting dust in your attic or basement that you know you’ll never watch again, either because all of those movies are available on DVD or a streaming service, or because you haven’t had a working VCR since 2003, there might be a way of putting them to good use in another way. With the miles of tape available in just a few cassettes, [brtv-z] shows us how to use that tape as filament for a 3D printer.
The first step of the build is to actually create the filament. He uses a purpose-built homemade press to spin several tapes into one filament similar to how cotton or flax is spun into yarn. From there the filament is simply fed into the 3D printer and put to work. The tape filament needs to be heated higher than a standard 3D printer filament so he prints at a much slower rate, but the resulting product is indistinguishable from a normal print except for the color. It has some other interesting properties as well, such as retaining its magnetism from the magnetic tape, and being a little more brittle than PET plastic although it seems to be a little stronger.
While the VHS filament might not be a replacement for all plastic 3D prints, it’s still a great use for something that would likely otherwise head straight to the landfill. There are some other uses for this magnetic tape as well, like if you wanted to build a DIY particle accelerator.
