Brushless Motor Thrust Stand Provides Useful Data

When designing model aircraft of any shape or size, it’s useful to know the performance you can expect from the components chosen. For motors and propellers, this can be difficult. It’s always best to test them in combination. However, with the numbers of propeller and motor combinations possible, such data can be tough to come by. [Nikus] decided it would be easier to just do the testing in-house, and built a rig to do so.

The key component in this build is the strain gauge, which comes already laced up with an Arduino-compatible analog-digital converter module. Sourced for under $10 from Banggood, we can’t help but think that we’ve got it easy in 2018. A sturdy frame secures motor and propeller combination to the strain gauge assembly. An ATMEGA328 handles sending commands to the motor controller, reading the strain gauge results, and spitting out data to the LCD.

It’s a cheap and effective build that solves a tricky problem and would be a useful addition to the workshop for any serious modeler. We’ve seen other approaches in this area too, for those eager to graph their motor performance data. Video after the break.

[Thanks to Baldpower for the tip!]

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Shape Shifting Structures Work With Magnets

In The Dark Knight, Lucius Fox shows Bruce Wayne a neat bit of memory weave fabric. In its resting state, it is a light, flexible material, but when an electrical current is applied, it pops into a pre-programmed shape. That shape could be a tent or a bat-themed paraglider. Science has not caught up to Hollywood in this regard, but the concept has been demonstrated in a material which increases its rigidity up to 318% within one second when placed in a magnetic field. Those numbers do not mean a lot by themselves, but increasing rigidity in a reversible, non-chemical way is noteworthy.

The high-level explanation is that hollow tubes are 3D printed and filled with magnetorheological fluid which becomes more viscous in the presence of a magnet because the ferrous suspended particles bunch up to form chains instead of sliding over one another. Imagine a bike tire filled with gel, and when you need a little extra traction the tire becomes softer, but when you are cruising on a paved trail, the tire becomes as hard as a train wheel to reduce friction. That could be darn handy in more places than building a fast bike.

Manhattan Mystery of Creepy Jingles and Random Noises Solved

Here’s a puzzler for you: If you’re phreaking something that’s not exactly a phone, are you still a phreak?

That question probably never crossed the minds of New Yorkers who were acoustically assaulted on the normally peaceful sidewalks of Manhattan over the summer by creepy sounds emanating from streetside WiFi kiosks. The auditory attacks caused quite a stir locally, leading to wild theories that Russian hackers were behind it all. Luckily, the mystery has been solved, and it turns out to have been part prank, part protest, and part performance art piece.

To understand the exploit, realize that New York City has removed thousands of traditional pay phones from city sidewalks recently and replaced them with LinkNYC kiosks, which are basically WiFi hotspots with giant HDTV displays built into them. For the price of being blitzed with advertisements while strolling by, anyone can make a free phone call using the built-in VOIP app. That was the key that allowed [Mark Thomas], an old-school phreak and die-hard fan of the pay telephones that these platforms supplanted, to launch his attack. It’s not exactly rocket surgery; [Mark] dials one of the dozens of conference call numbers he has set up with pre-recorded audio snippets. A one-minute delay lets him crank the speakerphone volume up to 11 and abscond. The recordings vary, but everyone seemed most creeped out by the familiar jingle of the [Mr. Softee] ice cream truck franchise, slowed down and distorted to make it sound like something from a fever dream.

Yes, it’s a minimal hack, and normally we don’t condone the misuse of public facilities, even ones as obnoxious as LinkNYC appears to be. But it does make a statement about the commercialization of the public square, and honestly, we’re glad to see something that at least approaches phreaking again. It’s a little less childish than blasting porn audio from a Target PA system, and far less dangerous than activating a public safety siren remotely.

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Imploding Tiny 3D Prints

If you think about 3D printing, the ultimate goal would be to lay down specific atoms or molecule and build anything. Despite a few lab demonstrations at that scale, generally, it is easier to print in the macro scale than the micro. While it won’t get down to the molecule level, implosion fabrication is a new technique researchers hope will allow you to print large things and then shrink them. The paper describing the process appeared in Science. If you don’t want to pay your way through the paywall, you can read a summary on NewScientist or C&EN. Or you can scour the usual sources.

The team at MIT uses the same material that is found in disposable diapers. A laser traces patterns and the light reacts to a chemical implanted in the diaper material (sodium polyacrylate). That material can swell to many times its normal size which is why it is used in diapers. In this case, though, the material is swollen first and then reduced back to normal size.

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This 6502 Made From 74-Series Logic Can Run At 20 MHz

If you always wished you could get closer to the hardware with the 6502 in your classic microcomputer you’re in luck, because [Drass] has created a beautiful implementation of a 6502 using TTL logic chips. What makes it special is that it sits on a very neat set of PCBs, and due to its use of 74AC series logic it can run at much higher speeds than the original. A 20 MHz 6502 would have been revolutionary in the mid-1970s.

Neat reworking of what looks to be a reversed bus.
Neat reworking of what looks to be a reversed bus.

Through a flying ribbon cable, it can plug directly into the 6502 socket on classic microcomputers, and the website shows it running a variety of software on a Commodore VIC20. There is also a custom SBC as part of the suite, so no need for a classic micro if you want to put the CPU through its paces. The boards are not quite perfect, the website has a picture of some very neat reworking where it appears that a bus has been applied to a chip in reverse, but it certainly has the feel of a professional design about it.

This is a very tidy 6502, but it’s not the first we’ve seen and neither is it the most dis-integrated. There is a fascinating world of 74 logic CPUs to be explored, so it’s difficult to pick only one other to show you.

Thanks [Jeff] for the tip.

Maze Generator Keeps Plotter (and Kids) Busy

We can tell that [Jon Howell] is our kind of guy. After updating his vintage 1985 Hewlett-Packard plotter with WiFi and the ability to load SVG files, he obviously needed to find a bunch of stuff to run off with it. Gotta justify those hacks somehow. So he doubled down and decided support a hack with another hack by writing a maze generator to keep his plotter well fed. He was kind enough to unleash his creation on an unsuspecting Internet as an open source project, and now we all can benefit from a couple of reams worth of mazes.

The generator itself is written in Java, and should work on whatever operating system your box happens to be running thanks to the *nix and Windows wrapper scripts [Jon] provides. To create a basic maze, one simply needs to provide the script with the desired dimensions and the paper size. You can define the type of paper with either standard sizes (such as --paper a4) or in the case of a plotter with explicit dimensions (--paper 36x48in).

If you aren’t a big fan of right angles, there’s support for changing the internal geometry of the maze to use a hexagonal or triangle grid. You can even pass the program a black and white PNG “mask” which it will use as the boundaries for the maze itself, allowing for personalized puzzles of whatever shape catches your fancy. [Jon] even ran the Wrencher though his software, leading to the creation of a maze which we can neither confirm nor deny will be making an appearance on our Christmas cards this year.

Whether you need to prove to your significant other that the hours you spent fiddling with your plotter are well spent, or an easy way to entertain the junior humans in your life, you can thank [Jon] for your solution.

Young Entrepreneurs Learn What Really Goes Into Making a Product

Just to be clear, the primary goal of the Papas Inventeurs (Inventor Dads) was to have the kids make something, have fun, and learn. In that light, they enjoyed a huge success. Four children designed, made, and sold laser-cut napkin rings from a booth at the Ottawa Maker Faire as a fun learning process (English translation, original link in French.) [pepelepoisson] documented the entire thing from beginning to end with plenty of photos. Things started at proof of concept, then design brainstorming, prototyping, manufacture, booth design, and finally sales. While adults were involved, every step was done by the kids themselves.

It all began when the kids were taken to a local fab lab at the École Polytechnique and made some laser-cut napkin holders from plywood for personal use. Later, they decided to design, manufacture, and sell them at the Ottawa Maker Faire. Money for the plywood came from piggy banks, 23 different designs made the cut, and a total of 103 rings were made. A display board and signs made from reclaimed materials rounded out the whole set.

In the end, about 20% of people who visited and showed interest made a purchase, and 60 of the 103 pieces were sold for a profit of $126. Of course, the whole process also involved about 100 hours of combined work between the kids and parents and use of a laser cutter, so it’s not exactly a recipe for easy wealth. But it was an incredibly enriching experience, at least figuratively, for everyone involved.

Possibly the biggest takeaway was the way manufacturing involved much more than just pressing “GO” on a laser cutter. Some pieces needed sanding after laser cutting, and each piece got two coats of varnish. If you missed it, [Bob Baddeley] showed how labor, and not materials, ends up being the most expensive part of a product.