Smart Sphere Or Magnetic Magic

June 19, 2023 by Brian McEvoy 10 Comments

Sometimes a coworker sees something on your desk, and they have to ask, “Where can I get one of those?” and that has to be one of the greatest compliments to a maker. [Greg Zumwalt] nailed it with his “Marblevator Line Follower.” Roboticists will immediately recognize a black line on a white surface, but this uses hidden mechanics instead of light/dark sensors. Check out the video after the break to see the secrets, or keep bearing with us.

Inside the cylinder is a battery, charging circuit, inductive receiving coil, and a motor turning a magnet-laden arm beneath the cap. The overall effect is an illusion to convince people that the marble has a mind of its own. You can pick up the cylinder, and it keeps moving as expected from an autonomous bot. The black line is actually a groove, so the bearing follows a curvy course without any extra movements from the magnets within. The two-tone look is super-clean, but the whimsy of a “smart bearing” makes this an all-around winner.

“Marblevator Line Follower” is not the first Marblevator we featured, and we love our bouncing-bearing baubles and music-making machines.

Continue reading “Smart Sphere Or Magnetic Magic” →

3D Printing LEGO-like Blocks

June 10, 2023 by Bryan Cockfield 8 Comments

LEGO are perhaps the perfect children’s toy, at least until you step on the errant brick while walking around the house. Available in all kinds of sets with varying themes and characters, they encourage building and creativity in kids like no other. Those with 3D printers might have considered creating their own specialty blocks, but the manufacturing of real LEGO blocks involves steel molds with extremely tight tolerances far outside the realm of most 3D printers. To print blocks capable of interconnecting in a similar way involves taking advantage of the characteristics of 3D printers and their materials instead, as [CNC Kitchen] demonstrates with these PrintABloks.

The PrintABlok was the idea of [Joe Larson] aka [3D Printing Professor] and is built around a one-unit base block, which has holes on all of its sides, paired with small connecting pieces which are placed in the holes to connect the various blocks to one another. Using your CAD software of choice (although they were originally built using Blender), the base block can be lengthened or widened for printing various different types of blocks, and the diamond-shaped hole can even be added to various prints that aren’t blocks at all. This means that a wide variety of parts can be made, all designed to interlock with the bricks or various other shapes. [Joe] even created an array of themed sets like robots, castles, and dinosaurs and although he sells these more complex models, he released his base set and interconnection mechanism for free and is available for anyone to use.

Another perk of the PrintABlok system is that they are scalable, mitigating safety risks for smaller children that might try to swallow some of the smaller parts. It’s an excellent way to put the 3D printer to work if there are any children around in the house. But this isn’t the only LEGO-inspired build we’ve ever seen, and they aren’t always going to be used to make children’s toys. [Ivan] recently used similar 3D-printed interlocking bricks more in the style of LEGO Technic to attempt to build a human-rideable go-kart.

Continue reading “3D Printing LEGO-like Blocks” →

Front and back views of a square, purple PCB with op amps and BNC outputs

Op Amp Contest: Generate Spirograph Shapes Using Only Op Amps And Math

June 5, 2023 by Robin Kearey 13 Comments

If you’re a child of the ’80s or ’90s, chances are you’ve spent hours tracing out intricate patterns using the pens and gears of a Spirograph kit. Simple as those parts may be, they’re actually a very clever technique for plotting mathematical functions called hypotrochoids and epitrochoids. [Craig] has spent some time analyzing these functions, and realized you can also implement them with analog circuits. He used this knowledge to design a device called Op Art which generates Spirograph shapes on your oscilloscope using just a handful of op amps.

To draw either a hypotrochoid or an epitrochoid, you need to generate sine and cosine waves of various frequencies, and then add them with a certain scaling factor. Generating sines and cosines is not so hard to do with op amps, but making an adjustable oscillator that reliably churns out matching sine and cosine waves over a large frequency range turned out to be tricky. After a bit of experimentation, [Craig] discovered that a phase-shift oscillator was the right topology, not only for its adjustability but also because it generates sine, cosine and inverted sine terms that all come in handy when drawing various Spirograph shapes. Continue reading “Op Amp Contest: Generate Spirograph Shapes Using Only Op Amps And Math” →

Gyroscope Walks The Tightrope

May 23, 2023 by Danie Conradie 13 Comments

Gyroscopes are one of those physics phenomena that are a means to many ends, but can also enjoyed as a fascinating object in their own right. Case and point being [Hyperspace Pirate]’s tightrope-balancing crawler in the video after the break.

Inside the PLA and aluminum shell is a 3D-printed wheel with steel bolts around the edge for added moment of inertia. It is powered by a low-KV brushless motor with a 3:1 GT2 belt-drive and controlled by a simple servo tester, running on a 4 cell LiPo battery. The 3D-printed drive wheel is powered by a geared DC motor hooked directly to the battery. [Hyperspace Pirate] goes over the math of the design, showing that path to stability is a high speed and high moment of inertia flywheel, while staying well within the strength limits of the wheel’s material.

It’s balancing act was first demonstrated on a length of PVC conduit and then on a section of rope, with the characteristic circular wobbling of a gyroscope, known as gyroscopic precession. Without active correction, this the angle of procession will steadily increase until the machine falls over. Even so, it’s still great to watch a small scale version, like the one that inspired this build, would make a pretty cool desk toy.

Gyroscopes are commonly used in attitude indicators and and heading indicators in aircraft, and we’ve also seen them get used for balancing robots. Any ideas for practical uses for a mono-wheel rail/rope walker? Drop them in the comments below.

Continue reading “Gyroscope Walks The Tightrope” →

Remote-Controlled Hypercar Slices Through Air

May 23, 2023 by Bryan Cockfield 17 Comments

Almost all entry-level physics courses, and even some well into a degree program, will have the student make some assumptions in order to avoid some complex topics later on. Most commonly this is something to the effect of “ignore the effects of wind resistance” which can make an otherwise simple question in math several orders of magnitude more difficult. At some point, though, wind resistance can’t be ignored any more like when building this remote-controlled car designed for extremely high speeds.

[Indeterminate Design] has been working on this project for a while now, and it’s quite a bit beyond the design of most other RC cars we’ve seen before. The design took into account extreme aerodynamics to help the car generate not only the downforce needed to keep the tires in contact with the ground, but to keep the car stable in high-speed turns thanks to its custom 3D printed body. There is a suite of high-speed sensors on board as well which help control the vehicle including four-wheel independent torque vectoring, allowing for precise control of each wheel. During initial tests the car has demonstrated its ability to corner at 2.6 lateral G, a 250% increase in corning speed over the same car without the aid of aerodynamics.

We’ve linked the playlist to the entire build log above, but be sure to take a look at the video linked after the break which goes into detail about the car’s aerodynamic design specifically. [Indeterminate Design] notes that it’s still very early in the car’s development, but has already exceeded the original expectations for the build. There are also some scaled-up vehicles capable of transporting people which have gone to extremes in aerodynamic design to take a look at as well.

Continue reading “Remote-Controlled Hypercar Slices Through Air” →

We’ve Got A Saxaboom At Home Son

May 21, 2023 by Matthew Carlson 6 Comments

Most parents have heard a familiar story. Their lovely child comes up, having seen a celebrity rocking out with a funny $20 toy from the 80s, and asks for it. Of course, you reply, it’s just 20 dollars. However, a quick scan through eBay reveals that everyone else’s kid has also been asking for this obscure toy for a school event, which now costs around $700. [Ben] found himself in that exact position and made a crucial off-hand comment, “I bet I could make one of those.” That was how his hectic journey into the world of toy reproduction began.

All [Ben] had for reference when recreating a Sax-A-Boom were pictures and sound clips. Modeling complex sweeping shapes in CAD is difficult, and [Ben] commissioned a 3d model from a professional on Fiverr. [Ben] broke down the model into printable sections and tweaked it to account for buttons. After a concerning amount of putty, wet sanding, and elbow grease, [Ben] had a decently smooth body for an instrument. The device’s guts is an ESP32-based board called Sonatino, built around music generation. The music samples came from a virtual instrument clone on GitHub and loaded onto an SD card.

Time pressure crept in towards the end, and [Ben] had to go for some dirty solution that he would have preferred (popsicle sticks and epoxy for button mounting). Yes, there were some gaps and paint flaws, but ultimately [Ben’s] son rocked the school presentation. It’s a beautiful journey through creating something with a high level of finish on a limited timescale.

Perhaps future versions of the Sax-A-Boom can take it further by adding a breath sensor, like this 3d printed MIDI instrument.

Continue reading “We’ve Got A Saxaboom At Home Son” →

Big Tactile Button Is Silly But Cool

May 18, 2023 by Lewin Day 8 Comments

Every hacker is familiar with those teeny little tactile buttons that are so enjoyable to click over and over again. [ROBO HUB] has built a giant version as a tribute, and it works just like the real thing!

The giant button has been scaled up 20 times compared to the original. For simplicity’s sake, [ROBO HUB] designed this replica to use materials readily available around the home. Thanks to its cardboard construction, it’s easy to replicate with a minimum of tools. One need merely cut out the various sections before assembling them together with hot glue, with popsicle sticks serving as the legs. A juice bottle is used as the primary button itself, with aluminium foil serving as the contacts and rubber bands standing in for the spring.

It’s not the most useful button, given that it it’s quite fragile and has a weak spring return. However, it would be a great teaching tool to show students exactly what’s going on inside an actual button. As a bonus, it looks like it would be remarkably fun to pound on to activate some kind of massive air horn. Just an idea.

Continue reading “Big Tactile Button Is Silly But Cool” →