So what exactly is sonoluminescence? The short answer is as the name suggests: a release of light caused by sound. In [Justin]’s case, he used an ultrasonic transducer to set up a standing wave at the resonant frequency of a flask of water. A drop of water is used to entrain a small air bubble, which is held in a stable position in the flask in much the same way as styrofoam beads are in an acoustic levitator. Turn off the lights and you’ll see that the bubble glows with a ghostly blue light.
What causes the glow? Good question. According to [Justin], we just don’t know for sure what causes it, although the leading theory is that cavitation of the bubble causes the trapped gas to compress and heat violently, turning into a brief bit of plasma. But there are problems with that theory, which is one of the reasons he wanted to show just how easy the process can be – now that he’s shaken out the bugs with five years of effort. It wasn’t easy getting the transducers attached and the driver circuit properly tuned, but with little more than a signal generator, an audio amp, and a spool of magnet wire, you too can make your own “star in a jar.”
Art installations are an interesting business, which more and more often tend to include electronic or mechanical aspects to their creation. Compared to more mainstream engineering, things in this space are often done quite a bit differently. [Jan Enning-Kleinejan] worked on an installation called Prendre la parole, and shared the lessons learned from the experience.
The installation consisted of a series of individual statues, each with an LED light fitted. Additionally, each statue was fitted with a module that was to play a sound when it detected visitors in proximity. Initial designs used mains power, however for this particular install battery power would be required.
Arduinos, USB power banks and ultrasonic rangefinders were all thrown into the mix to get the job done. DFplayer modules were used to run sound, and Grove System parts were used to enable everything to be hooked up quickly and easily. While this would be a strange choice for a production design, it is common for art projects to lean heavily on rapid prototyping tools. They enable inexperienced users to quickly and effectively whip up a project that works well and at low cost.
[Jan] does a great job of explaining some of the pitfalls faced in the project, as well as reporting that the installation functioned near-flawlessly for 6 months, running 8 hours a day. We love to see a good art piece around these parts, and we’ve likely got something to your tastes – whether you’re into harmonicas, fungus, or Markov chains.
Lasers work by emitting light that is “coherent” in that it doesn’t spread out in a disorganized way like light from most sources does. This makes extremely focused beams possible that can do things like measure the distance from the Earth to the Moon. This behavior isn’t just limited to electromagnetic waves, though. [Gigs] via [CodeParade] was able to build a device that produces a tightly focused sound wave, essentially building an audio laser.
Curiously enough, the device does not emit sound in the frequency range of human hearing. It uses a set of ultrasound speakers which emit a “carrier wave” in the ultrasound frequency. However, with a relatively simple circuit a second signal in the audible frequency range is modulated on top of it, much the same way that an AM radio broadcast has a carrier wave with an amplitude modulated signal on top of it. With this device, though, the air itself acts in a nonlinear way and demodulates the signal, producing the modulated signal as audible sounds.
There are some interesting effects of using this device. First, it is extremely directional, so in order to hear sound from the device you would need to be standing directly in front of it. However, once the ultrasound beam hits a solid object, the wave is instantly demodulated and reflected from the object, making it sound like that object is making the sounds and not the device. It’s obvious that this effect is hard to experience via video, but it’s interesting enough that we’d like to have one of our own to try out. It’s not the only time that sound waves and electromagnetic waves have paired up in interesting ways, either.
If you have ever used a scalpel to cut something tougher than an eraser, you can appreciate a hot knife or better yet, an ultrasonic cutter. Saws work too, but they have their own issues. [This Old Tony] uses a hobby store tool to cut some plastic and wood, then demos a commercial ultrasonic cutter to show how a blade can sail through with less brute force. The previous requires some muscle, finesse, and eventually a splash of Bactine antiseptic. The video can also be seen after the break.
This is more than a tool review, [Tony] takes it apart with a screwdriver and offers his snarky comments. On the plus side is that it cuts polystyrene well where a regular knife won’t do more than scratch or shatter it. Meanwhile in the negative category we don’t hear a definitive price, but they seem to cost half as much as his mini-lathe. If you need an estimated return on investment, consider the price of two-thousand X-acto blades, but you may also wish to factor in the reduced hand calluses. While you are shopping, maybe also think about a set of earplugs; when the video gets to 17:30 he tries to cut a ceramic fitting and manages to make a child-deafening screech instead. We warned you.
An ultrasonic knife is a blade that vibrates a tiny amount at a high frequency, giving the knife edge minor superpowers. It gets used much like any other blade, but it becomes far easier to cut through troublesome materials like rubber or hard plastics. I was always curious about them, and recently made my own by modifying another tool. It turns out that an ultrasonic scaling tool intended for dental use can fairly easily be turned into a nimble little ultrasonic cutter for fine detail work.
I originally started thinking about an ultrasonic knife to make removing supports from SLA 3D prints easier. SLA resin prints are made from a smooth, hard plastic and can sometimes require a veritable forest of supports. These supports are normally removed with flush cutters, or torn off if one doesn’t care about appearances, but sometimes the density of supports makes this process awkward, especially on small objects.
I imagined that an ultrasonic blade would make short work of these pesky supports, and for the most part, I was right! It won’t effortlessly cut through a forest of support bases like a hot knife through butter, but it certainly makes it easier to remove tricky supports from the model itself. Specifically, it excels at slicing through fine areas while preserving delicate features. Continue reading “Making An Ultrasonic Cutter For Post-processing Tiny 3D Prints”→
With the high availability of low-cost modular electronic components, building your own little robot buddy is easier and more affordable than ever. But while the electronics might be dirt cheap thanks to the economies of scale, modular robot chassis can be surprisingly expensive. If you’ve got a 3D printer you can always make a chassis that way, but what if you’re looking for something a bit more artisanal?
For his entry into the Circuit Sculpture Contest, [Robson Couto] has built a simple robot which dumps the traditional chassis for a frame made out of bent and soldered copper wire. Not only does this happen to look really cool in a Steampunk kind of way, it’s also a very cheap way of knocking together a basic bot with just the parts you have on hand. Not exactly a heavy-duty chassis, to be sure, but certainly robust enough to rove around your workbench.
The dual servos constrained within the wire frame have been modified for continuous rotation, which combined with the narrow track should make for a fairly maneuverable little bot. [Robson] equipped his servos with copper wheels built in the same style of the frame, which likely isn’t great for traction but really does help sell the overall look. If you aren’t planning on entering your creation into a contest that focuses on unique construction, we’d suggest some more traditional wheels for best results.
The brains of this bot are provided by an ATmega8 with external 16MHz crystal tacked onto the pins. There’s also a ultrasonic sensor board mounted to the servos which eventually will give this little fellow the ability to avoid obstacles. Of course, it doesn’t take a robotics expert to realize there’s currently no onboard power supply in the design. We’d love to say that he’s planning on using the copper loops of the frame to power the thing via induction, but we imagine [Robson] is still fiddling around with the best way to get juice into his wireframe creation before the Contest deadline.
Speaking of which, there’s still plenty of time to get your own Circuit Sculpture creation submitted. If it’s a functional device that isn’t scared to show off the goods, we’re interested in seeing it. Just document the project on Hackaday.io and submit it to the contest before the January 8th, 2019 deadline.
The build relies on an astounding number of ultrasonic transducers – 72, in fact. The device operates at 40 kHz to be well above the human range of hearing. 36 each are placed in the top and bottom shells of the device’s 3D printed chassis. Through careful construction, the transducers are placed an integer multiple of half the wavelength apart. This allows the device to create a standing wave, with several low-energy nodes in which small objects can be levitated. In this case, [Julius] uses small scraps of styrofoam, but notes that water droplets can also be used if one is careful to avoid spilling any on the electronics.
The transducers are energised with a square wave generated by an Arduino Nano. This allows the possibility of the frequency and phase of the wave to be altered, which can help tune the device and allow some movement in the vertical axis. Unfortunately, movement in the other axes isn’t possible as the transducers appear to be connected in parallel. However, this could be a good upgrade in a later revision.
This project shows that a device relying on incredibly precise measurement and control can now be constructed at home with a 3D printer and some off the shelf electronics.