Surf’s Up, A Styrofoam Ball Rides The Waves To Create A Volumetric Display

We are big fans of POV displays, particularly ones that move into 3D. To do so, they need to move even faster than their 2D cousins. [danfoisy] built a volumetric display that doesn’t move LEDs or any other digital display through space, or project light onto a moving surface. All that moves here is a bead of styrofoam and does so at up to 1 meter per second. Having low mass certainly helps when trying to hit the brakes, but we’re getting ahead of ourselves.

danfoisy vdatp 3d simulation

[danfoisy] and son built an acoustic levitator kit from [PhysicsGirl] which inspired the youngster’s science fair project on sound. See the video by [PhysicsGirl] for an explanation of levitation in a standing wave. [danfoisy] happened upon a paper in the Journal Nature about a volumetric display that expanded this one-dimensional standing wave into three dimensions. The paper described using a phased array of ultrasonic transducers, each with a 40 kHz waveform.

After reading the paper and determining how to recreate the experiment, [danfoisy] built a 2D simulation and then another in 3D to validate the approach. We are impressed with the level of physics and programming on display, and that the same code carried through to the build.

[danfoisy] didn’t stop with the simulations, designing and building control boards for each 100 x 100 10 x 10 grid of transducers. Each grid is driven by 2 Intel Cyclone FPGAs and all are fed 3D shapes by a Raspberry Pi Zero W. The volume of the display is 100 mm x 100 mm x 145mm and the positioning of the foam ball is accurate down to .01 mm though currently there is considerable distortion in the positioning.

Check out the video after the break to see the process of simulating, designing, and testing the display. There are a number of tips along the way, including how to test for the polarity of the transducers and the use of a Python script to place the grids of transducers and drivers in KiCad.

danfoisy vdatp schematic  danfoisy vdatp board layout

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Raspberry Pi Cosmic Ray Detector

[Marco] has a sodium iodide detector that indicates cosmic radiation by scintillation. The material glows when hit by cosmic rays and, traditionally, a photomultiplier tube detects the photos from the detection. After a quick demonstration that you can see in the video below, he built the Cosmic Pi, a CERN project to create a giant distributed cosmic ray detector. The Cosmic Pi uses scintillation, but not from a crystal. It uses a plastic scintillator and silicon photodetectors, so it is much easier to work with than a traditional detector.

Using a four-layer board and some harvested components, the device detects muons. There are two scintillation detectors and muons striking both detectors presumably don’t have a local origin. The instrument has a GPS to get accurate time and position data. There are other sensors onboard, too, to collect data about the conditions of each detected event.

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The Raspberry Pi Pico As An SDR Receiver

With the profusion of cheap RTL-SDR devices and the ever-reducing prices of more capable SDRs there might seem to be little place left for the low-bandwidth devices we’d have been happy with a decade or more ago, but there’s still plenty to be learned from something so simple. It’s something [Luigi Cruz] shows us with a simple SDR using the analogue-to-digital capabilities of the Raspberry Pi Pico, and since it works with GNU Radio we think it’s rather a neat project. CNX Software have the full story, and and quickly reveal that with its 500k samples per second bandwidth it’s not a machine that will set the SDR world on fire even when pushing Nyquist’s Law to the limit.

So with the exception of time signals and a few Long Wave broadcast stations if you live somewhere that still has them, you’ll need a fliter and receive converter to pull in anything of much use radio-wise with this SDR. But a baseband SDR with a couple of hundred kHz useful bandwidth and easy hackability through GNU Radio for the trifling cost of a Raspberry Pi Pico has to be worth a second look. You can see it in action in the video below the break, and if you’re at a loss for what to do with it take a look at Michael Ossmann and Kate Temkin’s 2019 Superconference talk.

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Raspberry Pi Pico ADC Characterized

[Markomo] didn’t find much useful information about the Raspberry Pi PIco’s analog to digital converter, so he decided to do some tests to characterize it. Lucky for us, he documented the findings and shared them. The results are in a series of blog posts that cover power supply noise, input-referred noise, signal to noise ratio, and distortions.

There are some surprising results. For example, the Pico’s low noise regulator mode appears to produce more noise than having it set for normal operation. There also appears to be a large spike in nonlinearity around certain measurements.

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Resilient AI Drone Packs It All In Under 250 Grams

When it was first announced that limits would be placed on recreational RC aircraft heavier than 250 grams, many assumed the new rules meant an end to home built quadcopters. But manufacturers rose to the challenge, and started developing incredibly small and lightweight versions of their hardware. Today, building and flying ultra-lightweight quadcopters with first person view (FPV) cameras has become a dedicated hobby onto itself.

But as impressive as those featherweight flyers might be, the CogniFly Project is really pushing what we thought was possible in this weight class. Designed as a platform for experimenting with artificially intelligent drones, this open source quadcopter is packing a Raspberry Pi Zero and Google’s AIY Vision Kit so it can perform computationally complex tasks such as image recognition while airborne. In case any of those experiments take an unexpected turn, it’s also been enclosed in a unique flexible frame that makes it exceptionally resilient to crash damage. As you can see in the video after the break, even after flying directly into a wall, the CogniFly can continue on its way as if nothing ever happened.

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Raspberry Pi Hitches A Ride In A 1989 BMW Dashboard

It probably won’t surprise you to find out that a 1989 BMW 325i doesn’t have much in the way of electronic gadgetry onboard. In fact, what passes for an in-dash “computer” in this vintage Beemer is just a digital clock with a rudimentary calendar function. Not content to waste his precious dashboard space any longer, [Ryan Henderson] used his time in quarantine to replace the clock module with a Raspberry Pi.

Nestled in a custom laser-cut housing is a touch screen LCD module that connects directly to the GPIO header of a Pi Zero. Combined with some Python code, this provides a very slick multipurpose interface for pretty much anything [Ryan] wants. Right now he’s got it hooked up to a GPS receiver so he can figure out things like speed and acceleration, but the only real limit on what this little drop-in upgrade can do is how much code you want to sit down and write.

Thankfully, it sounds like [Ryan] has done a lot of the hard work for you. He’s put together a Python library that allows the user to easily draw analog gauges on the screen. The faces are parametrically sized, and even have custom minimum/maximum marks. Of course if you’d rather just throw some text and images on the screen, that’s accomplished easily enough with existing libraries such as PyGame.

[Ryan] says he’s also working on some code to better integrate the Pi into the vehicle’s systems by way of a Bluetooth OBD2 adapter. In the most basic application that would allow you to throw various bits of engine data up on the screen, but on more modern cars, you could potentially tap into the CAN bus and bend it to your will.

While the physical size and shape of this particular modification is clearly focused on this model and year of BMW, the general concepts could be applied to any car on the road. [Ryan] has recently started a GitHub repository for the project and hopes to connect with others who are interested in adding a little modern complexity convenience to their classic rides.

The reality is that cars become more dependent on their onboard computers with each passing year. Already we’re seeing Tesla owners struggle with cooked flash chips, and things are likely to get worse before they get any better. While undoubtedly there are some that would rather keep their daily driver as simplistic as possible, we’re encouraged by projects like this that at least let owners computerize their cars on their own terms.

Overall view of Alta's Projects cyberdeck

Cyberdeck Running On Apple Silicon, Though An A12 Not An M1

[Alta’s Projects] built a two-in-one cyberdeck that not only contains the requisite Raspberry Pi (a zero in this case) but also eschews a dumb LCD and uses an iPad mini 5 for a display.

We need to address the donor case right away. Some likely see this as heresy, and while we love to see vintage equipment lovingly restored, upcycling warms our hearts and keeps mass-produced plastic out of landfills too. The 1991 AST 386SX/20 notebook in question went for $45 on an online auction and likely was never destined for a computer museum.

Why is Cupertino’s iOS anywhere near a cyberdeck? If a touch screen is better than an LCD panel, a tablet with a full OS behind it must be even better. You might even see this as the natural outgrowth of tablet cases first gaining keyboards and then trackpads. We weren’t aware that either was possible without jailbreaking, but [Alta’s Projects] simply used a lighting-to-USB dongle and a mini USB hub to connect the custom split keyboard to the iPad and splurged on an Apple Magic Trackpad for seamless and wireless multi-touch input.

Alta's Projects Cyberdeck Internal USB Wiring
Internal USB Wiring, Charging Circuit, and Pi Zero

The video build (after the break) is light on details, but a quick fun watch with a parts list in the description. It has a charming casual feel that mirrors the refreshingly improvisational approach that [Altair’s Projects] takes to the build. We appreciate the nod to this cyberdeck from [Tinfoil_Haberdashery] who’s split keyboard and offset display immediately sprang to mind for us too. The references to an imagined “dystopian future” excuse the rough finish of some of the Dremel cuts and epoxy assembly. That said, apocalypse or not, the magnets mounted at both ends of the linear slide certainly are a nice touch.

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