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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Quiet Dust Extractor From Scavenged Materials

As with many of the projects covered on hackaday, [bongodrummer]’s Dust Sniper came about because of a lack of effective commercial solutions, in this case to the problem of quiet dust extraction.

Workshops are generally full of dust and noise, both of which take their toll on the human body. This is why safety regulations exist for noisy and dusty workplaces and–as [bongodrummer] rightly points out–we have to take precautions in our own home and community workshops. Hearing protectors, dust masks and safety goggles are integral, but reducing the amount of dust and noise in the fist place is paramount.

Using mostly scavenged materials [bongodrummer] did a quality job building the Dust Sniper–and all for a bill of materials totaling £20. It has an integrated work surface, automatic switches on 2 vacuum lines to sync up with power tools, a cyclonic air filter that prevents clogging the HEPA filter and reducing suction power, inlet and outlet soundproofing, and a plain old power outlet for good measure.

Whether or not you’re interested in building an integrated workbench/extractor system like this one, we recommend you check out the details of the cyclone filter and the sound reducing components. Not only are they an interesting read, but they could be useful to apply in other projects, for example a soldering station with fume hood.

We think it would be really neat to include more cyclones in our projects. Stick around after the break to see [bongodrummer]’s prototype cyclone filter in action.

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Electric Bicycle


[garygadget15] in the UK has an interesting youtube page showing an electric bicycle. On his page titled, saving money the “green way” he has replaced his commuter car with one of these electric bikes. He then videos the commute with both to compare the results. The DIY electric bicycle kit he uses is made by Cyclone comes in multiple wattage’s ranging from 180 watts to 1500 watts where they do a great job of showing the conversion steps. They’ve got enough detail that you could fab your own from salvaged parts if you felt like it.