A 50W Speaker Made Of Light Bulbs

June 8, 2020 by Jenny List 27 Comments

When we think of a speaker, we are likely to imagine a paper cone with a coil of wire somewhere at the bottom of it suspended in a magnetic field. It’s a hundred-plus-year-old technology that has been nearly perfected. The moving coil is not however the only means of turning an electrical current into a sound. A number of components will make a sound when exposed to audio, including to the surprise of [Eric], the humble incandescent light bulb. He discovered when making an addressable driver for them that he could hear the PWM frequency when they lit up, so he set about harnessing the effect for use as a speaker.

Using an ESP32 board and with a few false starts due to cheap components, he started with MIDI files and ended up with PWM frequencies. It’s an interesting journey into creating multiple PWM channels from an ESP32, and he details some of his problems along the way. The result is the set of singing light bulbs that can be seen in the video below the break, which he freely admits is probably the most awful 50 W speaker that he could have made. That however is not the point of such an experiment, and we applaud him for doing it.

For more MIDI-based tomfoolery, take a look at the PCB Tesla coil.

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3D Printing Nuclear Reactors For Fun And Profit

June 8, 2020 by Maya Posch 18 Comments

Over the past decades, additive manufacturing (AM, also known as 3D printing) has become increasingly common in manufacturing processes. While immensely helpful in the prototyping of new products by allowing for rapid turn-around times between design and testing, these days additive manufacturing is used more and more often in the production of everything from small production runs of custom enclosures to hard to machine components for rocket engines.

The obvious advantage of additive manufacturing is that they use generic equipment and common materials as input, without requiring expensive molds as in the case of injection molding, or extensive, wasteful machining of raw materials on a lathe, mill, and similar equipment. All of the manufacturing gets reduced to a 3D model as input, one or more input materials, and the actual device that converts the 3D model into a physical component with very limited waste.

In the nuclear power industry, these benefits haven’t gone unnoticed, which has led to 3D printed parts being developed for everything from keeping existing plants running to streamlining spent fuel reprocessing and even the printing of entire nuclear reactors.

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Raspberry Pi Plays A MIDI Tune Wherever You May Roam

June 8, 2020 by Sven Gregori 1 Comment

MIDI controller keyboards are great because they let you control any synthesizer you plug them into. The only downside: you need a synthesizer to turn MIDI notes into actual sounds, slightly complicating some summer night campfire serenading. Not for [Geordie] though, who decided to build the nanoPi, a portable, MIDI instrument housing a Raspberry Pi.

Using a Korg nanoKEY2 USB MIDI controller as base for the device, [Geordie] took it apart and added a Raspberry Pi Zero W, a power bank to, well, power it, and a USB hub to connect a likewise added USB audio interface, as well as the controller itself. As the nanoKEY2 has a naturally slim shape, none of this would ever fit in it, so he designed and 3D printed a frame to extend its height. Rather than wiring everything up internally, he decided to route the power and data cable to the outside and connect them back to the device itself, allowing him to use both the power bank and the controller itself separately if needed.

On the software side, the Pi is running your common open source software synthesizer, Fluidsynth. To control Fluidsynth itself — for example to change the instrument — [Geordie] actually uses the Termius SSH client on his phone, allowing him also to shut down the Pi that way. While Fluidsynth’s built-in MIDI router could alternatively remap the nanoKEY2’s additional buttons, it appears the functionality is limited to messages of the same type, so the buttons’ Control Change messages couldn’t be remapped to the required Program Change messages. Well, there’s always the option to fit some extra buttons if needed. Or maybe you could do something clever in software.

As you may have noticed, the nanoPi doesn’t include any speaker — and considering its size, that’s probably for the best. So while it’s not a fully standalone instrument, it’s a nice, compact device to use with your headphones anywhere you go. And thanks to its flexible wiring, you could also attach any other USB MIDI controller to it, such as this little woodwind one, or the one that plays every pop song ever.

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A Look Behind The Canvas Of The “60 Billion Lights” Project

June 8, 2020 by Maya Posch 17 Comments

In May of this year, [Erich Styger] shows his project called “60 Billion Lights” off to the world. Now he has published an update on the making of this impressive work of art. As a quick recap, “60 Billion Lights” is a canvas art piece, which has 60 dual shaft stepper motors integrated into it. Each stepper motor has forty 24-bit RGB LEDs, making for a total of 60 billion position and light combinations on the entire canvas.

With the dual shaft stepper motors, one can control the position of laser-cut acrylic rods inside each of the forty depressions that make up a unit. Each unit has its WS2812B LEDs positioned around the inside edge.

As the embedded video (after the break) shows, it can be used to create a wide variety of effects. The whole of it is driven by 15 controller boards that run FreeRTOS on an NXP LPC845 (Cortex-M0+), connected via RS-485.

In the ‘Making Of’ video (embedded after the break) and article, more details are shown of the individual components, including the dual shaft stepper motors, stepper motor PCBs, the LED ring PCBs, and countless images of the construction, painting and assembly.

If the original article gave one the impression that this was an easy project, it is this behind the scenes look that gives one a good impression of the full scale. From the countless PCBs, controller boards, wiring, programming to the assembly and testing. Not to mention the painting of the canvas itself, which is an original work.
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