Carbohydrate foams derived from dead trees are not the first material that springs to mind when considering building audio equipment. But really, there’s no reason not to explore new materials for jobs normally reserved for metal or plastic, and when pulled off right, as with this wooden ribbon microphone, the results can both look and sound great.

To be fair, there are plenty of non-wood components in [Frank Olson]’s replica of a classic RCA model 44 microphone. After all, it’s hard to get wood to exhibit the electromagnetic properties needed to turn acoustic energy into electric currents. But that doesn’t mean that wood, specifically walnut veneer, isn’t front and center in this design. [Frank] worked with thin sheets of veneer; cut into shape with a commercial vinyl cutter and stacked up with alternating grains, the wood was glued up with copious cyanoacrylate adhesive to form a plywood of sorts. The dogbone-shaped body was fitted with two neodymium magnets, leaving a gap just wide enough for the microphone’s ribbon diaphragm. That was made from a thin piece of aluminum foil that was corrugated using a DIY crimp roller. Suspended between the magnets and connected to leads, the mic element was adorned with a wood and fabric windscreen and suspended from elastic bands in a temporary frame for testing. The narration on the video below was recorded with the mic, which sounds quite nice to our ears.

We’ve seen ribbon microphones before, as well as wooden microphones, but this is the first time we’ve seen a wooden ribbon microphone. It looks as though [Frank] has more work he wants to do to finish it off properly, and we eagerly await the finished product.

Continue reading “Wooden You Love To Build A Ribbon Microphone?”

Retired scientist [Mark Howe] spent the last couple months making an animatronic movie featuring his LEGO lunar lander in a video recreation of the Apollo 11 moon landing (also embedded below). [Mark] is not only the producer, but serves as the technical director, set designer, and cameraman as well. He designed and 3D-printed a custom special effects stage for the scene. It gives motion to the LEM using stepper motors, timing belts, pulleys, and a linear guide rod, all hidden inside a discrete upstage tower. He simulates the Lunar regolith using grout, spray adhesive, and a smattering of small rocks.

[Mark] implements the special effects sequencer in an Arduino Nano, and provides sound effects using an Adafruit audio sound board which he loaded up with sound files from the real Apollo 11 landing. Floor strip lighting is provided by an array of Neopixels, and a back-lit Earth is lowered from the fly space for one cut. He made a custom PCB motherboard to hold the Arduino, sound card and motor drivers.

The resulting production is quite impressive. This isn’t [Mark]’s first attempt to relieve the double boredom of both retirement and coronavirus isolation — back in December he produced a similar animatronic movie recreating a Saturn V launch. Thanks to [jhookie55] for the tip.

Continue reading “LEGO Lunar Lander Animatronic Movie Released”

If operating systems weren’t so useful, we would not be running them on every single of our desktop systems. In the same vein, embedded operating systems provide similar functionality as these desktop OSes, while targeting a more specialized market. Some of these are adapted versions of desktop OSes (e.g. Yocto Linux), whereas others are built up from the ground up for embedded applications, like VxWorks and QNX. Few of those OSes can run on a microcontroller (MCU), however. When you need to run an OS on something like an 8-bit AVR or 32-bit Cortex-M MCU, you need something smaller.

Something like ChibiOS (‘Chibi’ meaning ‘small’ in Japanese), or FreeRTOS (here no points for originality). Perhaps more accurately, FreeRTOS could be summarized as a multi-threading framework targeting low-powered systems, whereas ChibiOS is more of a full-featured OS, including a hardware abstraction layer (HAL) and other niceties.

In this article we’ll take a more in-depth look at these two OSes, to see what benefits they bring. Continue reading “Getting Started With FreeRTOS And ChibiOS”

For many in the RC community, blowing up an Electronic Speed Controller (ESC) means one thing: throwing it away and buying another one. However, if you’re regularly pushing the limits or simply hate waste, fixing failed units is an option. To assist in this task, [LouD] built an ingeniously simple ESC tester.

The board is designed to be wired in parallel with a brushless DC motor when hooked up to an ESC. The board packs two LEDs per phase, wired in opposite directions. Thus, current flow in both directions can be visualised on a phase-by-phase basis. If everything is operational, the red and green LEDs on each phase should glow evenly as the throttle is ramped up. However, if there are problems, it will be readily apparent as the blinking becomes erratic or one or more LEDs fails to light at all.

It’s a nifty little device that would prove useful when testing  a pile of possibly-defective units. It’s also a quick way to verify a fix. The project is up on OSHPark should you wish to order your own.

Continue reading “Visualise ESC Problems With LEDs”

The Onion Tau LiDAR Camera is a small, time-of-flight (ToF) based depth-sensing camera that looks and works a little like a USB webcam, but with  a really big difference: frames from the Tau include 160 x 60 “pixels” of depth information as well as greyscale. This data is easily accessed via a Python API, and example scripts make it easy to get up and running quickly. The goal is to be an affordable and easy to use option for projects that could benefit from depth sensing.

When the Tau was announced on Crowd Supply, I immediately placed a pre-order for about $180. Since then, the folks at Onion were kind enough to send me a pre-production unit, and I’ve been playing around with the device to get an idea of how it acts, and to build an idea of what kind of projects it would be a good fit for. Here is what I’ve learned so far.

Continue reading “New Part Day: Onion Tau LiDAR Camera”

Sometimes we are vaguely aware of the inexorable march of technological progress. Other times it thrums steadily under the surface while we go about our lives. And sometimes, just sometimes, it smacks us right in the face.

Few projects can demonstrate the advancement and miniaturization of computing technology like putting an entire functional computer inside a storage medium that once only held mere kilobytes of data. And that’s exactly what [JamHamster] has done by stuffing a Raspberry Pi Zero W inside a cassette tape to run his ZX Spectrum emulator. It’s an impressive and clean build, and it pairs so well with a downright gorgeous, retro inspired, CRT-lookalike LCD monitor, which is another creation of his.

A Raspberry Pi Zero with several areas lightly trimmed away inside an open cassette tape.

The Pi did have to undergo a bit of light surgery; though he managed to lose only four GPIO pins in the operation. He also put a ton of love into a literally-highly-polished aluminum heatsink, which is entirely hidden within the case but does keep the computer cool in its claustrophobic quarters. Of course, [JamHamster] isn’t new to these cassette builds. You may recognize his work from the TZXDuino, a virtual tape loader for the ZX Spectrum.

Honestly, sometimes we just have to sit back and be amazed at the kind of computer power that can be packed into such tiny packages. The Pi Zero isn’t the smallest or the most powerful of options, but it is far more capable than the computer it is emulating here. So whether they’re hiding inside outdated storage formats or powering a stock-looking sleeper PSP, we just can’t help but be impressed.

[chadaustin] has a favorite keyboard with a great ergonomic shape, key travel distance, and size, but after switching to Windows 10, the wireless connection introduced a terrible delay. Worse yet, the receiver is notoriously susceptible to interference from USB 3.0 hubs. To provide 128-bit AES encryption, the receiver is paired with the keyboard at the factory and cannot be replaced. If you lose that, you gain a highly ergonomic paper-weight. The solution for [chadaustin] was tethering the keyboard and receive several crash-courses in hardware hacking along the way. As evidenced by the responses to this project on ycombinator, many long-time fans of the Microsoft Sculpt Ergonomic Keyboard, introduced in 2013, suffer similar issues.

chadaustin's sculpt keyboard USB board layout
KiCad USB controller board layout

We really appreciate that [chadaustin] took an incremental approach, tackling one problem at a time and getting help from others along the way for first attempts at many complex steps. The proof-of-concept involved hand-soldering each lead from the keyboard matrix’s test pads to a QMK Proton C, which worked but couldn’t fit inside the keyboard’s case. For a more permanent and tidy solution, [chadaustin] tried a ribbon-cable breakout board and other microcontrollers, but none of those were compact enough to fit inside the case either. This required a custom PCB, another first for [chadaustin].

After a one-day intro to KiCad, [chadaustin] dug into the datasheets, completed a schematic for the board, and generously shared the process of choosing components and creating the layout. [chadaustin] ordered a board and found the mounting holes’ placement needed to be shifted.

With the full matrix mapped by [johnmilkspill], flashing QMK onto the AT90USB1286 controller went fairly smoothly. [chadaustin] chose to map both sides of the split spacebar back to the space key but did add a feature by repurposing the battery indicator LED to Caps Lock. And the results?

chadaustin's sculpt keyboard USB controller fit into case
USB controller fits into the plastic case, wires added to ISP for bootloader button

According to testing done with Is It Snappy?, the latency dropped from the wireless 78 ms down to 65 ms over USB. More importantly, this latency is now consistent, unaffected by USB hubs, and there is no receiver to lose. Of course, [chadaustin] has ideas for future improvement, including regaining the multimedia function keys, as these kinds of hacks are never really done; they are just in the current revision. No word on the fate of the detached number pad, but that likely needs its own tether and is a project for another day.

Thanks for the tip [Linus Söderlind]