For many of us, this whole pandemic thing has produced some unexpected upsides. One of [George Turvey]’s was finding a nice new scenic route to work that goes by a lake with bike trails. [George] thought it might be nice to go fishing after work, and use a folding bike to cover a lot of ground while looking for good spots on the shore. There was just one problem — riding a bike while transporting tackle is awkward.
Milling won out, at least for the initial proof of concept, and result is a modular mock-up that combines a milled Kydex connector and tackle box holder with a double-barrel PVC rod holder. This way, [George] had a prototype in a fraction of the time it would have taken to design and print it. Cast your line past the break to see how fast [George] can switch gears into fishing mode.
Sometimes the most useful hacks aren’t the flashiest, they’re the ones that improve an already great tool and make something better. Through hole components are still the fastest and perhaps most satisfying way to prototype a new electronics project so it’s extra frustrating when the happy hacker discovers their new devboard is too wide to fit in a standard breadboard. [Tobias] had the same thought and redesigned the standard ESP32 “NodeMCU” style devboard to be almost exactly the same, but narrower.
Interactive BOMs make assembly a snap
Not to trivialize, but that’s pretty much it. And we love it! The new design retains the great support of the original devboard but adds a few nice tweaks. Obviously there’s the small size change that allows it to fit on a standard 5×5 breadboard leaving sockets available on either side for interfacing. Even in this smaller size [Tobias] managed to retain the boot mode and reset buttons though the overall pinout has changed slightly. And for easier connections ye olde micro USB socket has been swapped for sleek modern USB-C. You have cables for that common standard now, right?
How do you get one? As far as we know [Tobias] isn’t selling these but the design is completely open source and the design, fab, and BOM files are all in the github repository. [Tobias] even went so far as to include the extremely handy interactive BOM to speed up hand assembly. The real trick here is that the board is designed to facilitate the extremely inexpensive turnkey assembly now available from our favorite fab houses, with an example cost of $8/piece for a run of five. The repo includes a properly formatted BOM and fab files to make ordering them a snap. See the bottom of the README for details about what to order.
It is hard to remember how expensive an electronic hobby used to be. It wasn’t long ago, for example, that a solderless breadboard was reasonably expensive and was likely to have some sort of baseboard. The nicer ones even had a power supply or some simple test instruments. While you can still buy that sort of thing today, the low cost of bare breadboards have made them much more common. [Sebastian] decided to use his 3D printer to give those cheap breadboards a nice home.
The design looks great, and frankly isn’t much of a technical triumph, but it is useful and clean looking. The build uses some banana jacks, a switch, an LED, a 9V battery, and a common small power supply module. Of course, you also need a few breadboards.
A chaotic drone of meaningless sound to lull the human brain out of its usual drive to latch on to patterns can at times be a welcome thing. A nonsense background din — like an old television tuned to a dead channel — can help drown out distractions and other invading sounds when earplugs aren’t enough. As [mitxela] explains, this can be done with an MP3 file of white noise, and that is a solution that works perfectly well for most practical purposes. However he found himself wanting a more refined hardware noise generator with analog controls to fine tune the output, and so the Rumbler was born.
It’s a tight fit, but it does fit.
The Rumbler isn’t just a white noise generator. White noise has a flat spectrum, but the noise from the Rumbler is closer to Red or Brownian Noise. The different colors of noise have specific definitions, but the Rumbler’s output is really just white noise that has been put through some low pass filters to create an output closer to a nice background rumble that sounds pleasant, whereas white noise is more like flat static.
Why bother with doing this? Mainly because building things is fun, but there is also the idea that this is better at blocking out nuisance sounds from neighboring human activities. By the time distant music (or television, or talking, or shouting) has trickled through walls and into one’s eardrums, the higher frequencies have been much more strongly attenuated than the lower frequencies. This is why one can easily hear the bass from a nearby party’s music, but the lyrics don’t survive the trip through walls and windows nearly as well. The noise from the Rumbler is simply a better fit to those more durable lower frequencies.
[Mitxela]’s writeup has quite a few useful tips on analog design and prototyping, so give it a read even if you’re not planning to make your own analog noise box. Want to hear the Rumbler for yourself? There’s an embedded audio sample near the bottom of the page, so go check it out.
The idea of trying to prototype with SMD parts on the fly sounds like insanity, right? But then we watched [Leo Fernekes] walk calmly and carefully through his process (video, embedded below). Suddenly, SMD prototyping jumped onto our list of things to try soon.
[Leo] speaks from a lot of experience and tight client timelines, so this video is a fourteen-minute masterclass in using copper-clad board as a Manhattan-style scratch pad. He starts by making a renewable tool for scraping away copper by grinding down and shaping an old X-Acto blade into a kind of sharpened Swiss Army knife bottle opener shape. That alone is mind-blowing, but [Leo] keeps on going.
In these prototypes, he uses the through-hole version of whatever microcontroller is in the design. For everything else, he uses the exact SMT part that will end up on the PCB that someone else is busy designing in the meantime.
After laying the board out on paper, [Leo] carves out the islands of conductivity, beep-checks them for shorts, shines the whole thing with steel wool, and goes to town.
The tips and tricks keep coming as he makes jumps and joins ground planes with bare copper wire insulated with heat-proof Teflon tubing, and lays out the benefits of building up a stash of connectors and shelling out the money for a good crimp tool.
The Valve Index VR headset incorporates a number of innovations, one of which is the distinctive off-ear speakers instead of headphones or earbuds. [Emily Ridgway] of Valve shared the design and evolution of this unusual system in a deep dive into the elements of the Index headset. [Emily] explains exactly what they were trying to achieve, how they determined what was and wasn’t important to deliver good sound in a VR environment, and what they were able to accomplish.
First prototype, a proof-of-concept that validated the basic idea and benefits of off-ear audio delivery.
Early research showed that audio was extremely important to providing a person with a good sense of immersion in a VR environment, but delivering a VR-optimized audio experience involved quite a few interesting problems that were not solved with the usual solutions of headphones or earbuds. Headphones and earbuds are optimized to deliver music and entertainment sounds, and it turns out that these aren’t quite up to delivering on everything Valve determined was important in VR.
The human brain is extremely good at using subtle cues to determine whether sounds are “real” or not, and all kinds of details come into play. For example, one’s ear shape, head shape, and facial geometry all add a specific tonal signature to incoming sounds that the brain expects to encounter. It not only helps to localize sounds, but the brain uses their presence (or absence) in deciding how “real” sounds are. Using ear buds to deliver sound directly into ear canals bypasses much of this, and the brain more readily treats such sounds as “not real” or even seeming to come from within one’s head, even if the sound itself — such as footsteps behind one’s back — is physically simulated with a high degree of accuracy. This and other issues were the focus of multiple prototypes and plenty of testing. Interestingly, good audio for VR is not all about being as natural as possible. For example, low frequencies do not occur very often in nature, but good bass is critical to delivering a sense of scale and impact, and plucking emotional strings.
“Hummingbird” prototype using BMR drivers. Over twenty were made and lent to colleagues to test at home. No one wanted to give them back.
The first prototype demonstrated the value of testing a concept as early as possible, and it wasn’t anything fancy. Two small speakers mounted on a skateboard helmet validated the idea of off-ear audio delivery. It wasn’t perfect: the speakers were too heavy, too big, too sensitive to variation in placement, and had poor bass response. But the results were positive enough to warrant more work.
In the end, what ended up in the Index headset is a system that leans heavily on Balanced Mode Radiator (BMR) speaker design. Cambridge Audio has a short and sweet description of how BMR works; it can be thought of as a hybrid between a traditional pistonic speaker drivers and flat-panel speakers, and the final design was able to deliver on all the truly important parts of delivering immersive VR audio in a room-scale environment.
As anyone familiar with engineering and design knows, everything is a tradeoff, and that fact is probably most apparent in cutting-edge technologies. For example, when Valve did a deep dive into field of view (FOV) in head-mounted displays, we saw just how complex balancing different features and tradeoffs could be.
Wearables are kind of a perplexing frontier for electronics. On the one hand, it’s the best possible platform for showing off a circuit everywhere you go. On the other hand, the whole endeavor is fiddly because the human body has no straight lines and moves around quite a bit. Circuits need to be flexible and comfortable. In other words, a wearable has to be bearable.
[Konstantin], [Raimund], and [Jürgen] have developed an intriguing system for prototyping e-textiles that opens up the wearables world to those who don’t sew and makes the prototyping process way easier for everyone.
It’s a small and portable roll-on ironing device that lays down different kinds of custom ‘tapes’ on to textiles. The conductive fabric tapes can be used as touchable traces, and can support components such as flexible e-ink screens and solar panels. Some tapes provide single or multiple points of connectivity, and others are helper substrates like polyimide tape that multiply the possibilities for complex circuits.
The device uses a modified soldering iron to transfer the tapes, which are loaded onto 3D-printed spools that double as the wheels. Check it out after the break — there’s a 30-second tour and a 5-minute exploration of the whole process.
