Author: Dan Maloney

3373 Articles

This Simple Light-Controlled Synth Has A Surprisingly Rich Sound

September 15, 2022 by 5 Comments

Audio synthesizers can range from vast racks of equipment with modules stitched together by a web of patch cords to a couple of 555s wired together in an Atari punk arrangement. This light-controlled synth comes in closer to the lower extreme of that range, but packs a sonic punch that belies its simplicity.

The project is the latest version of [lonesoulsurfer]’s “Moog Light Synthesizer,” which shares a lot of the circuitry found in his first version a couple of years ago. This one has a lot of bells and whistles, but it all starts with a PWM oscillator that contributes to the mean, growling quality of its sound. There’s also a low-pass filter that’s controlled by a couple of light-dependent resistors, which can be played by blocking them off with a fingertip. A couple of inverters form a drone oscillator that can be switched into the circuit, as well as a 555-based arpeggiator to chop things up a bit.

All those circuits, as well as support for a thirteen-key keyboard, live on one custom PCB. There’s also an off-the-shelf echo/reverb module that’s been significantly hacked to add to the richness of the sound. The custom wood and acrylic case make the whole thing look as good as it sounds.

We noted that [lonesoulsurfer]’s previous “Box of Beezz” drone synth seemed to evoke parts of the “THX Deep Note” at times; similarly, some of the sounds of this synth sound like they’d come from the soundtrack of a [Christopher Nolan] film  — check it out in the video below.

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Neon Lamps — Not Just For Pilot Lights

September 13, 2022 by 30 Comments

It’s easy to see why LEDs largely won out over neon bulbs for pilot light applications. But for all the practical utility of LEDs, they’re found largely lacking in at least one regard over their older indicator cousins: charm. Where LEDs are cold and flat, the gentle orange glow of a neon lamp brings a lot to the aesthetics party, especially in retro builds.

But looks aren’t the only thing these tiny glow lamps have going for them, and [David Lovett] shows off some of the surprising alternate uses for neon lamps in his new video. He starts with an exploration of the venerable NE-2 bulb, which has been around forever, detailing some of its interesting electrical properties, like the difference between the voltage needed to start the neon discharge and the voltage needed to maintain it. He also shows off some cool neon lamp tricks, like using them for all sorts of multi-vibrator circuits without anything but a few resistors and capacitors added in. The real fun begins when he breaks out the MTX90 tube, which is essentially a cold cathode thyratron. The addition of a simple control grid makes for some interesting circuits, like single-tube multi-vibrators.

The upshot of all these experiments is pretty clear to anyone who’s been following [David]’s channel, which is chock full of non-conventional uses for vacuum tubes. His efforts to build a “hollow state” computer would be greatly aided by neon lamp circuits such as these — not to mention how cool they’d make everything look.

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Heavy Engineering Hack Chat

September 13, 2022 by 1 Comment

Join us on Wednesday, September 14 at noon Pacific for the Heavy Engineering Hack Chat with Andy Oliver!

Here at Hackaday, we focus mainly on engineering at the small end of the spectrum. Millimeter waves, nearly microscopic SMD components, nanoscale machines like MEMS accelerometers, and silicon chips with features that measure in the nanometer range. We’ve all become pretty good at wrapping our heads around problems at the wee end of the spectrum.

And while all that tiny stuff is great, there’s a whole, big world out there to explore, with big engineering to solve big problems. Think of things like dam spillways, lift bridges, and canal locks — big stuff that still has to move, and has to do it safely and efficiently. Those are problems that demand an entirely different way of thinking, and skills that not a lot of us have.

join-hack-chatAndy Oliver works in the world of big, movable structures, designing control systems for them. He’ll drop by the Hack Chat to discuss the engineering that not only makes these structures work but also keeps them safe and reliable. If you’ve ever wondered how big things work, you won’t want to miss this one.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, September 14 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

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Hackaday Links: September 4, 2022

September 4, 2022 by 19 Comments

Say what you will about Tesla, but there’s little doubt that the electric vehicle maker inspires a certain degree of fanaticism in owners. We’re used to the ones who can’t stop going on about neck-snapping acceleration and a sci-fi interior. But the ones we didn’t see coming are those who feel their cars are so bad that they need to stage a hunger strike to get the attention of Tesla. The strike is being organized by a group of Tesla owners in Norway, who on their website enumerate a long list of grievances, including design defects, manufacturing issues, quality control problems, and customer service complaints. It’s not clear how many people are in the group, although we assume at least 18, as that’s the number of Tesla cars they used to spell out “HELP” in a parking lot. It’s also not clear how or even if the group is really off their feed, or if this is just a stunt to get the attention of Tesla honcho and notorious social media gadfly Elon Musk.

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Machine Learning App Remembers Names So You Don’t Have To

September 3, 2022 by 9 Comments

Depending on your point of view, real-life conversations with strangers can either be refreshing or terrifying. Some of us are glib and at ease in new social situations, while others are sure that the slightest flub will haunt them forever. And perhaps chief among these conversational faux pas is forgetting the name of the person who just introduced themselves a few seconds before.

Rather than commit himself to a jail of shame on such occasions, [Caleb] fought back with this only slightly creepy name-recalling smartphone app. The non-zero creep factor comes from the fact that, as [Caleb] points out, the app crosses lines that most of us would find unacceptable if Google or Amazon did it — like listening to your every conversation. It does this not to direct ads to you based on your conversations, but to fish out the name of your interlocutor from the natural flow of the conversation.

It turns out to be a tricky problem, even with the help of named-entity recognition (NER), which basically looks for the names of things in natural text. Apache OpenNLP, the NER library used here, works well at pulling out names, but figuring out whether they’re part of an introduction or just a bit of gossip about a third party is where [Caleb] put the bulk of his coding effort. That, and trying to make the whole thing at least a little privacy-respecting. See the video below for a demo.

To be sure, this doesn’t do much more than a simple, ‘remind me of your name again?’ would, but without the embarrassment. It’s still pretty cool though, and we’re especially jazzed to learn about NER and the tons of applications for it. Those are projects for a future day, though. We’re just glad to see that [Caleb] has moved on from monitoring the bodily functions of his dog and his kid. At least for now.

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Fixing A Hot Shop, With Science

September 2, 2022 by 42 Comments

We know that pretty much everybody in the Northern hemisphere has had a hellish summer, and there’s little room for sympathy when someone busts out with, “Oh yeah? You think THAT’s hot? Well, lemme tell you…” But you’ve got to pity someone who lives in north Texas and has a steel Quonset hut for a shop. That’s got to be just stupidly hot.

But stupid hot can be solved — or at least mitigated — with a little smarts, which is what [Wesley Treat] brought to bear with this cleverly designed shop door heat shield. When it pushes past 42°C — sorry, that sounds nowhere near as apocalyptic as 108°F — the south-facing roll-up door of his shop becomes a giant frying pan, radiating heat into his shop that the air conditioner has trouble handling. His idea was to block that radiant heat with a folding barrier, but to make sure it would be worth the effort, he mocked up a few potential designs and took measurements of the performance of each. His experiments showed him that a layer of extruded polystyrene (XPS) foam insulation covered with reflective Mylar did better than just the foam or Mylar alone.

The finished heat shield is an enormous tri-fold plywood beast that snugs up against the door when things get toasty in the shop. There’s a huge difference in temperature between the metal door and the inside surface of the shield, which will hopefully keep the shop more comfortable. We imagine that the air between the door and the shield will still heat up, and convection could still distribute all that hot air into the shop. But at least he’s giving the AC a fighting chance.

In addition to great shop tips like this and his custom storage bins, [Wesley] is a talented signmaker. He’s pretty funny too — or maybe that’s just the heat talking.

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Truthsayer Uses Facial Recognition To See If You’re Telling The Truth

September 2, 2022 by 18 Comments

It’s hard to watch [Mark Zuckerberg]’s 2018 Congressional testimony and not come to the conclusion that he is, at a minimum, quite a bit different than the average person. Of course, having built a multibillion-dollar company that drastically changed everything about the way people communicate is pretty solid evidence of that, but the footage at least made a fun test case for this AI truth-detecting algorithm.

Now, we’re not saying that anyone in these videos was lying, and neither is [Fletcher Heisler]. His algorithm, which analyzes video of a person and uses machine vision to pick up cues that might be associated with the stress of untruthfulness, is far from perfect. But as the first video below shows, it is a lot of fun to see it at work. The idea is to capture data like pulse rate, gaze direction, blink rate, mouth posture, and even hand position and use them as a proxy for lying. The second video, from [Fletcher]’s recent DEFCON talk, has much more detail.

The key to all this is finding human faces in a video — a task that seemed to fail suspiciously frequently when [Zuck] was on camera — using OpenCV and MediaPipe’s Face Mesh. The subject’s pulse is detected by watching for subtle changes in the color of a subject’s cheeks as blood flows through them, which we’ve heard about plenty of times but never before seen presented so clearly and executed so simply. Gaze direction, blinking, and lip compression are fairly easy to detect too. [Fletcher] also threw in the FER library for facial expression recognition, to get an idea of the subject’s mood. Together, these cues form a rough estimate of the subject’s truthiness, which [Fletcher] is quick to point out is just for entertainment purposes and totally shouldn’t be used on your colleagues on the next Zoom call.

Does [Fletcher]’s facial mesh look familiar? It should, since we once watched him twitch his way through a coding interview.

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