Detail of a circuit sculpture in the shape of a lighthouse

Op Amp Contest: This Lighthouse Sculpture Flickers In The Rhythm Of Chaos

Op amps are typically used to build signal processing circuits like amplifiers, integrators and oscillators. Their functionality can be described by mathematical formulas that have a single, well-defined solution. However, not every circuit is so well-behaved, as Leon Chua famously showed in the early 1980s: if you make a circuit with three reactive elements and a non-linear component, the resulting oscillation will be chaotic. Every cycle of the output will be slightly different from its predecessors, and the circuit might flip back and forth between different frequencies.

A circuit sculpture in the shape of a lighthouseA light modulated with a chaotic signal will appear to flicker like a candleflame, which is the effect [MaBe42] was looking for when he built a lighthouse-shaped circuit sculpture. Its five differently-colored LEDs are driven by a circuit known as Sprott’s chaotic jerk circuit. A “jerk”, in this context, is the third-order derivative of a variable with respect to time – accordingly, the circuit uses three RC integrators to implement its differential equation, along with a diode to provide nonlinearity.

The lighthouse has three chaotic oscillators, one in each of its legs. Their outputs are used to drive simple pulse-width modulators that power the LEDs in the top of the tower. [MaBe42] used the classic LM358 op amp for most of the circuits, along with 1N4148 diodes where possible and 1N4004s where needed – not for their higher power rating, but for their stronger leads. As is common in circuit sculptures, the electronic components are also part of the tower’s structure, and it needs to be quite sturdy to support its 46 cm height.

[MaBe42] used 3D printed jigs to help in assembling the various segments, testing each circuit before integrating it into the overall structure. The end result is a beautiful ornament for any electronics lab: a wireframe structure with free-hanging electronic components and randomly flickering lights on top. Want to learn more about circuit sculpture? Check out this great talk from Remoticon 2020.

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This Tabletop Lighthouse Will Get Your Attention

If you wear headphones around the house with any regularity, you’re probably missing out on a lot of audio cues like knocks at the door, people calling your name, or maybe even the smoke alarm. What if you had a visual indicator of sound that was smart enough to point it out for you?

That is the point of [Jake Ammons’] attention-getting lighthouse, designed and built in two weeks’ time for Architectural Robotics class. It detects ambient noise and responds to it by focusing light in the direction of the sound and changing the color of the light to a significant shade to indicate different events. Up inside the lighthouse is a Teensy 4.0 to read in the sound and spin a motor in response.

[Jake]’s original directive was to make something sound-reactive, and then to turn it into an assistive device. In the future [Jake] would like to add more microphones to do sound localization. We love how sleek and professional this looks — just goes to show you what the right t-shirt stretched over 3D prints can do. Check out the demo after the break.

Seaside lighthouses once used gas lights giant Fresnel lenses, but now they use LEDs. A company in Florida is using CNC machines to crank out acrylic Fresnels.

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This Is Your Solution For Open Source Motion Tracking

The HTC Vive Tracker adds real-world objects to your virtual world. While these real-world objects in virtual environments are now mostly limited to a Nintendo Zapper for a Duck Hunt clone and a tennis racket, the future is clear: we’re going to be playing Duck Hunt and Wii Sports while wearing headsets. The future is so bright, it burns.

Of course, with any piece of neat computing hardware, there’s an opportunity for building an Open Source clone. That’s what [Drix] is doing with his Hackaday Prize entry. He’s created an Open Source Vive Tracker. It’s called the HiveTracker, and it is right now the best solution for tracking objects in a 3D space.

After a few missteps with ultrasonic and magnetic approaches, the team decided to piggyback on the HTC Vive lighthouses. These two base stations scan a laser beam across the room, first vertically, then horizontally. It’s an incredible piece of technology that [Alan Yates] talked about at the 2016 Hackaday Superconference.

While most microcontrollers don’t operate fast enough to see these laser sweeps, the team behind the HiveTracker found one microcontroller, with Bluetooth, and a feature called ‘PPI’. This programmable peripheral interconnect is kinda, sorta like a cross-bar, but designed for more real-time control of applications. With the right software, the team behind the HiveTracker was able to detect the lighthouses and send position and orientation data back to a computer.

This is a stupendous amount of work, and the results are remarkable. You can check out the video below and see that, yes, this is a real, Open Source Vive Tracker.

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Antique Lighthouse Lens Via CNC

Before the invention of the high-powered LED, and even really before the widespread adoption of electric lights in general, lighthouses still had the obligation of warning ships of dangers while guiding them into various safe harbors. They did this with gas lights and impressive glass lenses known as Fresnel lenses which helped point all available light in the correct direction while reducing weight and material that would otherwise be used in a conventional lens.

Now, a company in Florida is using acrylic in reproductions of antique Fresnel lenses. At first glance, it seems like acrylic might not be the best substitute for glass, but the company is able to achieve extreme precision using a CNC machine and then polishing and baking the acrylic which makes it transparent and excellent for use in lighthouse lenses like this. The reproduction lenses are built out of brass, and the lens elements are glued in place with a special adhesive. It’s a convincing replication worthy of use in any lighthouse.

Be sure to check out the video below to see how these lenses are built, and although we’re not entirely sure what exactly is being sprayed on the lenses when they are being polished, perhaps someone in the comments section can illuminate that for us. Of course, there are other uses for Fresnel lenses than in lighthouses, and we’ve seen some great examples of them put to use for many different applications.

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Superconference Interview: Alan Yates

In 2015, virtual reality was the future, which means we should all have it right now. One of the most technologically impressive VR sets is the HTC Vive, an amazing piece of kit that’s jam-packed with sensors and has some really cool tech going on inside it.

One of the developers of the HTC Vive and the ever-important ‘Lighthouse’ position sensors is [Alan Yates]. He’s of Valve and gave a talk at last year’s Superconference on Why the Lighthouse Can’t Work. Being able to determine the absolute position of the Valve’s headset is hard, but absolutely necessary for VR. Anything else would be an incomplete VR experience at best, and give you nausea at worst.

We sat down with [Alan] after his talk last year, and now that interview is up. You can check that out below.

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Vive Tracker Brings Easier VR Hacking

CES 2017 is over and there were VR gadgets and announcements aplenty, but here’s an item that’s worth an extra mention because it reflects a positive direction we can’t wait to see more of. HTC announced the Vive Tracker, to be released within the next few months.

The Tracker looks a bit like a cross between a hockey puck and a crown. It is a self-contained, VR trackable device with a hardware port and built-in power supply. It can be used on its own or attached to any physical object to make that object trackable and interactive in VR. No need to roll your own hardware to interface with the Vive’s Lighthouse tracking system.

Valve have been remarkably open about the technical aspects of their hardware and tracking system, and have stated they want to help people develop their own projects using the system. We’ve seen very frank and open communication on the finer points of what it took to make the Lighthouse system work. Efforts at reverse-engineering the protocol used by the controller even got friendly advice. For all the companies making headway into VR, Valve continues to be an interesting one from a hacking perspective.

[Image source for bottom of Tracker: RoadToVR]


Alan Yates: Why Valve’s Lighthouse Can’t Work

[Alan Yates] is a hacker’s engineer. His job at Valve has been to help them figure out the hardware that makes virtual reality (VR) a real reality. And he invented a device that’s clever enough that it really should work, but difficult enough that it wasn’t straightforward how to make it work.

In his presentation at the Hackaday Supercon 2016, he walked us through all of the design and engineering challenges that were eventually conquered in getting the Lighthouse to market. We’re still a bit overwhelmed by the conceptual elegance of the device, so it’s nice to have the behind-the-scenes details as well.

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