TechyMagThings

Whether you’re using granules or filament, FDM printing relies heavily on a consistent flowrate of the extruder. This is also the challenge with [HomoFaciens]’s direct granule extruder. Version 7.1 here refines some parameters before being put through a number of printing tests to see how close it comes to something you’d want to use for production.

There’s also an accompanying blog post, on which the project files can be found for those who are playing along at home.

A big part of this V7.1 change was to simplify the design for manufacturing, removing the brass insert of V7.0, instead requiring some manual labor using a drill bit and a hand reamer to get the inside of the extruder tube just right.

The section with the heating element was also extended, though this didn’t have as much of an effect as expected. During testing the overall results were actually pretty good, with the extruder able to keep up with bridging tests while the feared air bubbles from air intruding into the tube remained absent.

On the Prusa Mk4 FDM printer, there are some definite limitations on testing features like input shaping resulting in wavy patterns in some rest prints, but for upcoming tests a different FDM printer will be used which should more clearly show the potential of this extruder design.

PCBs are traditionally designed with traces laid out to support a circuit full of electronic components. However, they’ve become increasingly popular as a way to produce functional visual artworks. This PCB map from [Jonathan] is a great example.

The PCB was designed as a map of the California East Bay area. The roads are laid out as the top-side copper layer, while the land and roads are used for the top solder mask layer, with the flipped land and roads area making up the solder mask on the bottom side. The map data itself was cribbed from Snazzy Maps. Behind the PCB, [Jonathan] mounted a 64 x 32 RGB LED array, which can be seen glowing through from behind the material. The LEDs are controlled by an ESP32, which grabs location data from [Jonathan’s] family member’s mobile devices over MQTT, and uses it to light their positions on the map. Files are on Github for the curious.

If you’ve got a family that is open to location tracking, and the money to pay for a custom PCB, you could probably recreate this project yourself. We’ve seen some other great PCB maps before, too, like this amazing metro tracker. Video after the break.

Typically, when we think of touch screens, we think of LCDs or OLEDs with a resistive or capacitive sensing layer laid over the top. However, a team from the University of Chicago has developed an entirely different type of touch-sensitive display that uses persistence-of-vision techniques.

The project is called BloomBeacon. It consists of a pair of spinning arms to create a stable round display in mid-air. One arm is covered in LEDs, while the other is covered with capacitive pads for touch sensing purposes.  The trick behind this device is evident in the name—the device uses soft, flexible arms which are hinged and “bloom” upwards as the device spins up to speed. This makes it safe to physically interact with the spinning blades while they’re in motion to create a touch-interactive display. The device can thus display user interface elements like buttons that the viewer can interact with by reaching out and touching them directly.

Normally we’d advise not sticking your fingers in a rotating piece of machinery, but in this case, BloomBeacon was designed specifically to make this safe. Even sticking your fingers or hand right through the spinning arms won’t cause injury.

We’ve featured some other cool POV projects over the years, like this neat volumetric display. Video after the break.

If it’s summer in a warm, humid climate, bugs can be the bane of your existence. A natural solution is to place a passive bug zapper to catch bugs at night. But what if that isn’t fancy enough? [Nicolas Boichat] spices it up with a passive bug zapper that tracks its kill count.

But how exactly do you detect a bug zap? With an antenna, of course! When a bug gets caught, it arcs, creating an electromagnetic pulse. A small loop antenna on the backside of the zapper receives the signal.

It was also in part an experiment to see how good you can “vibe-EE” and, well, mixed results. Claude was able to correctly identify basic concepts of EE needed here, but was largely worthless at making schematics. After some manual circuit doodling, then building, [Nicolas] successfully got an ESP32-C6 to detect the voltage spikes.

Of course, where there’s data, there must be a dashboard. Using existing graphing libraries and a custom PCB, [Nicolas] has the ultimate bug zapping experience.

We’ve covered a similar idea in the past, namely one based on current sensing.

A key part of any tertiary musical education is learning about all the wonderful (and less wonderful) types of chords out there. Typically this involves a great deal of exercises involving the identification of a given chord from its component notes. But how would you do this programmatically? Well, thankfully, the developers behind the WhatChord tool are happy to explain just how it’s done.

The problem with classifying chords is that the way musicians use them and construct them can be quite varied. Names can also be applied somewhat differently depending on the musical context of a given set of notes. To suit the musical reality of real players and composers, WhatChord uses a specially-developed scoring algorithm to try and nut out what a chord is actually supposed to be.

As an example, a major chord must require a root note and a major third interval. It can optionally include a perfect fifth. However, if there is a minor third, minor seventh, or major seventh present, then you’re almost certainly not looking at a simple major chord. WhatChord takes these things into account by weighting the different tones present and seeing which chord gets the highest score. The required notes add weight, while notes that shouldn’t be there add a penalty to the score. Then there are extra penalties for ambiguous “unexplained” tones, extensions, and a few other parameters to disambiguate edge cases.

If you’d like to see how it works in practice, you can check out the WhatChord app and see how good it is for yourself. Alternatively, explore some of the other chord-focused projects we’ve featured over the years, or send your best musical projects into the tipsline.

[Thanks to baschwar for the tip!]

Engineering design makes all kinds of tradeoffs. Power trades off with torque, strength trades off with weight, and cost can trade off with quality. For designing a hydroelectric turbine, one of the main tradeoffs is hydraulic head with flow rate. Many large dams meant for bulk power generation will go with high head (or medium) designs, and for small dams with low head it’s usually not cost effective to build any generation. But if you’re really determined, you’ll want to build a low head water turbine like this one.

The build aims to use easy-to-find materials and simple tools. It uses 110mm and 160mm PVC pipe to not only siphon water up and over a dam, but to house the turbine as well. The turbine is built from a computer fan and sits inside the pipe with a shaft running through a Y-type fitting to the generator. The generator is built from a scavenged hoverboard wheel, and outputs a reported 3.3A DC at 60V for around 200 watts of power with only around 3m of head. The design allows the turbine to be placed at the point in the pipe that best suits the environment.

[OpenSourceLowTech], the creators of this project, make a compelling case that this build is cheaper than a 150W solar panel and it might even be able to produce more energy as well over certain timeframes, provided there’s a reliable source of water available and the owners of the dam don’t mind someone siphoning water over it continuously. The build video is worth a watch as well if for nothing else than the animation, which documents the build in excellent detail. Generating usable energy from hydropower doesn’t even need this big of a dam; if all you need is to charge your phone this tiny waterwheel will get the job done.

Thanks to [Keith] for the tip!

A healthy aquarium ecosystem requires very specific conditions, with factors like the salinity and temperature having to be just right to keep said ecosystem happy. As some species are adapted to fairly cold water, this requires the use a water chiller. Recently [The Blunt Oracle] modified one of these aquarium-focused chillers with a much better controller to make it both more accurate and potentially more efficient as well.

The target for the surgery was a generic Shanhuchong Y-160 chiller that after a brief teardown turned out to use an STC-1000 style controller. The biggest disadvantage with this unit is probably that it just has one temperature probe, which monitored the temperature of the heat exchanger rather than that of the chilled water tank.

This controller was replaced with a Wi-Fi-equipped Elitech ECS-974T sourced for $50 off AliExpress that uses the same 71 x 29 mm form factor. Following that it was just a matter of some creative rewiring – as shown in the top image – and installing the twin temperature probes of the new controller.

Being able to monitor also the temperature of the chilled water adds a layer of redundancy that’s very welcome after splurging thousands of clams on a fancy aquarium and its inhabitants. As a bonus the Wi-Fi interface allows for it to be monitored and controlled remotely, with [The Blunt Oracle] pushing the Home Assistant configuration in a PR as well that recently got merged. They’d also like to extend their thanks to Elitech for having pretty good documentation that really helped with creating the HA configuration file, which is a rarity with many of such controllers.