A 3D Printer Scratch Built For Your Viewing Pleasure

November 23, 2019 by Tom Nardi 14 Comments

Today it’s almost always cheaper to buy an imported 3D printer kit than it is to source your own parts and build one yourself. But that doesn’t stop people from doing it anyway. Whether they’re looking for something a bit more solid, or just want to do things their own way, there are still valid reasons to design and build your own machine. Luckily for us in the audience, [Rob Mech] decided to document the build of his custom “LayerFused C201” printer on his YouTube Channel.

If you’ve ever dreamed of taking the plunge and building a 3D printer exactly the way you want, but were never able to manage the time, this seven video series might be the next best thing. Each video takes you through a different step of the construction, from building the frame out of aluminum extrusion all the way to wiring up the endstop switches and the 32-bit SKR v1.3 controller. There’s even a video that introduces the viewer to the concept of a “Frankenstein” printer that uses cobbled together parts just long enough to produce its own final components.

All told, [Rob] says the Bill of Materials for the LayerFused C201 comes to at least $200, but that’s going to take shopping around for the lowest possible prices and potentially even salvaging some components from other machines and projects. Like we said, building a cheap printer is absolutely not the goal here; it’s all about building a printer you want to use. Continue reading “A 3D Printer Scratch Built For Your Viewing Pleasure” →

Behold A 3D Display, Thanks To A Speeding Foam Ball

November 19, 2019 by Donald Papp 15 Comments

We’ve seen 3D image projection tried in a variety of different ways, but this is a new one to us. This volumetric display by Interact Lab of the University of Sussex creates a 3D image by projecting light onto a tiny foam ball, which zips around in the air fast enough to create a persistence of vision effect. (Video, embedded below.) How is this achieved? With a large array of ultrasonic transducers, performing what researchers call ‘acoustic trapping’.

This is the same principle behind acoustic levitation devices which demonstrate how lightweight objects (like tiny polystyrene foam balls) can be made to defy gravity. But this 3D display is capable of not only moving the object in 3D space, but doing so at a high enough speed and with enough control to produce a persistence of vision effect. The abstract for their (as yet unreleased) paper claims the trapped ball can be moved at speeds of up to several meters per second.

It has a few other tricks up its sleeve, too. The array is capable of simultaneously creating sounds as well as providing a limited form of tactile feedback by letting a user touch areas of high and low air pressure created by the transducers. These areas can’t be the same ones being occupied by the speeding ball, of course, but it’s a neat trick. Check out the video below for a demonstration.
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Water Flow Meter Knows Tank Level

November 11, 2019 by Al Williams 27 Comments

There’s almost always more than one way to get any particular job done. Suppose for instance you have a tank you fill up from a well, and you’d like to know when the time is right to refill the tank. The obvious answer is to measure the level of the tank, and there are plenty of ways to do that. However, [Liam Hanninen] has a different approach. Using a flow meter, he measures how much water leaves the tank. Assuming that you know it was once full, you can deduce how much water is left.

Using a YF-S201 flowmeter on a Raspberry Pi, the code uses Python to populate a database. The meter will need to be calibrated to get an exact volume measurement.

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Atari Tape Drive Turned Security DVR

November 1, 2019 by Tom Nardi 11 Comments

We know that a lot of our beloved readers don’t take kindly to abuse of vintage hardware, so the Atari fans in the audience may want to avert their eyes for this one. Especially if they’re particularly keen on spinning up their Jawbreaker cassette on authentic hardware, as [iot4c] has gutted an Atari XC12 Program Recorder to turn it into an enclosure for a Raspberry Pi video storage device.

Step one of this conversion was, as you might expect, removing all the original hardware from the cassette recorder case. From there, [iot4c] fitted the Raspberry Pi, a USB hard drive, and a YDS-5A DC-DC converter to power them. Depending on what the drive setup looks like, it might also make sense to add a USB powered hub. A length of Ethernet cable was left hanging out the back of the Atari XC12 so it could be plugged into the network, but a panel mount RJ45 connector could spruce things up a bit.

Of course, gutting an old piece of hardware and sticking a Pi into it isn’t exactly breaking any new ground at this point. But we did appreciate that [iot4c] went the extra mile to wire it up so the “Save” LED now doubles as a network activity indicator. Which pretty much brings it full circle in terms of functionality for a network-attached video recorder.

Earlier in the year [iot4c] converted a 65XE into a USB keyboard with the help of an Arduino Leonardo, but the vintage Atari aficionados will be happy to note that at least in that case the donor machine remained fully functional.

Monochrome CRT And Liquid Crystal Shutter Team Up For Color Video

October 1, 2019 by Dan Maloney 21 Comments

If you were tasked with designing a color video monitor, it’s pretty clear how you’d go about it. But what if you’d been asked to do so 20 years ago? Would it have been a cut and dried from an engineering standpoint? Apparently not, as this hybrid LCD-CRT video monitor demonstrates.

We’d honestly never heard of this particular design, dubbed “LCCS”, or liquid crystal color shutter, until [Technology Connections]’ partial teardown of the JVC monitor and explanation of its operation. The idea is simple and hearkens back to the earliest days of color TV in the United States, when broadcasters were busy trying to bring color to a monochrome world in a way that would maximize profits. One scheme involved rotating a color wheel in front of the black-and-white CRT and synchronizing the two, which is essentially what’s happening in the LCCS system. The liquid crystal panel cycles between red, blue, and green tints in time with the CRT’s images behind it, creating a full-color picture. “But wait!” you cry. “Surely there were small color CRTs back in the year 2000!” Of course there were, but they kind of sucked. Just look at the comparison of a color CRT and the LCCS in the video below and you’ll see why this system carved out a niche in the pro video market, especially for video assist monitors in the days before digital cinematography. A similar system was used by Tektronix for color oscilloscopes, too.

As usual, [Technology Connections] has managed to dig up an interesting bit of the technological fossil record and present it in a fascinating way. From video on vinyl to 1980s copy protection to the innards of a toaster, we enjoy the look under the hood of forgotten tech.

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A Raspberry Pi 4 Video Streaming Backpack

September 27, 2019 by Tom Nardi 33 Comments

Were you aware that there’s a market for backpack-housed live streaming video systems, and that they can cost as much as $1600? Apparently these things are popular with social media moguls who want to stream themselves living their fabulous lives to people sitting at home watching on YouTube or Twitch. But believing that even slack jawed yokels like us should have access to the same technology, [Speedify Labs] has been working on less expensive DIY alternative based on the Raspberry Pi 4.

Now you’ll note we didn’t use the term “cheap” to describe this build. As detailed here, it’s still going to cost you around $600. You could always swap out the Sony AS-300 camera and Elgato Cam Link capture device with cheaper versions, but the goal of this project was to deliver high quality HD video that’s comparable to what the professional rigs are capable of, so those kinds of concessions were avoided.

Whatever video source your audience and budget are comfortable with, it eventually gets fed into the Raspberry Pi 4 which uses an ffmpeg one-liner to encode the video and ultimately push it out as 720p at 24 FPS, which [Speedify Labs] says seems to be about as good as the Pi can do. The operator is able to start and stop the stream at will using a Circuit Playground Express and a Python script.

Of course, the trick to all of this is getting the video stream uploaded over potentially flaky mobile networks. But as you might have guessed, that’s where [Speedify Labs] gets to flex their eponymous product: a VPN with software channel bonding that allows you to combine multiple Internet connections for higher bandwidth and reliability. With their software, the Pi is able to stream the video through two mobile phones connected to it over USB. As demonstrated in the video below, the setup was able to maintain the stream even as they walked in and out of buildings.

Our very own [Lewin Day] wrote about his experiments with streaming video over 4G on the Raspberry Pi which might be of interest to anyone looking to take their show on the road. Though if you want to get serious it would be worth taking a look at the impressive mobile streaming rig that [Jenny List] saw at the BornHack 2019 hacker camp in Denmark.

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Speeding Up Drawing To MCU-Connected Serial Displays

September 23, 2019 by Maya Posch 13 Comments

Writing image data to serially connected (SPI/I2C) displays from a microcontroller is easy enough these days, courtesy of standards defined by the MIPI Alliance, yet there are some gotchas in it which may catch someone using it unaware. [Larry Bank] wrote up a good summary of how one can get maximum performance out of such a display link.

At the core is the distinction between pixel data and command transmissions. The change from command to pixel data mode requires signaling, which takes precious clock cycles away from transferring pixel data between the MCU and display. The common MIPI DCS instruction set allows for a big reduction in needed data transfers by allowing parts of the display to be addressed instead of requiring a full refresh. Yet by not properly segmenting command and data transfers, one ends up unnecessarily slowing down the process.

The result is that one can run something like a Pac-Man emulator on an AVR MCU with a sluggish 320×480 SPI LCD at 60 FPS, as one can see in the video that is embedded after the break. Check the article for another demo video as well.

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