Homebrew Radio Telescope Bags Pulsar

May 25, 2022 by 11 Comments

When one mulls the possibility of detecting pulsars, to the degree that one does, thoughts turn to large dish antennas and rack upon rack of sensitive receivers, filters, and digital signal processors. But there’s more than one way to catch the regular radio bursts from these celestial beacons, and if you know what you’re doing, a small satellite dish and an RTL-SDR dongle will suffice.

Granted, [Job Geheniau] has had a lot of experience exploring the radio universe. His website has a long list of observations and accomplishments achieved using his “JRT”, or “Job’s Radio Telescope.” The instrument looks like a homebrewer’s dream, with a 1.9-m satellite TV dish and precision azimuth-elevation rotator. Behind the feedhorn are a pair of low-noise amplifiers and bandpass filters to massage the 1,420 MHz signal that’s commonly used for radio astronomy, plus a Nooelec Smart SDR dongle and an Airspy Mini. Everything is run via remote control, as the interference is much lower with the antenna situated at his family’s farm, 50 km distant from his home in The Hague.

As for the pulsar, bloodlessly named PSR B0329+54, it’s a 5-million-year-old neutron star located in the constellation of Camelopardalis, about 3,500 light-years away. It’s a well-characterized pulsar and pulses at a regular 0.71452 seconds, but it’s generally observed with much, much larger antennas. [Job]’s write-up of the observation contains a lot of detail on the methods and software he used, and while the data is far from clear to the casual observer, it sure seems like he bagged it.

We’ve seen quite a few DIY radio astronomy projects before, both large and small, but this one really impresses with what it accomplished.

[via RTL-SDR.com]

Long-Distance Text Communication With LoRa

May 25, 2022 by 50 Comments

Affordable and reliable cell phones have revolutionized the way we communicate over the last two decades or so, and this change was only accelerated by the adoption of the smartphone. This is all well and good if you’re living in a place with cellular infrastructure, but if you’re in more remote areas you’ll have to be a little more inventive. This text-based communications device, for example, lets you send text messages without all of that cumbersome infrastructure.

While [Arthur] didn’t create this project specifically for off-grid use, it’s an interesting project nonetheless. The devices use a physical QWERTY keyboard and a small screen, reminiscent of BlackBerry devices from the late 2000s (partially because they are actually using BlackBerry keyboards). One of the other goals for this project was low power consumption, and between polling the keyboard, the memory LCDs, and receiving and transmitting messages using LoRa, [Arthur] was able to get the current draw down to 12 mA.

Between the relatively common nRF52840 and SX1262 chips, plus the fact that [Arthur] made the schematics available, this makes for an excellent off-grid device for anyone who likes to drive off into the wilderness or lives far enough outside of town that cell phone reception is a concern.

Looking for something a little easier to put together before your upcoming camping trip? This similarly styled LoRa communicator from [MSG] uses off-the-shelf modules to greatly reduce the part count. Another option for off-grid communications is to use existing smartphones paired with a LoRa network like we saw in this project.

HAL 9000 Becomes A Helpful Voice Assistant

May 24, 2022 by 12 Comments

There have been many robots and AIs in science fiction over the years, from Astro Boy to Cortana, or even Virgil for fans of the long-forgotten Crash Zone. However, all these pale into insignificance in front of the cold, uncaring persona of the HAL 9000. Thus, [Jürgen Pabel] thought the imposing AI would make the perfect home assistant.

The build is based on a Raspberry Pi Zero 2, which boasts more grunt than the original Pi Zero while still retaining good battery life and a compact form factor. It’s hooked up with a 1.28″ round TFT display which acts as the creepy glowing eye through which HAL is supposed to perceive the world. There’s naturally a speaker on board to deliver HAL’s haunting monotone, and it’s all wrapped up in an tidy case that really looks the part. It runs on the open-source voice assistant Kalliope to help out with tasks around the home.

[Jürgen]’s page shares all the details you need to make your own, from the enclosure construction to the code that laces everything together. It’s not the first HAL 9000 we’ve seen around these parts, either. Video after the break.

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Graphyne Finally Created

May 24, 2022 by 22 Comments

Before you jump down to the comments to chastise us for misspelling graphene, note that graphyne is similar to graphene but not the same. Like graphene, it is a two-dimensional structure of carbon. Unlike graphene, it contains double and triple bonds and does not always form hexagons. Scientists have postulated its existence for decades, but researchers at the University of Colorado Boulder have finally managed to pull it off. You can also download the paper if you want to wade through the details.

Carbon forms like fullerene and graphene are well-known and have many novel uses. Other allotropes of carbon include graphite and diamonds — certainly two things with wildly varying properties. Graphyne has conductivity similar to graphene but may also have other benefits.

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3D Printing Fabrics Is Easier Than You Think

May 24, 2022 by 15 Comments

Conventional textiles made of woven threads are highly useful materials. [Sara Alvarez] has had some success creating fabric-like materials through 3D printing, and though they’re not identical, they have some similar properties that make them unique and useful.

Fabrics are made by the weaving or knitting together many threads into a cohesive whole. [Sara]’s 3D-printed fabrics are different, since the printer can’t readily weave individual fibers together. Instead, a variety of methods are used to create similar materials.

The simplest is perhaps the chainmail method, where many small individual links join together to make a relatively rigid material. Alternatively, G-code or careful modelling can be used to create fabric-like patterns, which are printed directly in flexible material to become a fabric-like sheet. Finally, the infill method takes advantage of code inbuilt to a slicer to create a pattern that can be 3D-printed to create a fabric like material by removing the top and bottom layers of the print.

[Sara] demonstrates creating a simple “fabric” swatch using the slicer method, and demonstrates the qualities of the finished product. She also shows off various applications that can take advantage of this technique.

If you’re a 3D-printing enthusiast who also loves making clothes and apparel, consider printing up some shoes – like these we’ve seen before. Video after the break. Continue reading “3D Printing Fabrics Is Easier Than You Think” →

The STM32 Makes For A Cheap DIY USB Soundcard

May 24, 2022 by 14 Comments

Soundcards used to be giant long 8-bit ISA things that would take up a huge amount of real estate inside a desktop computer. These days, for most of us, they’re baked into the motherboard and we barely give them a second thought. [Samsonov Dima] decided to whip up a cheap little sound card of their own, however, built around the STM32.

The soundcard is based specifically on the STM32F401. readily available on the “Green Pill” devboards. A digital-to-analog converter is implemented on the board based on two PWM timers providing high-quality output. There’s also a simulated software sigma delta ADC implemented between the audio streaming in via USB and the actual PWM output, with some fancy tricks used to improve the sound output. [Samsonov] even found time to add a display with twin VU meters that shows the audio pumping through the left and right channels.

Without test gear on hand, we can’t readily quantify the performance of the sound card. However, as per the Youtube videos posted, it appears more than capable of recreating music with good fidelity and plenty of fine detail.

If you need a cheap, simple USB sound card that you can hack away on, this might be the one for you. If you need something more suitable for a vintage PC, however, consider this instead. Video after the break.

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Character VFD Becomes Spectrum Analyzer

May 24, 2022 by 7 Comments

These days, streaming services are a great way to listen to music or podcasts on your computer or on the go. However, they lack one feature of the MP3 players and streamers of old: visualizations! [mircemk] is a fan of those, and has built a hardware spectrum analyzer that pumps with the music.

The build relies on a 20×2 character VFD display that looks great, with high brightness and excellent contrast. It can be easily driven from a microcontroller, as it has a controller on board compatible with the typical HD44780 command set. On Arduino platforms, this means the display can easily be driven with the popular LiquidCrystal library.

The Arduino Nano inside takes in the audio signal via its analog inputs. It then processes the audio with the fix_fft library, which runs a Fast Fourier Transform in order to figure out the energy level of each frequency bin in the audio spectrum for both the left and right channels. This data is then sent to the screen for display. It’s impressively fast and smooth, with the display dancing along with the beat nicely as [mircemk] tests it out with some tunes.

If it looks familiar, it’s because it’s an updated version of a prior project from [mircemk]. We saw it previously as a VU meter that pulsed with the beat, an altogether simpler visualization but still a cool one. Video after the break.

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