Long-Distance Text Communication With LoRa

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.

Multiband Crystal Radio Set Pulls Out All The Stops

Most crystal radio receivers have a decidedly “field expedient” look to them. Fashioned as they often are from a few turns of wire around an oatmeal container and a safety pin scratching the surface of a razor blade, the whole assembly often does a great impersonation of a pile of trash whose appearance gives little hope of actually working. And yet work they do, usually, pulling radio signals out of thin air as if by magic.

Not all crystal sets take this slapdash approach, of course, and some, like this homebrew multiband crystal receiver, aim for a feature set and fit and finish that goes way beyond the norm. The “Husky” crystal set, as it’s called by its creator [alvenh], looks like it fell through a time warp right from the 1920s. The electronics are based on the Australian “Mystery Set” circuit, with modifications to make the receiver tunable over multiple bands. Rather than the traditional galena crystal and cat’s whisker detector, a pair of1N34A germanium diodes are used as rectifiers — one for demodulating the audio signal, and the other to drive a microammeter to indicate signal strength. A cat’s whisker is included for looks, though, mounted to the black acrylic front panel along with nice chunky knobs and homebrew rotary switches for band selection and antenna.

As nice as the details on the electronics are, it’s the case that really sells this build. Using quarter-sawn oak salvaged from old floorboards. The joinery is beautiful and the hardware is period correct; we especially appreciate the work that went into transforming a common flat washer into a nickel-plated escutcheon for the lock — because every radio needs a lock.

Congratulations to [Alvenh] for pulling off such a wonderful build, and really celebrating the craftsmanship of the early days of radio. Need some crystal radio theory before tackling your build? Check out [Greg Charvat]’s crystal radio deep dive.

Lofipi Keeps The Chill Beats Coming

These days, many people love having some lo-fi beats on when they chill and study. This has led to a cottage industry dedicated to producing said beats, and the format continues to grow in popularity. [Nicholas Sherlock] decided to build a custom audio device solely for the delivery of these comfortable tunes.

As seen on Reddit, the build relies on a Raspberry Pi 3B, paired with an X400 audio amplifier board and hooked up to a nicely-sized mid-range speaker. The hardware is assembled inside a case printed out of wood-effect PLA filament, giving it a nice old-school home audio aesthetic. As a bonus, the layer lines line up in such a way as to boost the woodgrain effect. Plug it in, and you will be immediately rewarded with lo-fi beats from boot.

Originally, the system ran a port of the code from lofigenerator.com, which algorithmically creates lo-fi beats from scratch. However, [Nicholas] could not in good conscience share the ported code, and has retooled the system to stream YouTube playlists using command line media player mpv instead. It’s set to stream typical lo-fi playlists, though could be repurposed to target anything on the platform.

It’s a nice build that really suits the lo-fi beats ideal. When you’re trying to study or focus, you don’t want to be mucking around with a YouTube tab open serving as a distraction. Instead, you can simply flick on the Lofipi, and vibe out.

The Raspberry Pi’s cheap price and great internet and media capabilities make it very popular for builds like these. They go some way to recreating the idea of receiving a broadcast, rather than forcing us into choice as per today’s modern on-demand media paradigm. If you’ve got thoughts on this, drop them in the comments, and if you’ve got your own great projects, do drop us a line.

Retrotechtacular: The Transatlantic Radiotelephone System Of The 1930s

With the web of undersea cables lacing the continents together now, it’s hard to imagine that it wasn’t until 1956 that the first transatlantic telephone cable was laid. Sure, there were telegraph cables under the Atlantic starting as early as the late 1800s, but getting your voice across the ocean on copper was a long time coming. So what was the discerning 1930s gentleman of business to do when only a voice call would do? He’d have used a radiotelephone, probably at an outrageous expense, which as this video on the receiving end of the New York to London radio connection shows, was probably entirely justified.

The video details the shortwave radiotelephone system that linked New York and London in the 1930s. It starts with a brief but thorough explanation of ionospheric refraction, and how that atmospheric phenomenon makes it possible to communicate over vast distances. It also offers a great explanation on the problems inherent with radio connections, like multipath interference and the dependency on the solar cycle for usable skip. To overcome these issues, the Cooling Radio Station was built, and its construction is the main thrust of the video.

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A beige 1960s radio receiver, inset with vacuum tubes

Busted 1960s Vacuum Tube Radio Sings Again

Restoring a vintage radio receiver has the potential to be a fun weekend project, but it pays to know what you’re up against. Especially in the case of vacuum tube electronics, running down gremlins in the circuits isn’t always a straightforward process (also, please mind the high voltage that is present in old vacuum tube equipment). [Mr Carlson] has a knack for getting old radios humming once again, and his repair of a 1960s General Electric barn find radio receiver is a thorough masterclass in vintage electronics servicing.

Seriously, if you’ve got a spare ninety minutes, the video (after the break) is a thorough and unabridged start-to-finish diagnosis and repair of a vintage radio, and an absolute must for anyone interested in doing the same. This barn find radio was certainly showing its age, and it wasn’t long before in-circuit testing found an open filament in one of several vacuum tubes, but the radio was still stubbornly silent. Further testing revealed that the IF transformers were out of spec, requiring servicing and alignment. After fine tuning both the IF and RF sections of the radio, things were definitely looking (and sounding) better.

Fine tuning the various components in the radio went a long way to living up to its “long range” claims, and by the end of the video, it’s almost impossible to find dead air on the AM dial of this radio. If you’ve never had to make fine adjustments to a receiver, especially of this vintage, this video has all the details you’ll need. With the board exposed, [Mr Carlson] also took care of some preventative maintenance, including replacing the original filter capacitor with newer components, as well as replacing the mains safety capacitor with an even safer modern alternative.

We can’t get enough of these restorations, so make sure to check out our detailed write-up of restoring a WWII aircraft radio.

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Owning A ShortWave Radio Is Once Again A Subversive Activity

An abiding memory for a teen fascinated by electronics and radio in the 1970s and 1980s is the proliferation of propaganda stations that covered the shortwave spectrum. Some of them were slightly surreal such as Albania’s Radio Tirana which would proudly inform 1980s Western Europe that every village in the country now possessed a telephone, but most stations were the more mainstream ideological gladiating of Voice of America and Radio Moscow.

It’s a long-gone era as the Cold War is a distant memory and citizens East and West get their info from the Internet, but perhaps there’s an echo of those times following the invasion of the Ukraine. With most external news agencies thrown out of Russia and their websites blocked, international broadcasters are launching new shortwave services to get the news through. Owning a shortwave radio in Russia may once again be a subversive activity. Let’s build one!

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ice fishing tent and antenna in a snowy field

Ice Fishing Tent Makes Winter Ham Radio Comfy

Cross-pollination between different activities and industries can yield some pretty useful techniques or product combinations, and [Steve] shares some details on using ice fishing gear to make winter ham radio activities more comfortable and portable.

Radio operator inside ice fishing tent in winterWith the help of a folding tent shelter, [Steve] was able to create a minimal and self-contained field station that hosted all his needed equipment, and with the help of a small propane heater, stayed quite comfortable during a 24 hour winter event.

For those interested in the radio end of what [Steve] was doing, he goes into detail about the radio equipment and antenna he used, which itself stows easily into a bag and withstood high winds with success. The goal of the event after all was emergency preparedness, and while radio can operate without a wider infrastructure to support it, antenna design is crucial for best results.

As for keeping the operator safe and sound during all this, it turns out that the problem of a pop-up winter shelter that is both light and compact has already been solved by ice fishers; and while it can be fun to roll one’s own solutions, there’s not always a need to re-invent the wheel.