Author: Bryan Cockfield

1708 Articles

Lawny Five Keeps Lawn Mowed, Snow Plowed

February 8, 2024 by 10 Comments

Although there’s been considerable excitement over the past half century of a Jetsons-like robotic future, outside of a few niche uses of our day-to-day lives there hasn’t been much in the way of robotic assistants coming to ease our physical household workloads. Sure, robots exist in manufacturing and other industrial settings, but the vast majority of us won’t see a robotic revolution unless we make it for ourselves. To that end, [Jim] has begun construction of a robot that can at least mow his lawn and eventually plow his driveway, among other potential tasks.

The robot, called the Lawny Five, is a tracked vehicle currently under remote control but with a planned autonomous capability. The frame includes a set of caster wheels at the front to take advantage of the differential steering of the tracks, and between everything is where the mower, plow, or other tool can sit. The attachment system is based on a 2″ receiver hitch, allowing the robot to eventually change tools at will while still preserving the usefulness of the tools in their original state. The robotic platform has been tested with the mower on a wet lawn with a 20° slope and showed no signs of struggle (and didn’t damage the grass) so it’s ready to take on more challenging tasks now as well.

With the core of the build out of the way, [Jim] is well on his way to a robotic lawnmower and potentially even an autonomous one, not to mention one with interchangeable tools that he hopes will be put to work in other ways like parking his boat in a small space by his house. For those maintaining a piece of land a little more involved than suburban turfgrass, there are other robotic platforms capable of helping out farmers with things like planting, watering, and weeding.

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Tetris Goes Full Circle

February 7, 2024 by 10 Comments

As a game concept, Tetris gave humanity nearly four solid decades of engagement, but with the possibility for only seven possible puzzle pieces it might seem a little bit limiting. Especially now that someone has finally beaten the game, it could be argued that as a society it might be time to look for something new. Sinusoidal Tetris flips these limits on their head with a theoretically infinite set of puzzle pieces for an unmistakable challenge.

Like Tetris, players control a game piece as it slowly falls down the screen. Instead of blocks, however, the game piece is a sinusoid that stretches the entire width of the screen. Players control the phase angle, amplitude, and angular frequency in order to get it to cancel out the randomly-generated wave in the middle of the screen. When the two waves overlap, a quick bit of math is done to add the two waves together. If your Fourier transformation skills aren’t up to the task, the sinusoid will eventually escape the playing field resulting in a game over. The goal then is to continually overlap sinusoids to play indefinitely, much like the original game.

While we’re giving Tetris a bit of a hard time, we appreciate the simplicity of a game that’s managed to have a cultural impact long after the gaming systems it was originally programmed for have become obsolete, and this new version is similar in that regard as well. The game can be quite addictive with a lot to take in at any given moment. If you’re more interested in the programming for these types of games than the gameplay, though, take a look at this deep-dive into Tetris for the NES.

Recreating The Quadrophonic Sound Of The 70s

February 6, 2024 by 23 Comments

For plenty of media center PCs, home theaters, and people with a simple TV and a decent audio system, the standard speaker setup now is 5.1 surround sound. Left and right speakers in the front and back, with a center speaker and a subwoofer. But the 5.1 setup wasn’t always the standard (and still isn’t the only standard); after stereo was adopted mid-century, audio engineers wanted more than just two channels and briefly attempted a four-channel system called quadrophonic sound. There’s still some media from the 70s that can be found that is built for this system, such as [Alan]’s collection of 8-track tapes. These tapes are getting along in years, so he built a quadrophonic 8-track replica to keep the experience alive.

The first thing needed for a replica system like this is digital quadrophonic audio files themselves. Since the format died in the late 70s, there’s not a lot available in modern times so [Alan] has a dedicated 8-track player connected to a four-channel audio-to-USB device to digitize his own collection of quadrophonic 8-track tapes. This process is destructive for the decades-old tapes so it is very much necessary.

With the audio files captured, he now needs something to play them back with. A Raspberry Pi is put to the task, but it needs a special sound card in order to play back the four channels simultaneously. To preserve the feel of an antique 8-track player he’s cannibalized parts from three broken players to keep the cassette loading mechanism and track indicator display along with four VU meters for each of the channels. A QR code reader inside the device reads a QR code on the replica 8-track cassettes when they are inserted which prompts the Pi to play the correct audio file, and a series of buttons along with a screen on the front can be used to fast forward, rewind and pause. A solenoid inside the device preserves the “clunk” sound typical of real 8-track players.

As a replica, this player goes to great lengths to preserve the essence of not only the 8-track era, but the brief quadrophonic frenzy of the early and mid 70s. There’s not a lot of activity around quadrophonic sound anymore, but 8-tracks are popular targets for builds and restorations, and a few that go beyond audio including this project that uses one for computer memory instead.

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Sailing (Directly) Into The Wind

February 6, 2024 by 22 Comments

Humans have been sailing various seas and oceans for thousands of years, and using boats for potentially even longer than that. But as a species we wouldn’t have made it very far if it was only possible to sail in the same direction the wind is blowing. There are a number of methods for sailing upwind, but generally only up to a certain angle. [rctestflight] wondered if there was some way of sailing straight upwind instead and built this rotary sail craft to test the idea.

Normally a boat sailing upwind will sail approximately 45° into it, then “tack” 90° across the wind until they’re at another 45° angle from the wind, this time facing the opposite direction. This back-and-forth nature is not the most efficient path, so this vessel uses a few propellers to bypass the traditional sail. The first iteration, built on a sleek catamaran hull, uses a large propeller to catch the wind’s energy, then transfers it mechanically through a set of shafts to an underwater prop.

It took a few tries to get the size and pitch of both propellers narrowed down to where the boat would move forward into the wind, but move it does. A second major iteration of the build uses a single shaft with no gears, with the trade-off that neither propeller is facing an ideal direction, but this has the added benefit of the boat naturally pointing itself upwind.

While none of the designs are speed demons, the concept is sound enough. It’s just that, in most cases, performing multiple tacks to get upwind is acceptable compared to the extreme efficiency losses and drag from propeller-driven sailing crafts like these. A more effective way of propelling a boat upwind, at least using modern technology, might be to trade sails for solar panels.

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Open-Source Solar Modules

February 5, 2024 by 13 Comments

As the price of solar panels continues to fall, more and more places find it economical to build solar farms that might not have been able to at higher prices. High latitude locations, places with more clouds than sun, and other challenging build sites all are seeing increased green energy development. The modules being used have one main downside, though, which is that they’re essentially a black box encased in resin and plastic, so if one of the small cells fails a large percentage of the panel may be rendered useless with no way to repair it. A solar development kit like this one from a group called Biosphere Solar is looking to create repairable, DIY modules that are completely open source, to help solve this issue.

The modular solar panel is made from a 3D printed holster which can hold a number of individual solar cells. With the cells placed in the layout and soldered together, they are then sandwiched between a few layers of a clear material like acrylic or glass with a seal around the exterior to prevent water intrusion. Since the project is open-source any number of materials can be used for the solar cell casing, and with the STL file available it’s not strictly necessary to 3D print the case as other manufacturing methods could be used. The only thing left is to hook up a DC/DC converter if you need one, and perhaps also a number of bypass and/or blocking diodes depending on your panel’s electrical layout.

The project is still in active development, and some more information can be found at the project’s website. While the “recyclability” of large-scale solar farms is indeed a problem, it’s arguably one which has been overblown by various interests who are trying to cast doubt on green energy. A small build like this won’t solve either problem anytime soon, so the real utility here would be for home users with small off-grid needs who want an open-source, repairable panel. It’s a great method to make sure solar technology is accessible and repairable for anyone that wants it, and in a way this approach to building hardware reminds us a lot of the Framework laptops.

HF In Small Spaces

February 3, 2024 by 22 Comments

Generally, the biggest problem a new ham radio operator will come across when starting out on the high frequency (HF) bands is finding physical space for the antennas. For a quick example, a dipole antenna for the 20 m band will need around 10 m of wire, and the lower frequencies like 80 m need about four times as much linear space. But if you’re willing to trade a large space requirement for a high voltage hazard instead, a magnetic loop antenna might be just the ticket.

Loop antennas like these are typically used only for receiving, but in a pinch they can be used to transmit as well. To tune the antennas, which are much shorter than a standard vertical or dipole, a capacitor is soldered onto the ends, which electrically lengthens the antenna. [OM0ET] is using two loops of coax cable for the antenna, with each end soldered to one half of a dual variable capacitor which allows this antenna to tune from the 30 m bands to the 10 m bands, although he is using it mostly for WSPR on 20 m. His project also includes the use of an openWSPR module, meaning that he doesn’t have to dedicate an entire computer to run this mode.

The main downsides of antennas like these is that they are not omnidirectional, are not particularly good at transmitting, and develop a significantly high voltage across the capacitor as this similar mag loop antenna project demonstrated. But for those with extreme limitations on space or who, like [OM0ET] want a simple, small setup for running low-power applications like WSPR they can really excel. In fact, WSPR is a great mode for getting on the air at an absolute minimum of cost.

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Satellite Provides Detailed Data On Antarctic Ice

February 2, 2024 by 19 Comments

Ever since the first satellites started imaging the Earth, scientists have been using the data gathered to learn more about our planet and improve the lives of its inhabitants. From weather forecasting to improving crop yields, satellites have been put to work in a wide array of tasks. The data they gather can go beyond imaging as well. A new Chinese satellite known as Fengyun-3E is using some novel approaches to monitor Antarctic sea ice in order to help scientists better understand the changing climate at the poles.

While it is equipped with a number of other sensors, one of the more intriguing is a piece of equipment called WindRad which uses radar to measure wind at various locations and altitudes based on how the radar waves bounce off of the atmosphere at various places.  Scientists have also been able to use this sensor to monitor sea ice, and can use the data gathered to distinguish new sea ice from ice which is many years old, allowing them to better understand ice formation and loss at the poles. It’s also the first weather satellite to be placed in an early morning orbit, allowing it to use the long shadows cast by the sun on objects on Earth’s surface to gather more information than a satellite in other orbits might be able to.

With plenty of other imaging sensors on board and a polar orbit, it has other missions beyond monitoring sea ice. But the data that it gathers around Antarctica should give scientists more information to improve climate models and understand the behavior of sea ice at a deeper level. Weather data from satellites like these isn’t always confined to academia, though. Plenty of weather satellites broadcast their maps and data unencrypted on radio bands that anyone can access.