Author: Bryan Cockfield

1546 Articles

Handheld Satellite Dish Is 3D Printed

December 23, 2024 by 3 Comments

Ham radio enthusiasts, people looking to borrow their neighbors’ WiFi, and those interested in decoding signals from things like weather satellites will often grab an old satellite TV antenna and repurpose it. Customers have been leaving these services for years, so they’re pretty widely available. But for handheld operation, these metal dishes can get quite cumbersome. A 3D-printed satellite dish like this one is lightweight and small enough to be held, enabling some interesting satellite tracking activities with just a few other parts needed.

Although we see his projects often, [saveitforparts] did not design this antenna, instead downloading the design from [t0nito] on Thingiverse. [saveitforparts] does know his way around a satellite antenna, though, so he is exactly the kind of person who would put something like this through its paces and use it for his own needs. There were a few hiccups with the print, but with all the 3D printed parts completed, the metal mesh added to the dish, and a correctly polarized helical antenna formed into the print to receive the signals, it was ready to point at the sky.

The results for the day of testing were incredibly promising. Compared to a second satellite antenna with an automatic tracker, the handheld 3D-printed version captured nearly all of the information sent from the satellite in orbit. [saveitforparts] plans to build a tracker for this small dish to improve it even further. He’s been able to find some satellite trackers from junked hardware in some unusual places as well. Antennas seem to be a ripe area for 3D printing.

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Dog Plays Chess On ESP32

December 22, 2024 by 8 Comments

The ESP32 is s remarkably powerful microcontroller, where its dual-core processor and relatively high clock speed can do some impressive work. But getting this microcontroller designed for embedded systems to do tasks that would generally be given to a much more powerful PC-type computer takes a little bit more willpower. Inspired by his dog, [Folkert] decided to program an ESP32 to play chess, a famously challenging task for computer scientists in the past. He calls this ESP32 chess system Dog.

One of the other major limitations of this platform for a task like this is memory. The ESP32 [Folkert] is using only has 320 kB of RAM, so things like the transposition table have to fit in even less space than that. With modern desktop computers often having 32 or 64 GB, this is a fairly significant challenge, especially for a memory-intensive task like a chess engine. But with the engine running on the microcontroller it’s ready to play, either in text mode or with something that can use the Universal Chess Interface (UCI). A set of LEDs on the board lets the user know what’s going on while gameplay is taking place.

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Training A Self-Driving Kart

December 21, 2024 by 1 Comment

There are certain tasks that humans perform every day that are notoriously difficult for computers to figure out. Identifying objects in pictures, for example, was something that seems fairly straightforward but was only done by computers with any semblance of accuracy in the last few years. Even then, it can’t be done without huge amounts of computing resources. Similarly, driving a car is a surprisingly complex task that even companies promising full self-driving vehicles haven’t been able to deliver despite working on the problem for over a decade now. [Austin] demonstrates this difficulty in his latest project, which adds self-driving capabilities to a small go-kart.

[Austin] had been working on this project at the local park but grew tired of packing up all his gear when he wanted to work on his machine-learning algorithms. So he took all the self-driving equipment off of the first kart and incorporated it into a smaller kart with a very small turning radius so he could develop it in his shop.

He laid down some tape on the floor to create the track and then set up the vehicle to learn how to drive by watching and gathering data. The model is trained with a convolutional neural network and this data. The only inputs that the model gets are images from cameras at the front of the kart. At first, it could only change the steering angle, with [Austin] controlling the throttle to prevent crashes. Eventually, he gave it control of the throttle as well, which behaves well except at the fastest speeds.

There were plenty of challenges along the way, especially when compared to the models trained at the park; [Austin] correctly theorized that the cause of the hardship in the park was a lack of contrast at the boundary between the track and any out-of-bounds areas. With a few tweaks to the track, as well as adding some wide-angle lenses to his cameras, he was able to get a model that works fairly well. Getting started on a project like this doesn’t have as high of a barrier to entry as one might imagine, either. Take a look at this comprehensive open-source Python library for self-driving projects. If you want to start smaller, perhaps don’t start with a self-driving kart.

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A Compass That Looks To The Stars

December 17, 2024 by 18 Comments

Although a lot of tools have been digitized and consolidated into our smartphones, from cameras, music players, calendars, alarm clocks, flashlights, and of course phones, perhaps none are as useful as the GPS and navigational capabilities. The major weakness here, though, is that this is a single point of failure. If there’s no cell service, if the battery dies, or you find yourself flying a bomber during World War II then you’re going to need another way to navigate, possibly using something like this Astro Compass.

The compass, as its name implies, also doesn’t rely on using the Earth’s magnetic field since that would have been difficult or impossible inside of an airplane. Instead, it can use various celestial bodies to get a heading. But it’s not quite as simple as pointing it at a star and heading off into the wild blue yonder. First you’ll need to know the current time and date and look those up in a companion chart. The chart lists the global hour angle and the declination for a number of celestial bodies which can be put into the compass. From there the latitude is set and the local hour angle is calculated and set, and then the compass is rotated until the object is sighted. After all of that effort, a compass heading will be shown.

For all its complexity, a tool like this can be indispensable in situations where modern technology fails. While it does rely on precise tabulated astrometric data to be on hand, as long as that’s available it’s almost failsafe, especially compared to a modern smartphone. Of course, you’ll also need a fairly accurate way of timekeeping which can be difficult in some situations.

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Rainwater From The Road To The Garden

December 15, 2024 by 59 Comments

Most small-scale, residential rainwater harvesting systems we’ve seen rely on using an existing roof and downspout to collect water that would otherwise be diverted out into the environment. These are accessible for most homeowners since almost all of the infrastructure needed for it is already in place. [SuburbanBiology] already built one of these systems to take care of his potable water, though, and despite its 30,000 gallon capacity it’s not even close to big enough to also water his garden. But with some clever grading around his yard and a special rainwater system that harvests rain from the street instead of his roof, he’s capable of maintaining a lush food forest despite living through a drought in Texas.

For this build there are actually two systems demonstrated, one which is gravity-fed from the road and relies on one’s entire property sloping away from the street, and a slightly more complex one that’s more independent of elevation. Both start with cutting through a section of sidewalk to pass a 4″ PVC pipe through to the street where the stormwater runoff can be collected. The gravity-fed system simply diverts this into a series of trenches around the property while the second system uses a custom sump pump to deliver the water to the landscaping.

For a system like this a holding tank is not necessary; [SuburbanBiology] is relying on the soil on his property itself to hold onto the rainwater. Healthy, living soil can hold a tremendous amount of water for a very long time, slowly releasing it to plants when they need it. And, at least where he lives, a system like this is actually helpful for the surrounding environment as a whole since otherwise all of the stormwater runoff has to be diverted out of the city or cause a flood, and it doesn’t end up back in an aquifer. If you’re more curious about a potable water system instead, take a look at [SuburbanBiology]’s previous system.

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An IPhone Case Study

December 15, 2024 by 14 Comments

Way back in 2008, Apple unveiled the first unibody Macbook with a chassis milled out of a single block of aluminum. Before that, essentially all laptops, including those from Apple, were flimsy plastic screwed together haphazardly on various frames. The unibody construction, on the other hand, finally showed that it was possible to make laptops that were both lightweight and sturdy. Apple eventually began producing iPhones with this same design style, and with the right tools and a very accurate set of calipers it’s possible to not only piece together the required hardware to build an iPhone from the ground up but also build a custom chassis for it entirely out of metal as well.

The first part of the project that [Scotty] from [Strange Parts] needed to tackle was actually getting measurements of the internals. Calipers were not getting the entire job done so he used a flatbed scanner to take an image of the case, then milled off a layer and repeated the scan. From there he could start testing out his design. After an uncountable number of prototypes, going back to the CAD model and then back to the mill, he eventually settles into a design but not before breaking an iPhone’s worth of bits along the way. Particularly difficult are the recessed areas inside the phone, but eventually he’s able to get those hollowed out, all the screw holes tapped, and then all the parts needed to get a working iPhone set up inside this case.

[Scotty] has garnered some fame not just for his incredible skills at the precision mill, but by demonstrating in incredible detail how smartphones can be user-serviceable or even built from scratch. They certainly require more finesse than assembling an ATX desktop and can require some more specialized tools, but in the end they’re computers like any other. For the most part.

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A Portable Chainsaw Sawmill

December 14, 2024 by 25 Comments

Unless you’re running a commercial logging operation, with specialized saws, log grapples, mills, transportation for the timber, and the skilled workers needed to run everything, it’s generally easier to bring a sawmill to the wood instead of taking the wood to the sawmill. Especially for a single person, something like a chainsaw mill is generally a much easier and cost effective way to harvest a small batch of timber into lumber. These chainsaw mills can still be fairly cumbersome though, but [izzy swan] has a new design that fits an entire mill onto a hand cart for easy transportation in and out of a forest.

The entire mill is built out of a sheet and a half of plywood, most of which is cut into strips and then assembled into box girders for the track. The remainder of plywood is machined on a CNC to create the carriage for the chainsaw to attach as well as a few other parts to fix the log in place. The carriage has a 4:1 reduction gear on it to winch the chainsaw along the length of the log which cuts the log into long boards. After the milling is complete, the entire mill can be disassembled and packed down onto its hand cart where it can be moved on to the next project fairly quickly.

For a portable mill, it boasts respectable performance as well. It can cut logs up to 11 feet in length and about 30 inches across depending on the type of chainsaw bar used, although [izzy swan] has a few improvements planned for the next prototypes that look to make more consistent, uniform cuts. Chainsaws are incredibly versatile tools to have on hand as well, we’ve seen them configured into chop saws, mortisers, and even fixed to the end of a CNC machine.

Thanks to [Keith] for the tip!

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