Author: Bryan Cockfield

1760 Articles

Pac-Man Ghost Helps With Air Quality Sensing

October 21, 2024 by 13 Comments

In the past, building construction methods generally didn’t worry much about air quality. There were enough gaps around windows, doors, siding, and flooring that a house could naturally “breathe” and do a decent enough job of making sure the occupants didn’t suffocate. Modern buildings, on the other hand, are extremely concerned with efficiency and go to great lengths to ensure that no air leaks in or out. This can be a problem for occupants though and generally requires some sort of mechanical ventilation, but to be on the safe side and keep an eye on it a CO2 sensor like this unique Pac-Man-inspired monitor can be helpful.

Although there are some ways to approximate indoor air quality with inexpensive sensors, [Tobias] decided on a dedicated CO2 sensor for accuracy and effectiveness, despite its relatively large cost of around $30. An ESP32 handles the data from the sensor and then outputs the results to an array of LEDs hidden inside a ghost modeled after the ones from the classic arcade game Pac-Man. There are 17 WS2812B LEDs in total installed on a custom PCB, with everything held together in the custom 3D printed ghost-shaped case. The LEDs change from green to red as the air quality gets worse, although a few preserve the ghost’s white eyes even as the colors change.

For anyone looking to recreate this project and keep an eye on their own air quality, [Tobias] has made everything from the code, the PCB, and the 3D printer files open source, and has used accessible hardware in the build as well. Although the CO2 sensors can indeed be pricey, there are a few less expensive ways of keeping an eye on indoor air quality. Some of these methods attempt to approximate CO2 levels indirectly, but current consensus is that there’s no real substitute for taking this measurement directly if that’s the metric targeted for your own air quality.

Open-Source, 3D Printed Trackpad

October 21, 2024 by 22 Comments

Touchpads, or trackpads, have been around since the 1980s. Today, you can often find them in laptops and notebook computers as pointing devices. With no moving parts, a trackpad are easy to integrate into the body of a portable computer.  they’re much smaller than the traditional mouse. Until the advent of multitouch and gestures over the past two decades, though, they were generally poor substitutes for an actual mouse. These days, trackpads have enough features that some users prefer them even on their desktop computers. If you’re that type of person and don’t want to shell out a big pile of money for an Apple, Logitech, or other off-the-shelf trackpad you can always build your own.

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The Design Process For A Tiny Robot Brain

October 20, 2024 by 13 Comments

As things get smaller, we can fit more processing power into devices like robots to allow them to do more things or interact with their environment in new ways. If not, we can at least build them for less cost. But the design process can get exponentially more complicated when miniaturizing things. [Carl] wanted to build the smallest 9-axis robotic microcontroller with as many features as possible, and went through a number of design iterations to finally get to this extremely small robotics platform.

Although there are smaller wireless-enabled microcontrollers, [Carl] based this project around the popular ESP32 platform to allow it to be usable by a wider range of people. With that module taking up most of the top side of the PCB, he turned to the bottom to add the rest of the components for the platform. The first thing to add was a power management circuit, and after one iteration he settled on a circuit which can provide the board power from a battery or a USB cable, while also managing the battery’s charge. As for sensors, it has a light sensor and an optional 9-axis motion sensor, allowing for gesture sensing, proximity detection, and motion tracking.

Of course there were some compromises in this design to minimize the footprint, like placing the antenna near the USB-C charger and sacrificing some processing power compared to other development boards like the STM-32. But for the size and cost of components it’s hard to get so many features in such a small package. [Carl] is using it to build some pretty tiny robots so it suits his needs perfectly. In fact, it’s hard to find anything smaller that isn’t a bristlebot.

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A Parts Bin MIDI Controller In 24 Hours

October 20, 2024 by 9 Comments

Part of the reason MIDI has hung on as a standard in the musical world for so long is that it is incredibly versatile. Sure, standard instruments like pianos and drums can be interfaced with a computer fairly easily using this standard, but essentially anything can be converted to a MIDI instrument with the right wiring and a little bit of coding. [Jeremy] needed to build a MIDI controller in a single day, and with just a few off-the-shelf parts he was able to piece together a musical instrument from his parts bin.

The build is housed in an off-brand protective case from a favorite American discount tool store, but the more unique part of the project is the choice to use arcade buttons as the instrument’s inputs. [Jeremy] tied eight of these buttons to an Arduino Uno to provide a full octave’s worth of notes, and before you jump to the comments to explain that there are 12 notes in an octave, he also added a button to the side of the case to bend any note when pressed simultaneously. An emergency stop button serves as a master on/off switch and a MIDI dongle on the other side serves as the interface point to a computer.

After a slight bit of debugging, the interface is up and running within [Jeremy]’s required 24-hour window. He’s eventually planning to use it to control a custom MIDI-enabled drum kit, but for now it was fun to play around with it in some other ways. He’s also posted the project code on a GitHub page. And, if this looks a bit familiar, this was not [Jeremy]’s first MIDI project. He was also the creator of one of the smallest MIDI interfaces we’ve ever seen.

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Self-Portaging Canoe Is Part Bicycle

October 19, 2024 by 10 Comments

Normally when making a long voyage in a canoe, an adventurer would paddle the vessel as far as possible and then “portage”, or carry, the canoe over the short sections of land separating the bodies of water. Portaging is a lot of work, though, since canoes generally aren’t particularly light or designed for traveling over land. To solve this problem, [Ben] is modifying his home-built canoe with some interesting parts to make it into an amphibious vehicle which can much more easily traverse land.

The wheels for the amphibious craft come from BMX bicycles, which have much smaller wheels as well as more robust frames when compared to more traditional bicycles. The rear of the canoe was modified to use a go-kart axle with two driven wheels. An additional set of cranks mounted outboard drive a custom-built paddle to propel the boat when traveling on water. The frame borrows heavily from recumbent bicycle design and includes a similarly comfortable seat, with steering handled by a wheel at the front when traveling on land and a rudder at the rear when traveling over water.

[Ben] intends to take this unique vehicle on a cross-country trip across Scotland, with the first part of the adventure on water via the Caledonian Canal and the return trip on land via the Great Glen Way. Hopefully, there’s no actual portaging required for his trip as the bike components add a tremendous amount of weight to the boat. [Ben] he even added a sail that could theoretically be used in either mode. We’ll be keeping watch for his next videos showing his adventure, and in the meantime daydreaming about other unique bikes that let you travel where bikes normally can’t.

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Access The Information Superhighway With A Mac Plus

October 17, 2024 by 5 Comments

For some time now, Apple has developed a reputation for manufacturing computers and phones that are not particularly repairable or upgradable. While this reputation is somewhat deserved, especially in recent years, it seems less true for their older machines. With the second and perhaps most influential computer, the Apple II, being so upgradable that the machine had a production run of nearly two decades. Similarly, the Macintosh Plus of 1986 was surprisingly upgradable and repairable and [Hunter] demonstrates its capabilities by bringing one onto the modern Internet, albeit with a few tricks to adapt the old hardware and software to the modern era.

The Mac Plus was salvaged from a thrift store, and the first issue to solve was that it had some rotten capacitors that had to be replaced before the computer could be reliably powered on at all. [Hunter] then got to work bringing this computer online, with the only major hardware modification being a BlueSCSI hard drive emulator which allows using an SD card instead of an original hard disk. It can also emulate an original Macintosh Ethernet card, allowing it to fairly easily get online.

The original operating system and browser don’t support modern protocols such as HTTPS or scripting languages like Javascript or CSS, so a tool called MacProxy was used to bridge this gap. It serves simplified HTML from the Internet to the Mac Plus, but [Hunter] wanted it to work even better, adding modular domain-specific handling to allow the computer to more easily access sites like Reddit, YouTube, and even Hackaday, although he does call us out a bit for not maintaining our retro page perhaps as well as it ought to be.

[Hunter] has also built an extension to use the Wayback Machine to serve websites to the Mac from a specific date in the past, which really enhances the retro feel of using a computer like this to access the Internet. Of course, if you don’t have original Macintosh hardware but still want to have the same experience of the early Internet or retro hardware this replica Mac will get you there too.

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Using The 555 For Everything

October 14, 2024 by 25 Comments

The 555 timer is one of the most versatile integrated circuits available. It can generate PWM signals, tones, and single-shot pulses. You can even put one in a bi-stable mode similar to a flip flop. All of these modes are available by only changing a few components outside of the IC itself. It’s also dirt cheap, so it finds its way into all kinds of applications its original inventors never imagined. There’s a bit of a trope around here as well that you ought not to use a microcontroller when one of these will do, and while it’s a bit of a played-out comment, it’s often more true than it seems. This video shows a few uncommon ways of using these circuits instead of putting a microcontroller to work.

After a brief overview of the internals of the hallowed 555, [Doctor Volt] walks us through some of its uses, starting with applications for digital inputs, including a debounce circuit and a toggle switch. From there, he moves on to demonstrating a circuit that can protect batteries from deep discharge, and a small change to that circuit can turn the 555 into a resetting fuse that can protect against short circuit events. Finally, the PWM capabilities of this small integrated circuit are put to work as an audio amplifier, although perhaps not one that would pass muster for the most devout audiophiles among us.

Even though it’s possible to offload a lot of the capabilities of a 555 onto a microcontroller, there’s certainly an opportunity to offload some things to the 555, even if your project still needs a microcontroller. However, offloading tasks like debounce or input latching to hardware rather than spending microcontroller cycles or pins can make a project more robust, both from reliability and software points of view. For some other useful circuits, some of which have been forgotten in the modern microcontroller age, it’s worth taking a look at some of these antique circuit books as well. While we are sure the 555 designers hoped it would be a big hit, no one imagined this giant one.

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