The build is based on the Arduino Uno, the humble mainstay of the Arduino line. It’s hooked up to an ILI9488 color touchscreen display, which acts as the primary user interface. Using a stylus, or presumably a finger, the user can draw directly on the screen to specify the desired waveform for the synth to produce. The Arduino reads the step-by-step amplitude values of the drawn waveform and uses them to synthesize audio according to MIDI messages received over its serial port. Audio output is via PWM, as is common in low-cost microcontroller projects.
When most of us think of seismometers, our minds conjure up images of broken buildings, buckled roads, and search and rescue teams digging through rubble. But when [Subir Bhaduri] his team were challenged with solving real world problems as frugally as possible as part of the 2020 Frugal Science course, he thought of farmers in rural India for whom losing crops due to raiding elephants is a reality. Such raids can and have caused loss of life for humans and elephants alike. How could he apply scientific means to prevent such conflicts, and do it on the cheap?
We invite you to watch the video below the break to find out how it works. You’ll be impressed as we were by [Subir]’s practical application of engineering principles. And keep your eyes open for the beautiful magnetic damper hack. It’s a real treat!
A beach is always a relaxing summer vacation destination, a great place to hang out with a drink and a book or take a swim in the ocean. For those who need a more active beach-going activity with an electronics twist, though, metal detecting is always a popular choice too. And, of course, with an Arduino and some know-how it’s possible to build a metal detector that has every feature you could want from even a commercial offering.
This build comes to us from [mircemk] who built this metal detector around an Arduino Nano and uses a method called induction balance detection to find metal. Similar to how radar works, one coil sends out a signal and the other listens for reflections back from metal objects underground. Building the coils and determining their resonant frequency is the most important part of this build, and once that is figured out the rest of the system can be refined and hidden treasure can easily be unearthed.
One of the more interesting features of this build is its ability to discriminate between ferrous and non-ferrous metals, and it can detect large metal objects at distances of more than 50 cm. There are improvements to come as well, since [mircemk] plans to increase power to the transmission coil which would improve the range of the device. For some of [mircemk]’s other metal detectors, be sure to check out this one which uses a smartphone to help in the metal detection process.
Have you ever heard of a Centurion minicomputer? If not, don’t feel bad — we hadn’t either, until [David Lovett] stumbled upon a semi-complete version of the 1980-ish mini in all its wood-trimmed, dust-encased glory. And what does a hacker do with such an acquisition but attempt to get it going again?
Of course, getting a machine from the Reagan administration running is not without its risks, including the chance of losing whatever is on the machine’s many ROM chips forever. When finding a commercial ROM reader supporting the various chips proved difficult, [David] decided to build his own. The work was eased considerably by the fact that he had managed to read one chip in a commercial reader, giving him a baseline to compare his circuit against. The hardware is straightforward — a 12-bit counter built from a trio of cascaded 74LS161s to step through addresses, plus an Arduino Nano to provide clock pulses and to read the data out to the serial port.
The circuit gave the same results as the known good read, meaning results would be valid for the rest of the chips. The breadboard setup made supporting multiple ROM pinouts easy, even for the chips that take -9 volts. What exactly the data on the ROMs mean, if anything, remains a mystery, but at least it’s backed up now.
Before anyone notes the obvious, yes, [David] could have used a 555 to clock the reader — perhaps even this one. We’d actually have loved that, but we get it — sometimes you just need to throw an Arduino at a job and be done with it.
When [John Floren] obtained a vintage Depraz mouse, he started out being content to just have such a great piece of history in his possession. But if you’re like him, you know it’s not enough to just have something. What would it be like to use it?
To find out, [John] embarked on a mission to build a USB adapter for his not so new peripheral.
Originally used in very early terminals with a Unix GUI, the Depraz mouse utilizes an unusual male DE9 connector rather than the more familiar female DB9 used in RS232 serial mice. Further deviating from the norm, he found that the quadrature encoders were connected directly to the DE9 connector.
Armed with an Arduino Pro Mini and some buggy sample code, he got to work. The aforementioned buggy code was scrapped and a fresh sketch for the Arduino Pro Mini gave the Depraz mouse the USB interface it lacked. [John] also found that he wasn’t the first hardware hacker to have modified the mouse for their use. Be sure to read to the end the article to find out about the vintage surprise lurking in the mouse shell itself! A demonstration of the mouse in action can be seen in the video below the break.
A 3D printer is a wonderful invention, but it needs maintenance like every machine that runs for long hours. [Rob Ward] had a well-used Robox 3D printer that was in need of some repairs, but getting the necessary replacement parts shipped to Australia was cost-prohibitive. Rather than see a beloved printer be scrapped as e-waste, he decided to rebuild it using components that he could more easily source. Unfortunately the proprietary software and design of the Robox made this a bit difficult, so it was decided a brain transplant was the best path forward.
Step one was to deduce how the motors worked. A spare RAMPS 1.4 board and Arduino Mega2560 made short work of the limit switches and XYZ motors. This was largely accomplished by splicing into the PCBs themselves. The Bowden filament driver motor had a filament detector and an optical travel sensor that required a bit of extra tuning, but now the challenging task was next: extruding.
The printer’s new custom hotend.
With a cheap CR10 hot end from an online auction house, [Rob] began modifying the filament feed to feed in a different direction than the Robox was designed for (the filament comes in at a 90-degree angle on the stock Robox). A fan was needed to cool the filament feed line. Initial results were mixed with lots of blockages and clogs in the filament. A better hot end and a machined aluminum bracket for a smoother path made more reliable prints.
The original bed heater was an excellent heater but it was a 240 VAC heater. Reluctant to having high voltages running through his hacked system, he switched them out for 12 VDC adhesive pads. A MOSFET and MOSFET buffer allowed the bed to reach a temperature workable for PLA. [Rob] upgraded to a GT2560 running Marlin 2.x.x.
With a reliable machine, [Rob] stepped back to admire his work. However, the conversion to the feed being perpendicular to the bed surface had reduced his overall build height. With some modeling in OpenSCAD and some clever use of a standard silicone sock, he had a solution that fed the wire into the back of the hot end, allowing to reclaim some of the build height.
It was a long twelves months of work but the write-up is a joy to read. He’s included STL and SCAD files for the replacement parts on the printer. If you’re interested in seeing more machines rebuilt, why not take a look at this knitting machine gifted with a new brain.
All of the technological improvements to vehicles over the past few decades have led to cars and trucks that would seem borderline magical to anyone driving something like a Ford Pinto in the 1970s. Not only are cars much safer due to things like crumple zones, anti-lock brakes, air bags, and compulsory seat belt use, but there’s a wide array of sensors, user interfaces, and computers that also improve the driving experience. At least, until it starts wearing out. The electronic technology in our modern cars can be tricky to replace, but [Aravind] at least was able to replace part of the instrument cluster on his aging (yet still modern) Skoda and improve upon it in the process.
These cars have a recurring problem with the central part of the cluster that includes an LCD display. If replacement parts can even be found, they tend to cost a significant fraction of the value of the car, making them uneconomical for most. [Aravind] found that a 3.5″ color LCD that was already available fit perfectly in the space once the old screen was removed, so from there the next steps were to interface it to the car. These have a CAN bus separated from the main control CAN bus, and the port was easily accessible, so an Arduino with a RTC was obtained to handle the heavy lifting of interfacing with it.
Now, [Aravind] has a new LCD screen in the console that’s fully programmable and potentially longer-lasting than the factory LCD was. There’s also full documentation of the process on the project page as well, for anyone else with a Volkswagen-adjacent car from this era. Either way, it’s a much more economical approach to replacing the module than shelling out the enormous cost of OEM replacement parts. Of course, CAN bus hacks like these are often gateway projects to doing more involved CAN bus projects like turning an entire vehicle into a video game controller.
If you suffer from nostalgia, you might remember carving a block of wood into a car, adding some wheels, and racing it against other contestants in a pinewood derby. Today’s derby is decidedly high tech though, and we were impressed with this car scale that also figures out the car’s center of gravity.
Based on an Arduino, of course, along with a pair of HX711 load cells. Why a pair? That’s how the device measures the center of gravity is by weighing the front and rear of the car separately.
We really liked the wooden case and found the use of wood satisfying if not ironic. Our only input is that since you need the wheelbase of the car to do the CG calculations, we’d have glued a ruler down. On the other hand, probably any self-respecting pinewood derby creator knows their wheelbase by heart.
Why does CG matter? If you are too far forward, you lose some acceleration. If you are too far back, the front wheels might pop up. With this device, you can know exactly where your center is and make adjustments accordingly.
The build runs twelve servos – three per leg – to enable for a great range of movement for each limb. The servos are all controlled by an Arduino Uno fitted with an Arduino Sensor Shield. Everything is fitted together with a 3D printed chassis and limb segments that bolt directly on to the servo output shafts. This is a common way of building quick, easy, lightweight assemblies with servos, and it works great here. Inverse kinematics is used to calculate the required motions of each joint, and the robot can take steps from 1 to 4cm long in a variety of gaits.
We’d love to see a few sensors and a battery pack added on to allow the ‘bot to explore further in an untethered fashion. [Technovation] has left some provision to mount extra hardware, so we look forward to seeing what comes next.
Like us, [Alberto] doesn’t compromise when it comes to a good cup of coffee. We figure that if he went to an office in the Before Times, he was the type of coworker to bring in their own coffee equipment so as not to suffer the office brew. Or perhaps he volunteered to order the office supplies and therefore got to decide for everyone else. Yep, that’s definitely one way to do it.
But like many of us, he is now operating out of a home office. Even so, he’s got better things to do than stand around pouring the perfect cup of coffee every morning. See, that’s where we differ, [Alberto]. But we do love Cafeino, your automated pour-over machine. It’s so sleek and lovely, and we’re sure it does a much better job than we do by hand — although we enjoy doing the pouring ourselves.
Cafeino is designed to mimic the movements of a trained barista’s hand, because evidently you’re supposed to pour the water in slow, deliberate swirls to evenly cover the grounds. (Our kettle has a chunky spout, so we just sort of wing it.) Cafeino does this by pumping water from an electric kettle and pouring a thin stream of it in circles with the help of two servos.
The three buttons each represent a different recipe setting, which specifies the amount of water, the hand pouring pattern, and the resting times between blooming the grounds and actually pouring the bulk of the water. These recipes are set using the accompanying web app via an ESP32, although the main brain barista is an Arduino Nano. Grab a cup and check out the demo after the break.
