MicroSynth, the business card-sized synthesizer

MicroSynth Mixes All-Analog Fun With A Little Business

September 30, 2021 by 14 Comments

While [MicroKits]’ MicroSynth is an all-analog synthesizer that fits on a business card-sized PCB, and he actually does use it to break the ice in business meetings, that’s not really the idea behind this project. Rather, [MicroKits] is keen to get people playing with synths, and what better way than a synth you can build yourself?

There was an ulterior motive behind this project, too: prototyping circuits for a more complete synthesizer. Thus, the design is purposely very simple — no microcontrollers, no logic chips, and not even a 555 to be found. It doesn’t even have buttons; instead, the one-octave keyboard just has interdigitated traces that are bridged by the player’s fingers, forming resistive touchpads. The keyboard interface circuit is clever, too — [MicroKits] uses a pair of op-amps to convert the linear change in resistance across the keyboard to a nearly exponential voltage to drive the synth’s voltage-controlled oscillator (VCO). The video below shows what it can do.

We love projects like these because they show what can be accomplished strictly using analog circuits. We don’t have any problem with other synth designs, mind you — this 555-based dub siren we featured recently was great, too. Continue reading “MicroSynth Mixes All-Analog Fun With A Little Business” →

NASA Sets Eyes On Deep Space With Admin Shuffle

September 30, 2021 by 17 Comments

Since the Apollo 17 crew returned from the Moon in 1972, human spaceflight has been limited to low Earth orbit (LEO). Whether they were aboard Skylab, Mir, the Space Shuttle, a Soyuz capsule, or the International Space Station, no crew has traveled more than 600 kilometers (372 miles) or so from the Earth’s surface in nearly 50 years. Representatives of the world’s space organizations would say they have been using Earth orbit as a testing ground for the technology that will be needed for more distant missions, but those critical of our seemingly stagnated progress into the solar system would say we’ve simply been stuck.

Many have argued that the International Space Station has consumed an inordinate amount of NASA’s time and budget, making it all but impossible for the agency to formulate concrete plans for crewed missions beyond Earth orbit. The Orion and SLS programs are years behind schedule, and the flagship deep space excursions that would have utilized them, such as the much-touted Asteroid Redirect Mission, never materialized. The cracks are even starting to form in the Artemis program, which appears increasingly unlikely to meet its original goal of returning astronauts to the Moon’s surface by 2024.

But with the recent announcement that NASA will be splitting the current Human Exploration and Operations Mission Directorate into two distinct groups, the agency may finally have the administrative capacity it needs to juggle their existing LEO interests and deep space aspirations. With construction of the ISS essentially complete, and the commercial spaceflight market finally coming together, the reorganization will allow NASA to start shifting the focus of their efforts to more distant frontiers such as the Moon and Mars.

Continue reading “NASA Sets Eyes On Deep Space With Admin Shuffle” →

Left: kids stomping spiders projected on a driveway. Right: the setup.

Make This Halloween A Spider-Stomping Good Time

September 30, 2021 by 11 Comments

We can count on one hand the number of times that we haven’t needed a coat on Halloween night around here. Even if it was fair and sunny the day before, you can count on Halloween being appropriately windy, cold, and spooky. Trick-or-treating only keeps a kid so warm, and we would have loved to happen upon a house with a spider-stomping sugar-burning good time of a game going on in the driveway.

[Kyle Maas] built this game a few years ago, and it has proved quite popular ever since. It’s so popular, in fact, that they have to have someone on duty with a vaudeville hook to yank spectators off the playing field. The point is to stomp as many spiders as you can in a set amount of time, though you only need to stomp one to win. It can handle one to four players, depending on the size of the projection, but [Kyle] says it’s kind of hard to track more than two at a time.

The setup is fairly simple, provided you can reliably affix your projector to something sturdy. [Kyle] used a Structure sensor for the 3D scanner, but you could easily use a Kinect instead. Conversely, the calibration was challenging. [Kyle] ended up using a DSP math trick known as the inverse bilinear transform to be able to calibrate the system using the 3D scanner itself.

If you’re more into scaring the children, just rig up a coffin bell. Either way, don’t forget about our Halloween Hackfest contest, running now through Monday, October 11th. There are more details over on IO. While you’re there, why not check out the list of entries?

The Coming Copper Shortage: Aluminium Or Carbon Nanotubes To The Rescue?

September 30, 2021 by 90 Comments

The use of aluminium in wiring is unlikely to bring a smile to the face of anyone who has had to deal with it in a 1960s, or early 1970s-era house. The causes behind the fires and other accidents were myriad, including failure to deal with the higher thermal expansion of aluminium, the electrically insulating nature of aluminium oxide, and the general brittleness of aluminium when twisted.

Yet while copper is superior to aluminium in terms of electrical conductivity and ease of installation, copper prices have skyrocketed since the 1970s, and are on the verge of taking off to the moon. A big part of the reason is the increased use of copper in everything from electronics and electrical motors to generators, driven by large-scale deployment of wind turbines and electrical vehicles.

As the world moves to massively expand the use of electrical cars and installation of wind turbines, copper demand is predicted to outstrip current copper supply. With aluminium likely to make a big return as a result, it’s worth taking a look at modern-day aluminium-based wiring, including copper-clad aluminium and the use of carbon-based replacements. Continue reading “The Coming Copper Shortage: Aluminium Or Carbon Nanotubes To The Rescue?” →

What’s In A Raspberry Pi Processor Update?

September 30, 2021 by 21 Comments

Those of us who have followed the Raspberry Pi over the years will be familiar with the various revisions of the little board, with their consequent new processors. What may be less obvious is that within the lifetime of any chip there will often be minor version changes, usually to fix bugs or to fine-tune production processes. They’re the same chip, but sometimes with a few extra capabilities. [Jeff Geerling] didn’t miss this when the Raspberry Pi 400 had a BCM2711 with a newer version number than that on the Pi 4, and now he’s notices the same chip on Pi 4 boards.

Why might they run two different revisions of the chip in parallel? It seems that the update changes the amount of memory addressable by the eMMC and the PCIe bus, the former could only see the first 1GB and the latter the first 3Gb. For the lower-spec Pi 4 boards this doesn’t present a problem, but for those with 8 gigabytes of memory it could clearly be an issue. Thus the Pi 400 and the top spec Pi 4 now have a newer BCM2711 version. This will almost certainly pass unnoticed for the average Raspberry Pi OS user, but the extra memory addressing space should be of interest for hardware experimenters wishing to expose that PCIe bus and talk to peripherals such as a GPU. That said, though he suggests the Compute Module 4  has the newer revision, his own experiments were unsuccessful.

[Editor’s Note: our own overclocking experiments show the C-version SOCs to run cooler/faster than their B counterparts, so it’s nice to have the better chips in the “normal” Pi form factor and not just the Pi 400 and compute modules.]

an image of the graffomat at work

Automate Your Graffiti With The Graffomat!

September 30, 2021 by 30 Comments

In Banksy’s book, Wall and Piece, there is a very interesting quote; “Imagine a city where graffiti wasn’t illegal, a city where everybody could draw whatever they liked…”. This sounds like it would be a very exciting city to live in, except for those of us who do not have an artistic bone in their body. Luckily, [Niklas Roy] has come up with the solution to this problem; the Graffomat, a spray can plotter.

The Graffomat is, in its creator’s own words, a “quick and dirty graffiti plotter.” It is constructed primarily from wood and driven by recycled cordless drills that pulls string pulleys to move the gantry.  The Arduino Nano at the heart of the Graffomat can be controlled by sending coordinates over serial. This allows for the connection of an SD card reader to drip-feed the machine, or a computer to enable real-time local or over-the-internet control.

We are especially impressed with how [Niklas] handled positional tracking. The cordless drills were certainly not repeatable like a stepper motor, as to allow for open-loop control. Therefore, the position of the gantry and head needed to be actively tracked. To achieve this, the axes are covered with black and white striped encoder strips, that is then read by a pair of phototransistors as the machine moves along. These can then be paired with the homing switches in the top left corner to determine absolute position.

Graffomat is not the first automated graffiti machine we’ve covered. Read here about the robot that painted murals by climbing smokestacks in Estonia. 

Continue reading “Automate Your Graffiti With The Graffomat!” →

A conventiongoer plays Pokemon on a working Color Game Boy costume.

Convention Plays Pokemon On Giant Color Game Boy Costume

September 29, 2021 by 2 Comments

Standard cosplay is fun and all, but what is there for admirers to do but look you up and down and nitpick the details? Interactive cosplay, now that’s where it’s at. [Jaryd Giesen] knows this, and managed to pull together a working color Game Boy costume in a few days.

The original plan was to use a small projector on an arm, like one of those worm lights that helped you see the screen, but [Jaryd] ended up getting a secondhand monitor and strapping it to his chest. Then he took the rest of the build from there. Things are pretty simple underneath all that cardboard: there’s a Raspberry Pi running the RetroPie emulator, a Pico to handle the inputs, and two batteries — one beefy 12,000 mAH battery for the monitor, and a regular power pack for the Pi and the Pico.

As you’ll see in the build and demo video after the break, nearly 100 people stopped to push [Jaryd]’s buttons. They didn’t get very far in the game, but it sure looks like they had fun trying.

Since we’re still in a pandemic, you may want to consider incorporating a mask into your Halloween costume this year. Just a thought.

Continue reading “Convention Plays Pokemon On Giant Color Game Boy Costume” →