Guitar Distortion With Diodes In Code, Not Hardware

August 23, 2023 by 14 Comments

Guitarists will do just about anything to get just the right sound out of their setup, including purposely introducing all manner of distortion into the signal. It seems counter-intuitive, but it works, at least when it’s done right. But what exactly is going on with the signal? And is there a way to simulate it? Of course there is, and all it takes is a little math and some Arduino code.

Now, there are a lot of different techniques for modifying the signal from an electric guitar, but perhaps the simplest is the humble diode clipping circuit. It just uses an op-amp with antiparallel diodes either in series in the feedback loop or shunting the output to ground. The diodes clip the tops and bottoms off of the sine waves, turning them into something closer to a square wave, adding those extra harmonics that really fatten the sound. It’s a simple hack that’s easy to implement in hardware, enough so that distortion pedals galore are commercially available.

In the video below, [Sebastian] explains that this distortion is also pretty easy to reproduce algorithmically. He breaks down the math behind this, which is actually pretty approachable — a step function with a linear part, a quadratic section, and a hard-clipping function. He also derives a second, natural exponent step function from the Schockley diode equation that is less computationally demanding. To implement these models, [Sebastian] chose an Arduino GIGA R1 WiFi, using an ADC to digitize the guitar signal and devoting a DAC to each of the two algorithms. Each distortion effect has its own charms; we prefer the harsher step function over the exponential algorithm, but different strokes.

Kudos to [Sebastian] for this easy-to-understand treatment of what could otherwise be a difficult subject to digest. We didn’t really expect that a guitar distortion pedal would lead down the rabbit hole to diode theory and digital signal processing, but we’re glad it did.

Continue reading “Guitar Distortion With Diodes In Code, Not Hardware” →

Wooden Wide-Angle Wonder Wows World

August 23, 2023 by 9 Comments

An old-fashioned film camera can be an extremely simple device to make, in that as little as a cardboard box with a pin hole in it will suffice. But that simplicity at heart leaves endless scope for further work, and a home-made camera can be every bit as much a highly-engineered object of beauty as its commercial stablemate. A great example comes from [Aaron Cré], whose desire for something close to a Hasselblad XPan panoramic camera led him to build his own equivalent out of wood.

The video below the break shows in detail how the wooden case is crafted, and how a lens mount ring sawn from a lens adapter is mounted on the front of it. He’s skipped making all the tiresome parts of the camera associated with winding and film transport and instead taken them from a cheap plastic snapshot camera. The original aspect ratio is stretched by cutting the guts of the snapshot camera apart, and extended to make a 75 mm long negative which also exposes over the sprocket holes.

The final camera is carefully finished to the point at which it really looks the part as well as taking those striking wide-angle photographs. We’re not photography buffs enough to identify the lens and shutter combination he’s using, but we can’t help envying him the results. Fancy making your own 35 mm camera too? Here’s another, in case you need inspiration.

Continue reading “Wooden Wide-Angle Wonder Wows World” →

SLR To DSLR Conversion Becomes Full Camera

August 22, 2023 by 8 Comments

At least as far as the inner workings are concerned, there’s not a whole lot of difference between an single-lens reflex (SLR) camera that uses film and a digital SLR (DSLR) camera that uses an electronic sensor except the method for capturing the image. So adding the digital image sensor to a formerly analog camera like this seemed like an interesting project for [Wenting Zhang]. But this camera ballooned a little further than that as he found himself instead building a complete, full-frame digital camera nearly from scratch.

The camera uses a full-frame design and even though the project originally began around the SLR mechanism, in the end [Wenting] decided not to keep this complex system in place. Instead, to keep the design simple and more accessible a mirrorless design is used with an electronic viewfinder system. It’s also passive M lens mount, meaning that plenty of manual lenses will be available for this camera without having to completely re-invent the wheel.

As far as the sensor goes, [Wenting] wanted something relatively user-friendly with datasheets available so he turned to industrial cameras to find something suitable, settling on a Kodak charge-coupled device (CCD) for the sensor paired with an i.MX processor. All of the electronics have publicly-available datasheets which is important for this open-source design. There’s a lot more work that went into this build than just picking parts and 3D printing a case, though, and we’d definitely recommend anyone interested to check out the video below for how this was all done. And, for those who want to go back to the beginnings of this project and take a different path, it’s definitely possible to convert an analog SLR to a digital one.

Continue reading “SLR To DSLR Conversion Becomes Full Camera” →

LaForge Demystifies ESIM

August 22, 2023 by 8 Comments

This talk at Chaos Communications Camp 2023 is probably everything you want to know about eSIM technology, in just under an hour. And it’s surprisingly complicated. If you’ve never dug into SIMs before, you should check out our intro to eSIMs first to get your feet wet, but once you’re done, come back and watch [LaForge]’s talk.

In short, the “e” stands for “embedded”, and the eSIM is a self-contained computer that virtualises everything that goes on inside your plain-old SIM card and more. All of the secrets that used to be in a SIM card are stored as data on an eSIM. This flexibility means that there are three different types of eSIM, for machine-to-machine, consumer, and IoT purposes. Because the secret data inside the eSIM is in the end just data, it needs to be cryptographically signed, and the relevant difference between the three flavors boils down to three different chains of trust.

Whichever eSIM you use, it has to be signed by the GSM Alliance at the end of the day, and that takes up the bulk of the talk time in the end, and in the excellent Q&A period at the end where the hackers who’ve obviously been listening hard start trying to poke holes in the authentication chain. If you’re into device security, or telephony, or both, this talk will open your eyes to a whole new, tremendously complex, playground.

Little Ionic Thruster Blows Out Candles With Ease

August 22, 2023 by 24 Comments

Want to generate some thrust by way of an exposed high voltage discharge that looks great when you turn down the lights? [Integza] has a video showing how to do exactly that with some simple components. His little thruster manages to blow out candles at surprising distances before being pressed into service propelling a model boat.

Here’s how it works: ionic wind is generated when a strong enough electric field causes nearby air to ionize, for example from sharp tips of a conductor carrying a high enough voltage. This discharge creates ionized air molecules with an electrical charge matching the polarity of the nearby conductor. Because matching polarities repel one another, the small cloud of ionized air molecules are repelled from both the nearby conductor, as well as from each other.

The result is a wind-like force from a device with no moving parts, and if the parts are structured right, it’ll blow out a candle with ease. [Integza] attached a cheap DC high-voltage transformer to a nickel strip cut into sharp points and rolled into a circlet. The other half of the thruster — in contrast to the thin crown of sharp points — is a smooth ring shaped a little like a thruster nozzle. 3D models of the parts are  available online should you wish to try it yourself without all the trial and error of trying to optimize.

In an effort to minimize mass, [Integza] electroplates a 3D-printed version of the large ring with great results, spraying it with graphite first to make it conductive. Cheap and safe copper electroplating is entirely within the reach of hobbyists, and the resulting unit does a pretty nice job. You can watch it in action in the video, embedded below.

Continue reading “Little Ionic Thruster Blows Out Candles With Ease” →

3D Printing With Clay, Thanks To Custom Extruder

August 22, 2023 by 14 Comments

When it comes to 3D printing clay, there are a lot of challenges to be met. An extruder capable of pushing clay is critical, and [davidsfeir] has an updated version suitable for an Ender 3 printer. This extruder is based on earlier designs aimed at delta printers, but making one compatible with an Ender 3 helps keep things accessible.

Lightly pressurized clay comes in via the clear tube. Air escapes out the top (motor side) while an auger homogenizes the clay and pushes it out the nozzle.

What’s special about a paste extruder that can push clay? For one thing, clay can’t be stored on a spool, so it gets fed into the extruder via a hose with the help of air pressure. From there, the clay is actually extruded with the help of an auger that takes care of pushing the clay down through the nozzle. The extruder also needs a way to deal with inevitable air bubbles, which it does by allowing air to escape out the narrow space at the top of the assembly while clay gets fed downward.

[davidsfeir] was greatly inspired by the work of clay-printing pioneers [Piotr Waśniowski] and his de-airing clay extruder, and [Jonathan Keep], who has documented 3D printing with clay comprehensively in a freely-available PDF. You can check out more of [david]’s designs on his Instagram page.

There are so many different aspects to printing with clay or clay-like materials that almost every part is ripe for innovation. For example, we’ve seen wild patterns result from sticking a thumping subwoofer under a print bed.

Start Your Semiconductor Fab With This DIY Tube Furnace

August 22, 2023 by 4 Comments

Most of us are content to get our semiconductors from the usual sources, happily abstracting away the complexity locked within those little epoxy blobs. But eventually, you might get the itch to roll your own semiconductors, in which case you’ll need to start gearing up. And one of the first tools you’ll need is likely to be something like this DIY tube furnace.

For the uninitiated, [ProjectsInFlight] helpfully explains in the video below just what a tube furnace is and why you’d need one to start working with semiconductors. Perhaps unsurprisingly, a tube furnace is just a tube that gets really, really hot — like 1,200° C. In addition to the extreme heat, commercial furnaces are often set up to seal off the ends of the tube to create specific conditions within, such as an inert gas atmosphere or even a vacuum. The combination of heat and atmospheric control allows the budding fabricator to transform silicon wafers using chemical and physical processes.

[ProjectsInFlight]’s tube furnace started with a length of heat-resistant quartz glass tubing and a small tub of sodium silicate refractory cement, from the plumbing section of any home store. The tube was given a thin coat of cement and dried in a low oven before wrapping it with nichrome wire. The wrapped tube got another, thicker layer of silicate cement and an insulating wrap of alumina ceramic wool before applying power to cure everything at 1,000° C. The cured tube then went into a custom-built sheet steel enclosure with plenty of extra insulation, along with an Arduino and a solid-state relay to control the furnace. The video below concludes with testing the furnace by growing a silicon dioxide coating on a scrap of silicon wafer. This was helped along by the injection of a few whisps of water vapor while ramping the furnace temperature up, and the results are easily visible.

[ProjectsInFlight] still needs to add seals to the tube to control the atmosphere in there, an upgrade we’ll be on the lookout for. It’s already a great start, although it might take a while to catch up to our friend [Sam Zeloof].

Continue reading “Start Your Semiconductor Fab With This DIY Tube Furnace” →