Modeling A Guitar For Circuit Simulation

Guitar effects have come a long way from the jangly, unaltered sounds of the 1950s when rock and roll started picking up steam. Starting in large part with [Jimi Hendrix] in the 60s, the number of available effects available to guitarists snowballed in the following decades step-by-step with the burgeoning electronics industry. Now, there are tons of effects, from simple analog devices that would have been familiar to [Hendrix] to complex, far-reaching, digital effects available to anyone with a computer. Another thing available to modern guitarists is the ability to model these effects and guitars in circuit simulators, as [Iain] does.

[Ian] plays a Fender Stratocaster, but in order to build effects pedals and amplifiers for it with the exact desired sound, he needed a way to model its equivalent circuit. For a simple DC circuit, this isn’t too difficult since it just requires measuring the resistance, capacitance, and inductance of the overall circuit and can be done with something as simple as a multimeter. But for something with the wide frequency range of a guitar, a little bit more effort needs to go into creating an accurate model. [Iain] is using an Analog Discovery as a vector network analyzer to get all of the raw data he needs for the model before moving on to some in-depth calculations.

[Iain] takes us through all of the methods of figuring out the equivalent impedance of his guitar and its cabling using simple methods capable of being done largely by hand and more advanced techniques like finding numerical solutions. By analyzing the impedance of the pickup, tone and volume controls, and cable, this deep dive into the complexities of building an accurate equivalent circuit model for his guitar could be replicated by anyone else looking to build effects for their specific guitars. If you’re looking for a more digital solution, though, we’ve seen some impressive effects built using other tools unavailable to guitarists in days of yore, such as MIDI and the Raspberry Pi.

What Can We Do With These Patient Monitor Videos?

So we’ll admit from the start that we’re not entirely sure how the average Hackaday reader can put this content to use. Still, these simulated patient monitor videos on YouTube gotta be useful for something. Right?

Uploaded by [themonitorsolution], each fourteen-minute 1080p video depicts what a patient monitor would look like in various situations, ranging from an adult in stable condition to individuals suffering from ailments such as COPD and sepsis. There’s even one for a dead patient, which makes for rather morbid watching.

Now we assume these are intended for educational purposes — throw them up on a display and have trainees attempt to diagnose what’s wrong with the virtual patient. But we’re sure clever folks like yourselves could figure out alternate uses for these realistic graphics. They could make for an impressive Halloween prop, or maybe they are just what you need to get that low-budget medical drama off the ground, finally.

Honestly, it seemed too cool of a resource not to point out. Besides, it’s exceedingly rare that we get to post a YouTube video that we can be confident none of our readers have seen before…at the time of this writing, the channel only has a single subscriber. Though with our luck, that person will end up being one of you lot.

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RoboPianist Is A Simulation For Advancing Robotic Control

Researchers at Google have posed themselves an interesting problem to solve: mastering the piano. However, they’re not trying to teach themselves, but a pair of simulated anthropomorphic robotic hands instead. Enter RoboPianist.

The hope is that the RoboPianist platform can help benchmark “high-dimensional control, targeted at testing high spatial and temporal precision, coordination, and planning, all with an underactuated system frequently making-and-breaking contacts.”

If that all sounds like a bit much to follow, the basic gist is that playing the piano takes a ton of coordination and control. Doing it in a musical way requires both high speed and perfect timing, further upping the challenge. The team hopes that by developing control strategies that can master the piano, they will more broadly learn about techniques useful for two-handed, multi-fingered control. To that end, RoboPianist models a pair of robot hands with 22 actuators each, or 44 in total. Much like human hands, the robot hands are underactuated by design, meaning they have less actuators than their total degrees of freedom.

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Freq Out With LTSpice

We always enjoy [FesZ’s] videos, and his latest about FREQ function in LTSpice is no exception. In fact, LTSpice doesn’t document it, but it is part of the underlying Spice system. So, of course, you can figure it out or just watch the video below. The FREQ keyword allows you to change component attributes in a frequency-depended way.

Of course, capacitors and inductors are frequency dependent by design. But the FREQ technique allows you to adjust things like voltage sources or resistance in arbitrary ways. By default, you must specify the frequency response data in decibels, which isn’t always convenient. However, [FesZ] shows you how to use other methods to express them using modifiers to the command.

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This Camera Does Not Exist

Blender is a professional-grade 3D-rendering platform and much more, but it suffers sometimes from the just-too-perfect images that rendering produces. You can tell, somehow. So just how do you make a perfectly rendered scene look a little more realistic? If you’re [sirrandalot], you take a photograph. But not by taking a picture of your monitor with a camera. Instead, he’s simulating a colour film camera in extraordinary levels of detail within Blender itself.

The point of a rendering package is that it simulates light, so it shouldn’t be such a far-fetched idea that it could simulate the behaviour of light in a camera. Starting with a simple pinhole camera he moves on to a meniscus lens, and then creates a compound lens to correct for its imperfections. The development of the camera mirrors that of the progress of real cameras over the 20th century, simulating the film with its three colour-sensitive layers and even the antihalation layer, right down to their differing placements in the focal plane. It’s an absurd level of detail but it serves as both a quick run-down of how a film camera and its film work, and how Blender simulates the behaviour of light.

Finally we see the camera itself, modeled to look like a chunky medium format Instamatic, and some of its virtual photos. We can’t say all of them remove the feel of a rendered image, but they certainly do an extremely effective job of simulating a film photograph. We love this video, take a look at it below the break.

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Take A Ride In The Bathysphere

[Tom Scott] has traveled the world to see interesting things.  So when he’s impressed by a DIY project, we sit up and listen. In this case, he’s visiting the Bathysphere, a project created by a couple of passionate hobbyists in Italy. The project is housed at Explorandia, which based on google translate, sounds like a pretty epic hackerspace.

The Bathysphere project itself is a simulation of a submarine. Sounds simple, but this project is anything but.  There are no VR goggles involved.  Budding captains who are up for the challenge find themselves inside the cockpit of a mini-submarine. The sub itself is on a DIY motion platform. Strong electric motors move the system causing riders to feel like they are truly underwater. Inside the cockpit, the detail is amazing. All sorts of switches, lights, and greebles make for a realistic experience.  An electronic voice provides the ship status, and let’s the crew know of any emergencies. (Spoiler alert — there will be emergencies!)

The real gem is how this simulation operates. A Logitec webcam is mounted on an XY gantry. This camera then is dipped underwater in a small pond. Video from the camera is sent to a large monitor which serves as the sub’s window. It’s all very 1960’s simulator tech, but the effect works. The subtle movements of the simulator platform really make the users feel like they are 20,000 leagues under the sea.

Check out the video after the break for more info!

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SMA Connector Footprint Design For Open Source RF Projects

When you first start out in the PCB layout game and know just enough to be dangerous, you simply plop down a connector, run a trace or two, and call it a hack. As you learn more about the finer points of inconveniencing electrons, dipping toes into the waters of higher performance, little details like via size, count, ground plane cutouts, and all that jazz start to matter, and it’s very easy to get yourself in quite a pickle trying to decide what is needed to just exceed the specifications (or worse, how to make it ‘the best.’) Connector terminations are one of those things that get overlooked until the MHz become GHz. Luckily for us, [Rob Ruark] is on hand to give us a leg-up on how to get decent performance from edge-launch SMA connections for RF applications. These principles should also hold up for high-speed digital connections, so it’s not just an analog game.

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