Simulating Cellular Biology In The Browser

[Technistuff] read a paper about simulating a “minimal” cell — apparently a cell with only 493 genes. This led to a goal: reproduce the simulation in TypeScript so it can run in a web browser. Why? We don’t know, but it is an interesting look at both in-depth biology and how to handle complex simulations. The code is available on GitHub.

For a point of reference, E. Coli has over 4,500 genes. The cell in question — JCVI-syn3A — actually has seven more genes than truly necessary. The data for this bacteria is available from a research lab, again, using GitHub.

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Arduino, Virtually

While simulating an Arduino isn’t a new idea, a recent project by [LRusso] provides an open source JavaScript simulator that runs in your browser. You can try it out live or host it yourself if you prefer.

The simulator looks much like the standard IDE, so there isn’t much to learn. You can select from several targets, including a UNO R3, a MEGA 1280, a MEGA 2560, or a NANO V3. At the bottom of the screen, you’ll see the correct number of digital pins, analog pins, and the serial monitor. The code is relatively new, and we noticed that the digital and output pins seem to work only for outputs. There is no way to modify any of the values from the user interface. You can, however, enter things into the serial monitor.

You can run a canned demo that uses digital and analog output. There is also another sample that uses the serial port. Unlike some other simulators, you can’t really add much external circuitry but, for some purposes, that isn’t a problem.

If you are looking for more, there is Simulide, which is also free. Falstad can do mixed signal simulations with Arduino code. There’s also Wokwi, which we’ve covered a few times before.

Designing A PCB GPS Antenna From Scratch

These days, when it comes to GPS devices the antenna is typically part of the package. But what better opportunity for [Pepijn] to learn how to make a GPS antenna from scratch for a badge add-on?

A patch antenna is an antenna of a flat design, which [Pepijn] was going to put directly on a PCB. However, there was added complexity due to GPS being a circularly polarized signal, and that meant doing some research.

Sadly, nowhere did [Pepijn] encounter a straightforward reference design or examples, but in the end success came from going with a truncated corner patch antenna design and using simulation software to figure out exactly what dimensions were needed. (The openEMS free simulation software didn’t bring success, but the non-free Sonnet with a trial license did the trick.) The resulting PCB may not look particularly complex, but every detail matters in such designs.

KiCad handled the PCB CAD design but the prototype came from cutting the PCB on a CNC machine instead of having it fabricated and shipped; a much cheaper and faster option for those with access to the right tools. A bit more testing had the prototype looking good, but the real proof came when it successfully received GPS signals and spewed valid NMEA messages. The design files are on GitHub but as [Pepijn] says, the project was about the journey more than anything else.

QSPICE Picks Up Where LTSpice Left Us

[Mike Engelhardt] is a name that should be very familiar to the hardcore electronics nerd. [Mike] is the developer responsible for LTSpice, which is quite likely the most widely used spice-compatible simulator in the free software domain. When you move away from digital electronics and the comfort of software with its helpful IDEs and toolchains, and dip a wary toe into the murky grey waters of analog or power electronics, LTSpice is your best friend. And, like all best friends, it’s a bit quirky, but it always has your back. Sadly, LTSpice development seems to have stalled some years ago, but luckily for us [Mike] has been busy on the successor, QSpice, under the watchful eye of Qorvo.

It does look in its early stages, but from a useability point of view, it’s much improved over LTSpice. Performance is excellent (based on this scribe’s limited testing while mobile.) Gone (thankfully!) is the uncommon verb-noun usage paradigm — replaced with a more usual cut-n-paste flow. Visually it still kind of looks like LTspice in places, but nicer with a clear and uncluttered design that gets straight to the point. Internally, the simulation engine has improved in speed and accuracy, as well as adding native support for modern semiconductor types, such as wide bandgap materials like SiC. Noted is that this updated software has a particular emphasis on power integrity and noise analysis, which are sticky problems that have a big impact on modern high-power systems.

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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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