This Air Particulate Sensor Can Also Check Your Pulse Rate

March 26, 2024 by 7 Comments

The MAX30105 is an optical sensor capable of a great many things. It can sense particulate matter in the air, or pick up the blinking of an eye. Or, you can use it as a rudimentary way to measure your heart rate and blood oxygen levels. It’s by no means a medical grade tool, but this build from [Taste The Code] is still quite impressive.

The MAX30105 contains red, green, and infrared LEDs, and a very sensitive light detector. The way it works is by turning on its different LEDs, and then carefully measuring what gets reflected back. In this way it can measure particles in the air,  such as smoke, which is actually what it was designed for originally. Or, if you press your finger up against it, it can measure the light coming back from your blood and determine its oxygenation level. By detecting the variation in the light over time, it’s possible to pick up your pulse, too.

Getting this data out of the sensor is remarkably easy. One need only hook it up to a suitable microcontroller like the ESP8266 and use the MAX3010X library to talk to it. [Taste The Code] did exactly that, and also hooked up a screen for displaying the captured data. Alternatively, if you want the raw data from the sensor, you can get that too.

It should be noted that this build was done for educational purposes only. You shouldn’t rely on a simple DIY device for gathering useful medical data; there are reasons the real gear is so expensive, after all. We’ve looked at this sensor before, too, not long after it first hit the market. Continue reading “This Air Particulate Sensor Can Also Check Your Pulse Rate” →

Documenting Real Hidden Messages In Music

March 25, 2024 by 22 Comments

During the 1980s, a moral panic swept across the landscape with the mistaken belief that there were Satanic messages hidden in various games, books, and music that at any moment would corrupt the youth of the era and destroy society as we knew it. While completely unfounded, it turns out that there actually were some hidden messages in vinyl records of the time although they’d corrupt children in a different way, largely by getting them interested in computer science. [Dandu] has taken to collecting these historic artifacts, preserving the music and the software on various hidden recordings.

While it was possible to record only programs or other data to vinyl, much in the same way that cassette tapes can be used as a storage medium, [Dandu]’s research focuses mostly on records, tapes, and CDs which had data included alongside music. This includes not only messages or images, but often entire computer programs. In some cases these programs were meant to be used with the accompanying music, as was the case for The Other Side Of Heaven by Kissing The Pink with a program for the BBC Micro. Plenty of other contemporary machines are represented here too including the ZX Spectrum, Atari, Apple II, and the Commodore 64. The documentation extends through the CD era and even into modern music platforms like Spotify and Apple Music.

The process of extraction and recovery is detailed for each discovery, making it a comprehensive resource for retro computing enthusiasts stretching from the 80s to now. There are likely a few hidden pieces of data out there hidden in various antique storage media that [Dandu] hasn’t found yet, either. You could even make your own records with hidden programs provided you have some musical and programming talents, and a laser engraver for the record itself.

Complex Organic Chemistry In Sulfuric Acid And Life On Venus

March 25, 2024 by 25 Comments

Finding extraterrestrial life in any form would be truly one of the largest discoveries in humankind’s history, yet after decades of scouring the surface of Mars and investigating other bodies like asteroids, we still have found no evidence. While we generally assume that we’re looking for carbon-based lifeforms in a water-rich environment like Jupiter’s moon Europa, what if complex organic chemistry would be just as happy with sulfuric acid (H2SO4) as solvent rather than dihydrogen monoxide (H2O)? This is the premise behind a range of recent studies, with a newly published research article in Astrobiology by [Maxwell D. Seager] and colleagues lending credence to this idea.

Previous studies have shown that organic chemistry in concentrated sulfuric acid is possible, and that nucleic acid bases – including adenosine, cytosine, guanine, thymine and uracil which form DNA – are also stable in this environment, which is similar to that of the Venusian clouds at an altitude where air pressure is roughly one atmosphere. In this new article, twenty amino acids were exposed to the concentrations of sulfuric acid usually found on Venus, at 98% and 81%, with the rest being water. Of these, 11 were unchanged after 4 weeks, 9 were reactive on their side chains, much like they would have been in pure water. Only tryptophan ended up being unstable, but as the researchers note, not all amino acids are stable in water either.

Continue reading “Complex Organic Chemistry In Sulfuric Acid And Life On Venus” →

Are Minimills Worth It?

March 25, 2024 by 64 Comments

These days, the bar for home-built projects is high. With 3D printers, CNC, and cheap service providers, you can’t get away with building circuits in a shoe box or an old Tupperware container. While most people now have access to additive manufacturing gear, traditional subtractive equipment is still a bit less common. [Someone Should Make That] had thought about buying a “minimill” but he had read that they were not worth it. Like a lot of us, he decided to do it anyway. The pros and cons are in the video you can watch below.

During setup, he covered a few rumors he’d heard about these type of mills, including they are noisy, have poor tolerances, and can’t work steel. Some of these turned out to be true, and some were not.

Continue reading “Are Minimills Worth It?” →

AxxSolder 3.0 Now Takes USB Power Delivery

March 25, 2024 by 12 Comments

If you’re big into the soldering iron scene, you’ve probably heard of the AxxSolder project. Now, it’s been updated with a whole host of nifty new features. It’s AxxSolder 3.0!

If you’re not intimately familiar with AxxSolder, it’s an open-source iron design based around the popular JBC soldering iron tips. Relying on the STM32G431CBT6 to run the show, it comes in two versions—a lightweight portable design, and a desktop version based around the JBC ADS soldering iron stand. So far, so familiar.

The new 3.0 version adds new functionality, however. Where the previous model ran off any old DC power source from 9 to 26 volts, the new version can run off a USB Power Delivery supply. Thus, you can grab any old USB-PD device, like a laptop charger, and run your iron off that.

The new version also uses a larger color TFT screen with some buttons added on as an improved user interface. Thermal performance is improved, and it’s additionally capable of measuring the current draw by the tip, so you can monitor the performance of the iron in great detail.

We’ve featured the AxxSolder project previously, too, along with some other great soldering iron projects. If you reckon you’ve just designed the hottest new soldering tool yourself, let us know about it!

The Cryotron Remembered

March 25, 2024 by 16 Comments

[Sean Haas] is a “dangerous freelance historian,” and his recent talk at the Vintage Computer Festival in Southern California covers the cryotron — a strange detour on the road to computers circa 1956. The NSA wanted a computer to break codes, but in 1956, there wasn’t much to pick from, especially since they wanted a very fast computer.

As you might expect from the name, a cryotron depends on superconductivity. The original device was a tantalum wire wrapped with a niobium wire coil. When the device is soaked in liquid helium, both wires become superconducting. The tantalum wire can carry way more current in that state unless the niobium coil generates a magnetic field, which kills the wire’s superconductivity. On the plus side, you have a relay-like switch that works with no moving parts. On the negative side, you need liquid helium.

Continue reading “The Cryotron Remembered” →

Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Pickle Pi

March 25, 2024 by 1 Comment

Image by [jefmer] via Hackaday.IO
The unstoppable [jefmer] wrote in to alert me to Pickle Pi, their latest Keebin’-friendly creation. Why “Pickle Pi”? Well, the Pi part should be obvious, but the rest comes from the Gherkin 30% ortholinear keyboard [jefmer] built with Gateron Yellows and, unfortunately, second-choice XDA keycaps, as the first batch were stolen off of the porch.

If you’re wondering where the rest of the keys are, they are accessible by holding various keys rather than tapping them. Shift is Shift when tapped held, but becomes Enter when tapped. [jefmer] wrote out their entire project description on the thing in order to break in the Gherkin.

The brains of this acrylic sandwich tablet is a Pi Zero 2, with a Pro Micro for the keyboard controller. Although programs like Ghostwriter and Thonny work fine, Chromium is “painfully slow” due to the RAM limitations of the Pi Zero 2. On the upside, battery life is 7-8 hours depending on usage. Even so, [jefmer] might replace it with a Pi 4 — the current battery pack won’t support a Pi 5.
Continue reading “Keebin’ With Kristina: The One With The Pickle Pi” →