Night Vision The Old Way

Solid state electronics have provided lighter weight night vision units that work better than the old-fashioned gear that used photomultiplier tubes, but there was an even older technology as [Our Own Devices] shows us in a recent video. The Metascope Type B was a first-generation passive night vision viewer that relied on moonlight.

The video shows a 1946 technical paper from the Office of Scientific Research and Development with [Vannevar Bush] credited as the institute’s director. If that name sounds familiar, you may remember that he foresaw hypertext (inspiring both [Doug Englebart] and the creation of the Web).

The Type B was an improvement over the older Type A, which had been tested during the invasion of North Africa in 1942. The type A weighed less than two pounds and was much smaller than the type B. However, it didn’t work very well, so they stopped making them and did a redesign, which is what you see in the video. The type B weighed almost 5 pounds.

To use the metascope, you had to “charge” it with light and then wait. Eventually, you’d need to charge it again. The type B allowed you to charge one phosphor plate while using another one. When that plate became weak, you could swap the plates to continue using the device.

If you aren’t keen on the history, you can skip to just before the 15-minute mark of the video for the hardware examination. He doesn’t open the device, but that’s probably wise, given the nature, age, and rarity of the metascope.

Modern image sensors are very sensitive to infrared, and normal cameras usually have filters to keep them out. Not that you can’t remove it, of course. If you want to see something more modern, [Nick] built his own AN/PVS-14 night vision scope and you can too.

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How Does Time Work On The Moon?

We’re looking to go back to the Moon. Not just with robots this time, but with astronauts, too! They’ll be doing all kinds of interesting things when they get there. Maybe they’ll even work towards establishing a more permanent presence for humanity on the lunar surface, in which case they’ll have to get up in the morning, eat breakfast, and get to work.

This raises the question—how does time work on the Moon? As simple as they can be down here, Earthly days and years have little meaning up there, after all. So what’s going on up there?

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Reprogrammable Transistors

Not every computer can make use of a disk drive when it needs to store persistent data. Embedded systems especially have pushed the development of a series of erasable programmable read-only memories (EPROMs) because of their need for speed and reliability. But erasing memory and writing it over again, whether it’s an EPROM, an EEPROM, an FPGA, or some other type of configurable solid-state memory is just scratching the surface of what it might be possible to get integrated circuits and their transistors to do. This team has created a transistor that itself is programmable.

Rather than doping the semiconductor material with impurities to create the electrical characteristics needed for the transistor, the team from TU Wien in Vienna has developed a way to “electrostatically dope” the semiconductor, using electric fields instead of physical impurities to achieve the performance needed in the material. A second gate, called the program gate, can be used to reconfigure the electric fields within the transistor, changing its properties on the fly. This still requires some electrical control, though, so the team doesn’t expect their new invention to outright replace all transistors in the future, and they also note that it’s unlikely that these could be made as small as existing transistors due to the extra complexity.

While the article from IEEE lists some potential applications for this technology in the broad sense, we’d like to see what these transistors are actually capable of doing on a more specific level. It seems like these types of circuits could improve efficiency, as fewer transistors might be needed for a wider variety of tasks, and that there are certainly some enhanced security features these could provide as well. For a refresher on the operation of an everyday transistor, though, take a look at this guide to the field-effect transistor.

This Air Particulate Sensor Can Also Check Your Pulse Rate

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

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

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.

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Are Minimills Worth It?

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.

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