Author: Maya Posch

1889 Articles

TTL And CMOS Logic ICs: The Building Blocks Of A Revolution

December 6, 2021 by 33 Comments

When starting a new electronics project today, one of the first things that we tend to do is pick the integrated circuits that make up the core of the design. This can be anything from a microcontroller and various controller ICs to a sprinkling of MOSFETs, opamps, and possibly some 7400- or 4000-series logic ICs to tie things together. Yet it hasn’t been that long since this level of high integration and miniaturization was firmly in the realm of science-fiction, with even NORBIT modules seeming futuristic.

Starting with the construction of the first point-contact transistor in 1947 and the bipolar junction transistor (BJT) in 1948 at Bell Labs, the electronics world would soon see the beginning of its biggest transformation to that point. Yet due to the interesting geopolitical circumstances of the 20th century, this led to a fascinating situation of parallel development, blatant copying of designs, and one of the most fascinating stories in technology history on both sides of the Iron Curtain. Continue reading “TTL And CMOS Logic ICs: The Building Blocks Of A Revolution” →

Christian Hahn Starlink capture showing guard region.

Analyzing Starlink Satellite Downlink Communications With Software Defined Radio

November 26, 2021 by 23 Comments

Often, mere curiosity is sufficient to do something. This is also the case with people trying to analyze the communication setup and protocol which SpaceX is using with their Ku-band based Starlink satellites.  One of these fine folk is [Christian Hahn], who has recently posted some early findings to r/StarlinkEngineering over at Reddit. Some of the captured data seems to include the satellite ID system that ground-based user stations would presumably use to keep track of overhead Starlink satellites.

For the capturing itself, [Christian] is using a second-hand dish for capture and a DIY SDR using KC705 FPGA-based hardware – which may have begun its life as crypto mining hardware – along with the usual assortment of filters and other common components with this kind of capture. Even at this early time, some features of the Starlink protocol seem quite obvious, such as the division into channels and the use of guard periods. Nothing too earth-shattering, but as a fun SDR hobby it definitely checks all the boxes.

[Christian] has also announced that at some point he’ll set up a website and publish the findings and code that should make Starlink signal analysis easy for anyone with a readily available SDR receiver.

 

Fully assembled DobsonianDSC.

Find Your Way In The Starry Skies With DobsonianDSC

November 25, 2021 by 13 Comments

An obvious problem with the use of a telescope is getting the former to point at the proper part of the sky which you intend to observe, or vice versa when you spot something interesting and wish to record the exact location. While all of this can be done manually with some trouble, there’s a lot to be said for automating this process. Unfortunately these Digital Setting Circles (DSC) features are not cheap even as add-on, which is why [Vladimir Atehortúa] created DobsonianDSC as a low-cost DIY solution.

As the name suggests, this project is based around a Dobsonian-style telescope: Newtonian tube with simple altazimuth base. Aside from the mechanical construction, this system uses an ESP32 as its controller along with two rotary encoders, with the simple circuit detailed in a build guide. The firmware for the ESP32 is written in the Arduino C dialect, and a guide for flashing the ESP32 with the Arduino IDE and connecting it to the WLAN is provided as well.

After setup, the resulting telescope system can be used either via WiFi or Bluetooth from existing apps such as SkySafari that support the ‘Basic Encoding System’. An initial calibration is required, but after that you should have a telescope that works in concert with SkySafari or similar to automate this tedious part of astronomy away.

Obviously this is not a ready-to-install system, as every telescope is shaped and sized differently, but inspiration for mounting solutions is provided as well.

Water beading up on a feather

PFAS: The Organofluorines Your Biochemist Warned You About

November 22, 2021 by 49 Comments

Sometimes it begins to feel like a tradition that a certain substance or group of substances become highly popular due to certain highly desirable chemical or physical properties, only for these chemicals then to go on to turn out to form a hazard to the biosphere, human life, or both. In the case of per- and polyfluoroalkyl substances (PFAS) it’s no different. Upon the discovery that a subgroup of these – the fluorosurfactants – have the ability to reduce water surface tension significantly more than other surfactants, they began to be used everywhere.

Today, fluorosurfactants are being used in everything from stain repellents to paint, make-up, and foam used by firefighters. In a recent study of 231 cosmetic products bought in the US and Canada (Whitehead et al., 2021), it was found that all of them contained PFAS, even when not listed on the packaging. The problematic part here is that PFASs are very stable, do not decay after disposal, and bioaccumulate in the body where they may have endocrine-disrupting effects.

Some areas have now at least partially banned PFAS, but the evidence for this is so far mixed. Let’s review what we do know at this point, and which alternatives we have to continuing to use these substances. Continue reading “PFAS: The Organofluorines Your Biochemist Warned You About” →

Back of Rigol DS1104Z oscilloscope with the Ethernet and USB ports visible.

SCPI: On Teaching Your Devices The Lingua Franca Of Laboratories

November 17, 2021 by 31 Comments

One could be excused for thinking sometimes that the concept of connecting devices with other devices for automation purposes is a fairly recent invention. Yet for all the (relatively) recent hype of the Internet of Things and the ‘smart home’, laboratories have been wiring up their gear to run complicated measurement and test sequences for many decades now, along with factories doing much the same for automating production processes.

Much like the chaotic universe of IoT devices, lab equipment from different manufacturers feature a wide number of incompatible protocol and interface standards. Ultimately these would coalesce into IEEE-488.1 (GPIB) as the physical layer and by 1990 the first Standard Commands for Programmable Instruments (SCPI) standard was released that built on top of IEEE-488.

SCPI defines (as the name suggests) standard commands to interact with instruments. It has over the past decades gone on to provide remote interaction capabilities to everything from oscilloscopes and power supplies to exotic scientific equipment. Many off the shelf devices a hobbyist can buy today feature an SCPI interface via its Ethernet, USB or RS-232C port(s) that combined with software can be used to automate one’s home lab.

Even better is that it’s relatively straightforward to add SCPI functionality to one’s own devices as well, so long as it has at least an MCU and some way to communicate with the outside world.

Continue reading “SCPI: On Teaching Your Devices The Lingua Franca Of Laboratories” →

Sulfur Hexafluoride: The Nightmare Greenhouse Gas That’s Just Too Useful To Stop Using

November 10, 2021 by 75 Comments

Sulfur hexafluoride (SF6) is not nearly as infamous as CO2, with the latter getting most of the blame for anthropogenic climate change. Yet while measures are being implemented to curb the release of CO2, for SF6 the same does not appear to be the case, despite the potentially much greater impact that SF6 has. This is because when released into the atmosphere, CO2 only has a global warming potential (GWP) of 1, whereas that of methane is about 28 over 100 years, and SF6 has a GWP of well over 22,000 over that same time period.

Also of note here is that while methane will last only about 12.4 years in the atmosphere, SF6 is so stable that it lasts thousands of years, currently estimated at roughly 3,200 years. When we touched upon sulfur hexafluoride back in 2019 in the context of greenhouse gases, it was noted that most SF6 is used for — and leaks from — high-voltage switchgear (mechanical switches), transformers and related, where the gas’ inert and stable nature makes it ideal for preventing and quenching electrical arcing.

With the rapid growth of highly distributed energy production in the form of mostly (offshore) wind turbines and PV solar parks, this also means that each of these is equipped with its own (gas-filled) switchgear. With SF6 still highly prevalent in this market, this seems like an excellent opportunity to look into how far SF6 usage has dropped, and whether we may be able to manage to avert a potential disaster.

Continue reading “Sulfur Hexafluoride: The Nightmare Greenhouse Gas That’s Just Too Useful To Stop Using” →

Fukushima Daiichi at night

A Tritium Story: How Afraid Should You Be Of Hydrogen’s Big Brother?

October 12, 2021 by 30 Comments

Despite being present in everything that contains water, tritium is not an isotope that many people were that familiar with outside of select (geeky) channels, such as DEF CON with a tritium-containing badge, the always excellent NurdRage’s assembly of a tritium-based atomic battery, or the creation of a tritium-phosphor-based glow-in-the-dark tesseract cube.

Tritium is a hydrogen isotope that shares a lot of characteristics with its two siblings: 1H (protium) and 2H (deuterium), with the main distinction being that tritium (3H) is not a stable isotope, with a half-life of ~12.32 years that sees it decay into 3He. Most naturally occurring tritium on Earth originates from interactions between fast neutrons (>4.0 MeV) from cosmic radiation and atmospheric nitrogen.

Recently tritium has become a politically hot topic on account of the announced release of treated water at the Japanese Fukushima Daiichi nuclear plant. This has raised for many the question of just how much tritium is ‘too much’ and what we’re likely to notice from this treated — but still tritium-containing water — being released into the ocean.

Continue reading “A Tritium Story: How Afraid Should You Be Of Hydrogen’s Big Brother?” →