The Great ADS1115 Pricing And Sourcing Mystery

October 24, 2025 by Maya Posch 6 Comments

The AdaFruit ADS1115 board hooked up for testing. (Credit: James Bowman)

Following up on the recent test of a set of purported ADS1115 ADCs sourced from Amazon [James Bowman] didn’t just test a genuine Ti part, but also dug into some of the questions that came up after the first article. As expected, the AdaFruit board featuring a presumed genuine Ti ADS1115 part performed very well, even performing significantly better on the tested parameters than the datasheet guarantees.

Thus we can confirm that when you get the genuine Ti part, you can expect very good and reliable performance for your ADC purposes. Which leaves the unaddressed questions about what these cheapo Amazon-sourced ADS1115 ICs are, and how it can be that LCSC has what should be the same parts for so much cheaper than US distributors?

As far as LCSC pricing is concerned, these are likely to be genuine parts, but also the subject of what is known as price discrimination. This involves pricing the same product differently depending on the targeted market segment, with e.g. Digikey customers assumed to be okay with paying more to get the brand name assurance and other assumed perks. Continue reading “The Great ADS1115 Pricing And Sourcing Mystery” →

How Bad Can A Cheap Knockoff ADS1115 ADC Be?

October 15, 2025 by Maya Posch 29 Comments

Although the saying of caveat emptor rings loudly in the mind of any purveyor of electronic components, the lure of Very Cheap Stuff is almost impossible to resist. Sure, that $0.60 Ti ADS1115 ADC on LCSC feels like it almost has to be a knock-off since the same part on Digikey is $4 a pop, and that’s when you buy a pack of 1,000. Yet what if it’s a really good knockoff that provides similar performance for a fraction of the price, such as with those cheap ADC boards you can get from Amazon? Cue [James Bowman] letting curiosity getting the better of him and ordering a stash of four boards presumably equipped with at least some kind of cheapo knockoff part, mostly on account of getting all boards for a mere $2.97.

The goal was of course to subject these four purported ADS1115s to some testing and comparison with the listed performance in the Ti datasheet. Telling was that each of the ADCs on the boards showed different characteristics, noticeably with the Data Rate. This is supposed to be ±10% of the nominal, so 7.2 – 8.8 times per second in 8 samples per second mode, but three boards lagged at 6.5 – 7 SPS and the fourth did an astounding 300 SPS, which would give you pretty noisy results.

Using a calibrated 2.5 voltage source the accuracy of the measurements were also validated, which showed them to be too low by 12 mV. The good news was that a linear correction on the MCU can correct for this, but it shows that despite these parts being ADS1115 compatible and having features like the PGA working, you’re definitely getting dinged on performance and accuracy.

[James] said that he’s going to run the same tests on an ADS1115 board obtained from Adafruit, which likely will have the genuine part. We would also love to see someone test the $0.60 version from LCSC to see whether they can match the datasheet. Either way, if you are eyeing this ADC for your own projects, it pays to consider whether the compromises and potential broken-ness of the knockoffs are worth it over coughing up a bit more cash. As they say, caveat emptor.

Spy Tech: The NRO And Apollo 11

September 25, 2025 by Al Williams 13 Comments

When you think of “secret” agencies, you probably think of the CIA, the NSA, the KGB, or MI-5. But the real secret agencies are the ones you hardly ever hear of. One of those is the National Reconnaissance Office (NRO). Formed in 1960, the agency was totally secret until the early 1970s.

If you have heard of the NRO, you probably know they manage spy satellites and other resources that get shared among intelligence agencies. But did you know they played a major, but secret, part in the Apollo 11 recovery? Don’t forget, it was 1969, and the general public didn’t know anything about the shadowy agency.

Secret Hawaii

Captain Hank Brandli was an Air Force meteorologist assigned to the NRO in Hawaii. His job was to support the Air Force’s “Star Catchers.” That was the Air Force group tasked with catching film buckets dropped from the super-secret Corona spy satellites. The satellites had to drop film only when there was good weather.

In the 1960s, civilian weather forecasting was not as good as it is now. But Brandli had access to data from the NRO’s Defense Meteorological Satellite Program (DMSP), then known simply as “417”. The high-tech data let him estimate the weather accurately over the drop zones for five days, much better than any contemporary civilian meteorologist could do.

When Apollo 11 headed home, Captain Brandli ran the numbers and found there would be a major tropical storm over the drop zone, located at 10.6° north by 172.5° west, about halfway between Howland Island and Johnston Atoll, on July 24th. The storm was likely to be a “screaming eagle” storm rising to 50,000 feet over the ocean.

In the movies, of course, spaceships are tough and can land in bad weather. In real life, the high winds could rip the parachutes from the capsule, and the impact would probably have killed the crew.

Continue reading “Spy Tech: The NRO And Apollo 11” →

Think You Need A New PC For Windows 11? Think Again

September 18, 2025 by Tyler August 25 Comments

As the sun sets on Windows 10 support, many venues online decry the tsunami of e-waste Windows 11’s nonsensical hardware requirements are expected to create. Still more will offer advice: which Linux distribution is best for your aging PC? [Sean] from Action Retro has an alternate solution: get a 20 year old Sun Workstation, and run Windows 11 on that.

The Workstation in question from 2005 is apparently among the first Sun made using AMD’s shiny new 64-bit Opteron processor. Since Windows has no legacy 32-bit support– something it shares with certain Linux distributions– this is amongst the oldest hardware that could conceivably install and run Redmond’s latest.

And it can! Not in unaltered form, of course– the real hack here is courtesy of [ntdevlabs], whose “Tiny11” project strips all the cruft from Windows 11, including its hardware compatibility checker. [ntdevlabs] has produced a Tiny11Builder script that is available on GitHub, but the specific version [Sean] used is available on Archive.org.

[Sean] needed the archived version of Tiny11 because Windows 11 builds newer than 22H2 use the POPCNT operation, which was not present in AMD’s first revision of the x86_64 instruction set. POPCNT is part of Intel’s SSE4 extension from 2007, a couple years after this workstation shipped.

If you’re sick of being told to switch to Linux, but can’t stomach staying with Windows either, maybe check out Haiku, which we reported as ready for daily driving early last year.

Continue reading “Think You Need A New PC For Windows 11? Think Again” →

FPGA Brings UNIX V1 To The DEC J-11

August 30, 2025 by Bryan Cockfield 13 Comments

If you’ve never used a PDP-11 before it’s probably because you simply weren’t around in the 70s and 80s. Although they started as expensive machines only in research labs and industry, they eventually became much more accessible. They’re a bit of a landmark in computing history, too, being largely responsible for the development of things like UNIX and the C programming language. [ryomuk] is using an FPGA in combination with an original DEC J-11 to bring us a new take on this machine. (Google Translate from Japanese)

The FPGA used in this build is a Tang Nano 20k, notable for its relatively low cost. The FPGA emulates the memory system and UART of a PDP-11 system down to the instruction set, while the original, unmodified DEC chip is left to its own devices. After some initial testing [ryomuk] built a PC11 paper tape emulator to ensure the system was working which runs a version of BASIC from the era. The next thing up was to emulate some disk drives and co-processors so that the machine can run the first version of UNIX.

[ryomuk] also developed a PCB for the DEC microprocessor and the FPGA to sit on together, and it includes all of the jumpers and wiring needed to allow the computer to run UNIX, as well as handling other miscellaneous tasks like power. It’s an interesting build that gets to the heart of the early days of computer science. PDP-11 computers did eventually get smaller and more accessible, and if you want to build a modern version this build fits a complete system into an ATX case.

Thanks to [RetepV] for the tip!

Wayland Will Never Be Ready For Every X11 User

July 28, 2025 by Maya Posch 140 Comments

After more than forty years, everyone knows that it’s time to retire the X Window System – X11 for short – on account of it being old and decrepit. Or at least that’s what the common narrative is, because if you dig into the chatter surrounding the ongoing transition there are some real issues that people have with the 16-year old spring chicken – called Wayland – that’s supposed to replace it.

Recently [Brodie Robertson] did some polling and soliciting commentary from the community, breaking down the results from over 1,150 comments to the YouTube community post alone.

The issues range from the expected, such as applications that haven’t been ported yet from X11 to Wayland, to compatibility issues – such as failing drag and drop – when running X11 and Wayland applications side by side. Things get worse when support for older hardware, like GeForce GT610 and GT710 GPUs, and increased resource usage by Wayland are considered.

From there it continues with the lack of global hotkeys in Wayland, graphics tablet support issues, OBS not supporting embedded browser windows, Japanese and other foreign as well as onscreen keyboard support issues that are somehow worse than on X11, no support for overscanning monitors or multiple mouse cursors, no multi-monitor fullscreen option, regressions with accessibility, inability of applications to set their (previously saved) window position, no real automation alternative for xdotool, lacking BSD support and worse input latency with gaming.

Some users also simply say that they do not care about Wayland either way as it offers no new features they want. Finally [Brodie] raises the issue of the Wayland developers not simply following standards set by the Windows and MacOS desktops, something which among other issues has been a point of hotly debated contention for years.

Even if Wayland does end up succeeding X11, the one point that many people seem to agree on is that just because X11 is pretty terrible right now, this doesn’t automatically make Wayland the better option. Maybe in hindsight Mir was the better choice we had before it pivoted to Wayland.

Continue reading “Wayland Will Never Be Ready For Every X11 User” →

Diagnosing Whisker Failure Mode In AF114 And Similar Transistors

July 6, 2025 by Maya Posch 12 Comments

The inside of this AF117 transistor can was a thriving whisker ecosystem. (Credit: Anthony Francis-Jones)

AF114 germanium transistors and related ones like the AF115 through AF117 were quite popular during the 1960s, but they quickly developed a reputation for failure. This is due to what should have made them more reliable, namely the can shielding the germanium transistor inside that is connected with a fourth ‘screen’ pin. This failure mode is demonstrated in a video by [Anthony Francis-Jones] in which he tests a number of new-old-stock AF-series transistors only for them all to test faulty and show clear whisker growth on the can’s exterior.

Naturally, the next step was to cut one of these defective transistors open to see whether the whiskers could be caught in the act. For this a pipe cutter was used on the fairly beefy can, which turned out to rather effective and gave great access to the inside of these 1960s-era components. The insides of the cans were as expected bristling with whiskers.

The AF11x family of transistors are high-frequency PNP transistors that saw frequent use in everything from consumer radios to just about anything else that did RF or audio. It’s worth noting that the material of the can is likely to be zinc and not tin, so these would be zinc whiskers. Many metals like to grow such whiskers, including lead, so the end effect is often a thin conductive strand bridging things that shouldn’t be. Apparently the can itself wasn’t the only source of these whiskers, which adds to the fun.

In the rest of the video [Anthony] shows off the fascinating construction of these germanium transistors, as well as potential repairs to remove the whisker-induced shorts through melting them. This is done by jolting them with a fairly high current from a capacitor. The good news is that this made the component tester see the AF114 as a transistor again, except as a rather confused NPN one. Clearly this isn’t an easy fix, and it would be temporary at best anyway, as the whiskers will never stop growing.

Continue reading “Diagnosing Whisker Failure Mode In AF114 And Similar Transistors” →