Quieting Noisy Resistors

February 21, 2026 by Al Williams 20 Comments

[Hans Rosenberg] has a new video talking about a nasty side effect of using resistors: noise. If you watch the video below, you’ll learn that there are two sources of resistor noise: Johnson noise, which doesn’t depend on the construction of the resistor, and 1/f noise, which does vary depending on the material and construction of the resistor.

In simple terms, some resistors use materials that cause electron flow to take different paths through the resistor. That means that different parts of the signal experience slightly different resistance values. In simple applications, it won’t matter much, but in places where noise is an important factor, the 1/f or excess noise contributes more to errors than the Johnson noise at low frequencies.

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MicroGPT Lets You Peek With Your Browser

February 21, 2026 by Al Williams 2 Comments

Regardless of what you think of GPT and the associated AI hype, you have to admit that it is probably here to stay, at least in some form. But how, exactly, does it work? Well, MicroGPT will show you a very stripped-down model in your browser. But it isn’t just another chatbot, it exposes all of its internal computations as it works.

The whole thing, of course, is highly simplified since you don’t want billions of parameters in your browser’s user interface. There is a tutorial, and we’d suggest starting with that. The output resembles names by understanding things like common starting letters and consonant-vowel alternation.

At the start of the tutorial, the GPT spits out random characters. Then you click the train button. You’ll see a step counter go towards 500, and the loss drops as the model learns. After 500 or so passes, the results are somewhat less random. You can click on any block in the right pane to see an explanation of how it works and its current state. You can also adjust parameters such as the number of layers and other settings.

Of course, the more training you do, the better the results, but you might also want to adjust the parameters to see how things get better or worse. The main page also proposes questions such as “What does a cell in the weight heatmap mean?” If you open the question, you’ll see the answer.

Overall, this is a great study aid. If you want a deeper dive than the normal hand-waving about how GPTs work, we still like the paper from [Stephen Wolfram], which is detailed enough to be worth reading, but not so detailed that you have to commit a few years to studying it.

We’ve seen a fairly complex GPT in a spreadsheet, if that is better for you.

Displaying The Rainbow

February 20, 2026 by Al Williams 23 Comments

True or false? Your green laser pointer is more powerful than your red one. The answer is almost certainly false. They are, most likely, the same power, but your eye is far more sensitive to green, so it seems stronger. [Brandon Li] was thinking about how to best represent colors on computer screens and fell down the rabbit hole of what colors look like when arranged in a spectrum. Spoiler alert: almost all the images you see of the spectrum are incorrect in some way. The problem isn’t in our understanding of the physics, but more in the understanding of how humans perceive color.

Perception may start with physics, but it also extends to the biology of your eye and the psychology of your brain. What follows is a lot of math that finally winds up with the CIE 1931 color space diagram and the CIE 2012 system.

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The History Of The View-Master

February 19, 2026 by Al Williams 27 Comments

We are going to bet that as a kid, you had a View-Master. This toy has been around for decades and is, more or less, a handheld stereoscope. We never thought much about the device’s invention until we saw a recent video from [View Master Travels and Peter Dibble]. It turns out that the principle of the whole thing was created by the well-known [Charles Wheatstone]. However, it was piano repairman [William Gruber] who invented what we think of as the View-Master.

[Gruber] didn’t just work on normal pianos, but complex player pianos and, in particular, the pianos used to record player piano rolls. He was also, as you might expect, a stereo photography enthusiast. Many of the ideas used in automating pianos would show up in the View-Master and the machines that made the reels, too. In the 1930s, stereoscopes were not particularly popular and were cumbersome to use. Color film was also a new technology.

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The Requirements Of AI

February 19, 2026 by Al Williams 76 Comments

The media is full of breathless reports that AI can now code and human programmers are going to be put out to pasture. We aren’t convinced. In fact, we think the “AI revolution” is just a natural evolution that we’ve seen before. Consider, for example, radios. Early on, if you wanted to have a radio, you had to build it. You may have even had to fabricate some or all of the parts. Even today, winding custom coils for a radio isn’t that unusual.

But radios became more common. You can buy the parts you need. You can even buy entire radios on an IC. You can go to the store and buy a radio that is probably better than anything you’d cobble together yourself. Even with store-bought equipment, tuning a ham radio used to be a technically challenging task. Now, you punch a few numbers in on a keypad.

The Human Element

What this misses, though, is that there’s still a human somewhere in the process. Just not as many. Someone has to design that IC. Someone has to conceive of it to start with. We doubt, say, the ENIAC or EDSAC was hand-wired by its designers. They figured out what they wanted, and an army of technicians probably did the work. Few, if any, of them could have envisoned the machine, but they can build it.

Does that make the designers less? No. If you write your code with a C compiler, should assembly programmers look down on you as inferior? Of course, they probably do, but should they?

If you have ever done any programming for most parts of the government and certain large companies, you probably know that system engineering is extremely important in those environments. An architect or system engineer collects requirements that have very formal meanings. Those requirements are decomposed through several levels. At the end, any competent programmer should be able to write code to meet the requirements. The requirements also provide a good way to test the end product.

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Ancient Ice Production

February 18, 2026 by Al Williams 53 Comments

Today, we take ice for granted. But having ice produced in your home is a relatively modern luxury. As early as 1750 BC, ancient people would find ice on mountains or in cold areas and would harvest it. They’d store it, often underground, with as much insulation as they could produce given their level of technology.

A yakhchāls in Yazd province (by [Pastaitkaen] CC BY-SA 3.0).

By 500 BC, people around Egypt and what is now India would place water in porous clay pots on beds of straw when the night was cold and dry. Even if the temperature didn’t freeze, the combination of evaporation and radiative cooling could produce some ice. However, this was elevated to a high art form around 400 BC by the Persians, who clearly had a better understanding of physics and thermodynamics than you’d think.

The key to Persian icemaking was yakhchāls. Not all of them were the same, but they typically consisted of an underground pit with a conical chimney structure. In addition, they often had shade walls and ice pits as well as access to a water supply.

Solar Chimney

The conical shape optimizes the solar chimney effect, where the sun heats air, which then rises. The top was typically not open, although there is some thought that translucent marble may have plugged the top to admit light while blocking airflow. yakhchālThe solar chimney produces an updraft that tends to cool the interior. The underground portion of the yakhchāl has colder air, as any hot air rises above the surface.

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Retrotechtacular: Mr. Wizard Jams With IBM

February 16, 2026 by Al Williams 29 Comments

You may not remember [Mr. Wizard], but he was a staple of nerd kids over a few decades, teaching science to kids via the magic of television. The Computer History Archives Project has a partially restored film of [Mr. Wizard] showing off sounds and noise on a state-of-the-art (for 1963) Tektronix 504 oscilloscope. He talks about noise and also shows the famous IBM mainframe rendition of the song “Daisy Bell.” You can see the video along with some extras below.

You might recall that the movie “2001: A Space Odyssey” paid homage to the IBM computer’s singing debut by having HAL 9000 sing the same song as it is being deactivated. The idea that HAL was IBM “minus one” has been repeatedly denied, but we still remain convinced.

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