A 2D simple regression analysis.

Making Math Less Stressful With A Python Super-Calculator

October 26, 2025 by No comments

In a recent write-up, [David Delony] explains how he built a Wolfram Mathematica-like engine with Python.

Core to the system is SymPy for symbolic math support. [David] said being able to work with symbolic math easily has helped his understanding of calculus and linear algebra. For statistics support he includes NumPy, pandas, and SciPy. NumPy is useful for creating multidimensional arrays and supports basic descriptive statistics such as mean, median, and standard deviation; pandas is a library for operating on tabular data arranged into “DataFrames”, it can load data from spreadsheets (including Excel) and relational databases; and SciPy is a “grab bag” of operations designed for scientific computing, it includes some useful statistics operations, including common probability distributions, such as the binomial, normal, and Student’s t-distribution.

For regression analysis [David] includes statsmodels and Pingouin. If you’re not familiar with the term “regression analysis” it basically refers to the process of curve fitting. When your data is two-dimensional, with one dependent variable, the simple linear regression algorithm will generate a function that fits the data as y = mx + b, including the slope (m) and the y-intercept (b); this can be extrapolated to higher dimensional data and other types of regression.

If you have an interest in symbolic math you might enjoy learning about Mathematica And Wolfram On The Raspberry Pi.

Spreadsheets Apple ][ Style

October 26, 2025 by 2 Comments

It is hard to remember a time when no one had a spreadsheet. Sure, you had big paper ledgers if you were an accountant. But most people just scribbled their math on note paper or, maybe, an engineering pad. [Christopher Drum] wanted to look at what the state of the art in 1978 spreadsheet technology could do. So he ran VisiCalc.

Surprisingly, VisiCalc got a lot of things right that we still use today. One thing we don’t see much of is the text-based menu. As [Christopher] puts it, when you press the slash key, “what first appears to be ‘the entire alphabet’ pops up at the top of the screen.” In reality, it is a menu of letters that each correspond to some command. For example, C will clear the sheet (after prompting you, of course).

Interestingly, VisiCalc of the day didn’t do a natural order of evaluation. It would process by rows or by columns, your choice. So if cell A1 depended on cell B5, you’d probably get a wrong answer since A1 would always be computed before B5. Interestingly, the old Apple didn’t have up and down keys, so you had to toggle what the right and left keys did using the space bar. Different times!

This is a great look into a very influential piece of software and its tutorials. If you have old VisiCalc files you want to drag into the 21st century, [Christopher] explains the convoluted process to get mostly there.

We’ve been known to abuse spreadsheets pretty badly, although we’ve seen worse.

HRV Gets Home Automation Upgrades

October 26, 2025 by 4 Comments

In our modern semi-dystopia, it seems like most companies add automation features to their products to lock them down and get consumers to buy even more proprietary, locked-down components. The few things that are still user-upgradable are getting fewer and farther between, but there are still a few things that can be modified and improved to our own liking like this control panel for a heat recovery ventilator (HRV).

HRVs are systems that exchange fresh, outside air with stale, inside air while passing them both through a heat exchanger to keep from wasting energy. Many systems run continuously but they aren’t always needed, so some automation is beneficial. This upgrade from [vincentmakes] improves the default display for a Zehnder Comfoair Q350 HRV with a color display as well as adding it in to a home automation system, letting a user control fan speeds remotely as well as alerting the user when it’s time for filter replacements and providing up-to-date information from all the sensors in the HRV.

The project builds on a previous project which adapted an ESP32 to interact with the CAN bus used on these devices. With these upgrades the user can forgo the $300 proprietary upgrade that would be needed to get the same functionality otherwise. It’s also fully open-source so all that’s needed is to flash the firmware, replace the display, and enjoy the fresh air. There’s other modern HVAC equipment that can benefit from new controllers and a bit of automation as well.

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Windows 95, With Just A Floppy Drive

October 26, 2025 by 7 Comments

It’s something of a shock to be reminded that Microsoft’s Windows 95 is now 30 years old — but the PC operating system that brought 32-bit computing to the masses and left behind a graphical interface legacy which persists to this day, is now old enough that many in the community have never actually seen it. The original requirements were a 386 or better, 4 megabytes of memory, and a hard drive. [Robert’s Retro] is exploding one of those requirements, creating a full Windows 95 install using only a floppy drive.

As you might imagine, even if you had one of the super-rare 2.88 megabyte drives, such a feat would require a few tricks. In this case the biggest trick is the FlashPath, a curious 1990s peripheral that allows a SmartMedia card to be used in a floppy drive. With a special DOS driver it allows what is in effect a 32 megabyte floppy disk, but even that’s not enough for ’95. In come a couple of further tricks, installing Windows 95 to a compressed DriveSpace volume which is copied to the FlashPath, and copying the Drivespace volume to a RAM drive and mounting it, on boot. It needs a conventional floppy to boot before swapping to the FlashPath and it seems the copying process is extremely slow, but we’d expect Windows 95 from RAM to be very quick indeed.

There have been other minimalist Windows 95s over the years, but what makes this one unusual is that it’s a full install. Five years ago at the OS’s quarter century we took a look at it with 2020 eyes, and tried gauge its effect on modern desktops.

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A Nuclear Physics Lab In Your Pocket

October 25, 2025 by 4 Comments

If you want to work with radioactive material, a cheap Geiger counter isn’t really what you want. According to [Project 326], you need a gamma ray spectrometer. The video below reviews the Radiacode 110. The channel has reviewed other Radiacode products, and they haven’t always been pleased with them, apparently. Is the 110 better?

The little spectrometer uses a scintillation crystal and performs a spectrogram on the result. It has a large library of materials so, at least for radioactive materials, you can point it at something and tell what kind of material you are dealing with and how radioactive it is.

While the smartphone app seems well done, the Windows application left something to be desired. Even still, it was able to identify several isotopes. The device can even pick up some alpha emitters that don’t directly register. However, it can identify some materials by different decomposition products. Unlike some earlier models, this device is supposed to be highly sensitive and high-resolution.

To confirm this, [Project 326] built a lead shielding structure and read a reference sample. Crunching some numbers confirmed that the claimed performance was accurate. It could even read very low-energy sources, though there were some limitations. The ergonomics of the device could be better, apparently, but it does deliver on performance.

Do you need a gamma ray spectrometer? We don’t know, but we suspect if you do, you don’t need us to tell you.

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A photo of the robot and the controller

A Simple $25 Robot Based On The ESP32

October 25, 2025 by 11 Comments

[Paul McCabe] wrote in to let us know about his $25 robot. This small wheeled robot is based on an ESP32 and made using cardboard and hot glue.

You drive the contraption using a Bluetooth game controller thanks to the Bluepad32 library, which boasts a long list of supported hardware. [Paul] provides a Bill of Materials (BoM), complete with current component pricing. We don’t know about you, but it struck us as funny that the microcontroller is less expensive than the battery! Ah, the times we live in. Also [Paul] assumes you already have an appropriate Bluetooth controller and doesn’t include that in the total cost.

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What If Tinkercad Was Self-Hosted?

October 25, 2025 by 12 Comments

While we use a lot of CAD tools, many of us are fans of Tinkercad — especially for working with kids or just doing something quick. But many people dislike having to work across the Internet with their work stored on someone’s servers. We get it. So does [CommonWealthRobotics], which offers CaDoodle. It is nearly a total clone of Tinkercad but runs on Windows, Linux, Mac, or even Chrome OS.

Is it exactly Tinkercad? No, but that’s not always a bad thing. For example, CaDoodle can work with Blender, FreeCAD, OpenSCAD, and more. However, on the business end, it sure looks like the core functions of Tinkercad.

The program appears fairly new, so you have to make some allowances. For example, the Linux AppImage seems to have difficulty loading plugins (which it needs to import many of its file formats). In addition, on at least some systems, you have to resize the window after it starts, or it won’t respond. But, overall, it is pretty impressive. The Settings, by the way, has a checkbox for advanced features, and there are some other goodies there, too.

One reason we found this interesting is that we sometimes go into schools, and they don’t want us to have kids on the Internet. Of course, they don’t like us installing random software either, so you can pick your battles.

Tinkercad, of course, continues to add features. Not all of which you’d expect in a drawing package.