Cute Face Tells You How Bad The Air Quality Is

February 13, 2025 by Lewin Day 3 Comments

You can use all kinds of numbers and rating systems to determine whether the air quality in a given room is good, bad, or somewhere in between. Or, like [Makestreme], you could go for a more human visual interface. He’s built a air quality monitor that conveys its information via facial expressions on a small screen.

Named Gus, the monitor is based around a Xiao ESP32-C3. It’s hooked up with the SeeedStudio Grove air quality sensor, which can pick up everything from carbon monoxide to a range of vaguely toxic and volatile gases. There’s also a THT22 sensor for measuring temperature and humidity. It’s all wrapped up in a cute 3D-printed robot housing that [Makestreme] created in Fusion 360. A small OLED display serves as Gus’s face.

The indications of poor air quality are simple and intuitive. As “Gus” detects poor air, his eyelids droop and he begins to look more gloomy. Of course, that doesn’t necessarily tell you what you should do to fix the air quality. If your issue is pollution from outside, you’ll probably want to shut windows or turn on an air purifier. On the other hand, if your issue is excess CO2, you’ll want to open a window and let fresh air in. It’s a limitation of this project that it can’t really detect particulates or CO2, but instead is limited to CO and volatiles instead. Still, it’s something that could be worked around with richer sensors a more expressive face. Some will simply prefer hard numbers, though, whatever the case. To that end, you can tap Gus’s head to get more direct information from what the sensors are seeing.

We’ve seen some other great air quality projects before, too, with remarkably similar ideas behind them. Video after the break.

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DIY Microwave Crucibles

February 12, 2025 by Al Williams 12 Comments

You know the problem. You are ready to melt some metal in your microwave oven, and you don’t have any crucibles. Not to worry. [Shake the Future] will show you how to make your own. All you need is some silicon carbide, some water glass (sodium silicate), and some patience.

The crucible takes the shape of a glass container. Don’t get too attached to it because the glass will break during the crucible construction. You can also use 3D-printed forms.

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USB Hub-A-Dub-Dub: Weird Edge Cases Are My Ruin

February 3, 2025 by Lewin Day 69 Comments

The Universal Serial Bus. The one bus to rule them all. It brought peace and stability to the world of computer peripherals. No more would Apple and PC users have to buy their own special keyboards, mice, and printers. No more would computers sprout different ports for different types of hardware. USB was fast enough and good enough for just about everything you’d ever want to plug in to a computer.

We mostly think of USB devices as being plug-and-play; that you can just hook them up and they’ll work as intended. Fiddle around around with some edge cases, though, and you might quickly learn that’s not the case. That’s just what I found when I started running complicated livestreams from a laptop…

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Why Not Build Your Quadcopter Around An Evaluation Board?

January 31, 2025 by Lewin Day 3 Comments

Quadcopters are flying machines. Traditionally, that would mean you’d optimize the design for lightweight and minimum drag, and you’d do everything in a neat and tidy fashion. The thing is, brushless motors and lithium batteries are so power-dense that you really needn’t try so hard. A great example of that is this barebones quadcopter build from [hebel23] all the way back in 2015.

The build is based around the STM32F4 Discovery Board, which [hebel23] scored as a giveaway at Electronica in Munich way back when. It’s plopped on top of a bit of prototyping board so it can be hooked up to the four controllers driving the motors at each corner. The frame of the quadcopter similarly uses cheap material, in the form of alloy profiles left over from an old screen door. Other equipment onboard includes a GY-273 electronic compass module, a MPU6050 3-axis gyroscope and accelerometer to keep the thing on the straight and level, and the Fly Sky R9B RC receiver for controlling the thing.

It might look crude, but it gets off the ground just fine. We’ve seen quadcopters using the STM32 in more recent years with more refined designs, but there’s something amusingly elegant about lacing one together with an evaluation board and some protoboard in the middle. If you’re working on your own flying projects, don’t hesitate to notify the tipsline!

Copper Candle Burns Forever… Just Add Fuel

January 30, 2025 by Al Williams 46 Comments

[Zen Garden Oasis] wanted to heat and light a space using a candle. But candles aren’t always convenient since they burn down and, eventually, you must replace them. So he built copper candles using a common copper pipe and an old glass jar. Of course, the candle still takes fuel that you have to replace, but the candle itself doesn’t burn down.

The basic idea is that the copper tube holds a high-temperature carbon wick that stays saturated with fuel. The fuel burns, but the wick material doesn’t. The copper part is actually concentric with a 3/4-inch pipe mostly enclosing a 1/2-inch pipe.

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Inside Vacuum Fluorescent Displays

January 29, 2025 by Al Williams 2 Comments

VFDs — vacuum fluorescent displays — have a distinctive look, and [Anthony Francis-Jones] is generally fascinated with retro displays. So, it makes sense that he’d build a VFD project as an excuse to explain how they work. You can see the video below.

VFDs are almost miniature CRTs. They are very flexible in what they display and can even use color in a limited way. The project [Anthony] uses as an example is an indicator to show the video number he’s currently making.

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A gif of a BlueSky feed, visualized as Matrix-style digital rain.

It’s Raining From The BlueSky

January 28, 2025 by Kristina Panos 15 Comments

Which would you rather feel? The blast of a fire hose, or a cool, digital rain? That’s what we thought. Introducing Blue Rain — the fire hose that is the BlueSky feed, falling semi-cryptically down your screen in Matrix-style letter droplets. Ahh, isn’t that nice?

Now, the rain doesn’t have to be blue. You can change the color, the speed at which it falls, the font, the font size, and other stuff like toggling NSFW, uh, tweets. (Wait, what are we calling BlueSky messages, anyway? Skeets? Really?)

You can even choose between a few fonts for the rain. And if you want to like, actually read one of the skeets, just shoot one carefully with your mouse while it’s still falling.

[Simone] has the project files on GitHub, but you should really read the blog post. Inspired by the lovely firehose3d, [Simone] thought instead of displaying the BlueSky fire hose as digital rain.

First, she collects as many skeets as there are empty columns on a screen from a Jetstream sever. This is calculated based on font style and size. She wrote an algorithm loosely inspired by CodePen, which does digital rain. If the skeet doesn’t fully render by the time it reaches the bottom of the screen, the rest appears at the top of the same column and falls until it’s done displaying. Then the column clears out and waits for a new skeet.

Want to take Matrix-style digital rain on the go? You can cram it onto a Pico, you know.

Thanks for the tip, [FrancisF]!