LED Hourglass Is A Great Learning Project

December 9, 2025 by No comments

An hourglass tells you what it is in the name — a glass that you use to measure an hour of time passing by. [EDISON SCIENCE CORNER] has built a digital project that mimics such a thing, with little beads of light emulating falling sand in the timekeepers of old.

The build is designed around the Arduino platform, and can be constructed with an Arduino Uno, Nano, or Pro Mini if so desired. The microcontroller board is hooked up with an ADXL335 three-axis accelerometer, which is used for tracking the orientation and movement of the digital hourglass. These movements are used to influence the movement of emulated grains of sand, displayed on a pair of 8×8 LED matrixes driven by a MAX7219 driver IC. Power is courtesy of a 3.7 V lithium-ion cell, with a charge/boost module included for good measure. Everything is wrapped up in a vaguely hourglass-shaped 3D printed enclosure.

The operation is simple. When the hourglass is turned, the simulated grains of sand move as if responding to gravity. The movement is a little janky — no surprise given the limited resolution of the 8×8 displays. You also probably wouldn’t use such a device as a timer when more elegant solutions exist. However, that’s not to say builds like this don’t have a purpose. They’re actually a great way to get to grips with a microcontroller platform, as well as to learn about interfacing external hardware and working with LED matrixes. You can pick up a great deal of basic skills building something like this.

Would you believe this isn’t the first digital hourglass we’ve featured on the site?

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RP2350 Done Framework Style

December 8, 2025 by No comments

Ever want a microcontroller addon for your laptops? You could do worse than match one of the new and powerful microcontrollers on the block to one of the most addon-friendly laptops, in the way the Framework RP2350 laptop card does it. Plug it in, and you get a heap of USB-connected IO coming out of the side of your laptop – what’s not to love?

The card utilizes the Framework module board space to the fullest extent possible, leaving IO expansion on SMD pads you could marry to a male or female header, your choice. With about seventeen GPIOs, power, and ground, there’s really no limit on what you could add to the side connector – maybe it’d be a logic analyzer buffer, or a breadboard cable, or a flash chip reader, maybe, even an addon to turn it into a pirate version of a Bus Pirate? There’s a fair few RP2350 peripherals available on the side header GPIOs, so sky’s the limit.

Naturally, the card is fully open-source, and even has two versions with two different USB-C plug connectors, we guess, depending on which one is better liked by your PCBA process. Want one? Just send off the files! Last time we saw an addon adding GPIOs to your laptop, it was a Pi Zero put into the optical bay of a Thinkpad, also with an expansion header available on the side – pairing yet another legendary board with a legendary laptop.

The Engineering That Makes A Road Cat’s Eye Self-Cleaning

December 8, 2025 by 11 Comments

Although most people manage to navigate roads without major issues during the day, at night we become very reliant on the remaining navigational clues. The painted marks on the asphalt may not be as obvious in the glare of headlights, not to mention scuffed up and/or covered by snow and hidden by fog. This is where cat’s eyes are a great example of British ingenuity. A common sight in the UK and elsewhere in Europe, they use retroreflectors embedded in the road. Best of all, they are highly durable and self-cleaning, as [Mike Fernie] details in a recent video on these amazing devices.

Invented in the 1930s by [Percy Shaw], cat’s eyes feature a sturdy body that can take the abuse of being driven over by heavy trucks, along with a rubber dome that deforms to both protect the reflectors and wipe them clean using any water that’s pooled in the area below them. They also provide an auditory clue to the driver when they pass the center line, which can be very useful for night-time driving when attention may be slipping.

In the video the cat-squishing cleaning process is demonstrated using an old cat’s eyes unit that seems to have seen at least a few decades to road life, but still works and cleans up like a charm. Different color cat’s eyes are used to indicate different sections of the road, and modern designs include solar-powered LEDs as well as various sensors to monitor road conditions. Despite these innovations, it’s hard to beat the simplicity of [Percy]’s original design.

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Build Yourself A Graphing Weather Display

December 8, 2025 by 2 Comments

These days, Internet connectivity is ubiquitous, so you can look up live weather data on just about any device around you. Regardless, [Jozerworx] wanted a simple, clean, independent weather display, and came up with this simple design. 

The build is based on the Lilygo T5 EPD devboard, which combines an ESP32-S3 microcontroller with a nice 4.7-inch e-paper display. This display has the benefit that it only uses power when it’s being updated, making it particularly suitable to run off a battery for extended periods of time. Meanwhile, the ESP32 and its inbuilt Wi-Fi connectivity allow it to query the internet for updated weather forecasts. Weather data is sourced via the OpenWeather API, which [Jozerworx] notes comes with the caveat of requiring an API key. It’s a little fussy, but if you want good weather data, there are few easier ways to get it. The display shows a forecast for the next five days, while also showing graphs of ambient temperature and humidity along with useful information like the sunset and sunrise schedule.

Files are on Github for those eager to learn more. [Jozerworx] also notes that getting started with the display is particularly easy with the inclusion of a setup mode. This allows the display to act as a Wi-Fi access point with a web page that you use enter your home Wi-Fi connection details.

We’ve featured a great many charming weather displays over the years, too. If you’re working to plot, chart, or even predict the weather—don’t hesitate to show us your cool projects over on the tipsline!

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One Lucky 3DS Gets A Switch-Style Dock

December 8, 2025 by 2 Comments

The Nintendo Switch dock set a new bar for handheld docking user experience – just plug your console in to charge it, output image to your monitor, and keep it working with any USB peripherals of your choice. What if a 3DS is more your jam? [KOUZEX] shows off a Switch-style dock design for his gorgeous yellow 3DS, with Switch Pro controller support, and this dock wasn’t just a 3D printing job – there’s a fair bit of electronics to show, too.

While the 3DS looks stock at a glance, it has already been upgraded internally – there’s a USB-C capture card built in, half-ticking the “monitor output” requirement, and a Raspberry Pi board turns that output into HDMI. Building a charging dock is also pretty simple, with just two contacts on the side that desire 5V. Now, the pro controller support was a fair bit harder – requiring an internal modchip for emulating buttons, and trying out receiver boards for the Switch controller until a well-functioning one was found.

The build video is quite satisfying to watch, from assembling some QFNs onto tiny OSHPark boards using a hotplate and soldering them into the 3DS, to planning out, building, and dremeling some prints to create a true slide-console-into-dock experience, same way the Switch pulled it off. It even has the same USB-C and HDMI arrangement as the Switch dock, too! Want a simpler dock for your 3DS? Don’t forget that you can build a charger dock for yours with just a 3D print and a few wires.

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Trace Line Clock Does It With Magnets

December 8, 2025 by 5 Comments

We love a good clock project, and [byeh_ in] has one with a design concept we don’t believe we have seen before. The Trace Line Clock has smooth lines and a clean presentation, with no sockets or visible mechanical fixtures.

Reading the clock is quite straightforward once one knows what is going on. At its heart, the unmarked face is much like any other analog clock face, and on the inside is a pretty normal clock movement. The inner recessed track on the face represents hours, and the outer is minutes. The blue line connects the two, drawing a constantly changing line.

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Linux Fu: The SSD Super Cache

December 8, 2025 by 5 Comments

NVMe solid state disk drives have become inexpensive unless you want the very largest sizes. But how do you get the most out of one? There are two basic strategies: you can use the drive as a fast drive for things you use a lot, or you can use it to cache a slower drive.

Each method has advantages and disadvantages. If you have an existing system, moving high-traffic directories over to SSD requires a bind mount or, at least, a symbolic link. If your main filesystem uses RAID, for example, then those files are no longer protected.

Caching sounds good, in theory, but there are at least two issues. You generally have to choose whether your cache “writes through”, which means that writes will be slow because you have to write to the cache and the underlying disk each time, or whether you will “write back”, allowing the cache to flush to disk occasionally. The problem is, if the system crashes or the cache fails between writes, you will lose data.

Compromise

For some time, I’ve adopted a hybrid approach. I have an LVM cache for most of my SSD that hides the terrible performance of my root drive’s RAID array. However, I have some selected high-traffic, low-importance files in specific SSD directories that I either bind-mount or symlink into the main directory tree. In addition, I have as much as I can in tmpfs, a RAM drive, so things like /tmp don’t hit the disks at all.

There are plenty of ways to get SSD caching on Linux, and I won’t explain any particular one. I’ve used several, but I’ve wound up on the LVM caching because it requires the least odd stuff and seems to work well enough.

This arrangement worked just fine and gives you the best of both worlds. Things like /var/log and /var/spool are super fast and don’t bog down the main disk. Yet the main disk is secure and much faster thanks to the cache setup. That’s been going on for a number of years until recently.

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