These days, most of us take the instant availability of a high-speed link to the Internet for granted. But despite all of the latest technology, things still occasionally go pear-shaped — meaning that blistering fiber optic connection you’ve got to the world’s collected knowledge (not to mention, memes) can still go down when you need it the most.

After suffering some connectivity issues, [Arnov Sharma] decided to put together a little box that could alert everyone in visual range to the status of the local router. It won’t fix the problem, of course, but there’s a certain value to getting timely status updates. Using a 3D printed enclosure and a couple of custom PCBs, the build is fairly comprehensive, and could certainly be pressed into more advanced usage if given the appropriate firmware. If you’ve been thinking of a Internet-connected status indicator, this is certainly a project worth copying studying closely.

The aptly named “Wi-Fi Status Box” uses two PCBs: one to hold the Seeed Studio XIAO ESP32C3 microcontroller and four WS2812B addressable LEDs, and another that plays host to the IP5306 power management IC.

That latter board in particular is something you may want to file away for a future project, as it not only handles charging lithium-ion batteries such as common 18650 cells, but it also features an LED “fuel gauge” and the ability to boost the output power to 5 VDC with relatively few external components.

As for the firmware on this one, it’s simplicity itself. The goal is to see if the router has gone down, so all the code does is check every ten seconds to see if the ESP32 is still able to connect to the given wireless network. If the connection is good the LEDs are green, but if the link fails, they flip over to red. Combined with a printed front panel that uses transparent filament to soften the glow of the LEDs, and you’ve got an attractive way of knowing when it’s time to panic.

Too obvious for you? Perhaps you’d prefer this version that uses an analog multimeter to display when the net drops out.

In the past, building construction methods generally didn’t worry much about air quality. There were enough gaps around windows, doors, siding, and flooring that a house could naturally “breathe” and do a decent enough job of making sure the occupants didn’t suffocate. Modern buildings, on the other hand, are extremely concerned with efficiency and go to great lengths to ensure that no air leaks in or out. This can be a problem for occupants though and generally requires some sort of mechanical ventilation, but to be on the safe side and keep an eye on it a CO2 sensor like this unique Pac-Man-inspired monitor can be helpful.

Although there are some ways to approximate indoor air quality with inexpensive sensors, [Tobias] decided on a dedicated CO2 sensor for accuracy and effectiveness, despite its relatively large cost of around $30. An ESP32 handles the data from the sensor and then outputs the results to an array of LEDs hidden inside a ghost modeled after the ones from the classic arcade game Pac-Man. There are 17 WS2812B LEDs in total installed on a custom PCB, with everything held together in the custom 3D printed ghost-shaped case. The LEDs change from green to red as the air quality gets worse, although a few preserve the ghost’s white eyes even as the colors change.

For anyone looking to recreate this project and keep an eye on their own air quality, [Tobias] has made everything from the code, the PCB, and the 3D printer files open source, and has used accessible hardware in the build as well. Although the CO2 sensors can indeed be pricey, there are a few less expensive ways of keeping an eye on indoor air quality. Some of these methods attempt to approximate CO2 levels indirectly, but current consensus is that there’s no real substitute for taking this measurement directly if that’s the metric targeted for your own air quality.