915 MHz Forecast: Rolling Your Own Offline Weather Station

December 19, 2025 by Matt Varian 8 Comments

There are a lot of options for local weather stations; most of them, however, are sensors tied to a base station, often requiring an internet connection to access all features. [Vinnie] over at vinthewrench has published his exploration into an off-grid weather station revolving around a Raspberry Pi and an RTL-SDR for communications.

The weather station has several aspects to it. The main sensor package [Vinnie] settled on was the Ecowitt WS90, capable of measuring wind speed, wind direction, temperature, humidity, light, UVI, and rain amount. The WS90 communicates at 915 MHz, which can be read using the rtl_433 project. The WS90 is also available for purchase as a standalone sensor, allowing [Vinnie] to implement his own base station.

For the base station, [Vinnie] uses a weatherproof enclosure that houses a 12V battery with charger to act as a local UPS. This powers the brains of the operation: a Raspberry Pi. Hooked to the Pi is an RTL-SDR with a 915 MHz antenna. The Pi receives an update from the WS90 roughly every 5 seconds, which it can decode using the rtl_433 library. The Pi then turns that packet into structured JSON.

The JSON is fed into a weather model backend that handles keeping track of trends in the sensor data, as well as the health of the sensor station. The backend has an API that allows for a dashboard weather site for [Vinnie], no internet required.

Thanks, [Vinnie], for sending in your off-grid weather station project. Check out his site to read more about his process, and head over to the GitHub page to check out the technical details of his implementation. This is a great addition to some of the other DIY weather stations we’ve featured here.

Amiibo Emulator Becomes Pocket 2.4 GHz Spectrum Analyzer

December 11, 2025 by Matt Varian 11 Comments

As technology marches on, gear that once required expensive lab equipment is now showing up in devices you can buy for less than a nice dinner. A case in point: those tiny displays originally sold as Nintendo amiibo emulators. Thanks to [ATC1441], one of these pocket-sized gadgets has been transformed into 2.4 GHz spectrum analyzer.

These emulators are built around the Nordic nRF52832 SoC, the same chip found in tons of low-power Bluetooth devices, and most versions come with either a small LCD or OLED screen plus a coin cell or rechargeable LiPo. Because they all share the same core silicon, [ATC1441]’s hack works across a wide range of models. Don’t expect lab-grade performance; the analyzer only covers the range the Bluetooth chip inside supports. But that’s exactly where Wi-Fi, Bluetooth, Zigbee, and a dozen other protocols fight for bandwidth, so it’s perfect for spotting crowded channels and picking the least congested one.

Flashing the custom firmware is dead simple: put the device into DFU mode, drag over the .zip file, and you’re done. All the files, instructions, and source are up on [ATC1441]’s PixlAnlyzer GitHub repo. Check out some of the other amiibo hacks we’ve featured as well.

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Shelf Life Extended: Hacking E-Waste Tags Into Conference Badges

December 3, 2025 by Matt Varian 10 Comments

Ever wonder what happens to those digital price tags you see in stores once they run out of juice? In what is a prime example of e-waste, many of those digital price tags are made with non-replaceable batteries, so once their life is over they are discarded. Seeing an opportunity to breathe new life into these displays, [Tylercrumpton] went about converting them to be the official badge of the Phreaknic 26 conference.

Looking for a solution for a cheap display for the upcoming conference badge, [Tylercrumpton] recalled seeing the work [Aaron Christophel] did with reusing electronic shelf labels. Looking on eBay, he picked up a lot of 100 ZBD 55c-RB labels for just $0.70 a piece. When they arrived, he got to work liberating the displays from their plastic cases. The long-dead batteries in the devices ended up being easily removed, leaving behind just the display and the PCB that drives it.

Another hacker assisting with the badge project, [Mog], noticed that the spacing of the programming pads on the PCB was very close to the spacing of a DB9/DE9 cable. This gave way to a very clever hack for programming the badges: putting pogo pins into a female connector. The other end of the cable was connected to a TI CC Debugger which was used to program the firmware on the displays. But along the way, even this part of the project got an upgrade with moving to an ESP32 for flashing firmware, allowing for firmware updates without a host computer.

The next challenge was how to handle customizing 200 unique badges for the conference. For this, each badge had a unique QR code embedded in the back of the 3D printed case that pointed to an online customization tool. The tool allowed the user to change which of the images was used for the background, as well as input the name they wanted to be displayed on the badge. Once finished, the server would provide a patched firmware image suitable for flashing the badge. The original intent was to have stations where attendees could plug in their badge and it would update itself; however, due to some 11th hour hiccups, that didn’t pan out for this conference. Instead, [Tylercrumpton] ran the update script on his machine, and it gave him a great opportunity to interact with conference attendees as they stopped by to update their badges.

For the Phreaknic 27 badge, the plan is to once again use electronic shelf labels, but this time to utilize some of the advanced features of the tags such as the EEPROM and wireless communications. We’re eager to see what the team comes up with.

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Retrofits Done Right: Physical Controls For Heated Seats

November 24, 2025 by Matt Varian 37 Comments

We’ve all owned something where one tiny detail drives us nuts: a blinding power LED, buttons in the wrong order, or a beep that could wake the dead. This beautifully documented project fixes exactly that kind of annoyance, only this time it’s the climate-controlled seats in a 2020 Ram 1500.

[projectsinmotion] wasn’t satisfied with adjusting seat heating and ventilation only through the truck’s touchscreen. Instead, they added real physical buttons that feel just like factory equipment. The challenge? Modern vehicles control seats through the Body Control Module (BCM) over a mix of CAN and LIN buses. To pull this off, they used an ESP32-S3 board with both CAN and LIN transceivers that sits in the middle and translates button presses into the exact messages the BCM expects.

The ESP32 also listens to the CAN bus so the new physical buttons always match whatever setting was last chosen on the touchscreen, no mismatched states, no surprises. On the mechanical side, there are 3D-printed button bezels that snap into blank switch plates that come out looking completely stock, plus a tidy enclosure for the ESP32 board itself. Wiring is fully reversible: custom adapters plug straight into the factory harness. Every pinout, every connector, and every wire color is documented with WireVis diagrams we’ve covered before, making this an easily repeatable seat-hack should you have a similar vehicle. Big thanks to [Tim] for the tip! Be sure to check out some of our other car hacks turning a mass produced item into one of a kind.

Real-Time BART In A Box Smaller Than Your Coffee Mug

November 11, 2025 by Matt Varian 27 Comments

Ever get to the train station on time, find your platform, and then stare at the board showing your train is 20 minutes late? Bay Area Rapid Transit (BART) may run like clockwork most days, but a heads-up before you leave the house is always nice. That’s exactly what [filbot] built: a real-time arrival display that looks like it was stolen from the platform itself.

The mini replica nails the official vibe — distinctive red text glowing inside a sheet-metal-style enclosure. The case is 3D printed, painted, and dressed up with tiny stickers to match the real deal. For that signature red glow, [filbot] chose a 20×4 character OLED. Since the display wants 5 V logic, a tiny level-shifter sits alongside an ESP32-C6 that runs the show. A lightweight middleware API [filbot] wrote simplifies grabbing just the data he needs from the official BART API and pushes it to the little screen.

We love how much effort went into shrinking a full-size transit sign into a desk-friendly package that only shows the info you actually care about. If you’re looking for more of an overview, we’re quite fond of PCB metro maps as well.

RP2040 From Scratch: Roll Your Own Dev Board Magic

November 10, 2025 by Matt Varian 15 Comments

Have you ever looked at a small development board like an Arduino or an ESP8266 board and thought you’d like one with just a few different features? Well, [Kai] has put out a fantastic guide on how to make an RP2040 dev board that’s all your own.

Development boards are super useful for prototyping a project, and some are quite simple, but there’s often some hidden complexity that needs to be considered before making your own. The RP2040 is a great chip to start your dev-board development journey, thanks to its excellent documentation and affordable components. [Kai] started this project using KiCad, which has all the features needed to go from schematics to final PCB Gerber files. In the write-up, [Kai] goes over how to implement USB-C in your design and how to add flash memory to your board, providing a place for your program to live. Once the crystal oscillator circuit is defined, decoupling capacitors added, and the GPIO pins you want to use are defined, it’s time to move to the PCB layout.

In the PCB design, it starts with an outside-in approach, first defining the board size, then adding the pins that sit along the edges of that board, followed by the USB connector, and then moving on to the internal components. Some components, such as the crystal oscillator, need to be placed near the RP2040 chip, and the same goes for some of the decoupling capacitors. There is a list of good practices around routing traces that [Kai] included for best results, which are useful to keep in mind once you have this many connections in a tight space. Not all traces are the same; for instance, the USB-C signal lines are a differential pair where it’s important that D+ and D- are close to the same length.

Finally, there is a walk-through on the steps needed to have your boards not only made at a board house but also assembled there if you choose to do so. Thanks [Kai] for taking the time to lay out the entire process for others to learn from; we look forward to seeing future dev-board designs. Be sure to check out some of our other awesome RP2040 projects.

CardFlix: NFC Cards For Kid-Friendly Streaming Magic

November 5, 2025 by Matt Varian 7 Comments

For most of us, the days of having to insert a disc to play our media are increasingly behind us. But if you’d like to provide your kids with the experience, you could use CardFlix.

For the electronics, [Udi] used the readily available ESP8266 D1 Mini module connected via I2C to a PN532 NFC reader. To trigger the different movies, there are over 50 cards, each with not only its unique NFC tag but also small posters that [Udi] printed showing the show and then laminated, ensuring they will survive plenty of use. The D1 Mini and NFC reader are housed in a 3D printed case, which ends up being almost smaller than the 5V DC adapter powering it, allowing it to be mounted above an outlet out of the way. The deck of movie cards is also housed in a pair of printed boxes: the larger one for the whole collection and a small one for the most often used shows. Should you want to print your own, all the design files are provided in the write-up.

The D1 Mini was programmed using ESPHome. This firmware allows it to easily connect back to Home Assistant, which does most of the heavy lifting for this project. When a card is scanned, Home Assistant can tell which TV the scanner was near, allowing this system to be used in more than one location. It also knows which card was scanned so it can play the right movie. Home Assistant also handles ensuring the TV in question is powered on, as well as figuring out what service should be called for that particular movie to be shown.

Be sure to check out some of the other projects we’ve featured that use ESPHome to automate tasks.

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