ESP32

736 Articles

Live Train Departure Screens Keep You Abreast Of Transit Developments

November 28, 2025 by 3 Comments

If you want to know when the train is coming, you could pull up a webpage on your phone, or walk all the way to the station to look at the displays there. Or, like [eastfamilyreddish], you could build a neat little train info display to decorate your desktop instead.

The build is based on the work of [gadec-uk]—who developed a train information display some time ago. It’s based around an ESP32 D1 Mini, paired with a 256 x 64 OLED screen to display relevant train information. It accesses a National Rail API for train status information—known as the Darwin LDBWS (Live Departure Board Webservice). Configuration is via a web GUI hosted by the ESP32 itself.

[eastfamilyreddish] took the concept further by adapting this hardware into a more pleasing form. The ESP32 and OLED screen are built into a neat little hanging sign setup that apes one you might expect to see at a real railway station. You might expect that 3D printing was involved, but instead, this was achieved with lasercut parts and resin casting to create something with a beautiful finish. They even went so far as to include a wireless phone charging module in the base, making the device extra useful to really earn its place on the desktop.

The fact is, around these parts we love both trains and the displays you find around them. If you’ve got a railway-adjacent project, or you’ve just built your own awesome railway, don’t hesitate to let us know on the tipsline!

Build Your Own Compact Temp Gun

November 28, 2025 by 4 Comments

Sometimes you need to know what temperature something is, but you don’t quite want to touch it. At times like these, you might want a temp gun on hand to get a good reading, like the one [Arnov Sharma] built.

The build is a relatively simple one, and is based around an Waveshare ESP32 C6 development module that comes with a small LCD screen out of the box. The microcontroller is set up to read an MLX90614 infrared temperature sensor. This device picks up the infrared energy that is emitted by objects relative to their temperature. The sensor has a great range—from -70 C to 380 C. The readouts from this sensor are then displayed on the screen. Battery power is from a small 600 mAh LiPo cell, which is managed by a IP5306 charge module.

It’s worth noting that these infrared temperature sensors aren’t infallible devices. The temperature they perceive is based on certain assumptions about factors like an objects emissivity. Thus, they don’t always give accurate readings on metallic or shiny objects, for example. It’s also important to understand the sensor’s field of view. Despite many commercial versions featuring a laser pointer for aiming, many of these infrared temperature sensors tend to average their reading over a small spot that gets larger the farther away they are from the object being measured.

Tools like portable temp guns are pretty cheap, but sometimes it’s just fun to build your own. Plus, you usually learn something along the way. Video after the break.

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Styrofoam watercraft, PCB hydrofoil

A PCB Can Be A Hydrofoil, If It Really Wants To

November 23, 2025 by 10 Comments

You know those old cliche that the younger generations have begun to cynically despise: “follow your dreams!” “You can be anything you put your mind to!” — well, perhaps they are true on occasion. For instance when [rctestflight] had PCBs that dreamed of becoming a hydrofoil, he found a way to make that dream come true.

It’s kind of obvious in retrospect: printed circuit boards are made of FR4, which is a form of fiberglass, and you know what else is commonly made of fiberglass? Boats. So yes, the material is suited for this task. The fact that solder joints hold up to use in a little remote-control hydrofoil is less obvious, but good to know. It certainly makes for easier assembly for those of us who have developed an allergy to epoxy.

Ease of assembly wasn’t really the point here: the point was that by making the “mast” of the hydrofoil out of PCB– that’s the part that holds the underwater wing– [rctestflight] figured he could (shock!) print a circuit onto it. Specifically, a liquid-level sensor, and because microcontrollers are so cheap these days he went the “total overkill” route of embedding an ESP32 on each mast. He started with a resistive sensor, but since those self-corrode too quickly, the team switched to a capacitive sensor that doesn’t need to form a galvanic cell in salt water. Come to think of it, that might still be a problem with the solder joint between the PCBs. Good thing nobody will be riding this one.

Having such a sensor and brain close-coupled allows for a faster control loop than the sonar [rctestflight] had previously been using to control his hydrofoil’s altitude.. Pivoting each mast with its own servo made for a smooth flight over the water— well, once they got the PID tuning set, anyway. Check it out in the video embedded below.

We’ve seen PCB used for enclosures before, and even the chassis of a rover, but using it for a hydrofoil is a new hack. Continue reading “A PCB Can Be A Hydrofoil, If It Really Wants To” →

A circuit sculpture designed to help you sleep.

Sweet Sound Sculpture Helps You Sleep Soundly

November 21, 2025 by 9 Comments

Have trouble sleeping, or getting to sleep in the first place? You’ve no doubt heard of white noise machines, but know it would be much cooler to make your own. Enter Noise Maker, a DIY sound sculpture by [optimus103733], who wanted to learn something in the process of creating.

The best thing about this sound sculpture aside from the looks is that you can not only play five different sounds (e.g. birds, traffic, water, frog, white noise), you can mix them together into a rich but relaxing cacophony.

As you can probably see from the picture, Noise Maker is based on the ESP32 and uses an SD card module, an amplifier, and five six pots. Be sure to check out the pictures, because there are three layers of copper connections and a lot of careful bending to make it all come together. In the video after the break, you can hear it in action.

It seems [optimus103733] isn’t completely satisfied and wants to make a few improvements in the future, such as a voltage regulator, a power switch, and a timer to automatically stop playback once (we assume) sleep has come. Evidently the ESP32 struggles a little with mixing six audio sources, but hey, lesson learned.

Wait, why do we sleep in the first place?

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Building A Smart Speaker Outside The Corporate Cloud

November 17, 2025 by 15 Comments

If you’re not worried about corporate surveillance bots scraping your shopping list and manipulating you through marketing, you can buy any number of off-the-shelf smart speakers for your home. Alternatively, you can roll your own like [arpy8] did, and keep your life a little more private.

The build is based around an ESP32 microcontroller. It connects to the ‘net via its inbuilt Wi-Fi connection, and listens out for your voice with an INMP441 omnidirectional microphone module. The audio data is trucked off to a backend server running a Whisper speech-to-text model. The text is then passed to Google’s Gemini 2.5 Flash large language model. The response generated is passed to the Piper Neural Voice text-to-speech engine, sent back to the ESP32, and spat out via the device’s DAC output and a speaker attached to an LM386 amplifier. Basically, anything you could ask Gemini, you can do with this device.

By virtue of using a commercial large language model, it’s not perfectly private by any means. Still, it’s at least a little farther removed than using a smart speaker that’s directly logged in to your Amazon/Google/Hulu/Beanstikk account. Files are on Github for those eager to dive into the code. We’ve seen some other fun builds along these lines before, too. Video after the break.

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Cheap Multimeter Gets Webified

November 12, 2025 by 14 Comments

[Mellow Labs] wanted to grab a multimeter that could do Bluetooth. Those are cheap and plentiful, but the Bluetooth software was, unsurprisingly, somewhat lacking. A teardown shows a stock Bluetooth module. A quick search found a GitHub with software. But then he had a fiendish idea: could you replace the Bluetooth module with an ESP32 and use WiFi instead of Bluetooth?

This was as good an excuse as any to buy a cheap logic analyzer. Armed with some logic captures, it was easy to figure out how to fake the meter into thinking a Bluetooth client was connected.

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An Audio Brick For Your Smart Home

November 1, 2025 by 38 Comments

If you’ve ever wanted to pump sound to all the rooms of your house, you might use any one of a number of commercial solutions. Or, you could go the more DIY route and whip up something like the Esparagus Audio Brick built by [Andriy]. 

The concept is simple—it’s a small unit, roughly the size of a brick, which streams high-quality audio. It’s based around an ESP32, which pulls in digital audio over Wi-Fi or Ethernet. The microcontroller is hooked up to a TAS5825M DAC, which comes with a built-in amplifier for convenience. The Esparagus is designed for integration with Home Assistant, allowing for easy control as part of a smart home setup. It’s also compatible with Spotify Connect, AirPlay, and Snapcast—the latter of which provides excellent sync when using multiple units across several rooms.

Design files are available on Github for the curious. We’ve seen other neat projects in this space, before, too—like the charmingly-named OtterCast. Video after the break.

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