MatTris, MirrorBallBot, and the ESP32 Science Tricorder
Issue 58 brings hands-on builds spanning a pocket Arduino arcade, a Raspberry Pi robot balancing on a ball, and an open-source ESP32 science tricorder—plus practical projects for…
IoT
Build an ESP32 SHT41 Temperature and Humidity Monitor
An ESP32 and SHT41 form a compact environmental monitor with simple four wire I2C connections. The Arduino IDE can send readings to the Serial Monitor or an OLED. With factory calibration, useful accuracy, low power needs, and SHT4x compatibility, this build provides a practical base for larger IoT projects.
Read the build on randomnerdtutorials.com: Build an ESP32 SHT41 Temperature and Humidity Monitor3D Printing
M3-CRETE: A Meter Scale Paste Printing Reference
M3-CRETE gives qualified teams a documented starting point for meter scale cementitious paste printing. It covers mechanical design, low voltage interfaces, configuration, and BOM information, while leaving high risk electrical work, material validation, safety engineering, and construction compliance to each builder and their own controlled facility.
Read the build on github.com: M3-CRETE: A Meter Scale Paste Printing ReferenceArduino
Self Contained PIR Trigger for Halloween Props
A small 9V module gives Halloween animatronics a portable motion trigger. An HC-SR501 senses movement, while a PC817 optocoupler separates that sensor circuit from the prop control wiring. A custom two part enclosure protects the electronics, holds the battery hardware, and keeps the assembly easy to place.
Read the build on blog.adafruit.com: Self Contained PIR Trigger for Halloween PropsPocket Tetris Arcade with Arduino and LED Matrix
A familiar block game becomes a real tabletop object in MatTris Arcade. An Arduino-compatible controller runs the game, an LED matrix shows the playfield, and physical buttons handle play. The 21-step build follows the enclosure, wiring, assembly, programming, and testing needed to make the console feel complete.
Read the build on instructables.com: Pocket Tetris Arcade with Arduino and LED MatrixDIY Electronics
Build a Knock Activated Monster Box
A tiny knock becomes a surprisingly expressive Halloween reaction. This child friendly box uses an electret microphone, a one transistor amplifier, an Arduino, and a servo to sense sound and move a monster. Its schematic and construction notes also teach biasing, AC coupling, threshold detection, and servo control through one playful build.
Read the build on build-electronic-circuits.com: Build a Knock Activated Monster BoxOnePage: Build an ESP32 C61 E Reader
OnePage turns an ESP32 C61 board into the center of a complete DIY e reader project. Its repository connects electronics, firmware, enclosure files, a board SDK, and browser tools, giving makers a practical way to inspect, source, fabricate, assemble, and adapt a wireless handheld reading device.
Read the build on github.com: OnePage: Build an ESP32 C61 E ReaderBuilding a PYNQ-Z2 Mixed-Signal Oscilloscope
A custom PCB turns the PYNQ-Z2 into an open measurement platform with a dual channel, 16 bit oscilloscope, logic analyzer connection, and arbitrary waveform generator. FPGA logic handles acquisition and processing, while ngscopeclient provides a desktop view. The repository also documents planned AI integration, though implementation details remain limited.
Read the build on pcbway.com: Building a PYNQ-Z2 Mixed-Signal OscilloscopeRP1 Opens the Full Humanoid Robot Stack
RP1 treats a humanoid robot as a reproducible system, not a sealed demonstration. Its repository connects structure, joints, electronics, firmware, control, and learning tools, while publishing CAD, schematics, PCB layouts, Gerbers, BOM data, and assembly notes for builders with serious fabrication and robotics experience.
Read the build on github.com: RP1 Opens the Full Humanoid Robot StackOnePage: Build an ESP32 C61 E Reader
OnePage turns an ESP32 C61 board into the center of a complete DIY e reader project. Its repository connects electronics, firmware, enclosure files, a board SDK, and browser tools, giving makers a practical way to inspect, source, fabricate, assemble, and adapt a wireless handheld reading device.
Read the build on github.com: OnePage: Build an ESP32 C61 E ReaderESP32
Give an Arduino Wired Ethernet with ENC28J60
Getting a low-cost ENC28J60 board working with an Arduino Nano takes more than connecting an Ethernet cable. SPI wiring, chip-select settings, library choice, and voltage checks all matter. Once configured, the small controller can join a LAN for web pages or data exchange, though ESP32 users need different pins and software.
Read the build on tweaking4all.com: Give an Arduino Wired Ethernet with ENC28J60Build 16 Expandable GPIO Channels for ESP32
Running short on ESP32 pins is common when a project adds relays, buttons, sensors, and indicators. This compact MCP23017 board moves those signals onto I²C, provides 16 terminal connections, and supports eight addressable modules. Reverse polarity protection, 5 V regulation, and clear address LEDs keep the hardware practical.
Read the build on elektormagazine.com: Build 16 Expandable GPIO Channels for ESP32Connect a Zehnder ComfoAir Q to Home Assistant
An ESP32 and CAN transceiver give a Zehnder ComfoAir Q a practical link to Home Assistant. This ESPHome project carries ventilation data and airflow commands from the unit’s CAN bus to the ESPHome API, with board choices, wiring guides, power notes, and OTA updates included.
Read the build on github.com: Connect a Zehnder ComfoAir Q to Home AssistantBuilding an Open Source ESP32 Science Tricorder
This handheld cyberdeck packs an ESP32, custom sensor boards, a microspectrometer, a magnetometer, and a Python interface into a 3D printed enclosure. Its open repository includes firmware, PCB layouts, print files, assembly guidance, and design history, giving makers a practical reference for building portable scientific instruments.
Read the build on github.com: Building an Open Source ESP32 Science TricorderIoT
This ESP32 Bin Tracks Fill Levels and Collection Routes
Fixed collection schedules send crews to bins that may be empty while busy locations overflow. This project uses an HC-SR04, ESP32, Wi-Fi, MQTT, and a dashboard to measure fill levels, report alerts, and suggest collection routes. It offers a clear, practical IoT example for campuses, canteens, and municipal services.
Read the build on projectech.in: This ESP32 Bin Tracks Fill Levels and Collection RoutesESPHome Bridge Reads JK-BMS Data
Battery packs often contain useful data that stays trapped inside the BMS. This ESPHome component places an ESP32 between a JK-BMS and Home Assistant, using UART-TTL or BLE to decode pack and cell readings. It adds dashboards, alerts, and automations without replacing the battery system’s safety functions.
Read the build on github.com: ESPHome Bridge Reads JK-BMS DataBuild a Wi-Fi to Ethernet ESP32 Router
An ESP32 with a W5500 Ethernet interface can share an existing Wi-Fi connection with wired devices. This project provides a separate LAN, DHCP, NAT, routed mode, and optional WireGuard protection. It suits home labs, isolated IoT testing, and devices that cannot join enterprise Wi-Fi directly.
Read the build on github.com: Build a Wi-Fi to Ethernet ESP32 RouterTurning a CYD into a Wireless Security Toolkit
A $7 ESP32 Cheap Yellow Display can become a handheld wireless security tester with HaleHound CYD firmware. Its touchscreen groups more than 40 modules in one interface, while browser flashing keeps setup simple. Some functions need extra radios, so check the hardware notes before building and testing in an authorized lab.
Read the build on github.com: Turning a CYD into a Wireless Security ToolkitBuilding an ESP32 Audio Bridge for Beolab Speakers
Vintage Beolab speakers need a quieter signal than a PCM5102A normally provides. This ESP32-S3 bridge handles TV and network audio with careful attenuation, 32-bit processing, source trims, startup muting, and practical fault finding. Its lessons cover Ethernet timing, PCB footprints, power cleanup, and diagnosing audio task underruns.
Read the build on hackaday.io: Building an ESP32 Audio Bridge for Beolab SpeakersESP32 Field Camera Meets Reality
A low-cost camera node can capture images on a workbench, yet field use exposes weak links. This build connects an ESP32-S3, OV5640, Android phone, Flutter app, and cloud AI, then examines communication, image quality, app boundaries, and code maintenance.
Read the build on note.com: ESP32 Field Camera Meets RealityRaspberry Pi
13 Games on a $5 Raspberry Pi Pico 2
A breadboard, a small color display, physical switches, and a speaker turn a roughly $5 Raspberry Pi Pico 2 into a playable 13 game arcade. Pico2Arcade uses the RP2350 to handle graphics, controls, sound, and game timing at a claimed 60 frames per second. Its open source code and build notes are on GitHub.
Read the build on icode.com: 13 Games on a $5 Raspberry Pi Pico 2A Raspberry Pi Robot That Balances on a Ball
MirrorBallBot replaces wheels with one spherical contact point, using motorized rollers to keep its body upright and moving. A custom Raspberry Pi HAT connects the electronics, while camera feedback and Python software guide corrections. Demonstrations include finger following, disturbance recovery, and travel along predefined paths.
Read the build on instructables.com: A Raspberry Pi Robot That Balances on a BallRun a Local AI Assistant on Raspberry Pi
ZeroClaw provides a Rust-based, self-hosted agent runtime for Raspberry Pi projects. It can connect natural-language requests with software tools and interfaces such as GPIO, I2C, SPI, and USB. This is a software foundation, not a finished robot, so wiring, model setup, permissions, and safety rules remain your responsibility.
Read the build on github.com: Run a Local AI Assistant on Raspberry PiRobotics
Build a PID Line Following Robot
At the front of this small robot, several IR sensors read the floor while two motors make constant steering corrections. The project links sensing, position estimates, feedback code, motor control, calibration, and mechanical design in one machine that immediately shows whether each part is working.
Read the build on gra.ge: Build a PID Line Following RobotArduino PT100 and PT1000 PID Controller PCB
Stable temperature control starts with good feedback. TSRCT-PCB-01 pairs an Arduino Nano Every with PT100 and PT1000 inputs, PID firmware, and two 5 V SSR outputs. The KiCad board provides a practical base for experimental heaters, while details such as calibration, display hardware, and temperature range need confirmation.
Read the build on pcbway.com: Arduino PT100 and PT1000 PID Controller PCBRecommended reads
ESP32 Snake Game with MPU6050 and OLED
Embedded Nerd's motion-controlled build: MPU6050, OLED and a complete Arduino sketch. The tutorial we picked for this swap, wired end to end.
Read ESP32 Snake Game with MPU6050 and OLED: recommended newsletterTindie Blog
What makers actually sell: new gear, seller stories and open hardware news.
Read Tindie Blog: recommended newsletterCircuit Cellar
Embedded design articles from the magazine that has covered microcontrollers since 1988.
Read Circuit Cellar: recommended newsletterFrom the bench
Voltage drop and wire gauge
One of 15 free no-signup bench tools for the projects in this issue.
All 15 tools: free bench tools