What I made: a snap-fit enclosure that holds an Arduino UNO, a half-size breadboard, and a 9V battery pack — so a finished project doesn't end up as a loose pile of jumper wires on the desk. Designed in: Fusion 360 (free for personal use). STL + STEP files in the comments — your…
The HC-SR04 is the cheapest reliable way to measure distance with a microcontroller. It works by emitting a 40kHz ping and timing the echo's return. Effective range: about 2cm to 4m, with ±3mm accuracy in the sweet spot. Parts: • HC-SR04 ultrasonic module • Arduino UNO/Nano • 4…
Pi-hole is a DNS sinkhole. You point your home network's DNS at the Pi, and the Pi silently refuses to resolve domain names belonging to ad networks, trackers, and analytics services. Result: ads disappear in browsers, mobile apps, and even smart TVs — without installing anythin…
The non-I²C version of the standard 1602 LCD needs 16 wires and a contrast trimmer. The I²C backpack takes it down to 4 wires and gives you contrast control over software. If you're doing anything more than blinking an LED, this is the upgrade to make. Parts list: • 1602 charact…
Goal: get clean temperature + humidity readings from a DHT22 on a Raspberry Pi and log them to a CSV every 5 minutes for later graphing. Why the Pi is harder than an Arduino: the DHT22 has a strict ~50µs timing protocol. Arduino can bit-bang it deterministically because nothing…
This is NOT a real radiation detector. It's a teaching tool that produces statistically realistic Poisson-distributed clicks at any background rate you choose, so you can demonstrate randomness, dose-rate maths, and counter electronics without owning an actual SBM-20 tube. Why b…
What you'll build: a battery-friendly moisture sensor that publishes readings to Home Assistant over MQTT, so your phone tells you when each plant needs watering. Parts list: • Wemos D1 Mini (ESP8266) — small footprint, plenty of pins • Capacitive soil moisture sensor v1.2 (do N…
Weekend project I built with my 12-year-old. Result: an RC car you steer from any Android phone with a free Bluetooth joystick app. Range is about 8m line-of-sight, and a charge gets us roughly 40 minutes of zooming around the living room. Parts list: • Arduino Nano (clone is fi…
What you'll build: a small Wi-Fi weather station that exposes a JSON endpoint with live temperature + humidity, plus a tiny HTML page you can open from any phone on your network. Parts list: • ESP32 DevKit V1 board (any clone is fine) • DHT22 temperature + humidity sensor (DHT11…
Goal: a low-power, always-on home server that streams your local movies/shows to every device in the house and exposes a network share for the family laptops. Bill of materials: • Raspberry Pi 4 (4GB is plenty; 8GB if you want headroom for more services) • Official Raspberry Pi…
Project overview: a two-wheel-drive robot that follows a black line on a white surface using two IR reflectance sensors and proportional control on the motors. Parts list: • Arduino UNO • L298N dual H-bridge motor driver • 2WD chassis kit (2 yellow gear motors + 2 wheels + 1 cas…
What it does: the TCS3200 is a square chip with 64 photodiodes covered by R/G/B/clear filters. By selecting one filter at a time and counting the square-wave output frequency, you can measure how much of that colour the surface is reflecting. Use case: I used it in a small conve…
What it is: a flat MIDI controller with 12 capacitive touch pads on a sheet of acrylic. Plug it into a computer over USB and it shows up as a native MIDI device — no drivers, no extra software. Ableton, FL Studio, GarageBand all see it instantly. Why Teensy LC: it has native USB…
What it does: when someone presses the doorbell (or motion is detected), it snaps a photo and pushes it straight to my phone via a Telegram bot. Been running 3 months without a reboot. Parts list: • ESP32-CAM with OV2640 module • HW-104 USB-to-serial programmer for ESP32-CAM (or…
Why I built it: my cat had a strong opinion that 5am is breakfast time. I have a strong opinion that it isn't. The feeder mediates. Mechanical: • Started from a $15 plastic cereal dispenser from a kitchen store. • Removed the manual crank and 3D-printed a coupling that fits over…
The classic hard project. Beautiful in theory, brutal in tuning. Took me 3 evenings to get it balancing for more than 5 seconds — and another evening of tuning before it could be pushed and recover. Parts: • Arduino Nano (or any 16MHz AVR) • MPU6050 6-axis accel + gyro module (I…
This took about a month of weekends. The result is a full-size bartop arcade running RetroPie, with proper arcade buttons, joystick, marquee lighting, and authentic sound. Cabinet: • 18mm MDF cut on a friend's CNC — I'll share the DXF in the comments. • Dimensions: 460mm wide ×…
What you'll build: a desk clock that keeps accurate time with a coin-cell backup, displays HH:MM:SS + date on a crisp OLED, and stays accurate to better than 1 minute per year. No internet, no setup app, no apps to update. Parts list: • Arduino Nano • 0.96" SSD1306 OLED display…
If you've never flashed firmware before, this is the gentlest entry point into programming microcontrollers. End result: you can type Python directly into a REPL prompt on your ESP32 and see LEDs blink in real time. You need: • Any ESP32 dev board (DevKit V1, NodeMCU-32S, etc.)…
Goal: a replacement dashboard for my older hatchback that shows RPM, speed, coolant temperature, fuel level, and battery voltage on a big touchscreen. Pulls live data from the car's OBD-II port over Bluetooth — no manufacturer subscription, no cloud, no nonsense. Parts: • Raspbe…
Goal: a wireless soil + air sensor I can stake into the garden, powered entirely by sunlight, that runs for at least 6 months without intervention. Got there — has now survived monsoon season unattended. Power chain: • 6V / 2W solar panel (mini polycrystalline, ~115×85mm) • TP40…
The cool part: this doesn't need an Amazon developer account, an MQTT broker, or any cloud service. The ESP8266 pretends to be a Belkin Wemo smart switch, which Alexa discovers natively over your LAN. Parts: • Wemos D1 Mini (ESP8266) • 5V relay module (the kind with an opto-isol…
