Cool Arduino and robotics builds from around the internet — what people made, how they made it, and the parts behind it.
About seven dollars of hardware turns an Uno into a device that records data to a CSV file for days at a time. Here is the SPI wiring, the sketch, the pin 10 trap that hangs SD.begin(), and why close() is the line you must not delete.
A two-wheeled balancing robot is an inverted pendulum that falls over the instant your control loop is wrong. Here is how the MPU-6050, a complementary filter, and PID control keep it upright — and the three mechanical mistakes that sink most first attempts.
A DS18B20 sensor, a logic-level MOSFET, and a 12V fan add up to a real closed-loop thermostat you can build in an evening. Here is the wiring, the PWM detail nobody mentions, and the control logic that keeps it from chattering.
The electronics in a polished Arduino alarm are nearly identical to the ones in a science-fair version — the difference is a proper state machine with entry and exit delays, a keypad instead of a pushbutton, and wall power instead of a USB cable. Here is what actually separates the two.
A microphone module, a strip of addressable LEDs, and a short sampling loop will get you a music-reactive light bar this weekend. Here are the parts that actually work, the power and wiring gotchas that will bite you, and how to go from a loudness meter to a real frequency spectrum.
A servo-mounted ultrasonic sensor turns a two-wheel chassis into the smallest build that contains a whole robot: sense, decide, act. Here’s how the sweep-and-pivot loop works, the HC-SR04 limits to design around, and what to buy for either route.
A Bluetooth robot car is the shortest path from breadboard tinkering to something that actually drives across your floor. Here are the four parts that matter, the one resistor divider that keeps your HC-05 alive, and the power mistake that looks like a code bug.
The Arduino Mega isn’t the brain of a retro arcade cabinet — a Raspberry Pi is. It’s the part that makes the cabinet feel alive: lit buttons, an RGB marquee, a coin door that clicks. Here’s the division of labor these builds actually run on, and the USB gotcha that catches almost everyone.
A $35 ESP32-CAM build that sends a photo of whoever is at your door straight to your phone, with no subscription and no cloud storage. Full parts list, the GPIO conflicts nobody warns you about, and why the power supply is the step that kills most builds.
The EEZYbotARM MK2 uses a parallel linkage to keep every servo bolted to the base, so the moving arm is nothing but plastic. Here is why that design works, and the three parts you actually need to get it running.