Arduino
Digital weighing scale: HX711, load cells and the two-point calibration
A scale accurate to a gram or two, and the calibration maths that gets it there. Why a load cell outputs microvolts, why the mounting matters more than...
Arduino
Colour-sorting machine: making a TCS3200 tell red from orange
A sensor that reports colour as three frequencies, and the calibration that turns those into an answer. Why the white-balance step is the whole project, why the LEDs...
Arduino
Gesture-controlled robot: tilt your hand, the car moves
A glove with a gyroscope on it, a robot 30 metres away, and no lag. Reading tilt from an MPU6050 without the drift everyone complains about, and getting...
Build Log
ESP32-CAM security camera that messages your phone when something moves
A WiFi camera that photographs whatever triggered it and pushes the picture to your phone, for about Rs.850. The brownout that makes people think their board is dead,...
Build Log
A room monitor that serves its own dashboard: NodeMCU, DHT11 and no cloud account
Most IoT tutorials start by making you an account somewhere, then the free tier changes and your project is landfill. This one has no account and no broker:...
Arduino
RFID door lock with a solenoid: relays, flyback diodes and not frying your Arduino
A solenoid lock is the first thing most people build that can genuinely damage the microcontroller driving it. Optocoupler isolation, flyback diodes, why the RC522 must never see...
Arduino
Obstacle-avoiding robot with a scanning ultrasonic head
The standard obstacle avoider hits something, reverses and turns at random. Adding one servo turns it from a bumper car into something that surveys the room and picks...
Arduino
Line-following robot that actually follows the line: sensor spacing, proportional control and why yours weaves
Most line followers wobble down the track like they are drunk, and "reduce the speed" does not fix it. The oscillation is a control problem. Sensor spacing, per-sensor...
