First Builds
Your first working circuit. Start here — nothing assumes you already know.
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...
Arduino
Driving 12 servos from one board: PCA9685 wiring, power and pulse ranges
Six PWM pins is not enough. How to wire a PCA9685 correctly, budget the power supply so your board stops resetting, and work out the pulse counts instead...
