A fan that spins then stops on the IRF520 module means the MOSFET is only half on at Arduino’s 5 V. Honest limits, correct wiring, the flyback diode check, and when to switch to a relay.

Fix one end of the 5kg bar load cell to the base plate, hang the platform on the other, and the HX711 turns that tiny flex into grams on your Arduino — mounting, wiring, calibration and full code.

NO, COM and NC explained, the high/low trigger jumper decoded, and honest advice on 240V mains — wire a relay module to your Arduino or ESP32 the safe way, starting on low-voltage DC.

Uno for 5V offline builds, ESP8266 for cheap WiFi, ESP32 for Bluetooth and heavier IoT — an honest spec table, a buying guide by project type, and the traps that catch people switching boards.

Build a battery-backed digital clock with an Arduino Uno, DS3231 RTC and LCD1602 I2C display — three components, four wires each, and one sketch.

Build an automatic plant watering system with an Arduino Uno: capacitive soil moisture sensor, relay and 5V submersible pump — wiring, calibration and safe code.