A 28BYJ-48 turns in 2038 countable steps, not 2048 — here is the wiring, the connector-gender fix and a sketch that proves it.

Wire a 4×4 membrane keypad to an Arduino Uno, store the code in EEPROM and switch a 12V latch through a relay module — with the wrong-attempt lockout that is what actually makes the lock worth building.

Read the GY-521’s raw accelerometer and gyro values on an Arduino Uno, convert them with the real datasheet scale factors, and fuse them with a complementary filter into a stable live tilt angle on a 0.96-inch OLED.

Fit a JSN-SR04T waterproof probe to your water tank lid and an Arduino Uno turns the echo into a live level percentage on an OLED, with a buzzer alarm below 20%. Only the probe goes near water.

Connect an AS608 fingerprint sensor to an Arduino Uno, enrol fingers into the module’s own flash, and drive a relay to open a 12V lock – with the 5V-to-3.3V divider, full wiring table and a working match sketch.

Wire a GP2Y1010AU0F dust sensor and SCD30 CO2 sensor to an ESP32 with an OLED display – one sketch, honest trend readings for the jerebu season, and why it can never replace the official API.

Read an RFID card’s UID with the RC522, match it against your allowed list, and switch a 12V lock through a relay module – plus the honest truth about how secure it really is.

Build a DHT11 temperature and humidity monitor with a 0.96-inch OLED on an ESP32 – full wiring table, one runnable sketch, and no extra resistors needed.

Ten RBT electronics project ideas for Form 1-3, sorted by difficulty – from a no-code solar fan to a line follower robot – with the parts list and links to free step-by-step guides.

Build a working Arduino traffic light with three LEDs, 220 ohm resistors and a mini breadboard – complete wiring tables, full code and the mistakes we see real customers make.