This project uses an RFID module (RC522) to create an access control system with Arduino. The system checks RFID tags against a stored authorized UID and provides visual and audio feedback based on ...

LEDs: LED Arduino Pin Red LED D3 Yellow LED D4 Green LED D5 (Place a 220Ω resistor between each LED and GND.) Piezo Buzzer (2-pin): Buzzer Pin Arduino Pin Positive D7 Negative GND Explanation: RFID ...

But there are really just the two speeds with the current programming. Inside the cool laser-cut box is an Arduino Uno and a 9V battery, plus a current-limiting resistor and the all-important buzzer.