DOORLOCKSYSTEM - Aman

Door Lock PCB Project Using 555 Timer

The Door Lock PCB Project utilizing a 555 timer IC offers an innovative, electronic alternative to traditional mechanical locks. This system combines simplicity and functionality, centered around the versatile 555 timer configured in monostable mode to control a relay-based locking mechanism. Ideal for educational or DIY security applications, the project emphasizes hands-on learning in circuit design and embedded systems.

Components & Design
The core component, the 555 timer, is paired with resistors, capacitors, a relay, and a keypad input. When a correct code is entered via the keypad, the 555 timer triggers a single pulse, activating the relay. This pulse duration, during which the door remains unlocked, is determined by the RC network (T = 1.1RC). A 9V battery powers the PCB, while a diode protects the circuit from relay-induced back EMF. The compact PCB layout ensures efficient component placement, with clear traces for power distribution and signal integrity.

Functionality
Upon entering the correct code, the 555 timer’s output pin drives the relay, energizing a solenoid or motor to retract the lock. An LED indicates the unlocked state, and a buzzer may signal incorrect attempts. The system resets automatically after the preset time (e.g., 10–30 seconds), relocking the door. This delay can be customized by adjusting resistor/capacitor values.

Features & Applications
Key features include cost-effectiveness, reprogrammable codes, and elimination of physical keys. Safety measures like decoupling capacitors stabilize voltage, enhancing reliability. Suitable for homes, lockers, or offices, the project serves as a foundational security solution. It also offers scalability—integrating microcontrollers for advanced features like biometrics or remote access.