Project Hub /Artificial Intelligence & Edge ML/Face Recognition & Access Control/Make Your Own Password Locker

Intermediate

OTHER CONTROLLER

₹500 – ₹1,500

3 – 6 Hours

Partial Kit

Make Your Own Password Locker

A simple, low-cost, high-security six-digit password-operated locking system built around an ATtiny2313 microcontroller.

Originally published on ElectronicsForU

View original tutorial

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

5V 1 Channel Relay Module Rs. 45.00
2-Slot 18650 Holder with Protective Cover and On/Off Switch – Case Rs. 109.00
10pcs 5mm RED Diffused Light Emitting Diodes - LEDs Set Rs. 39.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
10pcs - 220 ohm 1/4 W Resistor Set Rs. 39.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

This list includes a generic resistor set as a placeholder — it is not matched to the exact value or part number this circuit needs. The correct one is specified on the original source page linked above; check it before buying.

We don't carry yet: LCD (generic / unspecified)
ATtiny
Transistors (BC547 / 2N2222 / TIP / MOSFET)
Capacitors
Header Pins / Terminals / Connectors
USB Host / Programmer (ISP/USBasp)
Custom PCB / PCB Fab

Browse all components

How It Works

The Make Your Own Password Locker project centers around an ATtiny2313 microcontroller, which serves as the core processing unit for managing security and user interaction. Users interface with the system using three push buttons labeled Up, Right, and Enter to input a secure six-digit password. Visual feedback and system prompts are provided via a 16x2 LCD display, allowing the user to track their input status. When a password is entered, the ATtiny2313 compares the sequence against a stored value in its memory. If the correct code is provided, the microcontroller drives a 2N2222 transistor (T1). Because an AVR microcontroller pin cannot supply enough current to drive an electromechanical relay directly, the 2N2222 transistor acts as a low-side electronic switch. When the base of the transistor receives a high signal from the microcontroller, it allows current to flow through the coil of the 5V single-changeover relay. Activating the relay triggers its internal switch, which can control external locking mechanisms or high-current devices. A blinker LED (LED1) provides visual status indication during operation, such as warning states or successful unlocking events. Additionally, a hardware jumper (J1) is included to facilitate a password reset procedure in case the code needs to be cleared or reconfigured. The entire circuit is powered by a stable DC source and programmed via an AVR Programmer using C software tools like Programmers Notepad.

Why Build This

Develop practical undergraduate-level engineering experience by designing a complete microcontroller-based security system with user interface and actuation elements.

Implement reliable password-protected access control for secure electronic door locks, safe boxes, and restricted-access storage compartments.

Gain hands-on exposure to discrete transistor switching, relay interfacing, and low-level firmware development using AVR microcontrollers.

Real-World Application

Secure electronic door locks, safe boxes, and restricted-access storage compartments.

Skills You'll Learn

AVR microcontroller programming

push-button debouncing and state machine design

16x2 LCD interfacing

transistor-based relay switching

hardware reset mechanism implementation

Safety Precautions

Ensure proper DC power supply ratings (5V DC, 300mA or above) and handle electromechanical relay connections carefully.

Technology Tags

AVR

ATTINY2313

MICROCONTROLLER

LCD DISPLAY

RELAY

SECURITY SYSTEM

EEPROM

C PROGRAMMING

Frequently Asked Questions

How do I reset the password if I forget it?

You can use the designated jumper (J1) on the circuit board to execute a password reset procedure as designed in the system firmware.

Can I connect a heavy electronic door lock directly to the ATtiny2313 output?

No, the microcontroller pins cannot provide enough current to drive a lock directly. The ATtiny2313 controls a 2N2222 transistor, which safely switches the 5V single-changeover relay to handle external loads.

What software do I need to program the ATtiny2313?

You can use Programmers Notepad with WinAVR or any standard AVR C compiler to write and compile the code, along with AVR flashing software to upload the hex file via an AVR programmer.

Gallery

This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.

Kitkraft Project Hub — curated from the maker community, credited at the source.

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