DIGITAL LOGIC DESIGN PROJECT PROPOSAL
PAK-AUSTRIA FACHHOCHSCHULE: INSTITUTE OF APPLIED
SCIENCES AND TECHNOLOGY DEPARTMENT OF ELECTRICAL
AND COMPUTER ENGINEEING.
SEMESTER 4
SUBMITTED TO:
SUBMITTED BY:
SIR RAGHIB
AIMEN KHAWAJA(B23F0030CYS036)
SIR AYAZ
MOMINA NAEEM (B23F0032CYS066)
MUSHAF SALEEM(B23F0001CYS005)
DATE:
28-03-25
TITLE: Password-Based Lock System Using Logic Gates and Counters
Objective:
A simple 4-bit password-based lock system using logic gates, flip-flops, and counters. The
system unlocks only when the correct 4-bit password is entered.
Components Required:
1.
2.
3.
4.
5.
6.
Logic Gates (AND, OR, NOT, XOR)
Flip-Flops (D or JK Flip-Flops)
4-Bit Counter (7493 or 74LS90)
7-Segment Display (Optional for feedback)
Push Buttons (For user input)
LEDs (To indicate LOCK/UNLOCK status)
Working Principle:
1. : The user enters a 4-bit password using push buttons
2. : The input is compared with a pre set password stored in logic circuits (XOR gates)
3. If the entered password matches an AND gate triggers the unlock signal
4. The lock LED turns OFF and the unlock LED turns ON.
5. If the password is wrong the lock remains active and an error signal (LED or buzzer)
activates.
:
6. If an incorrect password is entered the user must reset the system and try again
This can be done using a reset button connected to the counter/flip-flop
Circuit Diagram Overview:
We can breakdown compnents of our project in following
1. Input Section:
4 Push Buttons → Each represents a binary digit (0 or 1).
D Flip-Flops → Store each input bit temporarily.
2. Password Matching Circuit:
XOR Gates → Compares the stored input with the pre-set password
AND Gate → Outputs HIGH only if all XOR outputs are LOW (meaning input matches
the stored password)
3. Output Section:
LED 1 (LOCKED) → ON when password is wrong
LED 2 (UNLOCKED) → ON when the correct password is entered
Applications:
Digital Door Locks
Bank Lockers
Secured Access Control Systems