Project Report

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Subject: Semester Project of DLD- The Digital Locking System with Auto Lock Functionality.

Introduction
Digital Locking System with auto lock functionality has got several applications nowadays. As we are growing at high pace, we are getting more suspicious about our things. This locking system gives solution to that problem. This circuit described here activates only when the specified sequence of four digits is pressed. If a wrong key is touched, it will not unlock. The lock code is set by connecting nine SPST switches. The code lock circuit is built around two CD4013 dual-D flip-flop ICs. The clock pins of the four flip-flops are connected to that specified sequence of digits, which is the correct code sequence to unlock the system. The circuit also contains (555) timer IC to lock automatically after certain period of time.

Discussion
Equipments Used
* SPST switches.
* CD4013 Dual-D flip-flop ICs.
* 74LS147 Decimal to BCD Encoder.
* 74LS47 BCD-to-7-Segment Decoder IC.
* 7-Segment Display.
* 555 timer IC.
* Relay.
* 12V DC Power Supply.
Procedure
The Digital Lock Circuit diagram shows that the nine SPST switches are inputs to clock pulse of CD4013 dual D-flip flop. Push button switches are used for entering the code number. One side of all the push button switches are connected to +12V DC. The remaining ends of push buttons are connected to clock input pins of the flip-flops. When we press any switch the numbers will be displayed on seven segments if the combination matches to each flip flops pulse the circuit will activate, initially the set of flip flips will be as a low and reset will be common to operate the circuit properly. After the right sequence of four digits the lock will be open and then again to lock the 555 timer is used to control it. 25 seconds after unlocking it will automatically lock again. The relay is used to close the circuit when it energizes then the lock will be closed,...
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