1. DIGITAL SECURITY SYSTEM By R.SreeHarsha M.SaiSudeep Reddy

2. What is Digital Security? • It is a type of security which can be used to prevent intruders from entering our home. • The security system will sound an alert if there an attempt of break-in. • This is mainly used to minimize chances of losing possessions which can be traumatic and expensive. • When the intruder breaks in, the alarm will sound and most times will scare them off. • Limitations : The alarm will sound even if the user or his friends enter his home, providing an inconvenience to the user.

3. Why is this needed?

4. Circuit Diagram

5. Electronic Components • 5 Resistors: One 470 ῼ One 1K ῼ Three 47K ῼ resistors • Semi-Conductors: IC 1 – CD4511 IC 2 – CD4000 Q1 – BC 548 Display – LTS 543 • Miscellaneous: Two one way switches BZ – Buzzer IC Socket – 16 PIN-1 , 14 PIN-1 PCB

6. Circuit Construction • Wire loops 1,2 and 4 are connected to A,B and C inputs of the 7-segment decoder (IC 4511) while the D input of IC1 is grounded permanently. • The loops are also connected to a dual 3-input NOR gate which is then connected to a NOT gate to activate the alarm. • The 7-segment decoder is connected to a common cathode 7-segment display(LTS 543).

7. Brief Mechanism of Circuit • LTS 543 displays whether the loops are intact or not. • When the loops are intact, all the three inputs of the gate N1 remain low to give a high output. • This high output is further given to the NOT gate and as a result the final output remains low. This keeps the transistor in cut-off position and hence the buzzer does not sound. • When any loop is broken, the output of the N1 gate goes low. • As the input of the NOT gate is low, the final output will be high. • As the final output is high, the transistor conducts and the buzzer sounds to alarm the owner.

8. If the loop 1 is broken, the 7-segment display will show ‘1’. • Similarly if the loop 4 is broken, it shows ‘4’. • If both the loops 1 and 4 are broken, then it shows ‘5’ (1+4).

9. THANK YOU