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SIMPLE DIGITAL SECURITY SYSTEM

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    SIMPLE DIGITAL SECURITY SYSTEM

    PHERDAUS ISLAM


    You can use this simple and reliable security system as a watch dog by installing the sensing loops around your building. You have to stretch the loop wires two feet above the ground to sense the unauthorised entry into your premises.

    Wire loops 1, 2 and 4 are connected to the A, B and C inputs of 7-segment decoder 4511 (IC1), respectively, while the D input of IC1 is grounded permanently. The loops are also connected to a dual 3-input NOR gate and inverter CD4000 (IC2) to activate the alarm.




    Fig. 1: The digital security system circuit

    Fig. 1 shows the circuit of the digital security system, while Fig. 2 shows the proposed wiring diagram for the loops around the premises. Before using this security system, make sure that loops shown in Fig. 2 are connected as shown in Fig. 1. If you don’t want to use a buzzer, switch it off by opening switch S2.



    Fig. 2: The proposed wiring diagram of loops

    The circuit works off a 9V regulated power supply. However, battery back-up is recommended. A common-cathode, 7-segment display (LTS543) is used for displaying whether the loops are intact or not.

    If loop 1 is broken, the display will show ‘1’. If two or all the three loops are broken, the display will show the sum of the respective broken loop nently. The loops are also connected to a dual 3-input NOR gate and inverter CD4000 (IC2) to activate the alarm.

    Fig. 1 shows the circuit of the digital security system, while Fig. 2 shows the proposed wiring diagram for the loops around the premises. Before using this security system, make sure that loops shown in Fig. 2 are connected as shown in Fig. 1. If you don’t want to use a buzzer, switch it off by opening switch S2.

    The circuit works off a 9V regulated power supply. However, battery back-up is recommended. A common-cathode, 7-segment display (LTS543) is used for displaying whether the loops are intact or not.

    If loop 1 is broken, the display will show ‘1’. If two or all the three loops are broken, the display will show the sum of the respective broken loop numbers. For example, if loops 1 and 4 are broken, the display will show 5(1+4).

    When all the three loops are intact, the display will show ‘0.’ All the three inputs of gate N1 remain low to give a high output. This high output is further given to gate N2 and, as a result, its output remains low. This keeps transistor T1 in cut-off position and the piezobuzzer does not sound.

    When any loop is broken, the output of NOR gate N1 goes low, while the output of gate N2 goes high. Transistor T1 conducts and the buzzer sounds to alert you. You can mute the buzzer by switching off power to the circuit through switch S1.


     

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    Post Comment | 9 Comments



    chetan sinha   925 days ago

    i want to report in grief of this digital security system...but how ???????
    Reply  
    saurabh tandan   898 days ago

    plz send the project report of this project
    Reply   1 Reply
    Efy Admin   898 days ago

    We do not make entire project reports when we publish these circuits. You can refer to the write-up and the circuit diagram and other reference diagrams. We do not email project reports to anyone.
    Reply   1 Reply
    tharuni   207 days ago

    Can you Please Elaborate about the loops? I mean what do you exactly mean by loops?
    Reply   1 Reply
    Efy Admin   205 days ago

    Its just a conductor wire or jumper connecting two points. When you break this wire an alarm will sound.
    Reply  
    nikhil kulkarni   885 days ago

    is there any necessity to connect the leds.
    Reply  
    karunakar reddy   807 days ago

    WHY LOOP 3 IS NOT PRESENT IN THIS CIRCUIT ?
    Reply   1 Reply
    cool   698 days ago

    when loop2 and loop1 cuts then display shows 3.when loop3 cuts then display shows 3.this is confuse us that which side of building is unsecure.....therefore they use loop4 instead of loop3
    Reply  
    s.yashodhar   46 days ago

    This project is very nice.... but this is where will be useing ..pls give me any example............
    Reply  

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