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FIRE ALARM

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  • FIRE ALARM

    AJEET K. MALL  


    With the onset of summer, chances of fire accidents increase. Such fire accidents can be prevented if timely alarms are available. The circuit presented here warns the user against such fire accidents. The circuit should be placed in fire-prone areas such as a kitchen.



    Everyone is aware that when anything catches fire, smoke is produced. When this smoke passes between a bulb and an LDR, the amount of light falling on the LDR decreases. This causes the resistance of LDR to increase and the voltage at pin 2 of IC 555 goes below 1/3 Vcc. thus triggering IC 555 which is used here in bistable mode. As a result the voltage of pin 3 goes high. This high voltage (approximately +9V) completes the supply to the COB (chip-on-board).

    Different COBs are available in the market to generate different sounds. However, one may select a COB which generates sound such as ‘aag lag gai hai’. The signal generated by COB is amplified by an audio amplifier. In this circuit, the audio power amplifier is wired around IC2 TDA 2002.

    The sensitivity of the circuit depends on the distance between bulb and LDR as well as setting of preset VR1. Thus by placing the bulb and the LDR at appropriate distances, one may vary preset VR1 to get optimum sensitivity.

    Reset switch S1 is provided in the circuit to switch off the alarm after the fire has been noticed by the user.


     

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    Post Comment | 10 Comments



    hussain   1011 days ago

    what that cob
    Reply   2 Replies
    arun   750 days ago

    what is IC TDA 2002 ?
    Reply  
    saniya   1002 days ago

    COB is nothing bt the sound generating system
    Reply  
    raghav raghuwanshi   999 days ago

    what is the component of fire alarm ckt
    Reply  
    M.sai sowmya   865 days ago

    can you please send me full details about this project sirplease......
    Reply  
    venkat   842 days ago

    can u send me full details about this project to mail id
    Reply  
    vrushali raotale   836 days ago

    I want to m ake this project. send me the pcb layoutof the circuit.
    Reply   1 Reply
    nasir ayuba   525 days ago

    full requirement of projecs please ser
    Reply  
    plz send me ppt of fire alarm   667 days ago

    SEND ME PPT OF ALRM
    Reply  
    anirudh vyas   470 days ago

    if we remove cob and place short circuit does it will affect the circuit.
    Reply  

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