Night security light

Description.

 Here is a simple circuit switches on a light around 2 hours after midnight, the time at which most of the robberies taking place.

This simple circuit is build around a CMOS IC 4060 to obtain the required timing. During day time the LDR has low resistance and keeps the pin 12 of the IC1 high, preventing the IC1 from oscillating. When it is dark the LDR resistance becomes high and the pin 12 of IC1 becomes low and the IC starts oscillating, which indicated by the flashing of LED D3.The values of the timing components R1, R2, C4 are so selected that the out put pin3 of IC1 goes high after 8 hours. That means the high output drives the triac to switch on the lamp around 2’O clock. At morning, the LDR resistance drops and the pin 12 of IC1 goes high and stops the oscillation, making the lamp OFF. The switch S1 can be used to manually ON the lamp. The capacitor C2 prevents false triggering.

Circuit diagram with Parts list.

night-security-light

Notes.

  •  Assemble the circuit on a good quality PCB or common board.
  • The LDR can be general purpose LDR.
  • The light sensitivity can be adjusted using the preset R6.
  • The IC1 must be mounted on an IC holder.
Show Comments

12 thoughts on “Night security light

  1. Manjunath

    Hi,
    Can you please tell me on what basis we need to select the values of R1, R2 and C4. Is there any formula. Kindly revert.

    Reply
  2. NANDHINI

    HELLO SIR,I AM A 2ND YEAR ECE STUDENT.. I WANT DO A MINI PROJECT IN SECURITY SYSTEM .PLEASE SUGGEST ME SOME IDEAS FOR DOING THE PROJECT

    Reply
  3. thana

    Hello Sir , can i get simple night alarm light.This is for my final year project.Include the block diagram and the procedure…plz reply?

    Reply
  4. ganesha

    sir… I’m doing this as my mini project please tell me how to decrease the time of operation with respect to R1 and R2

    Reply
  5. abner

    i am a third year computer engineering student.i currently have electronic and circuit subjects and to be able to pass these, we will be making a circuit project composed of at least 15 components. please give me the best and cheapest project. please reply!

    Reply

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