smoke detector circuit using ldr


Posted on Feb 6, 2014

When there is no smoke the light from the bulb will be directly falling on the LDR. The LDR resistance will be low and so the voltage across it (below. 6V). The transistor will be OFF and nothing happens. When there is sufficient smoke to mask the light from falling on LDR, the LDR resistance increases and so do the voltage across it. Now the transis


smoke detector circuit using ldr
Click here to download the full size of the above Circuit.

tor will switch to ON. This gives power to the IC1 and it outputs 5V. This powers the tone generator IC2 to play a music. This music will be amplified by IC3 to drive the speaker.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Subwoofer Low pass filter
    Regulator Combination Circuits
    High Voltage power Supply
    Zener tester
    MHz FREQUENCY COUNTER
    555 Simple circuit diagram of the timing of time
    Simple quality-oriented PA 02
    Motor Speed and Speed protection circuit of small hydropower stations



    Top