dark detector led ldr


Posted on Feb 5, 2014

Here is a project of a simple dark detector LED circuit. In the previous topic we have discussed a light activated LED circuit. By simply changing the positions of the resistors and LDR we have converted the circuit in a dark detector LED or dark activated LED circuit. The circuit will light up an LED when it will detect no light. An LDR (Photores


dark detector led ldr
Click here to download the full size of the above Circuit.

istor) is used in this circuit for sensing the light and dark conditions, and transistor 2N2222 is working as a switch. When the LDR will detect no light it will open the transistor 2N2222 due to which the LED will light up. The 50K variable resistor (VR) is used to adjust the desired light condition on which the LED will light up and 1K resistor is used to protect the LDR from direct connecting to the supply when the 50K variable resistor is on zero. The 330 ohms resistor is used to provide the required current to the LED. The circuit can be operated with four 1. 5V batteries of any size.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    500kHz to 4 MHz Converter
    Sequential timer
    Clock Input Frequency Divider
    Sound Effects Generator Circuit
    File Alarm with LDR Sensor
    Photodiode Alarm
    doorknob alarm pcb
    Car alarm circuit
    The Audionics CC-2 Amplifier
    How To Build A Keypad-Operated Door-Lock Release
    Digital DC Millivoltmeter



    Top