• Register
  • Login
  • Here is one simple circuit of a general-purpose white LED security light with Passive Infrared (PIR) Motion sensing mechanism. At the heart of the circuit is a PIR sensor module SB0061. SB0061 is a pyroelectric sensor module which developed for human body detection. A PIR detector combined with a fresnel lens are mounted on a compact size PCB together with an analog IC, SB0061, and limited components to form the module. High level (3.3V) output of variable width is provided.

    In this security light circuit, High level (3.3V) output from SB0061 is used to switch on six 5mm white straw hat LEDs through a solid-state switch realized using transistors T1 & T2. PIR sensor modules usually have a 3-pin connection: Vcc (+) , Output, and Ground (-) . The pinout may vary, so it is recommend to check the manufacturer’s datasheet to confirm the pins. Besides PIR sensor module also has a 3-pin jumper selection for single or continuous trigger output mode.

    The two positions have labels H and L. When the jumper is at H position, the output remains high when the sensor is re-triggered repeatedly. In position L, the output goes high and low every time the sensor is triggered. So a continuous motion will give repeated high/low pulses in this mode.

    The PIR LED light security circuit can be powered from a compact 9V rechargeable battery. Note that the battery charger circuit is not included with the circuit schematic. You can use any suitable external 9V battery charger to re-charge the battery pack.

    PIR LED Security Light Circuit Schematic

    PIR LED security light circuit schematic


    • The PIR sensor requires an initial stabilization time of about 10 to 60 seconds in order to function properly. During this time, the sensor gets familiar with the surrounding environment, and any motion in its field of view should be avoided.
    • As stated above, the PIR Module needs a “warmup” period of about 10 to 60 seconds, during which time it’s adapting to ambient conditions and may trigger randomly. So anyone using this simple circuit needs to be prepared to accept random triggering for a while after startup.
    • Due to the high sensitivity of PIR sensor device, it is not recommended to use the module in the following or similar condition:
      • in rapid environmental changes
      • in strong shock or vibration
      • in a place where there are obstructing material (eg. glass) through which IR cannot pass within detection area.
      • exposed to direct sun light
      • exposed to direct wind from a heater or air condition
    • A 9V /250mAh NI-MH Rechargeable battery is used to test the prototype. If possible, try to use a 9V type with higher current capacity.
    • Value of R3-R4-R5 is optimised for the white LEDs used in the prototype. This needs a “re-touch”, based on the type of white LEDs used in your circuit.
    subscribe to newsletter

    12 Responses to "LED Security Light with PIR Motion Sensor"

    1. Here, in this circuit, T1 is acting as a switch to turn on T2. Although the prototype is working well, use of a base current limiter resistor for T2 is recommended.

      For this, just remove the interconnection between the “base of T2+lower end of R2″ junction and collector of T1. Then add a resistor in that place . Try to make this resistor near 1/10 times the value of R2.

      (“Base of T2+lower end of R2″ junction -> New Base current limiter resistor <- Collector of T1)

      This will improve the overall circuit performance, and helps to reduce the total current consumption.

    2. Bhavin_cp says: on March 9, 2013 at 11:42 am


      I have project regarding Human Detection.

      Can you help me to find the solution regarding Human Detection without motion using this or another circuit.

    3. Human detection without motion is a complex task! I regret, I am unable to offer a solution in a ready-to-use circuit form, now. You can refer this document to fetch some ideas http://vision.caltech.edu/~dmoore/dmoore-final-thesis.pdf

      • tiger_rajas tiger_rajas says: on March 10, 2013 at 4:19 pm

        is there possible to connect this circuit in 230v for detecting the human motion and to switch on the tube light?

      • The only way I know is to set up the PIR module so that it scans the area via physically via turning the sensor back and forth–this can be done via a cam actuated method or stepper motor, etc. The results must then be compared with a non-human presence reference level. Note that anything hot (or cold) in the area will provide a signature–this includes turning on a light bulb or heater–hot or cold spots can be physically masked so the sensor cannot see them. Difficult at best.

        A microcontroller could keep the reference level vs angle of rotation in memory in order to increase sensitivity and reliability. It could have two modes of operation in which it both scans and stops between scans to observe moving bodies etc.

    4. Bhavin_cp says: on March 15, 2013 at 9:30 am

      Thank you very much for your support. I have read the document which you have suggested to me. I want to detect the human sitting at one place or working with computer.

      My project is regarding detecting the human which are working on computer. Can any sensor or ready circuit detect the person in this condition???

      Can any combination circuit with PIR or any sensor with PIR detect the sitting and non movable humans??

    5. You may be able to sense body temperature with one of these IR Sensors:


      not cheap…

      • Bhavin_cp says: on April 27, 2013 at 12:50 pm

        As mentioned earlier, I want to detect human body in specific area or location. Human may be stable of with motion. Both should be detected. Please suggest some combination or idea to do that. For Example : I want to detect human working on computer, if he is sleeping or working its not our issue. Please help me to find out this.
        Specially thanks to T.K.Hareendran and Jim Keith.

      • Bhavin I have read your need and the only way that I can think of is to get a pressure mat that you put under the feet or chair of the person that you want to detect These mats are available as far as I know at firms that specialize in alarm installations

      • Mahmood ul haq says: on April 23, 2014 at 4:02 pm

        Sir i also want to measure the distance of body, which is detected by sensor

    6. can we use a battery greater than that of 9V,
      due to load of 6 LED’s ,LED’s are glowing dim , and can u tell me the range(in metres) in which it is applicable .

    7. I’m doing a project which uses PIR motion detector for detecting theft of solar panels on the roof of the building.Buzzer is the output for alerting the presence of thiefs.So please how can I under go in data analysis?I wellcom your consultation!

    What do you think about this article? Leave a comment!

    You may add a picture too