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    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.

    ask a question

    20 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. Sir,

      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 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. 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??

      • Bhavin_cp, The simple way to detect a person sitting (in front of a computer or not) would be to install a pressure switch in the padding of the chair. Alternately, you could aim a lazer (with companion receiver)at the location which would then have it’s beam broken when someone interrupted the beam. You could also get a very cheap keychain camera and wire it as a monitor of the specific location for both recording and/or motion detection downstream via software but that is usually for accomplishing a lot more complicated goals. If you just wanted to detect if someone has used the computer, again, a keychain camera could be wired to turn on when someone turns on the power switch of the targeted computer. You could even wire a throw away cell phone to predial a number when activity of your choice triggers a event. The solutions are many!!!

    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

      • Mahmood ul haq, to measure the distance that a body is from a given location, use a simple sonar circuit (available in kit or ready to use form). This circuit should produce a readout that gives you the info you need. If it is to be unattended then you will probably still need a simple pir sensor to activate the sonar. Also, if the sonar reading is unattended, you would need a simple processor like a Arduino to store the info and/or take some type of action when the reading matches a preset threshold, Actions like logging the reading along with a date/time stamp and/or taking a picture, again using a cheap keychain camera. It could even activate a infrared light to eluminate the detected target for night time photo shots.

      • shahrum ali says: on December 2, 2014 at 8:23 am

        what did you do bro!.i want the same as u wanted once

    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!

      • Daniel, if you need to protect solar panels from theft, there are any number of directions you could go depending on finances. The cheapest would be a simple set of mechanical contacts with a insulator in between them. By putting current through the circuit, when the insulator was disturbed by movement, the buzzer or alarm connected in series would activate. You could even go with a capacitance circuit that would detect when a person laid a hand on the solar cell. Another thing that could be done is to wire a extra lead into the power circuit that when it is unplugged or cut, would detect loss of power then set off a alarm and/or dial a given cell# using a cheap throw away cell phone. Also see my suggestions I gave to “behavin_cp” on September 28, 2014 at 7:53 pm where I talk about use of cheap keychain camera to take pictures.

    8. want to ask ho to calibrate the detection intensity of pir with the distance.tell me that if the above circuit is feasible on bread board ,i mean i made it on arduino. Hurry up final date is approaching

    9. sir, I would like to use the pir sensor in making an automatic model for a classroom, but for that I need the pir to remain on as long as a student is in its range and if he goes out of it, the pir should turn off. can you plz suggest how i can do this?

    10. Sir,
      I make complete project with help of your circular.
      Here is one problem with his project, when we switch on the unit light on and it for some time it is automatically light off it’ll motion is not detected (it is characteristics of this circuit) but here light not off it is work as lighting automatically go dimm and as in this position till motion not detecte, when motion detected light automatically dark and after motion not detected it lighting goes dimm and in this position till not switch off the device.

      Please suggest solution of it.

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