motion sensor

Automatic Room Light And Security Alarm circuit Using PIR Motion Sensor

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PIR Motion sensor Alarm circuit

Automatic Wash Room Light using PIR Motion Detector and Automatic Light Security Alarm Circuit using PIR Sensor.

In This Circuit PIR (Passive infrared ) Motion Sensor Is used which is used as a motion Detector. When Any Person, Animal Or Any Object Comes In The Range of the sensor. then Automatic Light Switched on. This Can Also used in Automatic Room Light, When Any Person Enter in The Room Then Light Automatic Turn on.


pir motion sensor circuit for human detection and lighting


• PIR Sensor is high sensitive With Any Motion/Movement of Anything Around This Range.

Use 9v DC to operate this circuit But Make sure that Sensor is Required only 5v dc so use a 5v voltage regulator LM7805.

• The Vcc pin of Sensor Is Connected with 5v Dc, Ground Pin Is connected With Negative DC Supply And Output Of Sensor Is Connected With  BASE Of NPN Transistor (Here BC547 Is used).

• Use a 9v Relay For connecting any Light And Make the Circuit As Relay Get supply 9v And Rest Part of Circuit Get 5v.

• If There is No Any Movement Or Motion Occur, Then Sensor Give LOW output And Transistor Is Turned Off Because There is No Any Input Of BASE terminal. When any Motion/Movement Occur, Then It Detects by Sensor And Its Output Is High. Because The Output Is HIGH, The Transistor Gets High input at the BASE and it Turns ON and Relay is activated. As Relay is activated the Light connected with this will Switched ON.

• The Output Of Sensor Is Automatic LOW After a Time Duration Set By User. So the Alarm Or Light Which Is connected is Automatically Switched Of After Some Time.

• If You Want To Use Only Alarm, Then No need to Relay And Alarm is Directly Connected With Collector Of transistor And Power Supply. But That time uses only 5v directly, no need to use any regulator.

• This Circuit of Security Alarm Using the PIR sensor is Also Works At Night in Dark. So This is very useful for Security   Alarm And Security Light Uses. 

Sensor is covered with Special Plastic Lensed For Detecting Maximum Range of area. It has 2 preset, one is Adjustment of Sensitivity of its and second is The Adjustment Of Time Delay Which Remain High at Output For A Duration.

There are may Different PIR Sensor Module From Fig Given in the image in Looking and circuit structure. But Working Mechanism is the Same For All.

Note – At Starting When Switch ON the Circuit , PIR Sensor Can Take 10-15 second Time To Adjustment of Stability And Then Starts Working Properly. So Wait For Some Moment When Circuit ON.

Demo Video


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 pir sensorPir Sensor

Related image

BC547 pin

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