Motion Sensing Light Circuit Diagram and Connection Procedure


What is Motion Sensing Light?


Motion sensing light is an inbuilt light with some sensing devices that turn off or turn on automatically, by the motion of any human or animal near to it. The motion-sensing light is used in homes, offices, canteen areas, auditoriums, and many more places. It is a very basic example of an automation system.

Here, in this article, we are going to see the internal circuit diagram of a motion-sensing light. This article is for electrical or electronic background people who want to know how a motion-sensing light works. For general, installation in your home or office you do not need to make this circuit because there are already compact devices available in the market. Anyway, let's see the circuit diagram.


Motion Sensing Light Circuit Diagram


Here, you can see the circuit diagram of a motion-sensing lighting PIR Motion sensor.

Motion Sensing Light Circuit Diagram and Connection


List of components Used

  • A 9V DC SMPS or you can use a 9V DC adapter even you can make a 9V DC Power supply circuit using a transformer, diodes, and other components
  • A three-pin 5V PIR Motion Sensor Module
  • A 9V Relay that can switch 230V AC power
  • 1 Pcs IC 7805
  • 1 Pcs BC547 Transistor
  • 1 Pcs 1N4007 PN Junction Diode
  • 1 Pcs 1 Kiloohm Resistor
  • A 230V Light
  • 230V power source
If your country has other utility voltage such as 120V then take a 120V light and a 9V Relay that can switch 120V power supply. Also, your 9V DC power supply device(SMPS) should have an input voltage rating of 120V. Other all the components should be the same.


Connection Procedure


  1. Connect the 1N4007 Diode in the reverse bias with the relay coil.
  2. Connect the neutral terminal of the light directly to the neutral terminal of the power supply.
  3. Connect the phase terminal of the light to the common terminal of the relay and the NO terminal of the relay to the phase terminal of the power supply.
  4. Connect the positive terminal of the relay coil to the positive terminal of the 9V power supply.
  5. Connect the negative terminal of the relay to the collector terminal of the transistor BC547.
  6. Connect the input of the IC7805 to the 9V power supply and connect the output of the IC7805 to the power input terminal of the PIR motion sensor module.
  7. Now connect the output terminal of the Sensor module to the base terminal of the Transistor BC547 through a 1 Kilo ohm resistor.
  8. Connect the emitter terminal of the transistor BC547 to the negative terminal of the 9V power supply.


Operation and Working Principle


All the power supplies should be turned on at all times. When there is no motion or movement near the sensor, the output of the sensor will be low so the transistor also is in the off condition hence the relay coil will get not any power supply. So the light also is in the off condition. But when there is any movement of a human or animal near the sensor, the output of the sensor will be high so the transistor will be activated hence the relay coil will get the power supply and it changes its NO contact into NC contact so the light will be turned on.

Here, the IC 7805 is used to convert the 9V DC into 5V DC as the sensor module needs a 5V DC power supply.


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Motion Sensing Light Circuit Diagram and Connection Procedure Motion Sensing Light Circuit Diagram and Connection Procedure Reviewed by Author on 8:00 pm Rating: 5