This project is a DIY Smart Light Adapter – which aims to build a smart light bulb based on your ordinary light bulb (which can be a CFL or an LED lamp) and a PIR sensor. The final output will be a light bulb that turns ON based on motion around a particular area within the range of PIR sensor attached to the ordinary light bulb. So lets begin!

DIY Motion Detector LIght
DIY Motion Sensor Light

If you are not willing to re-wire your home for smart lighting or not interested in spending a huge amount of money for the smart lighting system, then this DIY project is for you.

This simple adapter converts normal bulb into a smart Bulb, with the help of a PIR sensor. The mounting of the sensor is done in such a way that the angular position of the sensor can be adjusted, so that, the original position of the batten holder does not affect the sensing of human passage. This is achieved by using a 3.5 mm stereo jack and its socket. However, this type of mounting is up to your will and wish. It’s possible to wire directly without any mounting.

1Batten holder AdapterUniversal1
2AC/DC Adapter/SMPSO/P:12V DC,1Amp1
3RelayCoil:12V DC,Load >=1Amp1
4TransistorBC 547/BC5481
5Resistor1K Ohm1
6Diode1N 40071
73.5 mm Stereo jack connector pair---1
8PIR sensor3.3 to 20V DC input1
9General purpose PCB2” X 1”1
10Plastic Enclosure2-Way Switch box/Similar (3”X2.5”X1.5” Aprox.)1
11Plastic enclosure for PIR sensorold jewellery box/Similar (2”X1.5”X1.5” )Approx1
12LED Light sheet/Module12V As required

PIR Sensor:

This is a motion detector, which detects movement of human beings and triggers its output to High state. It operates in two modes. The mode is selected by the jumper provided on the rear side of the sensor PCB. If sensor with input voltage capability of 12V is not in your reach, use LM 7805 regulator for sensor part.

Normal Mode: When the sensor detects motion, it sets output to High until  set time and re-sets output to Low, independent of the movements during the output HIGH time. This is One-time triggering mode.

Re-Triggering Mode: When the sensor detects motion, it sets the output to High until a set time and resets the output to Low, but if it detects motion during its output High state, it again triggers the timer making it to count from zero.

Note 1: Read our tutorial on Interfacing PIR Sensor to Arduino to learn more about PIR Sensor.

Note 2: For more information, download data sheet of PIR sensor:

Fixing the adapter:

  •  Open the Batten adapter and measure the diameter of the threaded portion.

Snap 2

  • On the bottom of the enclosure, draw a square whose length of a side is equal to the diameter measured.
  • Limit the corner parts of the square and cut away to insert the adapter.
  • Placement should be decided as per the space available in the enclosure after placing the AC/DC  adapter.

Snap 3

  • The adapter must be placed in such a way that the contact pins should be in parallel with the wall of the enclosure. Use instant sticking glue to fix it (if necessary)

Snap 4

  • The LED sheet used here comes with double sided sticking tape.
  • Stick the module on the top ..that is on the top cover of the switch box.
  • Make sure that the holes for screwing are not covered and make a hole on one of the side walls of the box to insert LED input terminals.
  • Number of LEDs can be varied as per requirement, limiting the current drawn up to 1Amp.
  • The type of LED sheet is up to the user, but the voltage should be 12V.

Snap 5

Fixing the  3.5 mm stereo socket:

  • Make a hole on the side wall of the enclosure, round enough to insert the socket.
  • Screw the socket.

Snap 6

Mounting the sensor:

  • Measure the diameter of the Fresnel lens part (white color part).
  • Similar to the adapter, cut away the enclosure chosen for the sensor.
  • Place the sensor from the inside of the enclosure in such a way that the lens comes out of the enclosure.

Snap 7

  • Make a hole sufficient to insert the 3.5 mm jack and insert the jack before soldering the wires.

Snap 8

Circuit Diagram

Motion Detector Light - Circuit
Motion Sensor Light – Circuit Diagram
  • Place the SMPS and relay PCB and stick them using glue stick/gun. Snap 10


  • Solder 3.5 mm jack to the sensor as per the diagram and screw the jack.

Snap 11

  • Wire-up the adapter and the holder.
  • Close the box with the cover to which the LED sheet is fixed.

DIY Motion Sensor Bulb

  • The sensor part can be rotated 360° continuously, as we have inserted the sensor part through a stereo jack.
  • This makes it possible to adjust the sensor according to the direction of human passage by modifying the existing holder.


  1. Why do we need to use Relay 12v to turn on 12 V LED?
    Can we just move LED replace LED 12V?

    • Narasimha

      The LED module used in the circuit requires a minimum of 12V.
      If it is turned ON with a transistor or a MOSFET, the Voltage applied to LED reduces due to the voltage drop across the switch.

  2. vilas khare

    I want this kit from you so please let me know can it be possible and also if possible please mentioned the cost which will be sent by courier .

    • Narasimha Rao

      Thanks for the comment…
      Replied to your g-mail.