Automatic Staircase Lights using PIR Sensor and Relay


ByJayant 74

Automatic Room Lights using PIR Sensor and Relay

This automatic staircase light circuit switch on the staircase lights automatically when someone enters on the stairs and gets off after some time. There are two important components in this circuit, first is PIR Sensor (Passive Infrared Sensor) and second is Relay.


PIR Sensor

PIR sensor is used here to detect the Human body movement, whenever there is any body movement the voltage at output pin changes. Basically it detects the Change in Heat, and produce output whenever such detection occurs. You can learn more about PIR sensor here, there are some useful features in PIR sensor like how to change the distance range, how to set the duration for which the light should be ON etc.

Also check: Automatic Staircase light using AVR Microcontroller



Relay is an electromagnetic switch, which is controlled by small current, and used to switch ON and OFF relatively much larger current. Means by applying small current we can switch ON the relay which allow much larger current to flow. Relay is the good example of controlling the AC (alternate current) devices, using a much smaller DC current.  Commonly used Relay is Single Pole Double Throw (SPDT) Relay, it has five terminals as below:

SPDT Relay Working

When there is no voltage applied to the coil, COM (common) is connected to NC (normally closed contact). When there is some voltage applied to the coil, the electromagnetic field produced. Which attract the Armature (lever connected to spring), and COM and NO (normally open contact) gets connected, which allow larger current to flow. Relays are available in many ratings, here we used 6V operating voltage relay, which allow 7A-250VAC current to flow.


Relay is configured by using a small Driver circuit which consist a Transistor, Diode and a resistor. Transistor is used to amplify the current so that full current (from the DC source – 9v battery) can flow through coil to fully energies it. Resistor is used to provide biasing to transistor. And Diode is used to prevent reverse current flow, when the transistor is switched OFF. Every Inductor coil produces equal and opposite EMF when switched OFF suddenly, this may cause permanent damage to components, so Diode must be used to prevent reverse current. A Relay module is easily available in the market with all its Driver circuit on the board or you can create it by using above components. Here we have used 6V Relay module.

Relay Module


Circuit Explanation

Circuit Diagram for Automatic Room Lights using PIR Sensor and Relay

This automatic staircase light circuit can be easily explained. Whenever PIR sensor detects any body movement, its OUTPUT pin becomes HIGH, which applies the triggering voltage to the base of the transistor, transistor get  ON, and current started flowing through the coil. Coil in Relay gets energies and create electromagnetic field, which attracts the lever and COM and NO get connected. This allows a much larger current (220v AC) to flow, which turns ON the BULB. You can increase or decrease the Bulb ON duration by setting up PIR sensor.


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  • agentX44's picture
    Aug 17, 2015

    do you have any tutorial for this project from the start ?Sorry I'm beginner. Thanks in advance

  • VEERESH's picture
    Mar 16, 2016

    sir,may i know what kind of bulb u have used is it led bulb or regular zero watt bulb.
    What happens if i use a zero watt bulb ?
    Sir, I kindly request u to send me the clear picture of the connection because i am not understanding the PIR and the relay module connection from the above picture...THANK YOU..

  • Jayant's picture
    Mar 28, 2016

    Yes, you can use zero watt bulb. You can use any AC mains home appliances. Circuit diagram is already very clear, further you can check its Image at the top and Video at the end.

  • Bala Murugan's picture
    Bala Murugan
    Mar 30, 2017

    Ya you can use any kind of bulb for this project.Because you are using a 220v supply to the relay so no problem

  • NITYA $'s picture
    NITYA $
    Mar 25, 2016

    Hey, I like this project but
    what type of relay module u r using ,
    And if we use it in real it will work, or it will fuse after using for days
    Please reply,

  • Jayant's picture
    Mar 28, 2016

    This is a simple Relay module, if you dont have it, you can use simple Relay with resistors and diode, as shown in Circuit Diagram. Yes, it can work for long time.

  • NITYA $'s picture
    NITYA $
    Mar 25, 2016

    Can we use 5 v of relay module?

  • parveen's picture
    Apr 17, 2016

    can i use 12v relay ?

  • MrTiger's picture
    Apr 17, 2016

    Great content! I'm new to this world of electronics so I hope my questions are not too annoying. This circuit scares me a bit because I'm used to working with 9v, 6v, and less. This circuit diagram shows to hook up a 220v ac in series with a 9v dc battery. Clearly I am not understanding this correctly. Please advise what I need to read to correct my understanding.

  • Maddy's picture
    Apr 18, 2016

    No, its not in series, please look carefully. Wires joints are represented by Dots. Please be extra careful while working with AC mains, it can be lethal.

  • AlexG's picture
    Apr 18, 2016

    @Mr Tiger - you are mistaking the intersection points of the line going from B1 to VCC are connected to the 220v.
    There's no easy way to draw it where the lines cross. As a check, if you imagine that the B1 to VCC line was removed, you can clearly see the DC side is separate fron the AC side.

  • MrTiger's picture
    Apr 23, 2016

    Ok, ya I see this now. Thank you.

  • MrTiger's picture
    Apr 23, 2016

    I made this circuit this morning using components I already own. It was pretty cool to see it work. Thank you for sharing. For the sensor, and circuit I used 5.12 dc v(atm, my only steady power supply), and for the light source I used (9v battery, 330 Ohm, LED) because I fear an early death.

  • Tom's picture
    Apr 24, 2016

    Where did you purchase the relay module?

  • MrTiger's picture
    Apr 25, 2016

    I got the relay module from an Arduino starter kit by Seeed Studio. TIANBO HJR 4102E

  • Awes's picture
    May 20, 2016

    will this project work if we use 6v relay,instead of 12v

  • Naved Alam's picture
    Naved Alam
    Jun 04, 2016

    Can we use this for office light in retriggering mode,if person is in its area would it continue working or switch it On/off continuously?

  • Maddy's picture
    Jun 11, 2016

    Yes, it can be used in Re-triggering mode to keep the Light ON, until some movement is there. Check this to learn more about  PIR sensor.

  • arief's picture
    Jun 14, 2016

    may i ask this one using coding or not? like arduino or PLC ?

  • Abhishek's picture
    Jul 09, 2016

    No coding, it is just a simple circuit without any micro controller.

  • Sharojalhasan's picture
    Jun 18, 2016

    i have made this And Not Working :( please Anyone Help me

  • Kishore Relangi's picture
    Kishore Relangi
    Jun 26, 2016


    Is it possible to add more delay to this ?

    Because it will look very odd to switch the lights immediately.


  • Abhishek's picture
    Jul 09, 2016

    Then you need to use Microcontroller to add some delay after PIR detect any motion.

  • Jony Hossain's picture
    Jony Hossain
    Sep 07, 2016

    I want to build a transformerless power suply.Please help me and some suggestion

  • S.M. Bakhtiar's picture
    S.M. Bakhtiar
    Sep 08, 2016

    Dear Concern,
    I am working your project. which you have show is very much interesting. But my question is when one object is detected the how can i set long time as long as the object is present of that room then when the object is not in room then sensor will stop the supply.
    Thank in advanced

  • Deepti's picture
    Apr 15, 2017

    hi. how did u make it glow as long as there is a person and switch off when the person goes out of the room?
    Please send me the circuit diagram and the working.

  • S.M. Bakhtiar's picture
    S.M. Bakhtiar
    Sep 14, 2016

    Dear Concern,

    I have got the delay answer what i mention in my previous post.

    Now my question is , how do i connect LDR with the above circuit so that when there is dark on the room the light glow.

    Thanks in advanced

  • Aazan's picture
    Sep 19, 2016

    hi i dont know why but my project is not working i tried my best
    i saw all the connection
    i just did not put the relay module because i was not able to find it so i made the circuit as it was made in the digram still it does not work my light gets on but does not get closed wat do you thing wat will be the problem plz let me know plz help me sir plz and reply me as soon as possible plz some one help me i need help

  • Nazeer's picture
    Nov 18, 2016

    I purchased PIR Motion Sensor switch to fix in a room containing 9 small lights each 6 watt. So total load comes 54 watt. Motion switch indicates that it works up to maximum 1000 Watt. Please let me know if one switch will be enough to work for all nine lights. Moreover can we fix on/off switches to control individually.

  • Maddy's picture
    Dec 10, 2016

    yes you can trigger many devices with one PIR, and power depends upon relay's rating. To control individual lights, use some microcontroller.

  • shahid's picture
    Oct 10, 2016

    You don't mention R 2 on circuit diagram and also not to mention green colour tuning at your circuit diagram but I have see clearly those item (R2&green colour tuning) soldering at your Relay module and you have to use Relay module to complete your project not to flow your mention circuit diagram so please clear my confusing since I'm not a professional electronic person or stodent.

  • nassir's picture
    Oct 10, 2016

    instead of 6V Relay which one can I use?
    Please help me

  • Gokul MR's picture
    Gokul MR
    Jan 22, 2017

    does this circuit keeps the light 'ON' whenever there is a human presence at its range? or does it turns off after some time?? I've made a motion detector which turns of after some time (obviously!). also, i want to use a PIR based circuit for automatic light for my room. by that, when ever i enter my room, the light should turn on automatically and it will be on till i leave my room. so can i use this circuit for the same?? please advice. thanks in advance. :)

  • Ignis's picture
    Jan 26, 2017

    Starter here, i wanna ask how long does the bulb will lit up after a movement. Or it will turn off immediately if there's no more movement. Thank you in advance.

  • ujwal chavhan's picture
    ujwal chavhan
    Feb 04, 2017

    i make as all connection as per given above circuit diagram but my project not work properly . The light is continiously blow

  • noah's picture
    Feb 11, 2017

    I couldnt find 6v relay. what can I integrate 12 v relay into the circuit

  • Furqan Ali's picture
    Furqan Ali
    Mar 09, 2017

    This circuit incomplete because not show R 2 on circuit diagram

  • moses's picture
    Mar 17, 2017

    i can't find PIR sensor how can i have it

  • opare's picture
    Mar 21, 2017

    can i use tsop1738 sensor to replace ur own and use a tv remote

  • Deepti's picture
    Apr 14, 2017

    Hello Sir/Madam,
    I really liked the project. My professor asked me a question: Why are u using relays when transistors are much faster and long lasting? Relays are also electromagnetic sensitive.
    I could not answer this question. I am definitely missing something. Please clarify my question.


  • Deepti's picture
    Apr 15, 2017

    does the light remain on 'as long as' the person is there or does it switch off after a 'certain time' on its 'own'?

  • vural's picture
    May 06, 2017

    So helpful...

  • Manish 's picture
    May 13, 2017

    I wacth the video, in this video the light should automatically OFF after some seconds , when i used this CKT. In bathroom my the CKT. Dectet the motion and its ON (so, it will OFF in some seconds or it should ON till where should i was in bathroom ? ).

  • Abhishek's picture
    Jul 06, 2017

    In this circuit, light will remain On if there is continuous motion, otherwise it will switch off after some duration. you can control this duration,  You can learn more about PIR sensor here,

  • Dharm patel's picture
    Dharm patel
    Jun 29, 2017

    Dear sir ,
    I done this project as per diagram (as without relay module ,i connect relay switch)but my relay switch is countinuslly switching so plz solve it

    Thank u.

  • NEEL SHAH's picture
    Aug 04, 2017

    PLS SEND THE PCB LAYOUT ............
    I WANT PCB LAYOUT OF Automatic Staircase Lights using PIR Sensor and Relay

  • Dave's picture
    Aug 22, 2017

    Was very helpful

  • Ayan samanta's picture
    Ayan samanta
    Sep 06, 2017

    sir , please tell me that can i use 5or 12v relay for ths project?

  • Haziq's picture
    Sep 08, 2017

    Sir, i already follow the circuit diagram but my pir sensor does not working. Please I need your help.

  • Saran's picture
    Sep 27, 2017

    I am using a 5v relay module with red and green lights both are always on when I connect the battery. When I connect the light its on always and no effect from sensor. i tried keeping the sensor range to high and time to lowest nothing is happening. Please help.

  • Saran's picture
    Sep 28, 2017

    The 5v relay module does not have a transistor (BC547) or the 1k resistor as in the picture. Hence connected them separately as per the circuit diagram and now its
    working absolutely perfect.

  • kaushik patel's picture
    kaushik patel
    Oct 08, 2017

    When we enter in room at this time if room have all ready light then our circuit is not run but if it has darkness in room and we enter at this time room light is we connect LDR but in which place in circuit we connect LDR ??????

  • Aswinth Raj's picture
    Aswinth Raj
    Oct 09, 2017

    You have to use an LRR along with a voltage comparator. The circuit will need major modifications.

  • Finan's picture
    Oct 10, 2017

    Its not working properly how to connect the relay
    in the circuit

  • Dayaram Gora's picture
    Dayaram Gora
    Oct 13, 2017

    hi, i made connection according to you circuit diagram, but my relay is not turning on. when i connect led at place of realy then it work well . i tested all voltage by using DMM. when i connect led then Pir giver 3.5v or when i connect relay then pir sensor give 0.7v . due to 0.7v transistor not turning on. can you tell me where i am doing wrong or which is my part is not working.?
    thanks in advance.

  • Tufan's picture
    Dec 15, 2017

    I want to use it in my washroom. is it possible to raise its time limit when it activated with any motion and that put off.
    if any washroom controlling ckt available. pls send me via my email ID.

  • AISHA's picture
    Dec 19, 2017

    Yes you can use it. The time limit can be adjusted by just varying the potentiometer (yellow color) which is on the PIR sensor 

  • Suraj Potekar's picture
    Suraj Potekar
    Jan 15, 2018

    Want this project to implement at my college labs. Will it work ? It should be durable and reliable.
    Also I am confused first where to start from. Please guide me.

  • AISHA's picture
    Jan 15, 2018

    Start with something only then you will know where you have to be guided.. You can use the internet always

  • AISHA's picture
    Jan 15, 2018

    Also this is a very simeple circuit. You can easily get it done. So fear not and give it a try 

  • skufful's picture
    Jan 28, 2018

    I am working on a project that would require the use of multiple infrared detectors. I would like to use 4 + mini detectors. I would like each detector to have a maximum range less than 4 inches, and a rather narrow sensing range. I do not understand what the three legs do on a detector do, I assume positive, negative, and output? Some say the output drops off, some have high output? I just want to have a number of sensors that when any one of them detects a warm blooded animal within a few inch proximity (almost contact) to send a signal to a switch which closes it so that the normally open switch closes allow the power to flow like the light bulb (for a set time, 1 second or so) so the next function will occur. I am sure this is out there somewhere but I am not studied at all in this type of circuitry. Any help appreciated.

  • Amey's picture
    Aug 14, 2018

    Sir can we hold the output of our motion sensor?

  • Sanjay jhaveri's picture
    Sanjay jhaveri
    Aug 16, 2018

    Staircases light automatically if ready made its ok or please give PCB and components give the rate

  • Innocent's picture
    Sep 01, 2018

    Please, can i modify the circuit diagram by replacing the 9V to etA bridge rectifier and adding L7805 at the output before the resistor. Hope it will still work normally? 

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