Street light circuit.

Description.

The circuit diagram present here is that of a street light that automatically switches ON when the night falls and turns OFF when the sun rises. In fact you can this circuit for implementing any type of automatic night light.

The circuit uses a Light Dependent Resistor (LDR) to sense the light .When there is light the resistance of LDR will be low. So the voltage drop across POT R2 will be high.This keeps the transistor Q1 ON. The collector of Q1(BC107) is coupled to base of Q2(SL100). So Q2 will be OFF and so do the relay. The bulb will remain OFF.

When night falls the resistance of LDR increases to make the voltage across the POT R2 to decrease below 0.6V. This makes transistor Q1 OFF which in turn makes Q2 ON. The relay will be energized and the bulb will glow.

Circuit diagram with Parts list.

street-light-circuit.JPG

Notes.

  • POT R2 can be used to adjust the sensitivity of the circuit.
  • You can use bulb of any wattage, provided that relay should have the sufficient rating.
  • The circuit can be powered from a regulated 9V DC power supply.
  • Click Here! to get the power supply circuit for this project.
  • The relay K1 can be a 9V SPDT relay.
Show Comments

210 thoughts on “Street light circuit.

  1. Bayo

    hello,
    is it not possible to have the circuit work with a 9v battery or possibly 12v cos I am just looking at the circuit to be independent of mains supply?? I want a Circuit that’s independent of mains, please say something about the request?

    Reply
  2. Gowtham. A

    Hi sir.
    I am a student of diploma in electricals and electronics 4th sem. i need the project related to human counting and fan and light control. please help me getting this project. It should include content sheet, circuit diagrams, introduction, brief explaination of parts, applications, advantages and disadvantages, final conclusion.

    Reply
  3. adeelsafdar

    sir i m a student of electrical engineering 6th semester;;;; i m interestd in that project; i want the circuit ,block diagram of that project as well as applications

    Reply
  4. adeelsafdar

    I AM STUDENT OF THE ELECTRICAL ENGINEERING. I NEED FULL INFORMATION ABOUT THE automatic STREET LIGHT CONTROLLER LIKE THE CIRCUIT DIAGRAM, BLOCK DIAGRAM ITS INTRODUCTION, APPLICATIONS,BLOCK DIAGRAM AND GIVE THE INTRODUCTION ABOUT ALL COMPONENTS.MUST INCLUDE THE APPLICATIONS OF THAT PROJECT

    Reply
  5. zohra amreen

    please send me the apparatus required, its specifications, principle used along with all the details exactly in the way the project must be written to my email I’d
    thanks for assistance

    Reply
  6. Kisho

    To make a working clap switch .Sir, i have no facilitys to watch videos on youtube, so can please send me the circute diagrame and the camponants with valus wanted to make the circute please sir. It is very urgent to me to make a exhibit to my school anual exhibition so please help me sir.Please

    Reply
  7. Kisho

    Sir, i have no facilitys to watch videos on youtube, so can please send me the circute diagrame and the camponants with valus wanted to make the circute please sir. It is very urgent to me to make a exhibit to my school anual exhibition so please help me sir.Please

    Reply
  8. Ramkisan kumawat

    I AM STUDENT OF THE POLYTECHNIC 6th SAM. electrical ENGINEERING. I NEED FULL INFORMATION ABOUT THE automatic STREET LIGHT CONTROLLER LIKE THE CKT DIAGRAM, BLOCK DIAGRAM ITS INTRODUCTION, APPLICATIONS,BLOCK DIAGRAM AND GIVE THE INTRODUCTION ABOUT ALL COMPONENTS.

    Reply
  9. Neha

    Can u plz give me the connection of spdt relay…
    Sir I am using 12V supply and 12 V spdt relay without modifying any components…is it ok..??

    Reply
    • Muzammmil

      madam there is five terminals of relay system. three terminal side is used for output, while the other in between two terminals of output is used as common. which is used to connect anyone terminal of input terminals.

      Reply
  10. srikanth

    hello sir , we are doing project on ip encryptors, in this when one encryptor gone bad, other one should come into the action that is the theam. so we are using relay circuitry for shifting the control signal when encryptor fails to boot,so to drive that control signal we are using driver ic, but we are in confusion, where to place that ic, wheater before the relay or after the relay. please send your reply to mail !!!!!!!!!!!!!!!!

    Reply
    • Surjeet

      hi
      can u give me info about the components needed in ths ckt and also the cost for each component i will be vry thankful to you.

      Reply
  11. sravan

    i want to efficient power saver for street lights using ldr,rtc,leds light with solar power ppt pdf send to(sravanpaka28@gmail.com)plz sir

    Reply
    • Seetharaman

      Here accuracy is not very important as the circuit is only a binary control if it measuring analog information and calculating then an opamp is a must. for this circuit approximate light intensity is used for changeover which can be set by trial and error by the pot.

      Reply
  12. Archana

    we want to use micro-controller in this circuit and also want to replace bulb by LED.So what will be the estimated cost of this project? and what modifications will be required?Plz reply fast…

    Reply
    • Seetharaman

      No need to make the circuit complicated by micro control etc. the circuit is very simple and fail safe with very few components. You can use the relay’s potential free contact to switch on anything

      Reply
      • Manirathnam

        sir, i am a college student. i just want to do this project. i had a doubt that how the voltage drop occurs with the LDR device. can you please explain it sir. by connecting what device the voltage drop may occurs. please reply me sir. and i need your mail id to contact you.. please….

        Reply
  13. felistus

    hi pliz may you email me the calculations involved in choosing size of resistors, capasitors and transistors. Im doing a school project on this topic. Your help will be greatly appreciated

    Reply
  14. Tridip Sarma

    SIR,
    i want to project report of the circuit… i want its working principle in details… like how transformer BC107 and SL100 works… why relay is used.. and it is also work in above 9v supply… if not then why we used like that… and i also want to components specifications in details… and also uses in practical field… and also advantage, disadvantage and conclusion…

    Reply
  15. Pradeep Kumar

    How to made solar led circuit mini project. what are neccessary equipment to made it and how & where we will get these equipment.

    Reply
  16. Gautam

    SIR,
    I am working on the project of automated street light controller using LDR.
    My project is almost done but i have to sumbit a project report on the same and there is very little information about this topic.
    Can u please help me with it.

    Reply
  17. Avinash reddy

    wow,its amaizing I have done this project by replacing that 230v ac supply with a battery of 9v and bulb with a LED.it is working thank you for your circuit.

    Reply
  18. X_PLICIT

    please sir could you mail me full description of the working of this circuit d the estimated costs of the various components…. i need enlightment…. thanks

    Reply
  19. Sahithya

    Sir,
    Please send me the full report of this project.
    We have chosen and started work on this project but we didnt get the output.
    We have to submit this project by 25th.
    So please send it as soon as possible.

    Reply
  20. sreeram

    sir,
    we are selecting mini projects for our 6th sem(BTECH).and it is also high time for deciding on our topic.hence we would be most obliged if you could
    mail me the approximate cost and availability of the components.
    plz attach the full report also,if available.

    Reply
    • arun

      please reply me alternatly using another transisters in thise circuits. becou’s thise are not available nearly in my village (above circuit added components works surly) i take thise project in my class
      please give for more inporamtion sir

      Reply
  21. Mallikarjun N Sidaraddi

    >sir why we use 9v battery in the circuit.
    althoug all the circuit is operating in AC main current,plz tell me breafely why we use battery in the circuit.
    >plz send full report plz sir.

    Reply
  22. theju

    sir please tell me that in which place is this “automatic street lighting controllers using ldr and relay” are using practically……

    Reply
  23. kavitha

    sir i need the circuit diagram in cadd format sir.. please help sir and give a detailed descpiption for this sir please.

    Reply
  24. Kavitha

    sir i need a full description about the circuit diagram sir please reply sir.. and i need the circuit diagram in cadd format sir please explain about this sir please.

    Reply
  25. agbesi moses

    HI FRIENDS I AM STUDENT OF THE LAST YEAR e.c.e. I NEED FULL INFORMATION ABOUT THE STREET LIGHT CONTROLLER LIKE THE CKT DIAGRAM, BLOKE DIAGRAM ITS INTRODUCTION, APPLICATION, BLOKE DIAGRAM

    Reply
  26. Seetharaman

    Hi you can use a 6 volt relay but not 12 volt relay, as the voltage across it will be around 8.4 volts may not produce sufficient magnetic pull for the relay contact to change over.

    Reply
  27. sagar

    sir i have made the same connections as above but instead of 9V relay,I used 12V relay n gave 9V dc battery as in figure but i m not getting output.wud 12V relay make any difference? shuld i change it to 9V relay to get output?

    Reply
  28. mehboobelahi

    sir why we use 9v battery in the circuit.
    althoug all the circuit is operating in AC main current,plz tell me breafely why we use battery in the circuit

    Reply
  29. rohin

    circuitstoday.com is giving so much circuit but people are not satisfy with them.they always want another circuits for their need.

    Reply
  30. JNANESHWARA.K

    sir,we want automatic street light controller by using timer and counter.we want controlling the street light as follows,day time-6.30a.m to 6 p.m-light off,6.30 p.m to 7.30 p.m-light glows alternately,7.30 p.m to 6 a.m-light on,6 a.m-7 a.m-light glows alternately.So please send related circuit diagram,we are waiting for your circuit diagram.

    Reply
  31. Aabha

    gm sir
    i am student of 7th sem.i want to made this project as MINOR PROJECT.so pls send full information like ckt diagram,block diagram,rating of elements and full description…..

    Reply
  32. Navatha Reddy

    thank you sir for giving this circuit after many attempts i got this.and i want detailed description of working of this circuit to my email sir.

    Reply
  33. Prithvi

    sir,I’m doing this project and my bulb is glowing only when the upper two terminals(2 contacts) are shorted.so plz help me get output sir..n plz anybody who got the output for this, plz hello me out guys. …

    Reply
  34. sanjay

    sir during rainy season salt formation will be there on ldr so that light will glow day time also. how can we avoid this problem?
    and how to arrange the circuit on the street light in all seasons? i want to test this by connecting it to a street light. plz give me answer sir..

    Reply
  35. Binny

    I want to make any intresting and easy project at my home during my summer vacations. Will you guys plz suggest me any gud1…
    I m now B.Tech 2rd year student in ECE stream….
    Plzzz guys hlp me….

    Reply
  36. harish

    Sir,
    Can u suggest any additional features that can be added to the circuit above? I’d be really grateful.

    Reply
  37. Priya

    Sir,
    Can u suggest any additional features that can be added to the circuit above? I’d be really grateful.

    Reply
  38. Johnsheen

    This circuit is working very well. I have connected it to a flickering Flash light. I have a Farm house where the wild Elephants are the uninvited guests. I am using Xenon flash light to threaten the Elephants as they are very bright and consume less power. Also I am going to connect a Audio system which will play during the nights creating a feeling of presence of people inside the house.

    Reply
  39. Seetharaman

    Hi Harish THE PROBLEM MAY BE WITH YOUR ldr. WHAT IS THE DARK AND DAYLIGHT VALUES OF THE LDR. You can use 220k or 470k instead of 100k if your LDR values are high. To check whether the electronics is OK. disconnect LDR and fix a 47K resistance. now turn the pot from one end to other, at one point of the pot, the change should occur(relay energising and de energising). if it is not happening your wiring is wrong may be c b e is wrongly connected or may be the transistors are defective. connect a diode 1N4007 in parallel with the relay such that diode anode is conncted to 9vlt positive bus to protect Q2.

    Reply
  40. k.anil varma

    I AM STUDENT OF THE LAST YEAR ELECTRONICS ENGINEERING. I NEED FULL INFORMATION ABOUT THE STREET LIGHT CONTROLLER LIKE THE CKT DIAGRAM, BLOCK DIAGRAM ITS INTRODUCTION, APPLICATIONS,BLOCK DIAGRAM AND GIVE THE INTRODUCTION ABOUT ALL COMPONENTS.

    Reply
  41. pank

    hello sir
    i want to apply the things which is wrote there…
    can you tell me the required items with specific details…
    and
    also approximate cost in making it…

    i will be very much thankful to you…
    for your help….

    Reply
  42. pank

    hello sir
    i want to apply the things which is wrote there…

    can you tell me the required items with specific details…
    and
    also approximate cost in making it…

    and more clear diagram concept…

    i will be very much thankful to you
    for your help….

    Reply
  43. Seetharaman

    Hi Jainson increase the supply voltage to 12 volt DC regulated one capable of atleast 300mA. you have to provide a black tube of 6 to 8″ in length on the LDR such that it looks at open sky without getting the rays from the nearby light sources. The circuit is quite reliable and it works nicely.

    Reply
  44. Jainson

    sir
    i made d project …..bt the relay dnt gets switched with change in intensity of light….i used 12v relay….plz help

    Reply
  45. Tete Erastus Focho

    very impressed sir, need material to start my work. thanks to your inspiration. hope in times to come i will really make good use of your infos

    best regards

    Reply
  46. seetharaman

    Hi Ram SPDT is singe pole double throw contact, nothing but a relay with a change over contact. (volt DC is the supply for the circuit to operate. It should have been shown as 9vols DC plus (+9volts) and negative to common shown as ground (emitter of Q1 & Q2).

    Reply
  47. seetharaman

    Hi Ishan you can use 2N2222, 2N2221, 8050, 2N1711, BC167, BC237, BC317 any NPN small signal transistor can be used.

    Reply
  48. Ishan

    Sir, It’s not possible to find BC 107 in my country. is there any other equivalent transistor for this BC 107 ? thanks

    Reply
  49. Taofik

    Infact how do we go about the movement detector circuit? what form of sensor can be best used? should it be sound or metal or what? pls it’s urgent.

    Reply
  50. Taofik

    Owing to your comment on August 13th, I would like you to please send a circuit that will give room for a movement detector in your circuit, such that during off peak periods say after 10pm, the illumination will be reduced or using the 50% idea as u’ve said, but whenever an obstacle gets nearer, it gives full illumination or 100%.

    my email add: tofman2020@yahoo.com
    Pls it’s urgent.

    Reply
  51. seetharaman

    Hi Luckydile 220uF will be a very large value delay will be larger, still you can try. if 4.7uF is available you can try.

    Reply
  52. Luckydile

    sir pls,i’ve got this topic as a project.now,the 10microfarad 12V capacitor u added to cut off transient responses is not available around here.pls tel me another capacitor that wil do the job or wil 220microfarad 16V capacitor do? Thank you sir.

    Reply
  53. Luckydile

    pls sir,i’ve got this topic as a project.now,the 10microfarad 12V capacitor u added to cut off transient responses is not available around here.pls tel me another capacitor that wil do the job or wil 220microfarad 16V capacitor do? Thanks so much.

    Reply
  54. OJHA GAURAV

    HAY FRIENDS I AM STUDENT OF THE LAST YEAR DIPLOMA ELECTRONICS ENGINEERING. I NEED FULL INFORMATION ABOUT THE STREET LIGHT CONTROLLER LIKE THE CKT DIAGRAM, BLOKE DIAGRAM ITS INTRODUCTION, APPLICATION, BLOKE DIAGRAM,AND GIVE THE INTRODUCTION ABOUT ALL COMPONENTS AND VARYFICATION ABOUT IN
    IT.

    Reply
  55. seetharaman

    Hi James you can connect 2nos hi bright white LEDs in series and a resistance of 47 ohms 1/4 watt also in series connect them in place of the relay shown, such that anode of LED is towards 9 volt +ve.

    Reply
  56. seetharaman

    Hi Kecik you can but the circuit will not work if you shout near microphone the relay at the most can chatter, that is all.

    Reply
  57. seetharaman

    Hi Nandita for traffic sensing you can use Doppler Shift sensing method or IR movement detector or any movement detector. To avoid special circuits for florescent light dimming, use two lights in each fitting you need switch off one for 50% illumination. for switching you can use SSR or standard mechanical relays. You use a dark detector during dusk switch on both the lights after 4 hours it will switch off one light and with movement detector it can come on. once no movement is detected it will again switch off. during dawn both will go off. This will work when suddenly it becomes dark even during day time due to dark clouds

    Reply
  58. Nandita

    Sir, Im a final year Btech student, and would like to do an extension of this project. ie..The streetlight is fully bright during the peak hours of traffic, say from 6pm to 10pm.After 10pm it automatically goes to a power saving mode with 50% brightness, and then when a vehicle or pedestrian approaches, it again goes to 100% brightness. Hoping for your valuable suggestions.

    Reply
  59. VG Krishna, Hyderabad

    Sir, I assembled the above circuit along with the additions suggested by Sri Seetharaman (May 14, 2011 above -to avoid chattering and transient response)and using the light in my courtyard and it is working excellent. Whenever we go out (by locking the house) we switch it on and by the time we return during night, the light automatically is on during dusk. Very good facility and security to the house. The circuit is simple and better than other circuits which use a Triac (I also assembled the same) wherein I find lot of flicker in the incandescent light during the transition period(day/night). I Thank Circuitstoday for giving the above circuit.

    Reply
  60. Seetharaman

    Hi Abhijan Pl refer my comment dated 28th April. Adjust R2 for you requirement. If you want small delay you can add a capacitor of 10 to 100uF between Q2 base and common ground. If you want to have a small difference in light level between switching on and off add a 100k resistance between Q2 collector and Q1 base.

    Reply
  61. Abhijan

    Hello sir. The circuit is really helpful. I had a doubt though. I have a 12V bulb and a DC supply from the battery of the vehicle itself. How can I modify this circuit so that I can use the LDR system to automatically switch on the light with decrease in Visible light!

    Reply
  62. Seetharaman

    Hi Edwardson you are right you can fix a 10uF 12 volt capacitor in parallel to R2 that will take care of transient response. This simple circuit itself is having enough hysteresis hence chattering will not be a problem. Still if you feel it is not sufficient can add around 1M resistance between Q2 collector and Q1 base.

    Reply
  63. Edwardson

    Correct me if I’m mistaken but this circuit seems to be prone to at least two conditions:

    1. “chattering” — when ambient light level is at or crossing the trip point, the relay/load can rapidly switch on and off, the reason being that there’s no hysteresis built into the circuit. For better performance the ambient light level at which the load is switched on will be slightly lower than the level at which it is switched off.

    2. abrupt, transient, and large changes in ambient light level will “fool” the circuit into switching the load on/off. Example: during the night, lightning and car head lamps might make the circuit turn off the load for the duration of the high ambient light level. So there’s a need for a low pass filter to make the circuit reject these transients. A simple RC network connected to the base of Q1 might be sufficient.

    Reply
  64. Mouly

    Dear Sir,i can only find 12v relay in my place.Can i use 12v relay?any changes should i make in the circuit.Waiting for reply

    Reply
  65. ifeanyi

    Hi
    i am a final year student,i was given a project on the design of a street light using a low energy LED i dont know how to get the circuit diagram and also the procedure to follow in actualising the project.plz if you can help me with the circuit diagram send it to my email i need it urgently thank you in anticipation.email address:-
    kings_ifeanyi@yahoo.com

    Reply
  66. Seetharaman

    Hi Rajashree + of nine volt is given to line indicated as 9V DC. – is given to the common shown as ground. BC 107 is a small signal NPN transistor in T018 casing. SL100 is a medium power medium current transistor in T05 casing. Since the relay used is 9volt the supply also should be minimum 9 volt to operate it.

    Reply
  67. Rajashree

    Please tell me how 9v dc supply is given? And about sl 100 and bc 107? Why it is used and their properties? Please give the calculations of 9v dc suply to the circuit.

    Reply
  68. Seetharaman

    Hi Deepanshu Q1 is sensing comparator and Q2 is relay driver.When the light is falling on LDR it resistance becomes low biasing Q1. it conducts the base bias available for Q2 through R3. Q2 stops conducting and the relay is switched off. once the light falling on LDR reduces its resistance increased reducing the bias for Q1 and stops conduction. since Q1 is not conducting the bias for Q2 is made available, the relay conducts and the light is switched on. The light sensitive level to operate the relay can be adjusted with preset R2.

    Reply
  69. deepanshu

    sir,i m a ist year student…i want to know wat is the need of transistors in the above circuit…if possible,please send me details about the working of these two transistors….w8ing 4 ur reply..
    thank you

    Reply
  70. Navas basheer

    hi,i am doing a project on this same topic with an extension that it has an automatic intensity control circuit. the brightness must be adjusted when any car or object passes the street light..waiting for your valuable suggestion :)

    Reply
  71. melkamu

    sir
    i need the connection diagram of led street light b/c i need it to done in my country b/c as my country is a developing country and we use high power consumption lamp and they have not longer life so please tell me how to done this.
    thank you

    Reply
  72. Balu Bhargav

    Sir can we design an intelligent street light controller which switches itself on when a vehicle is detected? and then switches off by itself after the vehicle passes away?

    Reply
  73. shaivya

    sir,
    i used ur ckt n developed a ckt of automatic car headlight dipper…
    thnx 4 uploading ur ckt….
    having minor viva tomorrow…
    will tell u how it went related 2 ur ckt…

    Reply
  74. ELDHOSE

    sir ,
    when a light falls on ldr its resistance increase and current increases then ldr has high resistance in the absence of light
    then how the street light works

    Reply
  75. Seetharaman

    Hi Vikas 230volt AC to 15 volts SMPS are available in the market at reasonable cost. you can buy that and use with LED circuit. (why you require 15volts for the LED ?). can you kindly elaborate your requirement

    Reply
  76. VIKAS KUMAR

    Sir i am polytechnic stud. plese give me complyt cicuit diagram and project report to street light to 230 volt ac and pass to 15 volt dc supply for led

    Reply
  77. Ramesh

    Sir, I am doing my diploma in industrial electrical, I have to make diagram using Contactor, RCD or MCB, Timer for automatic switch on, six 400 watt flood lights,

    Reply
  78. seetharaman

    Hi bu i am just back from my pilgrimage you can use 2N2218 2N2219 BD135, 2N1711 any medium power NPN T05 casing or T0220 casing transistor will do.

    Reply
  79. naufil

    respected sir can we make this project(microcontroller base street light control )?
    if yes than how to implement it?give some brief information about circuit diagram?
    i look forward for positive speedy reply.thanking you. sir it’s urgent.

    Reply
  80. Ivan

    Sir,

    Only 12v relay is available in our area so what modifications has to be done to make the circuit work with a 12v power supply.

    Thanks.

    Reply
  81. Yogi

    Sir, Thank you very much for this circuit. I am a first year BTEC student. I have a question regarding the nine volts voltage applied in the light-detecting bit of the system. It is: How does the street light in our roads actually access a 9v supply? Do they use a step-down transformer and rectifier? Thank you sir.

    Reply
  82. seetharaman

    Hi Sunita You can use the Dew sensitive switch appeared in this column in “Circuits Today”(which uses LM358 dual OP amp). You can modify the circuit and use. Instead of using dew sensor replace it with LDR. output you can use an opto-coupled triac to control the Street Lighting. If you have any doubt please contact.

    Reply
  83. sunita

    sir,i am the student of B Tech 2nd year, I gonna do a mini project of topic ‘Automatic Street Light Switching Device’. I am using an integrated circuit ICLM358. sir please design the circuit diagram using this IC.

    Reply
  84. Michael Garoso

    sir, thanks for the circuit, I have made a prototype of street light circuit for our project, and guess what? I got the highest grade in our class. thank you very much sir!

    Reply
  85. Yasin

    How can we get a 9v DC in street lighting system which is totally working in ac supply. Is there any method to generate 9v Dc from universal ac mains 110-230 Vac without any resistor losses and heating issues. kindly help me.

    Reply
      • mehboobelahi

        sir why we use 9v battery in the circuit.
        althoug all the circuit is operating in AC main current,plz tell me breafely why we use battery in the circuit.

        Reply
        • nakul

          respected sir
          my self nakul gaba , a student of ECE diploma 4th semester.
          i have selected this project for my minor project work and i successfully made it but the probelum is about project report ……..please kindly send me the complete project report of this topic on my email id.
          i am very thankful to circuitstoday for my project ,thank you .

          Reply
          • RAJNISH ALOKE

            I AM STUDENT OF THE POLYTECHNIC 5 SEM ELECTRONICS ENGINEERING. I NEED FULL INFORMATION ABOUT THE STREET LIGHT CONTROLLER LIKE THE CKT DIAGRAM, BLOCK DIAGRAM ITS INTRODUCTION, APPLICATIONS,BLOCK DIAGRAM AND GIVE THE INTRODUCTION ABOUT ALL COMPONENTS.
            Reply

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