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Home » Basic Electronics » Automatic Street Light Control System.(Sensor using LDR & Transistor BC 547.) Very Simple.

Automatic Street Light Control System.(Sensor using LDR & Transistor BC 547.) Very Simple.

 Automatic Street Light Control System.(Sensor using LDR & Transistor BC 547.) Very Simple.

Her is our new simple Electrical/Electronics project about Automatic Street Light Control System. 
  • it is a simple and powerful concept, which uses transistor (BC 547 NPN) as a switch to switch ON and OFF the street light system automatically.
  • It automatically switches ON lights when the sunlight goes below the visible region of our eyes. (e.g in evening after Sunset). 
  • it automatically switches OFF lights when Sunlight fall on it  ( i.e on LDR ) e.g in morning, by using a sensor called LDR (Light Dependent Resistor) which senses the light just like our eyes. 


  • By using this Automatic system for street light controlling, we can reduce energy consumption because the manually operated street lights are not switched off properly even the sunlight comes and also not switched on earlier before sunset. 
  • In sunny and rainy days, ON  and OFF time differ noticeably which is one of the major disadvantage of using timer circuits or manual operation for switching the street light system.

Enough….Now lets begin ( Step by Step)

  • LDR Light Dependent Resistor
  • Take 2 transistors. (NPN transistor- BC547 or BC147 or BC548)
  • Resistor- 1K, 330Ohm, 470 ohm
  • Light emitting diode (LED) – Any color
  • Connecting wires- Use single-core plastic-coated wire of 0.6mm diameter (the standard size)-You can use wire that is used for Computer Networking.
  • Power supply-6V or 9V
  • Insert first transistor Q1-BC547 (NPN) on breadboard (or general PCB) as shown in the circuit diagram 1.
  • Connect another transistor Q2- BC547 (NPN) on breadboard as in step 1.
  • Connect  wires across emitter pin of both transistors and –ve terminal of battery (lowest/ bottom row of breadboard.)
  • Connect  a wire across Collector pin of transistor Q1 and Base pin of transistor Q2.
  • Connect a resistor 1K across positive terminal of battery (topmost row of breadboard) and Collector pin of transistor Q1.
  • Connect  Light Dependent Resistor (LDR) across positive terminal of battery (topmost row of breadboard) and base terminal of transistor Q1.
  • insert a resistor- 330 Ohm across base pin of transistor Q1 and negative terminal of battery (lowest bottom row of breadboard).
  • Connect a resistor 330R across positive terminal of battery (topmost row of breadboard) and anode terminal of LED (Light emitting diode) & Connect the cathode terminal of LED to Collector pin of transistor Q2.

The simple circuit is ready for testing now. Connect 6V battery terminals to the circuit as show in fig and see the output. As you block light falling on Light dependent resistor(LDR), the LED glows.

LED GLOWS EVEN IN LESS DARKNESS. Use torch light or Lighter if the LED glows in less darkness. in addition, you can try to adjust the sensitivity of this circuit by using a variable resistor in place of R1-300Ohm. Try this circuit with other resistances as well, (e.g, 1KΩ, 10KΩ and 100KΩ, etc)

PICs Story: ( For Zooming View images in new tab)


Circuit Diagram 1.Automatic Street Light Control System.(Sensor using LDR & Transistor BC 547.) Very Simple.  We have tried this one in this tutorial bu you can also try the second one

Circuit Diagram 2 .Automatic Street Light Control System.(Sensor using LDR & Transistor BC 547.) Very Simple.

As Light is falling on LDR ( Light Dependent resistor) So LED does not glow. ( LED = Off)                                                            Image Taken Our from Video

You can see now that we have blocked light falling on Light dependent resistor(LDR), so the LED glows ( LED = ON)             Image Taken Out from Video

By: Wasim Khan

Step by Step Procedure video…Coming Soon..

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  1. brother this ckt only work for very small load , if you wana going to do it paractically fo 25watt or above load then your bulb/load will start flickering , so there for paractical point of view i suggest to use 555 time , which can easily handle 100watt load with out flickering

    • Agree…But this is a simple project…I have also project report..where all Circuit diagrams available i.e. for small, normal and large loads..

    • Friend You can easily controll hight wattage Items by the using of 6VDC Relay Instead of 330 ohm Resistance and LED. By Using 2nd Circuit Displayed by Wasim Khan

    • @ Bhatti Soft kindly paste a link of the crkt displayed by wasim khan <br />thanks

    • do you know what is the main reason of flickering that is the light which is on the load feedback the LDR that&#39;s why an error-full control system will created need to separate the light source from your LDR.LDRshouldn&#39;t response on it&#39;s own circuit load and of-course you need to add relay or traic with very little labor to make it a strong circuit..BEST OF LUCK 🙂

    • Can u give me the diagram using relay

    • please guys I have as a final project&quot;automatic street lights&quot; using ldr, microcontroller,pwm,EE555.. can any one help please ?

  2. No dOubt eFForts aRe goOd nd simpLe…thnx buDDy.. :)<br /><br />

  3. am doing the same project will u send total project pdf ……please

    • If you face any problem.,then ask here…Thanks

    • It is very helpful for beginners like us. Thax a lot for sharing. Bro kindly provide a simple circuit, I need to control street light 220 v with using LDR. In sunlight my street light turns on &amp; at night turns off automatically, for that kindly provide a circuit.

      • sir, i have a problem i made “automatic street light circuit” according to circuit diagram 1 but there is a problem is that when i cover LDR the LED off and when i did not covered it its ligt on
        how can i solve this problem plz reply me quic as posible am waiting….!

  4. Good work, in present time to balance the lighting consumption it is very necessary to employ this lighting technique. Led lighting is good source of light; it will require less electricity and also provide much brighter light as compare to other traditional lighting sources. <br /><br />Reference: <a href="; rel="nofollow">

  5. Super.Now a days in solar streetlight systems some peoples are using voltage based Controllers.Is this right( i meant it voltage sensors).<br />If this is right please furnish the details about this type of circuit diagram.

  6. can this actually be incorporated practically in the streets..? how would one accomplish it using this simple circuit and installing it into real street lamps?<br />

    • I have a complete project on this…. i will upload and share pdf link…..Thhanks

    • plz upload soon &amp; provide link here.

    • It&#39;d be very simple actually. Swap out the low wattage components used in this example with some higher wattage ones, replace the battery with a 120/6 volt transformer + a rectifier and filter capacitor &amp; put the coil for a contactor that would switch the mains power for the street light on and off in series with the transistor. <br /><br />The circuit would be almost identical to the

  7. I personally liked using the services of for their great services, as they are truly professional, knowledgeable and trustworthy.

  8. i have to control around 6 tubelights in a room using this circuit bro<br />can u plz help me out with the circuit<br /><br />regards

    • We will update the circuit…Thanks

      • Reden Manatad

        Good day Sir,

        I am working as an ship electrician , My problem is that the Insulation Resistance Monitor is Normal but the phase indicator bulb (the 3 bulbs) the two are not so bright then the other one is very bright , can you please help me to correct this problem..any reply from you sir is highly appreciated..

        Thank you very much

  9. can we used relay instead of led?

  10. i&#39;m not sure if i&#39;m right, does the Q2 in the circuit 2 should be a pnp transistor instead?? please help me understand . thanks…

  11. i&#39;m now currently trying out the 2nd circuit, but then it didn&#39;t work out… i don&#39;t know if i mistakenly connect the components, but i&#39;ve tried dozen times already…can you please help me show the full circuit of it on breadboard? thanks

    • Have you tried the first one….if not then try it… the way…i have tried these both circuits and its working properly….Also, I will upload the video to YouTube and then share the link here.

    • hi<br />can some one suggest me how to incorporate with AC outdoor light for 100 watt…..Please suggest me how to use 12v relay to use higher load. Please provide me circuit diagram where AC out can be define there.<br />If you send me diagram on email ID, It will great for me.<br /><br />Regards<br />

  12. Undergraduate

    wait i realized that circuit 2 will turn on the led when there is no light on the ldr, while ciruit 1 turns on the led when there is light?? light decreases the ldr&#39;s resistance right???

  13. Undergraduate

    circuit 1 differs to circuit 2… circuit 1 is led on when there is light while circuit 2 is led on when there is no light… Is this correct??? resistance decreases with light right?

    • when there is bright outside , resistance decreases <br />and when there is dark outside, resistance increases (LDR)

  14. how can i make it more sensetive.. ………<br /> …mine led is also glowing in room light .. i have to provide an torch light to LDR to switch off<br />

  15. can i use a 9 volt battery??<br />plz replay

  16. Is there any project in which led glows in brightness .. What are its uses …

  17. Hi all.<br />First circuit is wrong. There is no doubt any expert eye can detect its mistake. :)<br />I am an electronics engineer

  18. hi can you tell me the function of each element you have used like what is the use of transistors in this ckt and resistors …..i would be very grateful if u wud help me out.<br />thnx in advance

  19. nawlesh singh

    can we use this ckt for ac 230v or more voltage<br /><br /><br />

  20. Simple and cheap. Can you give the details of the battery charger including overcharging protection.?

  21. In Electronics Store, You can Easily find a Battery charger about (6-9V, 0.6 – 1.2A)

  22. I would also likely to know about the use of transistor in the circuits…….. It would be very helpful

  23. Vishnu Satheesh

    can u please suggest some human and vehicle detection sensors used in street light????????

  24. Thank you so much with regard to giving me an update on this topic on your blog..Thanks for your time and consideration of other individuals by making this web site available.

  25. nitin kumbhar

    brother i do but when led on when ldr in light and when dark led off plz help…

  26. please send me a block diagram of automatic street light control system (LDR as the sensor).

  27. i cant get the output for second circuit LED is continously glowing,<br />and for the first circuit output is reverse. what to do?<br />

  28. Please help, what is the use of the transistor BC 547? and the other components? please help. i will be using this for my project..

  29. Which transistor is used

  30. Which circuit did you try… Make sure to connect all the components in proper direction….

  31. well done …………..(i&#39;m sri lanka )<br />

  32. What is the value of 6V battery in Amperes?

  33. i did this circuit and i have to answer 2 questions :<br />1- how can u improve your design ? <br />2- what other application that can be implemented ?<br />i dont know what to answers lol ..plz help<br />

  34. hey , will anyone help me ?? i amn&#39;t getting the output , before i block the LDR the led is glowing , hw can i coorect thiss??<br />

  35. hey wil anyone help me to do this doucument plzz

  36. nice one i want to do this one

  37. Andrew Isgonic

    Brilliant post! You explained everything quite intelligently. I will follow all the steps for automatically turning ON and OFF my garden lights, or I will simply forward this blog , thank you! You were a great help.

  38. I have finished first circuit but output get reverse ,light is ON ,LED is ON ,please help…

  39. plese upload video before 1 hour.

  40. any change inLDR, i will used 9v battery.

  41. I will used FIRST circuit.

  42. mine is not working can you explain how does this work THANKS

  43. How can I improve this simple DC project with AC 240V

  44. How can I improve this simple DC project with AC 240V.thanks.

  45. Can you give a brief working of the circuit asap?thank you

  46. this will work as a light finding sensor but this is not light control system. Please make sure about it.


  48. Mandeep Singh

    Sir, can you please explain the functions and importances of use of TRANSISTOR Q1-BC547 (NPN) and RESISTORS R1(1kohm) & R2(470ohm) [circuit 1] used in making this, in simple language , because i wanted to preform this project as my investigatory project (12class) and for practical & viva purpose i have to explain it and provide the answers of questions. { i hope u can understand my problem }.

  49. Sir can anyone tell about OLR connections? Do we have apotential free NO(it becomes NC when OLR trips) contacts in OLR?

  50. Gbolahan Ahmed

    Kindly notify me of new post by email.

  51. Sir, can you please explain the functions and importances of use of TRANSISTOR Q1-BC547 (NPN) and RESISTORS R1(1kohm) & R2(470ohm) [circuit 1] used in making this, in simple language , because i wanted to preform this project as my investigatory project (12class) and for practical & viva purpose i have to explain it and provide the answers of questions. { i hope u can understand my problem }

  52. Interesting circuit! well done guys

  53. can i connect multiple leds?


    i need some guidance about ma final project…it’s about street lights

  55. well,I think I got it, please help to get enough guidance on vehicle movement street light project

  56. I’ve done this project but there is light on the led is also on. when light is off the led is also off. waste project, waste of time, waste of money.

  57. can I use use LEDs at distances of about 10 cms apart from eachother

  58. Light is flickering what I have to do now to stop flickering ..?

  59. can u plz give me a detailed working bcoz i have to made i for project and i have to write working and have to give viva so plz teel me the working of circuit 2

  60. can anyone please tell me the reason why 470 ohm resistance is used particularly? why not some other value resistance?
    please do reply soon

  61. I built this circuit but the circuit work in the opposite direction. When there is sun the light switches on. And when it is dark the light switches off. What am I doing wrong?

  62. Jagjeet singh

    Can you pls tell me how it works?
    Means not procedure but working.

  63. Great article. Study another comprehensive article on how to design energy efficient automatic street light using micro-controller here :

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