Introduction: Simple Circuit for Every Electronics Beginners : #Automatic Night Lamp With LDR

Picture of Simple Circuit for Every Electronics Beginners :                                           #Automatic Night Lamp With LDR

Hey, guys ☺

Looking for some beginning DIY projects in electronics..! then you have come to the right place

In this project, I'm sharing my first electronic project.
Which I teach to every new one in electronics......

New to electronics..!
You are welcome to this place
Let's learn ......

(only for beginners ,if you are an expert skip this project.....)

Step 1: Beginning......

Picture of Beginning......

First, let us learn about the electronics components used for this project

● Resistor:
Used as what its name says(resistance)
It provides a potential difference in a circuit.

● Potentiometer(pot meter) :

Using this we can change or adjust resistance by turning the knob or moving it.

● Transistor (that 3 legged thingies)

Used as an amplifier, automatic switch etc.(in this project we are using it as an automatic switch).

● LDR (Light Dependent Resistors) also known as cadmium cell:

LDRs or Light Dependent Resistors are very useful, especially in light/dark sensor circuits. Normally the resistance of an LDR is very high, sometimes as high as 1000000 ohms, but when they are illuminated with light resistance drops dramatically

for more details visit this site

● LED (Light Emitting Diode) :

Gives out a light when electricity is applied to the respective electrode.

Step 2: Let's Start Building........

We are going to make a simple automatic light which automatically lights up when it's dark.

Step 3: Things You Need.....

Picture of Things You Need.....

1. 2N2222A transistor

2. 100k pot meter

3. 1k resistor (brown ,black,red codes)

4. 220ohm resistor

5. LDR

6. 9v alkaline battery

7. LEDs

8. Switch (optional)


they are available at less than 3-4$

● wire

● soldering iron and prototyping PCB (optional)
I first made it without soldering.

Step 4: Circuit Diagrams.......

Picture of Circuit Diagrams.......

Gather everything ......

Carefully follow the circuit diagram.

Note about potentiometer:

connect the middle and any other one pin of pot meter, leave other (as in picture 2 in this step) and connect it to the circuit.

Step 5: Transistor

Picture of Transistor

A transistor has 3 legs middle one is the base (B)and other two is the collector (C) and emitter (E) respectively as in the picture for this transistor.

You may be confused at this point if you are a beginner(I also was confused at first,I learned from my mistakes). That is why I remind you learn from mistakes , and don't give up if you fail,try till you win(at least that is what happened to me......). That is what the Edison did before he invented the light bulb . So NEVER EVER GIVE UP.

Step 6: Have You Finished.....

Picture of Have You Finished.....

All done.......

Ready to test........

Connect the circuit to a 9V battery positive and negative respectively.

(Please forgive me for my images ,if you didn't understand it.what do you expect , first tries,that too from a kid who does not have a soldering iron.......)

Step 7: Let's Test........

Picture of Let's Test........

Take the circuit to a dark place or hide LDR with your finger and switch on the circuit
The LED should light ,if not adjust the pot meter( turn it or move it).

After the LED glows take your hands away from LDR or come back to a lighted area,the LED should turn off,if not again adjust the pot meter.

if it all works as said.

it's ready .

if not rewire the circuit or find the fault(don't give up).

Frequently adjust pot meter for better performance .

you're done....

when its dark LED glows automatically

when it is bright it switches off automatically.

And don't forget to improve my instructable.......
I will be back soon with another instructable.........

This circuit is not that much powerful to work with a relay.if you want a circuit which works perfectly with a relay just like this one.I have tried the 555 one but it is a little bit laggy. if you want a more powerful circuit you can visit this instructable


Jules1050 (author)2017-01-23

NICE! Especially the LDR gif animation! :)

RutvikP4 made it! (author)2016-11-23

Thank you TECHNOMAN this was a very fun project!

I have enjoyed making this.

techno man (author)RutvikP42016-11-23

I'm glad to hear that you've enjoyed making \ (•◡•) /

RutvikP4 (author)techno man2016-12-15

I understood the overall working, etc. However one thing is not clear:

Can't we use a simple junction in place of the transistor? What its exact role? How it the common base configuration helpful?

Thank you one again!

NEloD1 (author)2016-08-18

hi there,

can anyone explain or show me best the way to interface switches and potentiometre as and input and LED as an output? and which system would you recomend to use in order to make it happen?

im stuck with my project.

My project is about lighting system in automotive... help help pleaseeeeeeee?!!!!

anyone out there?!!!!

hackerboy55 (author)2016-08-01

Do u make arduino projects?

BilalI10 (author)2016-06-13


i want to connect 12v charger and don,t want to use 9v battery. what components to be used?

babargee (author)2016-06-02


I want to make 220 volts direct drive LDR based lamp drive with minimum space to fit with same holder means transformer less even use triac or any solid state.

Prathamesh Padiyar (author)2016-05-13

Please answer my message....

I made a very simple circuit using a 9v battery , a LED , and a LDR. But I lights when there's light and turns off in dark. Please help.

u must have replace the base (ie , the middle leg of the transistor)

Redo do it

Prathamesh Padiyar (author)2016-05-17

I made it . Thanks...

Do u know I m just 12 years old , and I made that circuit on breadboard. ........

good work prathmesh

Prathamesh Padiyar (author)2016-05-17

I made it . Thanks...

Do u know I m just 12 years old , and I made that circuit on breadboard. ........

Prathamesh Padiyar (author)2016-05-17

I made it . Thanks...

Do u know I m just 12 years old , and I made that circuit on breadboard. ........

Prathamesh Padiyar (author)2016-05-17

I made it . Thanks...

Do u know I m just 12 years old , and I made that circuit on breadboard. ........

Prathamesh Padiyar (author)2016-05-17

I made it . Thanks...

Do u know I m just 12 years old , and I made that circuit on breadboard. ........

RuchirM1 (author)2016-03-22

Sir ,I want to insert a buzzer instead of an LED .please tell me which ae the other materials required for it & how to make it.please send me circuit diagram also.

techno man (author)RuchirM12016-03-22

Just remove the LED and 220 E resistor and connect a buzzer in that place.Make sure that you have conmected the +ve & -ve lead correctly (ie,connect the +ve lead of the buzzer to the emitter of the transistor and the other -ve lead to -ve of the battery

techno man (author)techno man2016-03-23

Take a look at this diagram

ozairsb (author)techno man2016-04-10

sir if i want to insert both led and buzzer using two transister ,then what will be the circuit?

RuchirM1 (author)2016-03-22

I m a beginner

PolinskiRandom made it! (author)2016-01-07

it works perfectly fine ,perfect for using in places where the light-to-dark cycle is fast

Tnx ☺

jgabut (author)2015-12-13

hello sir. can you please tell me why my circuit isn't working when its dark and it works when there's light.

techno man (author)jgabut2016-01-10

U must have replaced the base of the transistor
ie. the middle leg of the transistor

Check the Diagram and redo it

manveen26 (author)2015-11-17

Sir can u please tell how to use the resistance presets i.e. the variable resistor, the connections? Need it project

techno man (author)manveen262016-01-10

U can see 3 leads comming frm the Potentiometer .just simply join the middle and any one of the side leads together and make to leads

connect it to the circuit

JoannesK (author)2015-10-21

Hello sir, can I ask you if we can alter the circuit so that it can power up a DC motor 12V instead of the LED? I was using it for a little project of mine but when I changed the LED for the motor, it wont work. Can you help me how? thanks!

techno man (author)JoannesK2015-10-21

This circuit cannot work with a Relay or Motor because the output (current ) from the transistor is less to work with these things.

If you want to make the circuit which is able to controll motors

You can check out my 2nd instructable project

KhurshidA (author)2015-09-13

i got it for my university mini project.

thanx for such kind of project.

techno man (author)KhurshidA2015-09-14

tanq u for selecting my project ☺

calus (author)2015-08-26

Sir kindly give me its hand maded circuit diagram with labels of all things like resister , ldr etcc.....plz sir

techno man (author)calus2015-08-26

If you need any further hlp you can ask me

calus (author)calus2015-08-26

I need it immediately ...I have to show this in my clg....

calus (author)calus2015-08-26

Plz helppp

HarisC made it! (author)2015-08-21

Sir kindly help me i made 9v DC power supply with day night circuit but when i connect this circuit with power supply the LED on continously
The component i used for this day night circuit is
330 ohm resistor
220 k ohm resistor
BC 547 transistor

techno man (author)HarisC2015-08-23

Sorry for being not able to reply to your queries. I was offline for some days due to exams.

Can you pls send the picture of the dc power supply you used and also the wiring side picture of the night lamp circuit.

I think there may be some problems in wiring the circuit.I would suggest that you use the components described here otherwise it may not work properly.

HarisC (author)2015-08-21

Sir kindly help me i made 9v DC power supply with this day night circuit but this day night circuit does not when i connect the circuit with the power supply the LED on continously. Kindly tell me where is the fault
The conponents i used for day night circuit is
330 ohm resistor
220 kohm resistor
BC 547 transistor and LED

Subham Basu (author)2015-08-19

ManuelR14 (author)2015-07-30

09069412987 (author)2015-06-19

sir. can i consider this as a feedback control system?

techno man (author)090694129872015-06-27

I don't think this can work as a feedback controll system

i have not tried it yet

But u can try............

09069412987 (author)2015-06-21

may i have the block diagram of this proj. pls. asap. tnx

DeepR1 (author)2015-06-18

Sir can you explain the working of the whole in light the current cuts off from led and in darkness led glows..plz can u explain that with circuit diagram..

techno man (author)DeepR12015-06-19

Main part of this circuit is the LDR.This (LDR) thing senses the amount of light available and changes its resistance accordingly.
LDRs resistance increases in dark and deceases during day time or when light is hitting on it.This property of LDR is used here.

Transistor here works as a automatic switch.we have used NPN transistor here,this means that only when we apply a small positive voltage in base then only can current be transmitted from collecter to emitter thus completeing the circuit.

In this circuit transistors base is connected
between 1k resistor and LDR.During daytime resistance of LDR decreases so current takes the easiest route without much resistance. so it travels straight from 1K ,through LDR and reaches negative ignoring the base route
(it does not take the way through the transistor because its resistance is high compared to the resistance of LDR in this instance)

But when it is dark resistance of LDR increases more so current flows to the base of the transistor ( taking the easiest route again which now is through the transistor)

And from what i have said earlier about transistor we know that when a postive voltage is applied at the base, current will flow from collecter to emitter and then to LED lighting it up and staright to the negative electrode.

This is how this whole circuit works.
mainly it utilizes the pecularities of LDR and Transistor

(Resistor and potentiometer is used to regulate current in this circuit)

WanK1 (author)2015-05-13

can i use a 330 ohm resistor to replace 220 ohm resistor?

techno man (author)WanK12015-05-14

U can use one but the brightness of the LED will decrease according to the increase in resistance.

WanK1 (author)techno man2015-05-15

alright, thank you

LanCiro (author)2015-05-05

Can this circuit work without the potentiometer ?

techno man (author)LanCiro2015-05-07

This circuit may not work properly without potentio meter.

In this circuit potentiometer is used to control the triggering of LED when its dark.We have to continously set the potentiometer to desired level to make this circuit work properly.

I was unable to find the exact resistence to use instead of the potentiometer because the resistance needed to trigger changed continuosly according to the light and atmosphere.
So i have used a potentiometer so that we can change the resistance according to our desires.

About This Instructable




Bio: Just a Simple Maker.
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