Dark Sensor ( Light Sensor / Automatic Street Light )

Introduction: Dark Sensor ( Light Sensor / Automatic Street Light )

Here is my new simple Electronics project about  Automatic Street Light Control System or Dark Sensor.

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 ( e.g in morning ) , by using a sensor called LDR (Light Dependent Resistor) which senses the light just like our eyes.

Needs no manual operation for switching ON and OFF...

Step 1: Things You Need...

Parts:-

* 1    BC547 transistor
* 1   220 k resistor
* 1   330 ohms resistor
* 1   LED (any colour )
* 1   9v battery
* 1   battery clip
* 1   LDR ( light dependent resistor  )

Step 2: AND...

* Connecting wires
* soldering rod and wire
* wire stripper
* Cutter

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Step 3: Circuit Diagram

solder the transistor on the board and solder one wire of the LDR to the emitter and other to the base  , solder the negative wire of the LED to the base of the transistor with a 330 ohms resistor and also solder 220k resistor with the one side of the 330 ohmsresistor .






Step 4: Finsih... Uuuhuuuu... :p

The simple circuit is ready for testing now . Connect 9v 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 .

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Supercharged Contest

Participated in the
Supercharged Contest

Instructables Outdoor Projects Contest

Participated in the
Instructables Outdoor Projects Contest

2 People Made This Project!

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61 Comments

0
ChitranshN
ChitranshN

Question 1 year ago

What is the role of R1 in circuit ?

0
nurraginabusman
nurraginabusman

Question 2 years ago

Can 9v battery change to 12v battery. Is it will be working??

0
SuryanshS8
SuryanshS8

Question 2 years ago

Can we use only BC547 NPN transistor in automatic Street light

0
JustinF120
JustinF120

Question 2 years ago

what is the basis of its working. what are its applications

0
Sunilkumarthanga
Sunilkumarthanga

2 years ago

Hi, Can you help in a thing which i was unable to do?
The thing is i have a power supply through a battery 4.7v and its connected to a solar panel for charging & now the power is lasting for 12 hours but the power should automatically off after #4 Hours, what should i do? if there is any circuit please do share with me to make my need fulfill.

0
PrathamK5
PrathamK5

3 years ago

The Circuit works as Light sensor not Darkness. In dark, the LED dims, in pitch dark it turns off and in sunlight, LED glows bright

0
iceng
iceng

Reply 3 years ago

Sounds like you need to exchange the position of the LDR and the 220K resistor.

0
KoushikN3
KoushikN3

Question 3 years ago

how can i make darkness sensor using only 9v battery,LDR,BC547 transistor

0
iceng
iceng

Answer 3 years ago

You can not !

0
AritraG6
AritraG6

Question 3 years ago on Step 3

If instead of using 220 k resistance i use 22k only will there be any problem...actually my ckt is not wrkng??

0
iceng
iceng

Answer 3 years ago

Why do you change the design and act surprised when it fails ?

Changing the delicate current balance by a factor of ten may permanently turn the LED on...

0
rusellsison
rusellsison

Question 3 years ago on Introduction

Can we use light bulb instead of LED lights? I am asking for our research and this inspired me. Thank you for the idea. Please answer ASAP.Thank you

0
iceng
iceng

Answer 3 years ago

This circuit is only controlling 20ma using a peak 100ma collector BC547 NPN transistor.

If you have an incandescent light bulb that draws less then 20ma it might work.

The reason I say might is because any incandescent bulb is is a lot less resistance when cold and will draw ten times the current until it gets hot enough to produce light off of the filament glow..

What response say you ??

0
VilloriaJ
VilloriaJ

3 years ago

hi ! please help me , i want to connect 10 or more LED, asap thanks

0
PrathamK5
PrathamK5

3 years ago

Plz send the pic for wiring as it may clear all the doubt, I'm very New to electronics and the diagram is very Confusing.

0
JC143
JC143

4 years ago

Is it ok to use 6 volts

0
JC143
JC143

4 years ago

is that okey if i will use 6v insted of 9volts

0
dnfh1949
dnfh1949

4 years ago

Could the circuit be modified to work the other way round, so that it switches ON in sunlight and OFF in dark? I suspect its v. simple, but so am I!

0
SulaimaanC1
SulaimaanC1

Reply 4 years ago

Yeah just dont use the transistor