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

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 .


2 People Made This Project!

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56 Discussions

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PrathamK5

1 year 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

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icengPrathamK5

Reply 5 months ago

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

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KoushikN3

Question 8 months ago

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

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AritraG6

Question 10 months 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??

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icengAritraG6

Answer 5 months 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...

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rusellsison

Question 6 months 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

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icengrusellsison

Answer 5 months 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 ??

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VilloriaJ

1 year ago

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

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PrathamK5

1 year 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.

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JC143

1 year ago

Is it ok to use 6 volts

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JC143

1 year ago

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

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dnfh1949

2 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!

1 reply
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Er_tanmay_joshi

1 year ago

Which type of resistors I need to use

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Er_tanmay_joshi

1 year ago

I want to connect 10 white LEDs with 9 volt.. suggestion please guys

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danieljohn7291

1 year ago

Hey can someone help me plz?

can someone tell me what the 2 resistors specifically

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anilk194

2 years ago

How may bulbs can be connected in this circuit. Can you explain me ways to connect about 6 bulbs (total Approx 9 volts- 1.5 Volt Each). Also upto how much volt led i can connect in this circuit

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EastsidePrep

4 years ago on Introduction

How do you make sure that when the light turns itself on, it doesn't then sense the light and turn itself back off?