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...


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


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

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.

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

Is it ok to use 6 volts

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

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!

Yeah just dont use the transistor

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