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 )