In General, street lights turned on for the whole night and during the day they are turned off. But during the night, street lamps are not required if there is no traffic. Saving of this energy is very important factor these days as sources of energy are getting reduced day by day. Alternatives to natural resources are very less and our next generations may face a lot of problems because of the lack of these natural resources. We already have the schedule and the operation of Car Intensity control of Street Lights circuit in the earlier post. This article describes around the track that the street lighting switches on the detection of movement of the vehicle and remains off after certain time
Principle Behind this Circuit:
The proposed system consists of Atmega8 microcontroller, LDR, PIR sensor and RTC. This system controls the street lights using light dependent resistor and PIR sensor.
Street lights are switched on depending on the intensity of the Sun light on LDR. If the intensity of Sunlight on light dependent resistor is low, its resistance value is high. This value increases and becomes high when it is completely in dark. This resistance value decides when the street lights are required to switch ON.
As the resistance value is maximum in the midnights, real time clock comes into the play. The controller checks peak time during which there is no traffic and switch OFF the lights. When there is any vehicle on the road, it is detected by the PIR sensor.
Whenever PIR sensor is detected it just indicates the microcontroller to switch on the street lights. Then lights are switched on for 2 to 3minutes and switched off automatically.
Another way to this approach is, one can maintain minimum intensity without completely switching off the lights by using PWM and switch them on to maximum intensity whenever it detects the vehicle. But in this article the circuit is designed in such a way that lights are completely switched OFF and will be switched ON only when there is any vehicle.