Generally, the street lights come on all night and during the day, they go out. But at night, street lights are not necessary if there is no traffic. Saving this energy is a very important factor these days as energy resources are being reduced day by day.
The alternatives for natural resources are much lower and our next generations can face many problems due to the lack of these natural resources. We have already seen the circuit diagram and the operation of the Automatic Intensity Control of the Street Lights circuit in the previous post. This article describes about the circuit that changes the street lights on the vehicle's motion detection and stays off after fixed time.
Principle behind this circuit
The proposed system consists of the Atmega8 microcontroller, LDR, PIR sensor and RTC. This system controls the street lights using a light dependent resistor and a PIR sensor.
The street lights turn on depending on the intensity of sunlight in LDR. If the intensity of sunlight in the light-dependent resistance is low, its resistance value is high. This value increases and becomes high when it is completely dark. This resistance value decides when to turn on street lights.
As the resistance value is maximum at midnight, the real-time clock comes into play. The controller controls the peak time during which there is no traffic and turns off the lights. When there is a vehicle on the road, it is detected by the PIR sensor.
Whenever the PIR sensor is detected, it only indicates that the microcontroller to turn on the street lights. The lights turn on for 2 to 3 minutes and turn off automatically.
Another way to this approach is, one can maintain minimum intensity without totally turning off the lights using PWM and to turn them on at maximum intensity each time the vehicle detects. But in this article the circuit is designed in such a way that the lights are completely off and will light only when there is a vehicle.
Circuit diagram