Automatic Street Light Intensity Control


230 V AC supply is given to the step-down transformer. This step-down transformer steps down the voltage to 12V. This voltage is given to the rectifier. The rectifier used here is the bridge rectifier  this is formed by the 4  1N4007 diodes.

This rectifier gives the pulsating dc as the out put. This consists of ac ripples in order to remove this ac ripples we are connecting 1000 micro farads capacitor from which ac ripples are grounded

The 12V dc supply coming out from the rectifier divides into 2 ways .from that one is given to the regulator and other is given to the MOSFET driver.

Thus this 12V supply which is given to the regulator this regulator is the 7805 voltage regulator these coverts 12V to 5V since the micro controller needs 5V

In this microcontroller, we write the logic program by using pulse width modulation logic & by taking LDR as a base.LDR is nothing but Light Dependent Resistor this is constructed by using cadmium material, It is operated when solar light is increasing along with it LDR increase a voltage generation within due to this resistance value is to be decreased.

Whatever voltage is generated in the LDR is passed to the micro controller based on this signal pulse width modulation is operated according to this, In pulse width modulation width is increases or decreases by depending upon the LDR.

When micro controller operates it gives the pulse width modulation signals. Whatever signal is generated in the micro controller is forwarded to the MOSFET driver.

If the transistor is on, it will pull down MOSFET voltage to ground so MOSFET becomes off. Likewise, if transistor is off, MOSFET conducts to make LEDs on.

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