Automatic Street Light Controller

5191 Words Dec 24th, 2012 21 Pages
1. Introduction

Automatic Street Light Control System is a simple and powerful concept, which uses transistor as a switch to switch ON and OFF the street light automatically. By using this system manual works are removed. It automatically switches ON lights when the sunlight goes below the visible region of our eyes. It automatically switches OFF lights under illumination by sunlight. This is done by a sensor called Light Dependant Resistor (LDR) which senses the light actually like our eyes. By using this system energy consumption is also reduced because now-a-days the manually operated street lights are not switched off properly even the sunlight comes and also not switched on
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The collector current from the transistor toggle between ON or OFF modes.
3.2 Circuit Diagram
The circuit diagram of automatic street light controller is given below:

The description of all the components used in this circuit is given in chapter 5.

4. Component Description

4.1 Diode A diode is a two-terminal electronic component that conducts electric current in only one direction. A semiconductor diode is a crystalline piece of semiconductor material connected to two electrical terminals. A vacuum tube diode is a vacuum tube with two electrodes: a plate and a cathode. The most common function of a diode is to allow an electric current to pass in one direction while blocking current in the opposite direction. Thus, the diode can be thought of as an electronic version of a check valve. This unidirectional behavior is called rectification, and is used to convert alternating current to direct current and to extract modulation from radio signals in radio receivers. When p-type and n-type materials are placed in contact with each other, the junction is depleted of charge carriers and behaves very differently than either

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