Automatic Street Light

Supervisor doctor: Eng. Ibrahim N. Abu-Isbeih

Students names :

1- Moaz Mhd Zafer Al Hosny

Student number :201310175

2- Abdul Rhman Rachid Al Kousi Student number :201311772 3- Mohammed Ayman Al Nasser Student number :201220192

Content

1-introduction

2- Objectives of the Project

3-PRINCIPLE OF WORK

4--Circuit diagram

5-component

6-description each component

7- Conclusion.

1

-introduction:

Many of the people have a phobia of darkness, so to assist them in such situation, we have explained a simple circuit. It will automatically turn on street light in the way of LEDs or bulb coupled with relay.

Automatic street light system is very common nowadays as it provides

intelligent street lighting mechanism. It provides light automatically

during night without any human interference. These energy saving street

lights make use of incandescent lamps instead of LEDs .So here I will study

with you how to make an electronic circuit for street light automation

using simple electronics component .

- Objectives of the Project Reducing the wastage of power

Reducing physical efforts

Improve the system in our daily life

-CIRCUIT WORK PRINCIPLE:

The lamp(street bulb) should remain OFF during daytime and turn ON

automatically during night. The unique property of light depended resistor

is utilized here. LDR is a variable resistor which has very low resistance in

the presence of light and very high resistance in the absence of light.In this

circuit, we create a potential divider network with an ordinary resistor in

one arm and a LDR on the other arm. According to Ohm’s law (V=IR), voltage drop across the resistor increases when its resistance increases.

Here the drop across LDR varies with changes in light intensity. That is

voltage drop across the LDR is minimum in the presence of light and

maximum in the absence of light.

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When the morning come and light fall on LDR , the resistance of LDR is

low. So the voltage drop across R2 POT will be high. This keeps the

transistor Q1 fully ON. The collector of Q1 (BC547) is coupled to the

base of Q2 (BC547). So Q2 will turn off because Is fully off and so do

over. The lamp will remain off.

When night falls, the resistance of LDR increases to cause the voltage across R2 POT fall below 0.6 V. This causes the transistor Q1 fully OFF ,So Q2will turn in fully on and activates the relay . the lamp will light

-Circuit diagram

Circuit :

Fig.1 this is circuit diagram

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Eagle diagram :

Fig.2 eagle printed circuit diagram

-component: Transistor BC547

LDR (Light Dependence Resistor)

Diode

Resistor

Relay

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-description each component:

1- Transistor BC547

- BC547 is an NPN bi-polar

junction transistor. A transistor

-Here, for switching purpose it is

biased so that it remains on if there

is signal at its base , otherwise it is

completely off.

-It has an emitter terminal, a base

terminal and a collector terminal.

Fig.3

2- LDR (Light Dependence Resistor)

-LDRs or Light Dependent Resistors are very

useful especially in light/dark sensor circuits.

Normally the resistance of an LDR is very high,

sometimes as high as 1000000 ohms, but when

they are illuminated with light resistance drops

dramatically. Electronic onto sensors are the

devices that alter their electrical characteristics,

in the presences of visible or invisible light. The

best-known devices of this type are the light

dependent resistor (LDR), the photo diode and

the phototransistors. The figure-4 shoes that

when the torch is turned on, the resistance of the Fig. LDR falls, allowing current to pass through it is

shown in figure.

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3- Diode

Fig.5

-diode is a two-terminal electronic component that conducts primarily in

one direction (asymmetric conductance); it has low (ideally zero)

resistance to the flow of current in one direction, and high (ideally infinite)

resistance in the other.

-The work of this diode in the circuit as freewheeling diode to protect

the circuit from any reverse current from the relay coil.

-Since an inductor (the relay coil) cannot change it's current instantly, the

flyback diode provides a path for the current when the coil is switched

off. Otherwise, a voltage spike will occur causing arcing on switch

contacts or possibly destroying switching transistors.

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4- Relay:

Fig.6

- Relays is an electrically operated switch, Current flowing through the coil

of the relay creates a magnetic field which attracts a lever & changes the

switch contacts, It has 3-pin,4-pin,5-pin etc…but we have used 5-pin in our

circuit diagram.

-It has range of voltage so when the input voltage same the kind of the

relay voltage the switch go to normal open pin, but if the voltage less than

the basic voltage of the relay the relay still normally closed and the output

circuit still off.

- Conclusion

As we have seen, This project is simple to build and easy to control street

light without using microcontroller and using simple component and

very cheap and it will save power . this is final project shape:

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