The document outlines a project for an automatic street light system designed by students, featuring an electronic circuit that turns on street lights at night using a light-dependent resistor (LDR) and a relay. It details the project's objectives, working principle, circuit diagram, components, and component descriptions, emphasizing the system's simplicity and energy-saving benefits. The conclusion highlights the project's affordability and ease of implementation without the need for complex microcontrollers.

1. 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

2. Content
1-introduction
2- Objectives of the Project
3-PRINCIPLE OF WORK
4--Circuit diagram
5-component
6-description each component
7- Conclusion.
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3. -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
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Reducing physical efforts
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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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4. 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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5. Eagle diagram :
Fig.2 eagle printed circuit diagram
-component:
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Transistor BC547
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LDR (Light Dependence Resistor)
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Diode
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Resistor
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Relay
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6. -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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7. 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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8. 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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