Automatic Street Light On/Off

1. Shankersinh Vaghela Bapu Institute Of Technology
AUTOMATIC STREET LIGHT ON/OFF
Guided by – Prof. Ravi PatelPrepared By –
Krishnaditya Rana (IT 140750116048)
Kishan Patel (EC140750111004)
Yatin desai (EC 140750111001)
Yashpalsinh vaghela (EC 140750111007)
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2. Components-
LDR
 Resistance 100 ohM ( 2 )
LED Bulb ( 1 )
 Transistors BC 548 ( 2 )
PCB
 Solder Wire
 Soldering Iron
 Wire
 9 V Battery ( 1 ) 2

3. LDR: A photoresistor or light-dependent resistor (LDR) or photocell is
a light-controlled variable resistor. The resistance of a photoresistor
decreases with increasing incident light intensity; in other words, it
exhibits photoconductivity. A photoresistor can be applied in light-
sensitive detector circuits, and light- and dark-activated switching
circuits.
Resistor: A resistor is a passive two-terminal electrical
component that implements electrical resistance as a circuit element.
Resistors act to reduce current flow, and, at the same time, act to lower
voltage levels within circuits. In electronic circuits resistors are used to
limit current flow, to adjust signal levels, bias active elements,
terminate transmission lines among other uses.
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4. LED: A light-emitting diode (LED) is a semiconductor device that
emits visible light when an electric current passes through it. The light
is not particularly bright, but in most LEDs it is monochromatic,
occurring at a single wavelength.
Transistor: The BC548 is a general purpose epitaxial silicon
NPN bipolar junction transistor found commonly in European
electronic equipment, and part of an historically significant
series of transistors that began in 1966 with Philips'
introduction of the BC108 and its high-voltage BC107 and low-
noise BC109 variants
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5. Circuit Diagram-
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6. Image Of Project-
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7. WORKING-
LDR offers Very high Resistance in darkness. In this case the voltage drop
across the LDR is more than 0.7V.This voltage is more sufficient to
drive the transistor into saturation region.
In saturation region, Ic (Collector current) is very high. Because of this
Ic, The relay gets energized, and switches on the lamp.
LDR offers Very low Resistance in brightness. In this case the voltage
drop across the LDR is less than 0.7V.
This voltage is not sufficient to drive the transistor into saturation
region. Hence, the transistor will be in cut-off region.
In cut-off region, Ic is zero. Because of this Ic, The relay will not be
energized, and the lamp will be in ON state only.
diode is connected across the relay to neutralize the reverse EMF
generated.
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8. Applications-
Balcony
Street Light
Garden Lights
Parking lights
Road Lights
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9. Conclusion-
With the help of this project we can understand the mechanism of
AUTOMATIC STREET LIGHT On/Off.
As a conclusion, around 77% - 81% of power
consumption can be reduced by using this system towards
providing a solution for energy saving.
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