12-01-2011, 11:28 AM
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: RADHIKA U.K(42)
: REMYA JOHNY(44)
: SANGEETHA THOMAS(46)
: SUBIN P SUNNY(54)
CONTENTS
INTRODUCTION
OBJECTIVE
BLOCK DIAGRAM
CIRCUIT DIAGRAM
WORKING
COMPARITIVE STUDY OF CIRCUIT WITH AND WITHOUT PWM
FEATURES
ADVANTAGES AND DISADVANTAGES OF LED
COMPARISON OF LED LAMPS WITH OTHER LIGHTING TECHNOLOGIES
CONCLUSION
FUTURE SCOPE
REFERENCES
INTRODUCTION
Growing demand for the saving of electricity.
Failure in power supply causes difficulty and inconvenience.
An automatic emergency lamp that uses LED .
Highly bright due to use of white LEDs.
Turns on when mains supply fails ,turns off when power resumes.
Has own battery charger –stops charging automatically when fully charged.
This project aims to develop most power efficient and user friendly product.
OBJECTIVE
Reduce power consumption by using a low-cost, automatic white LED based emergency lamp using PWM.
WORKING
The circuit has three sections:
The charger power supply section:
Transformer: steps down(9V,500mA).
Bridge rectifier: rectifies transformer output.
LM317: voltage regulation.
Battery: provides supply when mains fails.
Zener diode: conducts when battery crosses its capacity.
FEATURES
Simple:
Simple circuit. Components are easily available and low cost.
Automatic:
Automatically switches ON when the mains fails and turns OFF when mains power resumes. Also has its own battery charger which when fully charged stops charging automatically.
Convenient :
Makes our lives simpler , convenient to use.
Economical:
Energy consumption is very less , proves to be more economic for the consumer.
ADVANTAGES AND DISADVANTAGES OF LED \Advantages:
Efficiency: more light per watt than incandescent bulbs.
Color: can emit of an intended color without use of color filters.
Size: very small.
On/off time: light up very quickly.
cycling: can be subjected to frequent on-off cycling.
Dimming: can be dimmed by PWM.
