SUBMITTED BY :MRIDUL SINGH RAWAT B120010243NIKITA DUTTA B120010260RAMITPAL SINGH KAMBOJ B120010320SAHIL SHARMA B120010345

AUTOMATIC EMERGENCY LIGHT

BASIC INTRODUCTION

• Basically a battery packed light device.

• Sort of device that is automatically switched on when the light is switched off or there is a blackout.

• Common in commercial and standard residential buildings.

NEED OF AUTOMATIC EMERGENCY LIGHT• Provides light when the ordinary lighting

fails due to a power cut.

• Required especially in villages where there are long power cuts.

• Important to install it near stairs or the place where level changes.

• Near safety signs it should be installed.

SOME PLACES REQUIRE EMERGENCY LIGHT

Near StairsNear Change

of Levels

WORKING PRINCIPLE• Automatic Emergency Light has a light sensor

installed in it known as Light Dependent Resistor(LDR).

• When the intensity of light falling on it decreases, its resistance decreases.

• As the circuit is completed the bulb installed glows.

• When the intensity of light falling on LDR is enough resistance of LDR increases and the circuit remains incomplete and bulb doesn’t glows.

THE MISCONCEPTION

• Automatic Emergency light is often considered same as a light device running on an inverter.

• It is considered a device which has its one end connected to a power source and when the power supply is cut, the bulb glows with the power of inverter.

BULB RUN BY AN INVERTER

CIRCUIT DIAGRAM

WORKING• Deep discharge is taken care by the LED

characteristic and over charge protection is taken care by the fixed voltage regulator.

• This uses a simple 3Pin fixed regulator which has a built in current limiting circuit.

• The only required adjustment is the preset which has to be set to ensure the LEDs just light up.

• The 5mm LDR is just mounted on top of the emergency light as shown in the photograph. LDR is used to avoid it lighting up during day time or when the room lights are ON.

• 2 LEDs are used in series; the dropping resistance is avoided and 2 LEDs light up with current that is required for a single LED,  by which energy is saved to a great extent.

ADVANTAGES

• Battery Efficient.

• Pollution free.

• Easy to use.

• Very cheap under Rs(200-300).

• Easy to install anywhere.

VERY CHEAP

ECO FRIENDLYBATTERY EFFICIENT

DISADVANTAGES

• Not Durable.

• A bit delicate circuit. 

REFERENCES• http://en.wikipedia.org/wiki/Emergency_light

• http://www.icel.co.uk/media/ICEL_LED_Emergency_Luminaires_EE_AP PROVED_JH.pdf

• http://www.candlepowerforums.com/vb/showthread.php?262331-Automatic-Emergency-Lighting

• http://www.radiolocman.com/shem/schematics.html?di=50653

• http://www.electronicsforu.com/electronicsforu/circuitarchives/view_article.asp?sno=365&article_type=1&id=516&tt=unhot