presented by:
GANGADHAR YADAV

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Automatic Emergency Light
AIM:-
To design the circuit of AUTOMATIC EMERGENCY LIGHT
INTRODUCTION:-
This is automatic emergency light used in night at emergency time when the power cut or off by some region. This emergency light takes 230V AC and it converts it in 12V DC and charge the battery which is used in this circuit. The power of the battery is used that time when the power is cut off or we need to use it. This light is used mostly in villages because there is the lack of electricity is provided.
In this circuit I use BD 140 transistor the advantage of this emergency light is that if we Use this emergency light in a room no other light source is required but in other emergency light we use another light source when the power is available.
BLOCK DIAGRAM
BLOCK DISCRIPTION
First the power supply is given 230 through the step down transformer, the transformer convert it into 12V 1A but it is not gives dc so rectifier is used in it to convert it into dc. For filter the signals in the circuit a capacitor is used on it which filter the signals and convert it into pure DC. It also charged the battery when the power is given in the circuit. A transistor is used to maintain the power supply regularly and the control units (Zener diode) it maintain the zener voltage and also used it as a switch in reverse biased condition after that battery is the second power supplier which charged first and give backup power when the main power is cut off.
CIRCUIT DIAGRAM
CIRCUIT DESCRIPTION
This is the circuit diagram of low cost emergency light based on white LED. The white led provides very bright light which turns on when the mains supply is not there. The circuit has an automatic charger which stops charging when the battery is fully charged. Here 230v is converted into 12v using step down transformer. Bridge rectifier is used to convert AC input to DC supply. Capacitor is used to filter the input AC supply. When the main supply is ON the charged capacitor voltage is much greater than the battery voltage which keeps the transistor T1 & T2 in reversed biased. As soon as the main supply fails or removed the capacitor voltage becomes lesser as compared to battery voltage. This puts both transistor T1 and T2 in forward biased and the LEDs will glow with the battery voltage.
Uses
1. Convert 120V-230V Ac into 12V Dc and charge the battery.
2. Use in that places where the power doesn’t supply properly.
Advantages
 Saves fuel.
 Pollution free.
 Easy to use.
 Very low cost under Rs(200-300)
 Easy to install anywhere.
Disadvantages
 It can be used only for short period.
 Delectated circuit.
IMPLEMENTATION
This project is useful to us. It is used in emergency.
Capacitors
Function
Capacitors store electric charge. They are used with resistors in timing circuits because it takes time for a capacitor to fill with charge. They are used to smooth varying DC supplies by acting as a reservoir of charge. They are also used in filter circuits because capacitors easily pass AC (changing) signals but they block DC (constant) signals.
Capacitance
This is a measure of a capacitor's ability to store charge. A large capacitance means that more charge can be stored. Capacitance is measured in farads, symbol F. However 1F is very large, so prefixes are used to show the smaller values.
Three prefixes (multipliers) are used, µ (micro), n (nano) and p (pico):
• µ means 10-6 (millionth), so 1000000µF = 1F
• n means 10-9 (thousand-millionth), so 1000nF = 1µF
• p means 10-12 (million-millionth), so 1000pF = 1nF
Capacitor values can be very difficult to find because there are many types of capacitor with different labelling systems!
There are many types of capacitor but they can be split into two groups, polarised and unpolarised. Each group has its own circuit symbol.
Electrolytic Capacitors
Electrolytic capacitors are polarised and they must be connected the correct way round, at least one of their leads will be marked + or -. They are not damaged by heat when soldering.
There are two designs of electrolytic capacitors; axial where the leads are attached to each end (220µF in picture) and radial where both leads are at the same end (10µF in picture). Radial capacitors tend to be a little smaller and they stand upright on the circuit board.
It is easy to find the value of electrolytic capacitors because they are clearly printed with their capacitance and voltage rating. The voltage rating can be quite low (6V for example) and it should always be checked when selecting an electrolytic capacitor. If the project parts list does not specify a voltage, choose a capacitor with a rating which is greater than the project's power supply voltage. 25V is a sensible minimum for most battery circuits.
Tantalum Bead Capacitors
Tantalum bead capacitors are polarised and have low voltage ratings like electrolytic capacitors. They are expensive but very small, so they are used where a large capacitance is needed in a small size.
Modern tantalum bead capacitors are printed with their capacitance, voltage and polarity in full. However older ones use a colour-code system which has two stripes (for the two digits) and a spot of colour for the number of zeros to give the value in µF. The standard colour code is used, but for the spot, grey is used to mean × 0.01 and white means × 0.1 so that values of less than 10µF can be shown. A third colour stripe near the leads shows the voltage (yellow 6.3V, black 10V, green 16V, blue 20V, grey 25V, white 30V, pink 35V). The positive (+) lead is to the right when the spot is facing you: 'when the spot is in sight, the positive is to the right'.
For example: blue, grey, black spot means 68µF
For example: blue, grey, white spot means 6.8µF
For example: blue, grey, grey spot means 0.68µF
Unpolarised capacitors (small values, up to 1µF)

This simple automatic emergencylight has the followingadvantages over conventionalemergency lights:1. The charging circuit stops automaticallywhen the battery is fullycharged. So you can leave the emergencylight connected to AC mainsovernight without any fear.2. Emergency light automaticallyturns on when mains fails. So youdon’t need a torch to locate it.3. When mains power is available,emergency light automatically turnsoff.The circuit can be divided into inverterand charger sections. The invertersection is built around timerNE555, while the charger section isbuilt around 3-terminal adjustableregulator LM317.In the inverter section, NE555 iswired as an astable multivibrator thatproduces a 15kHz squarewave. Outputpin 3 of IC 555 is connected to theDarlington pair formed by transistorsSL100 (T1) and 2N3055 (T2) via resistorR4. The Darlington pair drives ferritetransformer X1 to light up thetubelight.For fabricating inverter transformerX1, use two EE ferrite cores (of25×13×8mm size each) along with plasticformer. Wind 10 turns of 22 SWGon primary and 500 turns of 34 SWGwire on secondary using some insulationbetween the primary and secondary.To connect the tubelight to ferritetransformer X1, first short both terminalsof each side of the tubelightand then connect to the secondary ofX1. (You can also use a Darlington pairof transistors BC547 and 2N6292 for a6W tubelight with the same transformer.)When mains power is available, resetpin 4 of IC 555 is grounded viatransistor T4. Thus, IC1 (NE555) doesnot produce squarewave and emergencylight turns off in the presenceof mains supply.When mains fails, transistor T4does not conduct and reset pin 4 getspositive supply though resistor R3. IC1(NE555) starts producing squarewave and tubelight turns on viaferrite transformer X1.In the charger section, inputAC mains is stepped down bytransformer X2 to deliver 9V-0-9V AC at 500 mA. Diodes D1and D2 rectify the output of thetransformer. Capacitors C3 andC4 act as filters to eliminateripples. The unregulated DCvoltage is fed to IC LM317 (IC2).By adjusting preset VR1, theoutput voltage can be adjustedto deliver the charging voltage.When the battery getscharged above 6.8V, zener diodeZD1 conducts and regulator IC2stops delivering the chargingvoltage.Assemble the circuit on ageneral-purpose PCB and enclosein a cabinet with enoughspace for the battery andswitches. Connect a 230V ACpower plug to feed chargingvoltage to the battery andmake a 20W tube outlet in thecabinet to switch on thetubelight

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ABSTRACT
Today, in industries and as well as in household applications an emergency light is employed
where there is frequent non uniform voltage distribution occurs. Many types of emergency lights
from rechargeable torches to systems like generators are available in market. All of them require
a switch to operate them when frequent power failure occurs. The present one deals with a model
which senses the mains as well as daylight to switch on the emergency light. This emergency
light holds requirements of domestic purposes also. There is no need to search the switch in the
dark as it switches on /off automatically.
There are some special features in this project which are as follows:
 When mains power is available, it senses and switches off the lamp instantly. This may be
a common feature in any of the emergency power systems.
 It incorporates an opto-eye which senses the ambient light and when the ambient light
reaches a present low level when there is no power, it switches on the emergency light
automatically. The switching is instantaneous.
 In most of the emergency lights there is a drawback. The discharge level of the battery is
not being controlled to a safe level. The batteries get discharged completely and lose their
life rapidly. This is a very serious complaint from the users. In this one, cut-off is
provided at predefined manufacturers minimum discharge level which gives the specified
life of the battery.
The opto-eye mentioned in the above features is a special one in this automatic emergency light
and opto-eye consists of a photo transistor and some specific arrangement of resistors. Here
instead of photo transistor a photo diode is also used and we can also increase the sensitivity of
Photo diode in reverse configuration. We also come across different operational amplifiers,
diodes, light emitting diode. In addition to these we also employ step down transformer and we
also make use of one switch for proper operation of the devise. For different batteries, charging
voltage and lamp can be choosen accordingly to be more illuminated.
INTRODUCTION:
The present mini project deals with the recent requirements of emergency light both for
industries and domestic purposes. Many types of emergency lights from rechargeable torches to
systems like generators are available in the market. When compared to all other emergency lights
this one is quite efficient one as we make use of integrated circuits, voltage regulator and an
excellent feature of opto eye is included in this present mini project. The present one deals with a
model which senses the mains as well as daylight to switch on the emergency light.
The circuit consists of an LM324 quad operational amplifier which
consists of fourteen pins. A logic function is performed by using this type of IC. There are four
ICs involved in this circuitry. Also photo device is also included which makes the use of light
intensity according to which voltage is produced across its terminals. When the wired AND logic
function is fulfilled from the three ICs which work as comparators and the remaining another IC
respond to it according to which the bulb will be glown . It also consists of a Darlington pair of
pnp transistors whose set is capable of delivering the fifteen amperes to the load.
This present one has one on/off switch on operating which the emergency
light glows. In most of the emergency light there exists a drawback. The discharge level of the
battery is not being controlled to a safe level. The batteries get discharged completely and lose
their life rapidly. This is a very serious aspect in order to overcome this a cutoff is provided and
there exists a minimum discharge level which ensures the long life of battery used in the circuit.