# RELIABLE EMERGENCY LIGHTING CIRCUIT DIAGRAM

## RELIABLE EMERGENCY LIGHTING

The reliable emergency lighting circuit is an electronics project designed to give an emergency light when the power from main power supply fail or  there is an electric cutoff

This is done by a backup battery source which is charged by a main power supply, when the power fail the battery will discharge through the lamps

From the circuit diagram of the reliable emergency lighting circuit ,several components will be used to accomplish the project ,these components are of different properties depending on their intended operation on the circuit

The table below shows some important components with their specifications that will be used in construction of circuit.

The input voltage of about 220V ac is passed to the step-down transformer of 20:1 ratio.

From

NP/NS=VP/VS
10/1=220/VS
VS=22V AC

But

Vdc=0.636Vm
Vm= √2Vs
Where, Vs=22v
Vm= √2×22v
Vm=31.11
Vdc= 0.636x31.11
Vdc=19.79v dc

The currents will flow to the LED to indicate the presence of power amount current passing through it is determined by the resistor R1

Where

From the datasheet the current rating of the LED is 10mA and the voltage is 2V hence from the series connection of the LED and the resistor

Vs=Vd + Vr
19.79=2+Vr
Vr=19.79-2
Vr=17.79
Therefore
Vr=IR
R=Vr/I
R=19.79/10mA
1.979kΩ

The resistor used is approximately 2kΩ

Inductor, capacitor and the electrolytic capacitor perform the function of reducing ripple voltage, where the capacitor takes all the ac components to the ground .

The transistor help to energize the relay when it act as short circuit causing the battery to be charged by the main power supply.

From
V out =Vz-V be
V out =15.65-0.65
V out =15

This is the amount of constant voltage that will be allowed to pass out of Zener diode

Rz=(Vin-Vz)/Iz

Rz=R3=(15.65-0.65)/15.5mA

Rz=R3=0.967kΩ

The resistor used is approximately equal to 1k Ω

The out voltage charges the battery which will supply power to the lamps when the main power supply fail