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
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
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.
Rz=(Vin-Vz)/Iz
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