This circuit can be primarily used for charging 12V Ni-Cd battery packs. Any way 6V and 9V battery packs can be also charged

This is the circuit diagram of a simple UPS that can deliver 12V unregulated and 5V regulated DC. The transformer T1 steps down the mains voltage to 12V AC and then the bridge B1 rectifies it.

Some time disturbance of power supply creates a number of problems.  Especially in sensitive departments such as Radar System

An Inverter is a device that converts 12 volts dc to 120 volts ac, which is what we use in our homes. 

The multi-voltage supply circuit shown relies on a multi-winding transformer to generate several AC voltages from a single AC input.