need help about ups circuit diagram

My name is mohsin khan. i live in Pakistan. These days we have face electricity problem. These days i am working on ups but i have face so problem the one of the big problem is that in market the ups which are available are not relaiable the big problem is these no over load protection circuit. and there i have no found the ups diagram with protection circuit diagram

ups

the uninterpretable power supply works with diodes, you must have some cheap electronics over there is pakistan, no?