how to use 110v equipment with 220v without adapter or transformer

hi,

    I am always confused and don not understand how to us 110v equipment with 220v electrical supply without use of external transformer or adapter. When i think of some high brand equipment like sony tv can be used without any add with 110 or220v electrical supply. When i aske electrician how to use 110 with 220v they advise to use huge transformer for heavy equipment wich is not acceptable in normal condition.When i think of sony tv how it can be used in both voltage it seems to me very simple solution but i can not figureout that solution. So please if you have some simple solution for this problem please guide me for that because i have been thinking for this froblem from my childhood.

                                                       Thanks'

                                                                           sam shah