In this AC Power Switch Set paper, we introduce a new type of functions in bitopological spaces, namely, (1,2)*-proper functions.Also, we study the basic properties and characterizations of these functions.One of the most important of equivalent definitions to the (1,2)*-proper functions is given by using (1,2)*-cluster points of filters.Moreover we define and study (1,2)*-perfect functions and (1,2)*-compact functions in bitopological Planters spaces and we study the relation between (1,2)*-proper functions and each of (1,2)*-closed functions , (1,2)*-perfect functions and (1,2)*-compact functions and we give an example when the converse may not be true.