Supply for an appliance protector

Guys you will please help me out, im building an appliance protector which protect the appliance against over and under voltage but the circuit that i saw it was using two 741 comparator which were supplied by a dual supply +12 & -12 but i thought of using LM393 instead of 741 but im not sure if i stil need a dual supply or i dont know where to put the negative supply to a LM393

Post the circuit or link to it. Also, the 741 is a pretty old chip and there are likely better chips to replace it but without seeing the circuit you are talking about it is just about impossible to help.

Ron