hey guyz im having a problem with the dual supply for LM393, Im trying to build a power supply which will supply the two comparator with -12 & +12 volts but im only getting +12 V. im using two regulators 7912 and 7812 but only 78 type is giving +12. im not sure if its the way i connected the 7912(pin configuration).The full brigde that i have used is the one that comes in IC the AC inputs ~ and the DC outputs - +. i have tried to provide the circuit diagram