As one skilled in the art understands, {HEAD ~ a normal switching power supply} first converts {TAIL ~ the incoming AC} into a DC source 
As one skilled in the art understands , { HEAD ~ a normal switching power supply } first converts { TAIL ~ the incoming AC } into a DC source
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH