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