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