a voltage regulator, selectively enabled and disabled in {HEAD ~ response} to {TAIL ~ a control input}, a pair of voltage monitors, 
a voltage regulator , selectively enabled and disabled in { HEAD ~ response } to { TAIL ~ a control input } , a pair of voltage monitors ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH