The power circuit can be configured to engage {HEAD ~ a battery power supply} or {TAIL ~ an alternating current supply} 
The power circuit can be configured to engage { HEAD ~ a battery power supply } or { TAIL ~ an alternating current supply }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL