a proximity sensor in functional communication with {TAIL ~ said timing circuit} and via said timing switch further in functional communication with said {HEAD ~ at least one pair} of electrodes; and 
a proximity sensor in functional communication with { TAIL ~ said timing circuit } and via said timing switch further in functional communication with said { HEAD ~ at least one pair } of electrodes ; and
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH