A time switch comprises {HEAD ~ terminals} spaced around {TAIL ~ a slip ring} connected to a voltage source  
A time switch comprises { HEAD ~ terminals } spaced around { TAIL ~ a slip ring } connected to a voltage source
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH