This half wave voltage signal is fed to the base of a switching transistor T, whose collector lead is coupled across {HEAD ~ a resistor RC} to the positive power supply voltage of {TAIL ~ the apparatus} 
This half wave voltage signal is fed to the base of a switching transistor T , whose collector lead is coupled across { HEAD ~ a resistor RC } to the positive power supply voltage of { TAIL ~ the apparatus }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL