a microprocessor connected to {HEAD ~ the battery} through a regulator to obtain {TAIL ~ a suitable DC voltage}, the power supply switch and the illumination switch 
a microprocessor connected to { HEAD ~ the battery } through a regulator to obtain { TAIL ~ a suitable DC voltage } , the power supply switch and the illumination switch
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH