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