{HEAD ~ Two operational amplifiers} 68 and 70 form part of circuit 50 with inverting terminal 72 of op amp 68 common with {TAIL ~ anode} 54 of photodiode 52 
{ HEAD ~ Two operational amplifiers } 68 and 70 form part of circuit 50 with inverting terminal 72 of op amp 68 common with { TAIL ~ anode } 54 of photodiode 52
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH