In another circuit one of either the anodes or {HEAD ~ cathodes} of {TAIL ~ each diode} is common and the other is input into the inverting terminal of a separate operational amplifier 
of
In another circuit one of either the anodes or { HEAD ~ cathodes } of { TAIL ~ each diode } is common and the other is input into the inverting terminal of a separate operational amplifier
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH