Alternatively L1 and D2 may be functionally viewed as {TAIL ~ a smoothing filter} with {HEAD ~ an input} at terminal 15 
Alternatively L1 and D2 may be functionally viewed as { TAIL ~ a smoothing filter } with { HEAD ~ an input } at terminal 15
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH