I/P 90 TO 120V DC to a 20x resistive attenuator giving 4.5 to 6 V,
then
level shift by -4.125 V with an adjustable bandgap reference giving 0.375 to 1.875 V,
then
have the opamp give a transconductance of (20-4)/(1.875 to 0.375) = 10.7 millimhos, giving 4 to 20 mA.
Unless
your source can deliver sizeable amounts of current, and
unless
you need the 20 mA with the 90 V in.
I am trying to build control system for a transformer the i/p of transformer is 90-120V i want to take this range sample it and test if the ip goes out of it