We found this circuit in an old documentation, but the components used offer no difficulty in obtaining it. The CMOS integrated circuits are powered by a 6V supply.
March 2017 - Coilcraft SLR series inductors for currents up to 100 A can be obtained from Mouser...
I found this circuit on a December 1976 Radio Elettronica. The Italian magazine no longer exists, but...
This configuration can be applied to other transconductance operationals. The circuit has a gain...