We found this circuit in 1967 General Electric documentation. SCRs can be replaced by current equivalents. The circuit is for 110V power grid.
The operational amplifier taken as an example is uncommon today, but the configuration can be made...
The integrated circuit used in this regulator is not easy to obtain, since the publication is from...
This configuration was obtained in a 1977 FET Databook. The circuit can be practically any JFET...