In this circuit, the integrated amplifier used is uncommon today. The circuit is from an American documentation from the 70's making use of a power transistor for output. A TIP32 can be used.
We found this protection circuit for the power supply in a 1992 documentation. This circuit has...
I found this circuit in a documentation for radio amateurs from 1975. The FET could be the BF245....
Found in an American 80's documentation, this circuit can use common FETs like the BF245 and cover...