This shunt voltage regulator was found in an Electronic Design from the 90's. The power transistor must be in accordance with the load current and must be equipped with a heat sink.
We found this protection circuit for op amps in the Encyclopedia of Electronic Circuits Volume 5 from...
The use of field effect transistors in this circuit improves its performance. This configuration is from a...
Found in old American documentation, this circuit makes use of operational amplifiers from the 70s...