This circuit was obtained in a documentation from the 70s. The operational amplifiers used are uncommon today. Modern equivalent types can be tried out.
This circuit is from a 1982 documentation. It can be modernized using LEDs in series with 470 ohms...
This circuit was found in Signetics documentation from the 90's. The circuit performance curve is...
The integrated circuit used in this amplifier, from the 1982 SGS linear integrated circuit manual, is...