Scratch is the scratching noise that occurs mainly with old records. This high frequency noise is eliminated by the filter found in the February 1990 issue of Radio Electronics magazine.
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...