This circuit was found in the August 1997 Electronics Now magazine. The circuit uses well-known operational codes and generates signals up to 20 kHz.
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...