This circuit was found in an Electronics World of 1966. It has a range of 5 to 25 000 Hz at 1 dB and the diagram includes the power supply.
We found the configuration below, with unit gain, in the National Semiconductor Linear...
This circuit is from an Electronic Design from the 90's. The main integrated circuit is uncommon...
This circuit appears on this site from different sources. This is from documentation from the...