This filter was found in an old publication from 1977. The circuit must use a simple two-voltage source and the components can be changed for operation at other frequencies.
This circuit was obtained from a 90s Radio Electronics. The integrated circuit used HAA11508 is not...
This article was written by A. Fanzeres in the 1970s. We kept the original text. With the circuit we...
We found this circuit in an English publication in 1991. The circuit can be assembled with...