This 100 Hz filter was found in the August 1993 issue of Electronics Now. The components can be modified to operate at other frequencies.
This circuit is from an English magazine of 1977. The circuit is still current, just using BC547...
This circuit was obtained in an old Elektor. It is a reference, since the integrated products of the...
This circuit was found in a European technical documentation from 1991. It is a circuit that must...