We found this circuit in the 1982 SGS linear integrated circuit manual. The L149 is not common today and the circuit can be implemented with equivalents.
This circuit for audio signals was found in the March 1990 Radio Electronics magazine. The circuit...
The operational amplifiers used in this circuit are old. The circuit is from documentation of the 70's, but...
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...