This circuit was suggested by National Semiconductor and is present elsewhere on this site. The LM2575 is not very common today and should be mounted on a heatsink.
I found this circuit in a Popular Electronics from November 1999. The magazine is no longer...
This circuit was found in a 1970s documentation. The integrated circuit used is uncommon today....
This filter was found in Exar documentation from the 1980s. The circuit has an attenuation of 60 dB at the...