Wall Wart power supply add-on filter (clean up that wall wart hum)

[smackoj]

This may be ancient news for some of you but I just found this trick which makes all the 'ballpark' wall warts I found in bargain bins and could not use because of noise, now usable. I tried this on one of my 'closet queen' wall warts the other day and it works like a charm. I couldn't just copy the picture from the OLC (Officially Licensed Circuits) website so here is the link to the whole article. It's fairly short so not a 'long' read to get to the actual design.

http://www.olcircuits.com/documents/olc_powerfiltering_guide.pdf