[R-390] OT: Filter for 9VDC PS

[2002tii]

>That's about what I was figuring.  Is there anything better I can do 
>(short of spending bigtime for a really big choke) besides a big ol' capacitor?

Sure.  Build a capacitor-filtered 12 V supply and regulate it down to 
9 V.  To supply one amp, the regulator will need to dissipate 3 
W.  One of the larger LM317 packages mounted on a heatsink should do 
nicely.  Check the raw supply voltage under full load to make sure it 
stays above 10 V -- regulators need a bit of headroom.  (By "stays 
above 10 V," I mean the minimum voltage at the bottom of the ripple 
must be at least 10 V.)

Or just buy a 9 V, 1 A regulated power supply.

Best regards,

Don