Power Supply Filter Questions

[Schappy]

Im just starting to read schematics and had a question about power supply filtering.

Is it always necessary?

Which power supply filter do you choose?

Ive read that the filter isnt as necessary when using a regulated power supply.

Is a Dunlop DC Brick regulated?

[petemoore]

http://geofex.com/Article_Folders/Power-supplies/powersup.htm
 Ahh, the regulator, so easy, so much cleanup power.
  There's "DC" then theres DC. "DC" is what is marked on wall warts, DC would be a pure, exact, unwavering potential, say 9v, if you find it, let us know.

[G. Hoffman]

http://geofex.com/Article_Folders/Power-supplies/powersup.htm
 Ahh, the regulator, so easy, so much cleanup power.
  There's "DC" then theres DC. "DC" is what is marked on wall warts, DC would be a pure, exact, unwavering potential, say 9v, if you find it, let us know.

I've got a box full of batteries that do a pretty good job.


Gabriel

[petemoore]

  When I think "Is that the power supply?", Where's that battery, soon a comparison against one of the worlds most ripple free power supplies is under way.
  Hook to battery, if noise isn't still there, your circuit probably has a desire for a power supply with reduced ripple, a regulator always smoothed the DC, the only thing left is the ground.
  The way to lift [eliminate] ground is with transformers.
  So...transformer output is floating [no reference such as ground], the AC is turned to DC, filterd, regulated, then, filtered, then..probably so DC that you can't like it more than a battery DC.