L as last filter element?

[rman]

Hi all.

I was reading about someones preamp project where they
are using a large value plate load choke because they belive
it can deliver current for transients better than a power supply's
last capacitor. This got me to thinking, why can't the last element
in a psu filter be a choke? I have never seen a diagram for such,
it is always a capacitor. I can't imagine that no one has thought
of this before, so maybe there is some reason it is not a good
idea?

Just wondering.
Rolf

 

[sawreyrw]

The power supply output impedance should be small. The capacitor helps achieve this at higher frequencies. The impedance of an inductor goes up with frequency, so this is not a good idea.

 

[rman]

Thank's, that makes sense.