[sdiy] tube rectifiers

[Eric]

>Interesting, could you please give more information on this subject?
>I don't understand why diodes are slow and noisy at the same time.
>I thought that due to their low impedance the cap charging current 
>is larger and has sharper edges

NO. Sorry. You have something to learn.

There are stored (hole) charges that have to be swept out
of the junction when the polarity changes from forward 
(conducting) to reverse (nonconducting). In ordinary
silicon or germanium diodes, this happens at diffusion speeds.
The recovery time can take up to a few microseconds--
until all the leftover minority carriers are gone.
During the recovery, the rectifier passes huge forward
current. 

You can filter this, or use a snubber, or pay
a lot extra for a fast-recovery rectifier, with gold
doping or other special doping profiles. 
(Especially if high voltages are involved.)

(Or use a tube rectifier, which is the fastest of all.)

Get Vacuum Tube Valley issue 11 for more information.
Page 31. All this has been known by physicists
for decades....


Eric Barbour
METASONIX