[iyonix-support] Re: Some Guidance Required Please
- From: Jim Lesurf <jcgl@xxxxxxxxxxxxxxx>
- To: iyonix-support@xxxxxxxxxxxxx
- Date: Fri, 29 Apr 2011 13:07:03 +0100
In article <5c6939cb51.Iyonix@xxxxxxxxxxxxxxxxxxx>, Ron
<iyonix@xxxxxxxxxxx> wrote:
> In message <mpro.lkdlib02n7n2801k0.lists@xxxxxxxxxxxxxxxxxx> Steve
> Fryatt <lists@xxxxxxxxxxxxxxxxxx> wrote:
> >
> > I'm not even sure what the diode is supposed to achieve: the smoothing
> > will happen without it (using just another output cap), and adding
> > sufficiant capacitance to have any useful effect will still break the
> > PSU's startup to the point that either it or the Iyonix are likely not
> > to start at all.
> >
>
> Well, it would separate the smoothing capacitor and mainboard from the
> other less sensitive higher load components such as harddrive CDROM thus
> reducing current requirements of the smoothing components.
Eh? That doesn't make much sense to me as a reason for a series diode if
your concern is to limit the turn-one surge whilst getting higher levels of
filtering from the capacitor. Have I missed something from what has been
said?
If you want to avoid a surge you'd either need some series resistance,
and/or a series inductor, and/or a current limiter. If this is a real
problem it probably makes more sense to just get a better PSU rather than
fiddle about. And inductor would probably give other problems, and an
active current limoiter might be awkward if you need to keep to low
volts and a low drop. You'll end up redesigning the PSU.
> I recall silicon diodes dropping .4V Can you get large germanium diodes?
The drop will depend on the current. More like 0.5 to 0.7 V may be more
appropriate as a hand-waving estimate for silicon PN juntions.
If you want high current and low drop, use a shottky power diode. Although
it still isn't clear to me if this makes sense.
Slainte,
Jim
--
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
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