Peter, take a good scope and see the +5V on different points on your 1000$
processor + motherboard. You'll be surprised about what they say and what
you'll see ! Usual a poor PC ( 100Mhz to 450 MHz ) have the noise on the
board exactly as I told you ( in the best case is 500mV ). You know
better, there are variants of pentium processors which have local PSU
on the board, with dozens of huge capacitors. Only those have such small
noise as you said and only on small processor voltage ( 2.7 to 3.3V )
We don't talk about the bulshit design of common PSU. Right now I have in
my room about 30 various PC PSU and all are opened for some sort of breackdowns.
Outside, the fence is painted inside the leopard is watching :)
From 10 PSU claimed to know 200W only one is trully 200W, the others are
less than 120W... Let's don't talk anymore about noise because I will be
angry ... ;)


regards,
Vasile
http://www.geocities.com/vsurducan


On Tue, 4 Jun 2002, Peter L. Peres wrote:

> On Tue, 4 Jun 2002, Vasile Surducan wrote:
>
> >Me ? Today nothing is bothering me ! the sun is shining, the birds are
> >singing... ;o)
> >But your amplifier outputs will be heavy bothered if you'll supply it from
> >a switching one, mainly because the supply can't follow fast load
> >current change. As an example a common PC supply has 1 to 2V noise on +5V
> >line. A small noise on your amplifier input will gave you a lot of
> >problems.
>
> I don't know what PC supply that was but if I'd say it was badly broken it
> would be a major understatement. A PC supply nowadays regulates to 3% (0
> to full load - that's 500W sometimes) and has noise well under 50mV (1% of
> 5V) at full load. And spikes and fuzz on the 5V line are totally TOTALLY
> not allowed. This supply goes directly to the CPU secondary psu and the
> CPU can cost $1000. You don't want to glitch that. Search the web for a
> review/comparison of PC psu's in one of the recent numbers (PC Mag or some
> other I do not remember). They give all the figures you want.
>
> Peter
>
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>

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