RE: Star Wars Power Supply

> Somewhere along the
> line someone got the notion that switchers were more reliable than linear
> power supplies, and that's just not true.
>
I'll just toss my $0.02 in here now. I think the quality of PC power
supplies has gone down pretty fast over the years. (trying to stay ahead on
the price/performance curve) I have a lot of those old 62.5W PC/XT power
supplies that I use for games and projects and have never had a bad one.
Compare that with those little 230W "mini-tower" switchers which I've
personally had about 4 those die in the last year or two. (We too have a
power-supply grave-yard cubicle at work. ;-) Maybe big Pentium systems with
massive HD's, RAM, and power-hungry 3D cards contribute to their demise, but
I've seen a lot of touch-screen '486 motherboard based games with those
little mini-tower guys croak too.

On the other hand, switchers can supply pretty massive current in a small
space, and I've routinely been able to get them for about $15 *with* a
mini-tower case (which I consider a fancy shipping carton and toss in the
trash ;-) so when one dies I just pop in a new one and don't really worry
about trying to fix anything. (Although everyone assures me that switchers
are easy to fix...)

> Linear supplies produce quiter voltages, which, leads to, among
> other things, nicer sounding audio when you run amps off of them. No amp
> has an infinite PSRR, so when you hit it with the horrendous supply
> voltages that switchers produce (I'm no expert on switching supplies, but
> I think they switch at around 20 kHz, which gives you nice noise right at
> the "annoying edge" of the audio band) you'll get some distortion.
>
I agree that switchers for PC's are pretty noisy, but that's not true of all
switchers. We did a redundant, hot-swappable supply for a rack-mount modem
system a few years back-- those switchers were really quiet and pretty
bullet-proof. Of course I think there were some *caps* that cost $15 in
those, much less getting the whole supply for that much! ;-)

-Clay

>
Received on Tue Aug 17 11:16:26 1999