More 11/750 PSU Qs

From: Carl Lowenstein <cdl_at_proxima.ucsd.edu>
Date: Wed Apr 17 11:45:56 2002

> From: ard_at_p850ug1.demon.co.uk (Tony Duell)
> Subject: Re: More 11/750 PSU Qs
> To: classiccmp_at_classiccmp.org
> Date: Tue, 16 Apr 2002 03:01:23 +0100 (BST)
> In-Reply-To: <20020415200927.52402.qmail_at_web10301.mail.yahoo.com> from "Ethan Dicks" at Apr 15, 2 01:09:27 pm
> Sender: owner-classiccmp_at_classiccmp.org
> Reply-To: classiccmp_at_classiccmp.org
>
> > > > > NO!. SMPSUs do not like being run in parallel (unless designed to be
> > > > > used like that). One PSU will end up attempting to supply all the
> > > > > current and the other PSUs may not like having voltages applied to
> > > > > their outputs.
> > > >
> > > > And once the first one drops dead, the next
> > > > most "powerful" one repeats the process.
> > > > Proof by "induction" left as an exercise :-)
> > > >
> > > *giggle* OK, ok, thought it was best to ask.... *laughs manically*
> >
> > Presumably, if one could a) tolerate the voltage drops and b) find massive
> > diodes (many amps for the intended application in an 11/750), it could be
> > done safely. Please feel free to correct me if I'm wrong.
>
> Well, that would prevent one PSU from supplying a voltage to the outputs
> of another (something that can really confuse the regulation circuitry!),
> but it won't help with the current distribution problem. The PSU who's
> output after the diode drop is the highest voltage will end up sourcing
> all the current. Not what you really want.

Aren't there some power supplies that can be run in constant-current
or "current-limited" mode? I think I used to do that with a PDP8-E,
when the power drain of the add-in boards exceeded the original 1/2 Amp
per slot. A booster supply to provide more current.

    carl
-- 
        carl lowenstein   marine physical lab   u.c. san diego
                                          clowenstein_at_ucsd.edu
Received on Wed Apr 17 2002 - 11:45:56 BST

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