Date: Wed, 18 Mar 1998 18:55:29 -0600 From: David Kelly <dkelly@hiwaay.net> To: freebsd-hardware@FreeBSD.ORG Subject: Re: CD-R and Scanner recomendations for CD archiving of records? Message-ID: <199803190055.SAA16984@nospam.hiwaay.net> In-Reply-To: Message from Michael Porter <ocean@wavefront.com> of "Wed, 18 Mar 1998 12:27:51 CST." <35101227.A1274725@wavefront.com>
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Michael Porter writes: > > The problem is the power reaching the drives, which has to be > > hyper-smooth (have you ever seen the current spike on a 5V line caused > > by a modern disk performing a long cross-disk seek? Think of > > Everest/Buzz saw, you're along the right lines) > > Hmmm...Wouldn't a nice sized capacitor work well here? When I get another > computer I'm going to link the P/Ss together with caps(P/S=power supply, and > cap=capacitor in case you didn't know). That'll give me insurance from these > things blowing out too. Since the computer will be controlling my house (whe > n I build it starting next year :) I can't have that computer go off! You are asking for trouble. Placing additional capacitance on switching power supplies will disrupt its regulation. Even worse would be to attempt connecting multiple switching power supplies together in parallel. The ripple from one P/S will beat against the ripple of the other resulting in even worse ripple. The best solution for (if) CDR's are more sensitive to the quality of power than HD's, is to provide a separate P/S for the CDR. Just buy an external model. "Noisy power supply" should be a well known constraint to the designers of CD-R's. There is no excuse for them to design a product which fails in the crumby environment it is marketed at. Any additional filtering or regulation should have been placed on the critical internal components. Once that's said, I'll mention it is *hard* to eliminate noise in a noisy electrical environment. Much harder than simply "adding capacitors". -- David Kelly N4HHE, dkelly@nospam.hiwaay.net ===================================================================== The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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