24 Feb
2002
24 Feb
'02
1:20 p.m.
I didn't mean current limiting for the entire supply, but rather just for the
Termpwr. I'm no longer sure whether it's to be limited to one ampere or a
half an ampere, or what. I never used to forget once I had things written
down, and this is specified in the standard. Apple probably left out the
diode so they wouldn't have to put in the fuse. It does cost money, after
all. Diodes seem to make pretty cheap fuses, too, unless there's no fuse in
the circuit, in which case they'll hold up until some major component fails.
If there's a fuse, the diode will, of course, fail first.
Dick
----- Original Message -----
From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
To: <classiccmp(a)classiccmp.org>
Sent: Sunday, February 24, 2002 4:52 PM
Subject: Re: Apple SCSI TermPWR; Was Re: This is funny (ebay)
>
> If you're going to hack this in, and if there's no other current limiting,
be
Well, the Mac+ PSU does have internal current limiting (is there an SMPSU
that doesn't?)
> sure to include a fuse for, say, 1/2-1 ampere in series with the diode,
else
My experience suggests that diodes make pretty good fuses :-). In other
words, if you add a picofuse in series with the diode, the diode will
still fail first. Still, it can't hurt to add one.
-tony