Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!pasteur!betelgeuse!carlson
From: carlson@betelgeuse (Richard L. Carlson)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Need advice on hardware projects
Message-ID: <12763@pasteur.Berkeley.EDU>
Date: 23 Apr 89 05:32:31 GMT
References: <9891@netnews.upenn.edu> <6622@cbmvax.UUCP> <7916@killer.Dallas.TX.US>
Sender: news@pasteur.Berkeley.EDU
Reply-To: carlson@ernie.Berkeley.EDU (Richard L. Carlson)
Organization: University of California at Berkeley
Lines: 44

In article <7916@killer.Dallas.TX.US> elg@killer.Dallas.TX.US (Eric Green) writes:
>In message <6622@cbmvax.UUCP>, daveh@cbmvax.UUCP (Dave Haynie) says:
>$in article <9891@netnews.upenn.edu>, ranjit@eniac.seas.upenn.edu (Ranjit Bhatnagar) says:
>$> I'm considering building one or more of the following hardware
>$> projects, for kicks and to save some dough.  
>$That's cool, and really shouldn't be any major design problem.
>
>However, there may be some construction problems. I remember reading
>about noise nightmares with wire-wrapping on ancient S-100 busses
>using 2mhz 8080s, and similiarly with memory boards, so will
>definitely have to be a pc board.

Whoa...not so fast! :-)  I built a RAM expansion when it came across the
net 2-1/2 years ago (back when comp.sys.amiga wasn't comp.sys.amiga :-)
and I've been using it in my Amiga {1,2}000 ever since without any
problems.  It's all wire wrapped.  Agreed that you need to be careful to
keep signals as short as possible, make the power supplies very clean
(my supplies actually used wire heavier than wire-wrap gauge), etc.,
but it *is* possible to wire-wrap your hardware hacks.

>$> And where can I get a QUIET fan to put in the box?
>
>I always wonder about people who insist on QUIET fans. The first time
>I turned on an Amiga 1000, I almost freaked, because I didn't hear the
>vigorous "whoosh" of most AT-clone fans. That "whoosh" is reassuring
>to me...

Personally, when I want to be reassured, I want to have to listen carefully
to hear the fan, not have it announce its presence a couple of rooms away.

I recently had to replace my 2000's fan, though, and noticed something
interesting:  to make sure I had the fan wired right, I turned the power
supply on with the new fan just dangling---it was practically silent.
"Wow!" I thought, put everything back together, turned the power on,
and---the new fan was as noisy as the last one (but no more periodic
garbage disposal).  It looks to me like the 2000's fan is noisy only
because it's accoustically coupled to the rest of the machine.  I know
there is very little room in there, but has anyone tried to isolate the
fan so that its vibrations don't get transferred to the rest of the
machine?  I think it would improve the noise measurably...

-- Richard
   {tektronix,dual,sun,decvax,...}!ucbvax!ernie!carlson
   carlson@ernie.berkeley.edu