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From: Don Yuniskis <dgy@rtd.com>
Message-Id: <199512040435.VAA07145@seagull.rtd.com>
Subject: Re: No Thumbs??? (lack of concensus)
To: msmith@atrad.adelaide.edu.au (Michael Smith)
Date: Sun, 3 Dec 1995 21:35:54 -0700 (MST)
Cc: freebsd-hackers@freefall.FreeBSD.org (FreeBSD hackers)
In-Reply-To: <199512041406.OAA26318@genesis.atrad.adelaide.edu.au> from "Michael Smith" at Dec 4, 95 02:06:35 pm
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It seems that Michael Smith said:
> Don Yuniskis stands accused of saying:
> > Actually:
> > 	2.5A @ 5VDC (steady state)
> > 	0.8A @ 12VDC (steady state)
> 
> Worst-case steady state, not idle.  Big difference.

Possibly.  The spec is unclear.  I'll have to make some measurements when 
I get my Fluke unpacked.  However, I suspect this won't be far off.  I
know the drive has at least 2M of RAM in it and at least 600K of EEROM
(haven't poked into the hardware far enough to ascertain what's *really*
under the hood).
 
> > And:
> > 	3.0A @ 5VDC (max)
> > 	1.5A @ 12VDC (max)
> 
> Powerup or tape start.

Actually, I'd imagine it was highest during "spacing" operations.  The tape
really flies, then.  I'll have to do some more detailed measurements prior
to fully qualifying the tape for the application.  But, it's a good ballpark
power estimate (I suspect *much* better than an Exabyte or QIC tape, etc.)
 
> > I'm not disagreeing.  Rather, I'm just noting published specs on drives
> > and trying to infer their thermal characteristics in a manner comparable
> > to other equipment I have in similar enclosures.  'Cuda claims to be about
> > 13W.  Some of the Hawks appear to be ~9W.  The MC1991 claims to be 30W!
> > (comparing apples and orangatans!)
> 
> Bear in mind that the 1991 has _much_ more surface area than the 'cuda, so
> it can dissipate more power for the same dT.

Granted.  But I wonder if it really has 2.5 times the surface area... and,
if all that extra surface area is really *useful* for Pd.  I guess if you
had $$$$ to "burn", you could really cook up a neat little experiment...