Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!batcomputer!payne
From: payne@batcomputer.tn.cornell.edu (Andrew Payne)
Newsgroups: sci.electronics
Subject: Re: Powering PC from +12
Message-ID: <7321@batcomputer.tn.cornell.edu>
Date: 3 Feb 89 20:04:18 GMT
References: <00112@m5.UUCP>
Reply-To: payne@tcgould.tn.cornell.edu (Andrew Payne)
Organization: Cornell Theory Center, Cornell University, Ithaca NY
Lines: 25

In article <00112@m5.UUCP> keith@m5.UUCP (Keith J. McQueen) writes:
>Does anyone out there have a circuit for producing the
>necessary +12, -12, +5, -5 for powering an IBM PC from
>a single lead acid battery?  The supply should provide
>enough current to run a loaded PC with a hard disk drive,
>and a 12 volt monitor.

	My experience with computers/digital electronics has been that
90% of a given circuit runs from +5.  The other voltages are required for
a very small portion of the sytem (the most common being +12/-12 for the
serial RS-232 drivers).  Most hard drives/floppy drives want +5 and +12.
	If you could isolate any sections that use -5/-12 (like a RS232 
board), and work around such sections (like using the MAX232 chip for
RS232, which has an on board voltage doubler/inverter, and runs from a 
single +5 supply), you might be able to run the computer from a single 
12V battery and +5/+12 regulators.

	In this day of generic PCs with little or no tech documentation, 
this may be more trouble than it's worth....

-- 
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Andrew C. Payne               UUCP:  ...!cornell!batcomputer!payne
                          INTERNET:  payne@tcgould.tn.cornell.edu
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