Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!unmvax!pprg.unm.edu!hc!lanl!cmcl2!ccnysci!sukenick
From: sukenick@ccnysci.UUCP (SYG)
Newsgroups: sci.electronics
Subject: Re: Powering PC from +12
Message-ID: <1233@ccnysci.UUCP>
Date: 6 Feb 89 23:25:02 GMT
References: <00112@m5.UUCP> <7321@batcomputer.tn.cornell.edu>
Reply-To: sukenick@ccnysci.UUCP (SYG)
Organization: City College Of New York
Lines: 24

>>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.
>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.

If the -5, -12 sections don't draw much current, then why not wire
in a -12 & -5 volt inverter (either the integrated circuit or forreal
fun, the diode/capacitor combos ;-)) to the power bus ?

PC's are pretty  modular; to get it to work off of straight DC,
just remove the connector from the power supply and plug into your
DC supply.  There are some ~5 amp single chip regulators (with proper heat
sinking..)  one difficulty might be the 12 volt supply (as
well as current capacity for the negative supplies - you might want to
put an ammeter in with the PC loaded and accessing different accesories
to find the draw, and decide if you will need another battery- maybe a smaller
one will be all that is needed). Many regulators need  ~ 2 volts  over the
regulated   voltage - a lead   acid 12v is ~13.5 voltages when fully charged
so it might be sufficient.  National Semiconductor has a data book on
regulators which might be useful.
it  is to regulate