Newsgroups: comp.sys.laptops
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!quimby
From: quimby@madoka.its.rpi.edu (Quimby Pipple)
Subject: Re: Can Laptops be powered from Car Batteries?
Message-ID: <pkfhka+@rpi.edu>
Nntp-Posting-Host: madoka.its.rpi.edu
Reply-To: quimby@mts.rpi.edu
References: <18820001@hpspdra.spd.HP.COM> <18820003@hpspdra.spd.HP.COM> <RN.1238@mts.ucs.UAlberta.CA> <42224@ucbvax.BERKELEY.EDU>
Date: 23 May 91 06:54:54 GMT
Lines: 26

bks@shiva.Berkeley.EDU (Brian K. Shiratsuki) writes:

>i was wondering about all this discussion of inverters, too, unless
>the original question was about an old grid or somesuch.  my machine
>(no hard disk) is supposed to draw 1.1A at nine volts.  so it seems
>to me i could use a solid-state series-pass regulator along with the
>car electrical system.  it would need enough heat sink to dissipate,
>say, four watts.

It is pretty simple to do, but keep in mind that an automotive
electrical system is sometimes electrically nasty.  One tech
sheet lists surges of -50 to +80 V @ 100 msec, and 200-400V
microsecond range transients as possible.  Newer cars probably
aren't this bad, but it wouldn't hurt to put some sort of
protective circuitry in front of the 3 terminal regulator.
Maybe a fuse, series diode, transorb or MOV, and cap.  The
3 terminals are usually pretty bulletproof, though.

Quimby

-- 
quimby@mts.rpi.edu, quimby@rpitsmts.bitnet

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quimby@mts.rpi.edu, quimby@rpitsmts.bitnet

