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: Nntp-Posting-Host: madoka.its.rpi.edu Reply-To: quimby@mts.rpi.edu References: <18820001@hpspdra.spd.HP.COM> <18820003@hpspdra.spd.HP.COM> <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 -- quimby@mts.rpi.edu, quimby@rpitsmts.bitnet