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From: logan@titan.tsd.arlut.utexas.edu (Cary Logan)
Newsgroups: sci.electronics
Subject: Re: 12V to 5V DC conversion (for TTL logic in car) wanted
Message-ID: <887@titan.tsd.arlut.utexas.edu>
Date: 13 Jul 90 23:38:32 GMT
References: <1990Jul12.024412.122@mintaka.lcs.mit.edu>
Reply-To: logan@titan.titan.tsd.arlut.utexas.edu (Cary Logan)
Distribution: na
Organization: Applied Research Labs, University of Texas at Austin
Lines: 31



Streeter,

It is my impression that automotive voltage levels often exceed 12 volts.  My
guess is that it could reach 16 to 18 volts while the vehicle is running.  This
would mean that at 3 amps you need to disapate more that 30 watts in your power
supply.  I strongly suggest that you consider a dc-dc converter.  Interpoint
makes a wide variety of dc-dc converters, I'm sure they could sell you one to
meet your needs.  Their address is:

	Interpoint
	10301 Willows Road
	Redmond, WA 98052
	(800) 822-8782 Order and Applications Hotline

I have no idea what their prices are like, but they will certainly be more 
expensive than linear regulators. 

An alternative would be to check Radio Shack.  I belive they have voltage
converter that would plug into the lighter socket and supply you with either
3, 5, 9, or 12 volts out.  I don't recall what kind of power they they can
deliver.  I beleive that they cost on the order of $10.00. 

--
Cary Logan   logan@titan.tsd.arlut.utexas.edu
ARL:UT/TSD
P.O. Box 8029
10000 Burnet Road
Austin, TX 78713
(512) 835-3118