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From: depolo@eniac.seas.upenn.edu (Jeff DePolo)
Newsgroups: sci.electronics
Subject: Re: 12V to 5V DC conversion (for TTL logic in car) wanted
Message-ID: <27097@netnews.upenn.edu>
Date: 14 Jul 90 06:44:31 GMT
References: <1990Jul12.024412.122@mintaka.lcs.mit.edu> <887@titan.tsd.arlut.utexas.edu>
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In article <887@titan.tsd.arlut.utexas.edu> logan@titan.titan.tsd.arlut.utexas.edu (Cary Logan) writes:
>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.

The supposed standard is 12 VDC with no load on the battery - vehicle not
running, 13.8 VDC with no load on the battery - vehicle running, both
values +/- 15%.  However, there is probably quite a few cars out there
that fall outside of this spec range.  Most car electronics manufacturers
realize the problem and have some sort of voltage regulation built in,
particularly car stereos, radar detectors, portable TV's, etc.  I'd
suggest checking your electrical system with a volt meter with the
car running and not running, under heavy load (e.g. lights on,
heater fan running, rear defroster on), under no load, etc. to make
sure it falls within specs.  If it's higher than normal, expect more
heat dissipation from the regulators.	


							--- Jeff



+-----------------------+-----------------------------------------------------+
| Jeff DePolo N3HBZ/AA  | Internet: depolo@eniac.seas.upenn.edu               |
| Univ. of Pennsylvania | RF: 146.685- 224.40- 442.70+ 144.455s (Philadelpia) |
| Computer Science Eng. | Twisted pair: (215) 386-7199 home                   |
|     Class of 1991     | Carrier pigeon: 420 South 42nd St. Philly, PA 19104 |
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