Switching power for PC in cars

[FJB203 at aol.com]

> On the subject of using PC motherboards in automoble applications I would
>  suggest some care in the power supply could eliminate a lot of odd buggy
>  behaviour once you get in a real life enviornment. The PC unlike most
>  industrial equipment connects logic ground to the case. This prevents you
>  from having good control of ground loops on the I/O.  I would suggest that
>  you galvanicaly isolate ith incoming power to the PC. This might not be

What I had intended to do is emulate the PC chassis and power supply, by
mounting both circuit boards on metal standoffs attached to a metal
backplane, which then in turn mounts either to the underside of the top of
the dashboard, or to the fiberglass firewall in the front, above the
subwoofer inlets.  The systemboard I currently have, is a mere 8.5" wide with
seven slots, and a very short depth of 6 inches, thus making it feasible to
mount.  My other option is to utilize an IBM color thinkpad notebook, which I
have successfully run on 13V dc, however I do not have any A/D conversion
products that work with the thinkpad, though obviously the thinkpad has a
color LCD display which is a tradeoff.  for the PC systemboard, I have
several A/D aquisition cards as well as some interesting digital i/o cards,
together are the roots for a computer-controlled vehicle, such as suspension,
powertrain, etc.  Jeeez, I sidetracked again.

The A/D aquisition board I have is some cheap generic orient-made clone of
several american products, however the neat feature of it is that the A/D
inputs can swing above and below chassis ground, the A/D inputs are isolated,
meaning the grounds for the A/D lines are not necessarily the same as chassis
or electrical ground.  In an automotive application, being that the engine
sensors bolt into the block, most likely I will have to make those floaters
equal to true ground.  I'm not there yet nor have I gotten that far on the
research, just thinking aloud at this point.  One step at a time.

Thanks for the advice about the flyback converters, I'll be pulling
literature from various component manufacturers over the next week to get a
better feel of what my options are.

Frederic Breitwieser
http://members.aol.com/fjb203/index.htm
Bridgeport CT
"Homebrew-autos at bolis.com Mailing List"