Filtering supply lines

[Michael D. Porter]

Darrell Norquay wrote:
> 
> At 02:14 PM 7/24/96 +1100, Stuart Woolford wrote:
> 
> >>  The only way to guarantee you are at a true 0v ground is to run
> >> a wire back to the battery terminal.
> >
> >and what defines the battery terminal as 0v ground?
> --battery explanations snipped--
> 
> >really - the battery terminal can be a particularly noise prone
> >ground point depending on the charging system design.. (from too much
> >car sterio install experience..)
> 
> If this is the case, then the battery ground lead should be repaired or
> replaced.  Any voltage drop from the battery to the chassis will affect ALL
> devices attached to the chassis.  In my car I have separate 2Ga ground leads
> going to both the engine and the frame directly from the battery.  This
> alleviated a lot of noise problems I was having with the stereo.
>We experience horrendous problems with electronic equipment on the 
full-size buses we produce, and have been literally forced by some OEM 
manufacturers using electronic engine/transmission controls to provide 
direct or near direct battery grounds for those controls.  It's the only 
way in a big vehicle with long paths to everywhere to minimize the 
transients and the noise.

> running directly back to the battery, then any noise or voltage drop
> generated on any given ground lead would have no effect on any other lead.
> Unfortunately, this is not the case, and auto manufacturers rely on the
> assumption that the body itself is a single homogenous conductor, which
> unfortunately it is not.
>If every weld is great, if every ground contact point is perfect, if 
every nut on every ground stud gets clamped down properly, then things 
work _reasonably_ well.  Corrosion and vibration take care of that in 
about a week. <g>  We try to minimize surface grounds wherever possible 
simply because of the difficulties in maintaining them.
>   Grounding and
> ground noise is a whole black art unto itself.
>Amen.