component layouts?

[Jules Ryckebusch]

Ohhh Doggie! Compnent layout grounding and bypassing is always an art kinda
thing. There are some good downloadable things on it from Analog Devices web
site in their ap notes. I have found that grounding is usually the cuplrit in
most cross talk issues but being neat counts the most. I usually build "one
of's" that are bread boarded. I keep the power supply leads as short as
possible and bypass all IC's at the pins with a 10-47uf electrolytic and a .1uf
poly or ceramic cap too. On a couple occasions (Power amplifiers) I have found
the need to add additional bypass caps with in the circuit in places where a
current sink/source that was stable was needed. Another helpful thing is to
mount the PC board close to a ground plane. ie metal chassis of case etc.

Jules Ryckebusch

Jim Patchell wrote:

>     Boy, talk about opening a can of worms.....
>
>     Bypassing is both art and science.  My rule of thumb 1st of all, 1
> bypass cap, to ground, for each power supply pin.  There are exceptions to
> that rule of thumb, but that is another story.  It is also best to keep the
> distance between the bypass cap and the power supply pins as short as
> posible.  The idea of the bypass cap is to provide current for those peak
> useage times.  For analog sutff, this is not quite as critical as for high
> frequency switching, but the idea is still the same.
>
>     Another general rule, I cannot think of a case where it is posible to
> have too much bypassing.
>
>     Now, cross talk is another problem.  Even with good bypassing, you are
> going to want to look at the circuit and ask, where can extraneous signals
> get into things.
>
>     In conclusion, all I can say is that this is a pretty big subject.  I
> don't know of any articles on the net that cover this.  You will probably
> get enough replys to make an article though1 :-)
>
>     -Jim
>
> zapsn0n wrote:
>
> > hi all,
> >
> > can anyone point me to some general online info & tips on component
> > layouts, e.g. the placement of capacitors on DIY circuit boards to avoid
> > crosstalk, etc etc  ?
> >
> > thanks,
> > mark scetta