[sdiy] filter cap needed?

[Roy J. Tellason]

On Saturday 28 March 2009 02:29:27 pm David G. Dixon wrote:
> Thanks to all for your replies.  I understood the basic idea about
> switching transients.  I guess I'm just not convinced that putting the caps
> adjacent to IC power pins is significantly better than putting them an inch
> or so away on the power rail, near the ends of ICs.  I'd appreciate any
> comments in this regard.  If it looks like this would make a significant
> difference, then I might have to change my ways...
>
> Cheers,
> Dave

Well,  if you want something to _look_ at...

My Tek scope came with detachable ground leads for the probes,  of two 
different lengths.  The longer one was convenient for a lot of stuff and the 
shorter ones for those times it made a difference.  Or you could omit that 
altogether and let the third prong of the power connector do the job,  at 
some risk to the quality of the waveform that you're looking at.

If you have a scope,  try looking at some waveforms at different points along 
the same trace,  or use different ground connections,  or similar stuff.  
You'll see a difference.

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
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