[sdiy] filter cap needed?

[Simon Brouwer]

David G. Dixon schreef:
> In my (somewhat limited) experience with building electronic circuits, I
> have yet to detect any effect of adding or not adding 0.1uF bypass caps.  I
> have settled on the habit of adding one or two pairs of such caps to any
> circuit.  I generally try to line up my IC's so that they straddle a single
> pair of parallel power rail traces.  I typically put one pair of caps on
> either end of the string of IC's, very close to the rails.  I don't like
> cluttering up the areas in front of IC power pins with them, as this would
> complicate my PCB layout strategy.  I may add another pair between digital
> chips, but not usually between opamps.
>
> However, something has been troubling me about these caps: If several of
> them are connected between a rail and ground at various locations, wouldn't
> they end up fulfilling the same function as one cap, several times as large
> (given that they are capacitances in parallel)?
>   
If they are at different locations, there must be a conductor between 
them which has resistance and inductance.
So, for high frequencies, no they wouldn't .


-- 
Vriendelijke groet, 
Simon Brouwer. 

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