[sdiy] Nice info on decoupling caps

[Harry Bissell]

Wow thanks for these links. I just got a real booster course in decoupling capacitor understanding.

Many of the things I read I knew to (or not to) do, but not why. Of great interest to me were the facts
that...

paralleling different value caps (like .1uF, .01uF, .001uF) is totally ineffective unless the smaller
value capacitors are physically smaller as well (with lower self inductance).  Often we like to place
similar packages on a PCB design, like all "0603" but now I see that I'm wasing my time and money if I do that !!!

Why they make "1206" and "0612" capacitors... even though they take up the same board space, the self inductance
of the (less widely used) "0612" package is WAY smaller than the more common "1206"

How different capacitor choices can introduce frequency dependent resonances that might well be affecting my
RF emissions testing !!!

WHY Y5U capacitors SUCK !!!  (we know they did, but did ~you~ know ALL the reasons why ? ... hint, its NOT just temperature stability...)

Why TANTALUM caps (with their higher ESR) might be better than the new, smaller, cheaper Ceramic caps). We  have become accustomed to
avoid Tantalum caps (high price, bad delivery, chance of assembly error...) but maybe we should INSIST from time to time...

New ways that bad SPICE models can fvck you up.  Some of these I suspect I have actually seen before, now I have more insights to get
a simulation that runs and possibly reflects reality !

HAH !   And I thought I was pretty knowledgeable about decoupling caps. Thanks, Achim... for posting these excellent links
and I hope that anyone who might understand them (even a little bit) gives them a read.  Take away even one point and your
time will be well spent !

H^) harry



----- Original Message -----
From: ASSI <Stromeko at nexgo.de>
To: synth-diy at dropmix.xs4all.nl
Sent: Fri, 20 Jan 2012 14:26:08 -0500 (EST)
Subject: Re: [sdiy] Nice info on decoupling caps

On Thursday 19 January 2012, 11:21:41, Tim Parkhurst wrote:
> A nice little intro on decoupling caps for the uninitiated. Some good
> links for more info at the bottom of the article too:

And some that go much deeper into the why and how (including how to bypass a 
single transistor if the need arises):

http://eetimes.com/General/PrintView/400995
http://eetimes.com/General/PrintView/4009955
http://eetimes.com/General/PrintView/4009958
http://eetimes.com/General/PrintView/4009985
http://eetimes.com/General/PrintView/4015857
http://eetimes.com/General/PrintView/4015858
http://eetimes.com/General/PrintView/4015862
http://eetimes.com/General/PrintView/4015864
http://eetimes.com/General/PrintView/4015865
http://eetimes.com/General/PrintView/4015867
http://eetimes.com/General/PrintView/4009596

When you haven't been bitten by a problem a good number of experts talk 
about (and make their living from) it usually means you were lucky so far 
and very seldomly that it doesn't exist.


HTH,
Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

Samples for the Waldorf Blofeld:
http://Synth.Stromeko.net/Downloads.html#BlofeldSamplesExtra

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-- 
Harry Bissell & Nora Abdullah 4eva