[sdiy] PCB layout question

[David G. Dixon]

Paul,

Perhaps you can enlighten us, then, on the delicate art of seasoning pcbs
with bypass caps...?  Please, help us to parse our power-rail punctuation!

David G. Dixon
Professor
Department of Materials Engineering
University of British Columbia
309-6350 Stores Road
Vancouver, B.C.  V6T 1Z4
Canada
 
Tel 1-604-822-3679
Fax 1-604-822-3619
 
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-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Paul Perry
Sent: Saturday, November 01, 2008 5:00 PM
To: Synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] PCB layout question

Bypass caps are like commas in writing, or salt in cooking.

Some people sprinkle them in at random, hoping it will help somehow.
Others, who understand their function, know exactly when and where they are
needed.
Incidentally, while it is true that the bypass caps might not appear to make
much difference at audio frequencies - sometimes if you leave them out, you
will find RF oscillations! Unsurprising, with transistors having 200Mhz
cutoffs.

Is decoupling and bypassing a black art? Yes, if you do it in the dark.

paul perry Melbourne Australia

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