[sdiy] Distribution board bypass caps?

[James Coplin]

All the boards are on their own run back to the supply (a Power-One so a
good one) on 14 gauge stranded.  I have the supply under the desk and the
longest run would probably be 4' - 5'.

James R. Coplin

-----Original Message-----
From: Oscar Salas [mailto:osaiber at yahoo.es]
Sent: Tuesday, January 17, 2012 12:10 PM
To: James Coplin; Synth DIY List
Subject: Re: [sdiy] Distribution board bypass caps?

Yes , good question, I'm also thinking about it these days.

I think that must be considered the resistance of the cable that connects
the power supply to the board, and also the resistance of the traces of
the board, if connectors are placed as a bus.

For example if Distribution Board
is close to the Power Supply and the cables are short and thick, so low
resistance, it will no needed decoupling capacitors at all.

In the other hand if cables are
long and thin, so a considerable resistance, maybe you will need big
filter capacitors in order to avoid any noise, or undesired signal in the
audio range, looping through the modules to the distribution board.

Also must be considered that big
capacitors will increase or create inrush current. However if cables have
considerable resistance, they will limit it.

So I think that the idea is, to more (power supply to distribution board)
cable resistance, more big capacitors.

This is my thought.

More ideas?





----- Original Message -----
From: James Coplin <james at ticalun.net>
To: Synth DIY List <synth-diy at dropmix.xs4all.nl>
Cc:
Sent: Tuesday, January 17, 2012 5:51 PM
Subject: [sdiy] Distribution board bypass caps?

If I have a distroboard for 10 5u modules, what would be the "correct"
size for bypass caps?  I don't know what the exact draw of the modules
will be so I need something to reasonable cover a "typical" case.  The
supply is a 3A supply and there will be 4 distro boards total in the
system although as some modules are double width, I'll never have 40
modules installed.

James R. Coplin
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