[sdiy] Why dual grounds?

[David Ingebretsen]

This makes sense, thanks.

So keep the two grounds separate on the PCB and connect them at the PSU, (as
you answered in your other reply).

It's just nice to have some understanding as to why.

Thanks again JH.

David

~~ -----Original Message-----
~~ From: JH. [mailto:jhaible at debitel.net]
~~ Sent: Tuesday, June 08, 2010 11:39 PM
~~ To: David Ingebretsen; 'synth diy'
~~ Subject: Re: [sdiy] Why dual grounds?
~~ 
~~ > No other module has two separate grounds.
~~ 
~~ My PCBs often also have separate GND paths, even if they are not clearly
~~ marked as such.
~~ In a sensitive analogue circuit, you *must* separate "Dirty GND" and
~~ "Clean
~~ GND" to some degree, in order to keep your signals - which are voltages
~~ *between*(!) signal trace and GND trace - clean. This doesn't necessarily
~~ mean star-grounding at the PSU (which I suppose is what Steiner did), but
~~ it
~~ really means to keep clean and dirty apart.
~~ Having completely separate GNDs a bit like right hand for food, left hand
~~ for you know what. A good approach.
~~ Not completely separate GNDs means more care must be taken on cleaning,
~~ i.e.
~~ decoupling to the right points, etc. :)
~~ 
~~ JH.