[sdiy] 4069 vco gives v+ noise? - one last question

[Magnus Danielson]

From: Karl Ekdahl <_nial_ at yahoo.com>
Subject: Re: [sdiy] 4069 vco gives v+ noise? - one last question
Date: Thu, 15 May 2003 02:19:39 +0200 (CEST)

> Thansk to everyone who helped me with this problem, i
> temporarily changed my transformer to a 22v center tap
> that i found, so now it's working again!
> 
> I'm going to build a whole new powersupply based upon
> the information i've got from all of you so i might as
> well ask one last question that i've been thinking
> about; What the heck is separate grounds? I've read
> everywhere that i should have one "analog" and one
> "digital" ground. Could anyone please give me a short
> definition on how this works?

The point is that you want to keep the noisy part of the design (that digital
stuff) as separate as possible from the more noise-sensitive analogue parts.
One trick is to use a star style of powerfeeds, so at the powersupply they are
tied together, but on the board they run separately.

Cheers,
Magnus - who is impossible with numbers in my head late at night