gEDA-user: buzzing board

[Steven Michalske]

take your 3.3 volt bench supply and bypass the 3.3v switcher.  i have  
heard others suggest this i think in the thread.
if the noise continues you know it is another source.

Steve

On Sep 13, 2007, at 11:58 AM, John Coppens wrote:

> On Thu, 13 Sep 2007 11:38:57 -0400
> DJ Delorie <dj at delorie.com> wrote:
>
>>> Did you cheap out on the inductor?
>>
>> Not that I'm aware of.  I used these:
>
> By far the most probable cause is the inductor. I've made quite a few
> switchers, and several of them caused problems. I'm not so preoccupied
> with the noise by itself, but more by the possibility this may cause
> chafing and shorts on the long haul.
>
> The buzzing may appear only if a certain load (lower _or_ higher) is
> placed on the supply, as the switcher frequency passes through some
> resonance in the windings (even they should ideally be impregated).  
> Even
> 'fixed frequency' switchers vary a little...
>
> John
>
>
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