[sdiy] power woes

[Tom Corbitt]

Not trying to dodge the question, but what I'm reading tells me that
you your design needs more more to be tolerant to both low (hum from
linear supplies) and high frequency (whine from switchers) noise
inputs. You're trying to fix a internal problem externally.

If you spend some time making sure you handle filtering and RFI on
board, you can get away with using the cheapest PS you can find that
meets your specs. Always assume it's going to be garbage in.

Tom C.

On Sat, Mar 6, 2010 at 10:15 AM, dan snazelle <subjectivity at hotmail.com> wrote:
> Ok
>
> I am sitting here with a pile of DC adapters. (trying to find one to bundle with my products)
>
> half of them cause HUM, half of them cause a whine (switching)
>
> Only 2 out of the pile don't cause ANY noise
>
>
> One is a DUNLOP class 2, 60hz 7w, 9vdc 200ma adapter which is made in china and has a chinese model number of
>
> ad-0920
>
>
> i can find these online for $12-15 dollars a piece
>
>
>
> the other is one of the new BOSS switching adapters.
>
> (it costs 30 bucks!)
>
>
> one of the odd things is that some of the switching adapters or class 2 adapters have
> seemingly the same SPECS but cause different problems or noise
>
>
> SO...my question is whether anyone has any advice on DC adapters
>
>
> i might be able to get a bunch from dunlop but it still doesnt answer WHY some cause noise and some dont
>
>
> thanks so much!
>
>
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