[sdiy] power woes

[Travis Shire]

The switcher may cause gnd loop hum if its referenced to earth gnd and what 
you're using it with is not. I just went thru this with an inline switcher I 
bought for use with Univibe clone pedals. My amps inputs are not chassis 
grounded and I got all kinds of noise and bizarro behavior that way. I ended 
up ditching that and using a wall wart supply (still of inline design) with 
an external regulator. Problem solved. The transformer based ones can cause 
hum because they're not all that well filtered and unregulated. Maybe try an 
AC output version and use bridge rectification, stiff filtering and a 
regulator.



> 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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