>Common beginner mistake, you're seeing the difference in grounds between
>teh scope and your board.  What you need to do is ground the scope probe
>to your project ground.  There are usually ground clips that attach to the
>probe and can clamp onto a ground on the board you're testing.  Need to be
>CAREFUL especially if your project is not battery powered, though.  8)
>Now I'm sure half a dozen people with more knowledge of how scope grounds
>are isolated will jump in with more detail...

        I just have a clip that goes from the scope, to the bench power supply=
 ground ;o) Works every time. Never had any problems with this setup, since=
 everything is powered thru the PSUs on the bench, and ALL the grounds of=
 ALL the supplies are grounded togheter in a "star" way.


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Alexandre Souza
taito@terra.com.br
http://planeta.terra.com.br/lazer/pinball/

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