andy_c;177423 Wrote: > I noticed from your pics that the ground lead of the scope looks like a > clip lead (though it's hard to tell). What I've found in measurements > of mixed analog and digital systems (military applications) is that if > you try to measure the noise in the analog section with a probe having > a ground wire of just a couple of inches, you'll get greatly > exaggerated pickup of digital noise. The cure is to use a probe that > has two pins at the end. The first pin is of course the signal, and > the second is a spring-loaded ground pin that sticks out a bit further > than the signal pin. If you use such a probe, I think you'll find that > your measurement shows considerably less pickup than what you get with a > flying ground lead. I think the reason is that the loop formed by the > ground lead causes pickup of magnetic fields from the digital circuitry > such as clocks and other nasties.
Thanks for the advice! I did check for noise pickup by grounding the signal pin to the ground wire. Of course the impedance at the measuring point won't be zero, so that probably wasn't all that useful. If it is pickup, then I suppose making the loop smaller should alter the amplitude of the noise? (As a means of testing where the noise comes from.) Rgds -- P Floding No, I didn't ABX it. And I won't even if you ask me. (Especially not if you ask me.) ------------------------------------------------------------------------ P Floding's Profile: http://forums.slimdevices.com/member.php?userid=2932 View this thread: http://forums.slimdevices.com/showthread.php?t=32372 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
