Did you have another note you were referring to that I missed?
Charles R. Patton
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Charles R. Patton, Sr. Princ. Eng
fon: 949-932-7476 fax: 949-932-7314
Western Digital Corp.
8105 Irvine Center Dr.
Irvine, CA 92618
Douglas C. Smith wrote:
> Hi Charles,
> Interesting thought, however the current probe should be well shielded
> if constructed properly and as such would not respond to E fields on
> the conductor. Not sure if I am missing something.
> What I am measuring is just the series drop along the wire. The
> voltage between the wire and ground or the probe should not affect the
> Does this seem reasonable?
> "Charles R. Patton" wrote:
> > Doug,
> > I have a question re your "voltage measurements using a current probe"
> > after looking at the tech note. It would seem to me that the method is
> > suspect as it is exactly the same configuration as used for directional
> > couplers. So if there is an accompanying voltage swing, as there would
> > normally be for most signal wires, then how would you avoid confusing
> > the capacitive voltage coupling from the inductive di/dt coupling? It
> > would seem that twisting the probe 180 degrees would discern that the
> > effect is taking place, just as it does in directional couplers (i.e.,
> > Bird wattmeters) but without knowing the voltage/current ratio on the
> > line (in effect the line impedance) then I would guess that it would be
> > hard to extract the two simultaneous effects.
> > Sincerely,
> > Charles R. Patton
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