As much as I'd like to take credit (for all good ideas), it was Scott Lacey's idea t use the bubble pack. Previously I thought it was only good for making designers panic when they are testing a new power supply and you sneak up behind them and pop a few bubbles!
Jim > -----Original Message----- > From: Doug Smith [SMTP:[email protected]] > Sent: Monday, June 21, 1999 2:48 PM > To: Lacey,Scott; 'Jim Eichner' > Cc: '[email protected]' > Subject: RE: Current probe problem > > Hi All, > > Jim has a good idea here. I have an experiment I use in presentations > that > shows the amount of an ESD current that couples onto a probe body > (Fischer > F-33-1) varies by about a factor of two depending how the lead is > dressed > as it passes through the probe, perpendicular through the center being > the > lowest. > > Doug > > > At 01:46 PM 6/21/99 -0400, Lacey,Scott wrote: > > > >In my opinion, letting the cable insulation touch the probe body is > never a > >good idea. I always try to "shim" the cable and probe in order to > center the > >cable within the probe opening. The trick is to keep the shims > outside of > >the probe. A good trick is to make a "V block" out of wood, with a > deeper > >center notch for the probe body. This insures good radial and axial > >alignment (for consistency) and also prevents the probe body from > touching > >the ground plane. > >Scott > > > > -----Original Message----- > > From: Jim Eichner [SMTP:[email protected]] > > Sent: Monday, June 21, 1999 1:10 PM > > To: EMC-PSTC > > Subject: RE: Current probe problem > > > > > > In his write up of the problem, Doug writes > > > > "If possible, current probes should be positioned on the > measured > >cable > > so as to minimize the potential between the cable and the > current > >probe > > body. This usually means locating the probe near the > ground/chassis > >end > > of a circuit." > > > > Following a tip from someone on this forum quite a while ago, I > have > > observed significant variation in the spectrum of noise along > the > >length > > of a cable. I have started doing my cable current measurements > by > > sliding the probe over the length of the cable, with my spectrum > > analyzer in max hold mode. I assume I get a "worst case sweep" > by > >doing > > this, as I pick up the worst of everything at any position on > the > >cable. > > > > > > Following Doug's advice above, or any instance of using a > current > >probe > > in a single fixed position, could result in the probe being > >positioned > > right at a null for a frequency of interest, sending you on a > wild > >goose > > chase looking for some other source. > > > > Does Doug or anyone else have similar experience or a better way > to > > overcome the problem? > > > > Regards, > > > > Jim Eichner > > > Senior Regulatory Compliance Engineer > > Statpower Technologies Corporation > > [email protected] > > http://www.statpower.com > > Any opinions expressed are those of my invisible friend, who > really > > exists, but can only be seen by my dog. Honest. > > > > > > > > > > > > > > > > > >--------- > >This message is coming from the emc-pstc discussion list. > >To cancel your subscription, send mail to [email protected] > >with the single line: "unsubscribe emc-pstc" (without the > >quotes). For help, send mail to [email protected], > >[email protected], [email protected], or > >[email protected] (the list administrators). > > > > > > > > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
