I agree with Robert's comment. Although your probe is rated for 100MHz, it sounds like your spike is well above it's differential operating range. I measure signals in switching power supplies, and find my (single-ended) probe measurements are vastly improved when I wrap the scope lead through a ferrite core.
Pat On Tue, 23 Mar 2004 13:13:18 -0600, "Derek Walton" <[email protected]> wrote: >To monitor the signal I'm using a 100 MHz Diff scope probe. I've twisted >the sense leads together to minimise coupling in that loop. > >Z in the circuit is really low.... > >Mind you, I have made no provisions for the wiring that charges the >energy ctorage cap. Maybe i should better tie thoese down. Since I'm >using a "change over" relay, I wonder if what I'm seeing is to do with >the cap ESR being too low.... I'm using Mica Caps. > >The spike I refer to looks just like the spike on an ESD waveform in the >IEC standards. > >Cheers, > >Derek. > >robert Macy wrote on 3/23/2004, 1:03 PM: > > > Make certain the signal is real and not an artifact. > > > > I once chased a signal for four hours before I discovered > > it was the scope ground "bouncing" ..well that, and other > > stuff. Differentially, the signal WAS NOT THERE. > > > > - Robert - > > > > Robert A. Macy, PE .. [email protected] > > 408 286 3985 . . . .. . . fx 408 297 9121 > > AJM International Electronics Consultants > > 101 E San Fernando, Suite 402 > > San Jose, CA 95112 > > > > On Tue, 23 Mar 2004 09:57:30 -0800 > > "Price, Ed" <[email protected]> wrote: > > > > > > > > > -----Original Message----- > > > From: Derek Walton [mailto:[email protected]] > > > Sent: Tuesday, March 23, 2004 6:53 AM > > > To: [email protected] > > > Subject: Tweaking a transient Generator > > > > > > > > > Good day all, > > > > > > I've been developing a damped sine generator to perform > > > the DO-160 lightning > > > test, and have had some reasonable success. However ( > > > there is always a > > > gotcha ), the leading edge of the 1 MHz ring wave has a > > > very short ( around > > > 10 nS ) spike on it. I have tried a number of things to > > > kill the spike, but > > > to no avail. Does anyone have suggestions on what causes > > > this, and ways to > > > eliminate it? > > > > > > I have strived to keep stray inductance small, very > > > small, maybe too > > > small..... > > > > > > The switch is a high voltage vacuum relay. > > > > > > -- > > > Derek N. Walton > > > L F Research > > > Poplar Grove, IL 61065, USA > > > > > > > > > > > > Derek: > > > > > > Why not put up a schematic, plus a couple of > > > multiple-angle photos, and give > > > us a link so we can see what you are doing? > > > > > > Ed > > > > > > Ed Price > > > [email protected] WB6WSN > > > NARTE Certified EMC Engineer & Technician > > > Electromagnetic Compatibility Lab > > > Cubic Defense Applications > > > San Diego, CA USA > > > 858-505-2780 (Voice) > > > 858-505-1583 (Fax) > > > Military & Avionics EMC Is Our Specialty > > > > > This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
