[SI-LIST] An unusual use for comb generator

From: Doug Smith <doug@xxxxxxxxxx>
To: emc-pstc <emc-pstc@xxxxxxxx>, SI-List <si-list@xxxxxxxxxxxxx>
Date: Sun, 09 Aug 2009 20:22:15 -0700
 Hi Everyone,
It's time for me to post a new Technical Tidbit. This month's is:

The Square Shielded Loop - Part 6, Measurements in the Time Domain Using a
Comb Generator
(An unusual use for a comb generator)

Abstract: Possible sensitivity to electric fields/capacitive pickup has been
a factor in the past in selecting shielded magnetic loops over unshielded
ones. Data is presented to show that in the near field, shielded loops may
berequired for sensing signal currents in some cases. Data presented in
priorTechnical Tidbits have shown the opposite to be true for other cases.

It turns out both types of loops have problems in the near field and care
must be used. Shielded loops have a nasty resonance with the circuit under
test and unshielded loops can have capacitive pickup under some conditions.
Two Technical Tidbit articles on the resonance of shielded loops are:

http://emcesd.com/tt2008/tt060208.htm[1]
and
http://emcesd.com/tt2008/tt080108.htm[2]

Separately, I used a "comb generator" to generate the pulse for this
Technical Tidbit. It is unusual to use a comb generator as a pulse generator
in the time domain, but it worked quite well for this experiment.

Doug
-- ------------------------------------------------------- ___ _ Doug Smith
\/ ) P.O. Box 1457 ========= Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX:
408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-----( ) | o |
Email: doug@xxxxxxxxxx[3] \ _ / ] \ _ / Website: http://www.dsmith.org[4]
------------------------------------------------------- 

--- Links ---
   1 http://emcesd.com/tt2008/tt060208.htm
   2 http://emcesd.com/tt2008/tt080108.htm
   3 mailto:doug@xxxxxxxxxx
   4 http://www.dsmith.org
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[SI-LIST] An unusual use for comb generator

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