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Old 24th August 2008, 01:30 PM   #1
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Default Hunting down transformer EMF's

(Transformer magnetic fields)
In a Linear app note, Jim Williams mentions....

""An RF choke connected across a scope probe can determine the presence and relative intensity of transformer fields, aiding layout experimentation.""

Linear Technology AN-9 (page 3)

Can anyone explain a bit more on how to do this ?
(coil type, size)
(what to look for on the scope, etc)

thanks,
=RR=
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Old 24th August 2008, 01:41 PM   #2
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search "Electromagnetic field sniffer" -- there are commercial probes, hall effect sensors -- folks have used parts of disk-drives, etc., etc.

Here's a "how-to" found on EDN:

http://www.edn.com/archives/1998/060498/12DF_04.pdf
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Old 24th August 2008, 03:34 PM   #3
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perfect, thanks!!

=RR=
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Old 26th August 2008, 02:42 PM   #4
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I had this article printed out and found it yesterday -- reads Gauss directly with an Allegro linear Hall effect sensor -- the author gives a method of calibration:

http://www.edn.com/contents/images/6399102.pdf
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Old 27th August 2008, 11:02 AM   #5
AndrewT is offline AndrewT  Scotland
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Quote:
Originally posted by jackinnj
search "Electromagnetic field sniffer" -- there are commercial probes, hall effect sensors -- folks have used parts of disk-drives, etc., etc.

Here's a "how-to" found on EDN:

http://www.edn.com/archives/1998/060498/12DF_04.pdf
Jack,
my Adobe reader cannot open this file nor the other pdf.
What do I need to do?
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Old 27th August 2008, 11:03 AM   #6
SY is offline SY  United States
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Quote:
Originally posted by AndrewT

Jack,
my Adobe reader cannot open this file.
What do I need to do?
Get a better version of Acrobat.

Worked fine for me.
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Old 27th August 2008, 11:16 AM   #7
AndrewT is offline AndrewT  Scotland
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I'm on acrobat 7.0 and have just downloaded and installed the only update it offered.
It still can't open either of those pdf files.

DaM_2005_4.pdf opened OK.
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Old 27th August 2008, 11:30 AM   #8
SY is offline SY  United States
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I'm using Reader 8. Both files opened and saved without incident.
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Old 27th August 2008, 12:12 PM   #9
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Andy, PM me and I will send you the PDF -- are you using Mozilla as your browser?

Adobe is now mostly "bloat-ware" and "lurk-ware".
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Old 27th August 2008, 07:12 PM   #10
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Quote:
Originally posted by AndrewT

Jack,
my Adobe reader cannot open this file nor the other pdf.
What do I need to do?

Must be interference from electromagnetic fields.
You'll need to make a "field sniffer".
Catch 22.



Regarding the first EDN article mentioned earlier....
http://www.edn.com/archives/1998/060498/12DF_04.pdf

Am I interpreting it correctly, about the "cuts" that needs to be made ??
(I came up with an alternative method, if I can't find a thin enough saw blade....two pieces are cut, held in place at the proper distance, then soldered .)

Click the image to open in full size.

=RR=
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