Hunting down transformer EMF's

redrabbit · 24th August 2008, 01:30 PM

(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=

jackinnj · 24th August 2008, 01:41 PM

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

redrabbit · 24th August 2008, 03:34 PM

perfect, thanks!!

=RR=

jackinnj · 26th August 2008, 02:42 PM

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

AndrewT · 27th August 2008, 11:02 AM

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?

SY · 27th August 2008, 11:03 AM

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.

AndrewT · 27th August 2008, 11:16 AM

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.

SY · 27th August 2008, 11:30 AM

I'm using Reader 8. Both files opened and saved without incident.

jackinnj · 27th August 2008, 12:12 PM

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".

redrabbit · 27th August 2008, 07:12 PM

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 .)

=RR=

24th August 2008, 01:30 PM	#1
redrabbit diyAudio Member Join Date: Oct 2004	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=

27th August 2008, 11:30 AM	#8
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	I'm using Reader 8. Both files opened and saved without incident. __________________ If there's a sucker born every minute, where do the rest of them come from?

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24th August 2008, 01:41 PM	#2
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	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

24th August 2008, 03:34 PM	#3
redrabbit diyAudio Member Join Date: Oct 2004	perfect, thanks!! =RR=

26th August 2008, 02:42 PM	#4
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	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

27th August 2008, 11:16 AM	#7
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	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.

27th August 2008, 12:12 PM	#9
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	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".