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Old 25th September 2008, 03:56 AM   #1
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Default How to use FEMM?

I'm trying to build a very small high-excursion ribbon driver for headphone use, and I've been having a dickens of a time trying to figure out how to use FEMM. Anyone have a good tutorial?
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Old 25th September 2008, 06:55 PM   #2
el`Ol is offline el`Ol  Germany
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Unfortunately German, but this helped me a lot:
http://www.michaelgaedtke.de/SubMenu...M-Tutorial.htm
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Old 25th October 2008, 11:20 AM   #3
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If you run it through Google translate , most of it is understandable. If you have any more questions - shoot away.

One thing to remember is to get as much triangulation (nodes) in the gap as possible, it seems that the topic is covered in the tutorial. But I remember I learnt the hard way when I thought I had designed the perfect motor but I had just two triangles in the gap so it wasn't true at all...
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Old 25th October 2008, 05:49 PM   #4
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I found the Yahoo Group for FEMM to be a valuable resource. They have (or had..been a while since I looked) a tutorial in English in the files section, and the guy who wrote the program is the moderator...

http://tech.groups.yahoo.com/group/F...ec=group&slk=1

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Old 7th April 2009, 06:21 AM   #5
jaya000 is offline jaya000  India
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Anybody uv simulated loudspeaker magnet assembly?
If yes, then how about giving guidance to fellow members here.
waiting for response.
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Old 7th April 2009, 11:29 AM   #6
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Hi Jaya000

UV as I understand is short for ultraviolet, do you mean something else? I use FEMM for simulating loudspeaker magnet assemblies, I'm happy to answer any questions that I think I can answer.
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Old 7th April 2009, 01:06 PM   #7
jaya000 is offline jaya000  India
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Sorry Andrew Steele.
I mean to say hv & not uv.
Typing mistake.
Hope u understand
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Old 7th April 2009, 01:30 PM   #8
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What is HV?

If you could use full words and not abbreviation it might help.

I understand these are some common things you would simulate in a speaker motor with FEMM -

(B) - Tesla - A unit of measure for the amount of magnetic energy/force.

Bl - The sum of (B) multiplied by the length in meters of the voice coil in the gap. This measure is commonly presented in Thiele-Small parameters.

Xmax - not so much FEMM but can calculate where Bl drops to 80% of original Bl.

There are more things you can do. But if you can try to explain a bit more possibly someone can help.
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Old 7th April 2009, 02:43 PM   #9
el`Ol is offline el`Ol  Germany
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A short description:
File New - magnetic or electrostatic problem
Problem - define units, planar/radial
Grid Set Grid - define grid size (units per dot)
Grid Snap to Grid - defined points are aligned with grid dots
set points (with mouse)
select line icon
define lines by selecting two points
Properties Material Library
select materials by drag and drop to the right side
strange green icon is the material marker
set markers with mouse (better with deactivating snap to grid)
select marker with right mouse button
press blank on the keyboard
dialog opens, let femm choose mesh size is only recommended for air, 0.5mm is good for usual audio devices (you have to draw a frame around everything and label the inside with air)
File Save
yellow botton is for creating mesh, the wheel for calculation and the glasses for viewing
in the viewer press the colour icon and select "show density plot" to get everything nice and colourful
with the line icon you can draw a line and display a graph of the flux density over its length (typically define extra points in the editor before calculation)
press the blue graph icon for showing the graph
exporting pictures is done with Copy Paste
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Old 7th April 2009, 04:23 PM   #10
jaya000 is offline jaya000  India
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Thanks Andrew Steele & el`Ol,
I want to simulate magnet assembly of loudspeaker.
Many of us must have done it.
I just want the info to get started in FEMM.
Initial settings, selection of properties & analyzing magnetic flux bl linearity etc.
more info will help to learn more.
waiting for guidance from gurus here.
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