Diy planarspeakers

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Hi båndsei

I understand what you mean but you must use both drawings.
If you look to the first drawing you see clearly how the flux lines are running.
You must be in the flat horizontal flux lines with your aluminum.
Then if you look to the second drawing you know that in the first 10mm is the magnet so then begins the gap and it ends 10mm further.
This are the lower part of the graphs which is normal.
So you have to concentrate on that part of the graph.
And you see when you decrease the gap the flux gets higher in that part of the gap.

Rob
 
Hi Rob.

[URL=http://img695.imageshack.us/my.php?image=billede392.jpg][IMGDEAD]http://img695.imageshack.us/img695/7532/billede392.jpg[/IMGDEAD][/URL][/IMG

On this graph the magnets are placed where the graph shows 0,and and the strong field,where the "wires" are placed goes up and down, or + and - .
As i see it, you and i see it the same way but ,"my" graph shows it better and have an accurate reading of the field strength in the place and direction the "wires".
Hope it makes sence to your.


Bernt "båndsei"
 
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my.php

Ithink it shows the shape too. In my simm. it is shown in a distance of 2,5mm. to the magnets.
The picture abowe is with 4 magnets placed N-S-N-S.
my.php

This one shows how the field "colapses" as the distance betwine the magnets is too wide.(20mm.)
I could show a graph with one magnet.
my.php


Tinitus .It is interesting with your experiments with copper plates,it can be simmulated in FEMM. too.
 
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Ex-Moderator R.I.P.
Joined 2005
Hey, heres some shots of my magnet system

Though it is intended for a ribbon, its still the same magnet design as used in planars
 

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Hi again

For Femm simulations look at;

Magnet felt oversigt

click on the links and note how smooth the field is

Båndsei - you need to increase the number of points in the femm simulation

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.
 
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Ex-Moderator R.I.P.
Joined 2005
How is the magnets magnetized .. thru the sides ! ....shouldn't the wide sides be for the field !!!!

No, through the thickness

Field lines meet around the edges
And the field also strongest there, or just 1mm in front of magnets

Its easy to test with a small metal pin
You can actually feel the shape of the field
And its easy to feel when it gets weaker or stronger

The beauty of this motor design is that you can make it stronger by using similar relatively flat magnets, just wider
And field will still go from its edges

That said, it probably only work real well for ribbons, and small planar tweeters

With big planars you will experience dead zones directly in front of the magnet
Thus it makes little sense to choose wider magnets

With planars I think you need to be much more creative with the magnet/motor design
 

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