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previous: R.G. ... if you can believe this :ht... -- 9/12/2002 7:33 PM View Thread

Re: It looks like air cored...

9/12/2002 8:15 PM
Dr. Strangelove
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Re: It looks like air cored...
Sometimes very close. Yea, yer rite. I was confused.  
 
I dug up a a list of relative permeabilities so as to as to forestall any handwaving arguments I might initiate:  
 
1.000 - AIR  
1.034 - SmCo 20 MGOe  
1.048 - NdFeB 37 MGOe  
1.051 - Ceramic Ferrite 7  
1.103 - SmCo 27 MGOe  
1.110 - SmCo 24 MGOe  
1.178 - Ceramic Ferrite 6E  
1.223 - NdFeB 10 MGOe (Bonded)  
1.252 - Ceramic Ferrite 1  
1.269 - Ceramic Ferrite 8  
1.500 - Alnico 2  
1.500 - Alnico 5  
1.976 - Ceramic Ferrite 5  
3.300 - Alnico 6  
6.678 - Alnico 8  
 
SmCo = Samarium Cobalt  
NdFeB = Neodymium Iron Boron  
 
This suggests that A8 makes for a high inductance pickup, but you might not want to listen to it because the high coercivity would make it sound quite harsh.  
 
There are a lot of variations within Alnico 2's and 5's and you can never quite tell which unless you buttonhole the vendor's engineer. Even then, they won't guarantee B, Hc, and BHmax closer than 20%.  
 
Group Arnold has a good body of technical magnet info:  
 
<http://www.grouparnold.com/mtc/index.htm>  
 
-drh  
--

 
Replies:
WolfeMacleod Re:Alnico 8--Quite the opposite! -- 9/12/2002 8:22 PM
R.G. Bank and ortho winding and capacitance and... -- 9/12/2002 9:24 PM