[ARC5] mike current

[mac]

These things have been around for over 100 years now and there gotta  
be a large body of science and art out there in the technium on the  
composition, manufacture, etc. of just the carbon granules not to  
mention the microphone elements themselves.  I've observed a wide  
variation in the external characteristics (at least) of the elements  
found just in the venerable T-17 not to mention the many thousands of  
telephone, broadcast and other microphone elements that proceeded (and  
followed) it.   Browsed around on Google a bit and didn't find too  
much except for a reference to a 1934 paper that seemed to say that  
the interaction between granules in response to sound pressure is a  
simple make-break action, i.e., the element resistance overall  
decreases with increasing pressure because more granules come into  
contact with each other, not because increased pressure between  
individual granules lowers the resistance of the individual contacts.   
Anyone have a good reference(s) in this area?

Dennis D.  W7QHO
Glendale, CA