From: phil_a@tpg.com.au   
      
   "John Byrns" "   
   >   
   > It's interesting to note that 1950s, 1960s, and 1970s Telephones used to   
   > be full   
   > of varistors, both for protective purposes, and for regulating and   
   > controlling   
   > the speech level.   
      
      
   ** More likely called " VDRs"  ( Voltage Dependant Resistors ) and not   
   varistors or MOVs.   
      
   Although in the same general category, they are not identical.   
      
   Most modern MOVs are made from Zinc oxide, which gives them very low leakage   
   currents and sharper turn on characteristics compared to other types like   
   the older Silicon carbide VDRs.   
      
      
      
      
   ....  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)