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   sci.electronics.design      Electronic circuit design      143,102 messages   

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   Message 141,214 of 143,102   
   legg to christopher@librehacker.com   
   Re: coil impedance   
   13 Nov 25 08:01:33   
   
   From: legg@nospam.magma.ca   
      
   On Thu, 06 Nov 2025 10:25:11 -0900, Christopher Howard   
    wrote:   
      
   >In an coil with inductance and a distributed capacitance —   
   >neglecting resistance for the moment — do the inductance and   
   >distributed capacitance map over to the inductance and capacitance   
   >in a parallel LC circuit, or am I fundamentally misunderstanding   
   >something?   
      
   Interesting post on Linkedin, a short while ago, highlighting an   
   old audio amplifier trick. This was winding a low value inductor   
   around the body of an aluminum electrolytic can with vinyl insulated   
   wire - something you might have run into in Dynaco kit amplifiers,   
   as an example ('70s)   
      
   The <1uH schematic entry, in parallel with 10R, placed in series   
   with the output, was intended to prevent oscillstion driving   
   a capacitive load.   
      
   It was pointed out that the aluminum can presented a shorted   
   turn in that configuration.   
      
   With an air-cored inductor, the shorted turn didn't have the   
   same dramatic effect it might have had, if wound on a high   
   permeability medium, but did drop inductance by a factor of 3 - 5.   
      
   RL   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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