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Filter resistor wattage

  1. Aug 6, 2009 #1
    In a filter where 1/4 watt resistors is enough would the filter be less noisy if I use 1/2 watt or more or should I use the least wattage resistors needed?
     
  2. jcsd
  3. Aug 6, 2009 #2

    berkeman

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    Staff: Mentor

    The size of the resistor will not generally affect its noise. The construction may affect it (carbon composition versus metal film), but I haven't looked at that in a while.
     
  4. Aug 6, 2009 #3

    berkeman

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    Staff: Mentor

    Did a quick google search, and found this interesting article on resistor noise and composition:

    http://www.aikenamps.com/ResistorNoise.htm [Broken]

    .
     
    Last edited by a moderator: May 4, 2017
  5. Aug 6, 2009 #4
    You have two common catagories of resistor composite or metal. With surface mount parts, the composites are your referred to as thick film.
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    Metal will be called out as "thin film," metal film, or wirewound.
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    When you have little to no current flow through the resistor, thermal noise will likely dominate, and you're not likely to see a benefit of one over the other.
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    However, when you apply current, composite resistors become very noisy due to the irregular grains and contact transitions. Metal resistors remain very quiet though.
     
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