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Monday, January 21, 2013

Swamping or Q-Killing


Sounds like some new TV series on the Discover Channel, doesn't it? Actually it refers to efforts to stabilize oscillators by reducing the Q of components that may be helping to turn the amplifier into an oscillator.   A 300 ohm resistor across the primary of the output transformer on my most recent version of the JBOT amplifier recently solved my instability problem.  As part of an effort to understand how and why I came across a CQ magazine article by Doug DeMaw.  The relevant passage appears above.  

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4 comments:

  1. I dont understand how connect the resistor across the primary. Please help me

    ReplyDelete
  2. I dont understand how connect the resistor across the primary. Please help me

    ReplyDelete
    Replies
    1. What kind of circuit are you working on? Please send me an e-mail -- that will make communication easier: soldersmoke@yahoo.com
      You can just solder the resistor to the two wires or terminals that extend out from the primary coil of the transformer. It might help. It might not. Give it a try.

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  3. thanks for your answer. I have sent emails. among other things I will consult on whether it is possible to use transistors 2N2218A instead of 2N2218. I ask because I measured the voltage across the resistance of 5 ohms and the four give 0.28 volts. They have blown? or is there something wrong with my components?

    ReplyDelete

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