Help with function gen.

Discussion in 'General Electronics Chat' started by Nathan Hale, Dec 30, 2012.

  1. Nathan Hale

    Thread Starter Active Member

    Oct 28, 2011
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    2
    Does anyone here know why a function generator would output a sine wave that is very "bouncy". By being bouncy i mean the amplitude of the sine wave is constantly changing from 2.8 volts to 3.2 volts to 3 volts almost every second.
    I am performing a simple low pass and high pass ac filter experiment in my home and am worried the numbers might be way off due to this phenomenon.
    What can i do to fix this problem? Thank you for all the replies.
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    How do you measure the amplitude?
     
  3. #12

    Expert

    Nov 30, 2010
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    Could be as simple as a crusty solder joint.
     
  4. Nathan Hale

    Thread Starter Active Member

    Oct 28, 2011
    125
    2
    i have a Digital oscope that does it for me.
     
  5. #12

    Expert

    Nov 30, 2010
    16,322
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    If you know enough to be safe about it, open up the case and start poking things with a plastic rod. Tap the board or case and see if it responds to vibration. Only if that fails, start measuring to see where the instability resides.
     
  6. mlog

    Member

    Feb 11, 2012
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    Is there a potentiometer that controls the amplitude? If so, look for a 'flaky' pot.
     
  7. Jaguarjoe

    Active Member

    Apr 7, 2010
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    Where is the sinewave coming from? A LP&HP filter combination by itself does not make sines. What is the source? Maybe it's bobbling up and down.
    The LP and HP are in series, can you divide and conquer?
     
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