Understanding an LC meter

Discussion in 'Homework Help' started by PetrutM, Jun 29, 2013.

  1. PetrutM

    Thread Starter New Member

    Jun 29, 2013
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    I have an assignment to characterize an LC meter . The Circuit is based on circuits that appeared in Dangerous Prototypes ,Phill Rice' Blog and the uC part of things is running on an atMega328p with code adapted from Kerry D. Wong
    [​IMG]

    I know the measurement works by comparing the oscillating frequency of the circuit using different components.
    My questions are: What type of oscillator is this, what are it's main characteristics and where can I find more info on this?

    Any additional info is welcomed.
    I plan on building this circuit but I first need to understand it.


    Thanks.
     
    Last edited: Jun 29, 2013
  2. PetrutM

    Thread Starter New Member

    Jun 29, 2013
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    Update:
    The oscillator seems to be some sort of a Wien Bridge Oscillator, but the square wave output giving me doubts about this idea. A look at the lm311 datasheet from TI gave me another starting point: A 100kHz Free running Multivibrator. the schematic seems similar.
    P.S. I know the circuit was disscused before in this thread but I couldn't find formal definitions of the type of oscillator used.
    Going on another lead kindly offered by Google (sorry for referencing to another forum ) here (the schematic link is dead). I'll try a LTSpice simulation but I'm running very short on time. (Project due Monday 1st of July )

    Edit:
    Ok so now i Know L1 and C6 form a Tank oscillator (Info from Here) . How does the LM311 affect this circut? Does it play a role in sustaining the oscillations?
    Stay tuned for another impressive update in the saga of the oscillator (Yes, I had to much coffee)
     
    Last edited: Jun 29, 2013
  3. PetrutM

    Thread Starter New Member

    Jun 29, 2013
    3
    0
    I think the word I was looking for all along was a Schmitt trigger, something that D. Wong did mention but I did not pay attention as I used a different front-end. Reading this helped (PDF warning)
     
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