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Need help, Series RLC resonance circuit, not getting high voltage!

  1. Mar 21, 2013 #1
    Hi all.

    I am currently building a series RLC circuit as a magnetic field transmitter. Because I want to have a strong magnetic field, I need high voltage by making the circuit at resonance.
    Here are the parameter I used:
    L:1.15mH
    R: 50 (internal resistance from functional generator )+ 0.58 (from inductor)
    C: 1 nf.

    Using equation the equations w0=1/sqrt(LC), and Vc= Q Vs= 1/R*sqrt(L/C)*vs,
    w0=148kHz, and Q=21.2V, and Vs=5V(square wave), so voltage across capacitor should be around 108 V rms.

    But using the oscilloscope, the V pk-pk voltage measured is only about 60 V, Vmax is about 20V.

    So, why am I not getting the calculated result?
     
  2. jcsd
  3. Mar 21, 2013 #2

    Simon Bridge

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    A square wave is not a pure signal is it?
    What happens when you put a range of frequencies into a resonator?
    It could also be that your voltage source cannot provide more than 20V.
     
  4. Mar 21, 2013 #3

    Thank you for your reply
    The source is square wave, and it's jumping from 0 V to 5V. But the resonance voltage across the capacitor should be 5*Q=108V rms. One possiblity is that the functional generator doesn't provide that much current.
    Besides that,
    I don't know why my circuit doesn't know. Do you have any idea.
     
  5. Mar 21, 2013 #4

    Simon Bridge

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    You are going to be restricted by the available power yes.
    Have you tried driving the circuit with a sine wave?
     
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