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Loading of Series vs. Parallel tank circuits

  1. Aug 2, 2006 #1
    Hi All,

    I have a few questions about resonant circuits when they are loaded. Let’s say that we have a simple series LC circuit and a simple parallel LC circuit driven by a function generator at frequency X. If there is one coil that is inductively coupled to the coil of each circuit and a load of X ohms is placed on each coil, how will the two circuits respond to the load?

    From what I understand so far when I series LC circuit is driven at resonance, the source sees it as a dead short (plus whatever resistance there is) and the parallel circuit will not let as much power from the source through at resonance (please correct me if I got something mixed up here). But what happens in the case that the inductive load is placed on each circuit when they are driven at resonance? (assuming that they are not knocked out of resonance by the load).

    Jason O
  2. jcsd
  3. Aug 4, 2006 #2


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    In a series resonant circuit, you put the load in series with L and C. At resonance the LC behave as a short and the source sees only the resistive load.
    Ina parallel circuit, the load is in parallel with L and C. At resonance the LC behaves as an open circuit and again the source sees only the resistive load.
    If you use an inductive load coupled with the primary inductance this will alter the resonant frequency, but the circuit will still behave in the same manner.
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