LTSpice simulation not jiving with calculations

Discussion in 'Homework Help' started by metalimi, Aug 30, 2017.

  1. metalimi

    Thread Starter New Member

    Dec 19, 2016
    2
    1
    Hello,

    I am stepping through a tutorial on series RLC circuits located here:

    http://www.electronics-tutorials.ws/accircuits/series-circuit.html

    and am trying to simulate the simple RLC circuit displayed. The tutorial (and my calculations) state that there should be roughly 5.14A running through this circuit, however my SPICE simulation states that the max current drawn is 4.9A (see attached). I verified that all of the parasitic values for the source, capacitor, inductor, and resistor are set to 0. What am I missing here?
     
  2. ericgibbs

    Moderator

    Jan 29, 2010
    6,267
    1,194
    hi met,
    Please post your LTS asc file so that we can compare results.
    Eric
     
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  3. WBahn

    Moderator

    Mar 31, 2012
    23,214
    6,999
    I get the same 5.14 A as the peak current. You are looking at the waveform well enough along so that any transients should be long dead.

    It looks like you don't have a lot of samples near the peaks, so you might try reducing the time step on the transient simulation and see if that makes a difference.
     
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  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    8,857
    2,079
    Set the Maximum Time Step to 1u and you'll get closer to the theoretical value.
     
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  5. metalimi

    Thread Starter New Member

    Dec 19, 2016
    2
    1

    Yep! This was the problem! I decreased the stepsize by two orders of magnitude, and now I see the theoretical numbers! Silly mistake. Thank you all!
     
    wayneh likes this.
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    8,857
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    Not really a mistake: just one small part of the learning curve :).
     
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