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Help with Microsim Pspice

Discussion in 'Electronic Design' started by anand, Nov 5, 2006.

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  1. anand

    anand Guest

    Hi,

    I am currently learning the Microsim PSpice Evaluation version 8.In the
    transient analysis of circuits,I am unable to remove the initial
    conditions in the .tran statement.I get the same result in the probe
    analysis for the circuit even when the "UIC" or "SKIPBP" commands are
    not included in the .tran statement.I am not sure if I am missing some
    other fundamental part in the program which leads to this problem.I
    would be grateful if someone could help me out.

    Thanks,
    Anand
     
  2. Jim Thompson

    Jim Thompson Guest

    You don't provide enough information. Netlist at minimum... schematic
    (on ABSE) preferred.

    ...Jim Thompson
     
  3. anand

    anand Guest

    Hi,

    Thanks for your reply.This is the program I picked up from a PSpice
    basics tutorial book.It is a basic RL circuit with a current pulse
    source.I have defined the initial conditions for the current in the
    inductor in both cases.In the first part of the program,I do not
    consider the initial conditions on the inductor and in the second
    part,I make use of the initial conditions on the inductor.The problem I
    have is the graph I plot using probe gives me the same result for both
    cases.The initial current in the inductor for both cases starts from
    2.5,when in the first case,it should start from zero.

    R-L circuit with pulse source and no IC
    Is 0 1 PWL 2,0 2.01,4 5,4 5.01,0
    R10 1 0 5
    R12 1 2 5
    L20 2 0 20 IC=2.5
    ..tran 15 15
    ..probe
    ..end
    R-L circuit with pulse source and IC
    Is 0 1 PWL 2,0 2.01,4 5,4 5.01,0
    R10 1 0 5
    R12 1 2 5
    L20 2 0 20 IC=2.5
    ..tran 15 15 UIC
    ..probe
    ..end

    I do not know if I have misunderstood the concept of the UIC command as
    the book does not explain the command or the program in detail.I even
    tried substituting the "SKIPBP" command instead of "UIC" and still got
    the same result.I would be grateful if you could help me out.

    Thank you,
    Anand
     
  4. Jim Thompson

    Jim Thompson Guest

    [snip]

    L20 has an "IC", irrespective of your UIC command.

    Also, lose the commas as delimiters, they can confuse some netlisters.

    ...Jim Thompson
     
  5. Genome

    Genome Guest

    Seems strange.... The implication is that UIC (Use Initial Conditions)
    should be substituted with IIC (Ignore Initial Conditions).....

    DNA
     
  6. Jim Thompson

    Jim Thompson Guest

    There IS some discrepancy in the notation...

    IC conditions on components seem always to be used.

    ...Jim Thompson
     
  7. anand

    anand Guest

    Hi,

    Thanks.I will remove the "IC" command for the first case.

    Anand

     
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