Spice Help

Discussion in 'Homework Help' started by Steve1992, Aug 13, 2006.

  1. Steve1992

    Thread Starter Senior Member

    Apr 7, 2006
    100
    0
    Hi,

    Ive download a demo of 5Spice Analysis to help with my basic circuits.

    Why do I get this message?:

    ERROR: Iteration Limit Reached
    DC Operating Point Failure

    The help section just sends me in circles:confused:
     
  2. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
    4
    The message, in this instance, means that it failed to calculate the DC biasing point of the circuit after a specified number of iterations. Iterations are used in linearising the circuits.

    Simply, it means that you need to set an initial condition for one of the net in the oscillator loop. SPICE is easily confused when it encounters an oscillator loop and it fails to determine the initial conditions because of the parameters inter-dependencies.
     
  3. Steve1992

    Thread Starter Senior Member

    Apr 7, 2006
    100
    0
    n9352527,

    Could you please be more specific?
    If you drew this circuit what would you do to make it operate.

    Im thinking of downloading Electronic Workbench.
    Ive used an early version, where its possible to interact with the
    simulation while its running. eg pressing [space] to toggle switch.



    Steve
     
  4. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
    4
    Well.. you need to put an initial condition (.IC) at one of the net in the loop (e.g. the input of U1, left most) and set the .IC to the possible value (e.g. 0V). That should take care of the problem.

    Read your SPICE manual to find out how to put an .IC.
     
  5. Steve1992

    Thread Starter Senior Member

    Apr 7, 2006
    100
    0
    Runs ok now,
    Thanks.




    I didnt go to High School,
    I went to School High
     
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