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LtSpice something, strange happenings.

Discussion in 'Electronic Design' started by Joerg, Sep 17, 2012.

  1. Joerg

    Joerg Guest

    Did you see a submarine plow up the Guadalupe River, with a Chinese
    flag? So maybe ...

    Just kidding. If it's any comfort, the voltages shown down there may not
    mean much. I am doing sims right now and when I hold the cursor to a
    node at the top of a 3.3V DC source the text down there reads zero
    volts. Of course it isn't real, in the display window later it shows
    correctly.
     
  2. Jamie

    Jamie Guest

    I don't use Ltspice or any spice that much however, last night I pulled
    something out of my old sketch books and plotted it to LTspice, with a
    little change with values to be used for a specific task.

    I noticed something strange. As you hover over the nodes, it is
    convenient to look at the lower left corner to get information about
    that node. Things like voltage, current etc. However, with a specific
    drawing(this one), it is showing some off the wall or should I say off
    the map, readings in measuring units that are wrong and symbols that
    have no meaning for the scale unit.

    Not only that, the value that is displayed down there is not even
    related to what is at the node but dig this, when
    I double click on any of those nodes to show it in the graph above, the
    graph is correct, but the bottom view is still wrong, grossly wrong.

    Tonight, I popped in a simple drawing ect, it's fine.. But reloaded
    this one particular drawing, and it's all over the map down
    below?

    There must be something in there that is confusing the hell out of
    LTSpice?

    I have version 4.15s if that helps..

    it's not that much of a big deal, I do most of my stuff by hand and a
    few other little programs I have lying around here. Just thought I'd
    ask to see if any one else has noticed this?

    Jamie
     
  3. Joerg

    Joerg Guest

    What's JW? Not familiar with that but most of my education was overseas.

    Nothing better than father and son working together on a project. As
    long as there's a nice cold brewsky afterwards once it all works :)

    First time my dad did that with me was early highschool. The oil furnace
    did its telltale whoopah .. whoopah .. *POOF* and dad said "Son, I'll be
    off on a biz trip soon so let's go into the dungeon, time for you to
    learn how to fix that monster".
     
  4. Jamie

    Jamie Guest

    Yeah, I just found out why it does that, if you start the sim at 0 DC
    volts, the below display is showing you the initial values. THose could
    be all over the place. I guess if you want to know that information it
    could be useful :)

    I never used an emulator before. My youngest while in trade school used
    Workbench and I didn't really think much of that. When he entered JW for
    Electronic Engineering they used something but it sure wasn't LtSpice,
    it could of been some other spice program, I don't know.

    All I know is, when he'd come on for the weekends, I'd end up helping
    him with homework and getting some lab builds to work correctly..

    Jamie
     
  5. Robert Macy

    Robert Macy Guest

    shades of "A Christmas Story" and Darren McGavin's character as the
    famous 'furnace fighter'
     
  6. Hello Jamie,

    LTspice shows the DC-operating point in the left lower corner.
    This value will be calculated at the beginning before the circuit will be
    simulated over time.

    Best regards,
    Helmut
     
  7. Jamie

    Jamie Guest

    yeah, I found that out. I don't use it that much.

    I would bet there is a cursor/marker I can set on the sim to show me
    where at what point to show the values. Clicking on the nodes are find
    for value, I some times find it just simpler to look at the values as
    mouse over the nodes.

    Thanks.
    Jamie
     
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