LTspice simulator for circuit design

Discussion in 'General Electronics Chat' started by whale, Dec 10, 2009.

  1. whale

    Thread Starter Active Member

    Dec 21, 2008
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    0
    HELLO EVERYONE,

    Iam using LTspice for simulation of oscillator circuit and some how i got the right frequency and the out put is perfect. but the simulator displays the error message.

    the message was "WARNING: Node N005 is floating"

    please someone tell me whats it mean?

    will it affect the circuit performance? and can i conform the output of circuit?
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    That means you have a portion of the circuit that is not connected to anything. It may just be a piece of wire that you forgot to connect to something.

    In the Schematic Editor, click on View, then Zoom to Fit.

    Look around for a piece of wire that isn't connected to anything.

    That's hard to say without seeing the circuit. You forgot to post it.
     
  3. whale

    Thread Starter Active Member

    Dec 21, 2008
    111
    0
    but the connections are fine.

    here is the circuit , click here
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    Ahh, I see. You have capacitors in series.

    SPICE "sees" the node between two capacitors in series as a floating node, as in an ideal component, there is no current path to ground.

    In order to avoid these error messages, you can connect very high values of resistance across each capacitor. 99MEG should be high enough to not affect your circuit performance, yet will get rid of the error messages.
     
  5. whale

    Thread Starter Active Member

    Dec 21, 2008
    111
    0
    thanks sgtWooKie ,

    will it affect my practical circuit?

    can i involve in practice?
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    It should not affect a real-world circuit.

    Go ahead and build it.

    Remember that real components have tolerances; a 5% tolerance capacitor marked 10pF might be anywhere from 9.5 to 10.5pF.
     
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