LTSpice - varying frequency along time

Discussion in 'General Electronics Chat' started by atferrari, Feb 14, 2015.

  1. atferrari

    Thread Starter AAC Fanatic!

    Jan 6, 2004
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    LTSpice simulation.

    I could not find a way to implement this:

    a) Testing a circuit fed with a fixed amplitude sinusoidal voltage source varying frequency along a certain period. Say, in 2 seconds, between 6KHz to 450 Hz with 0.5 V amplitude.

    b) Later I would like to test the same circuit in the same period at a fixed frequency with a varying amplitude.

    c) And last, eventually, mixing both options.

    Is such a thing possible? I fear I am out of luck here.

    Please note:

    I am not trying to do a .tran simulation; my test is in one pass along time and stepping a parameter is not what I need either (well, the way I know to use it, at least...).

    Suggestions appreciated.

    Edit:

    Yes, it is a .tran simulation. My bad.

    /Edit
     
    Last edited: Feb 15, 2015
  2. MrAl

    Well-Known Member

    Jun 17, 2014
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    Hi,

    There is a VCO in there. Use a ramp as control.
     
  3. atferrari

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    Didn't know of a VCO. :eek:

    Off to look for it. Gracias.
     
  4. Alec_t

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    Sep 17, 2013
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    I think the VCO MrAl referred to is the 'modulate' device.
     
    atferrari likes this.
  5. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    1m.gif

    V(in) goes from 0V to 2V (because time goes from 0s to 2s) and V(B1) = V(in) = time.

    V(F) is 10Hz when V(in) is 0V specified by space=10).
    V(F) is 50Hz when V(in) is 1V specified by mark=50).
    V(F) is 90Hz when V(in) is 2V because the slope is 40Hz per volt.
     
    Last edited: Feb 14, 2015
    JohnInTX likes this.
  6. MrAl

    Well-Known Member

    Jun 17, 2014
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    Hi,

    Yes, that's it.
     
  7. atferrari

    Thread Starter AAC Fanatic!

    Jan 6, 2004
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    Gracias Mike. :) Using it now. Doing what I needed.
     
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