How to change amplitude for Delta functions

Discussion in 'Homework Help' started by Kaspars, Jun 9, 2011.

  1. Kaspars

    Thread Starter New Member

    Jun 9, 2011
    17
    0
    Hello,

    I have small problem. My input signal looks like this:
    [​IMG]

    I'm using this circuit:
    [​IMG]

    To get signal like in this graphic (green), so it would be impulses (Delta functions) from 0V to -0,8V:
    [​IMG]

    In simulations everything works fine, but in practice I have impulses from 0V to 1V. Why so? And how I can solve my problem?

    Thanks a lot :)
     
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    Not sure what you are trying to achieve.

    The only thing I see as strange is that V5=-0.8 volt with the source polarities as shown. Should V5 not be +0.8V, or have I missed the point?
     
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  3. Kaspars

    Thread Starter New Member

    Jun 9, 2011
    17
    0
    Yes, V5 is +0,8V, so in the V5 exit to transistor we get -0,8V becouse of polarities.
     
  4. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    OK. I'm not sure how your simulator works.

    When using mine, if I were to set a DC source voltage to -0.8V that effectively reverses the nominal (annotated) output polarities. In your plots I see the simulation appears to work with the output switching from 0V to -0.8V.

    When you say ".. in practice ..." - presumably you have done the simulation then actually built the circuit to see if it produces the same output at Q4 collector. You state the output pulses switch from 0 to 1V. Do you actually mean of the opposite polarity [0 to +1V] to that expected [0 to -0.8V]? How did you measure this? With a CRO?
     
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