Triangular to Division with AD633

Discussion in 'Digital Circuit Design' started by Nikos Mparoutis, Oct 29, 2016.

  1. Nikos Mparoutis

    Thread Starter New Member

    Oct 8, 2016
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    Hello i have for input a triangular function and i do the the division with AD633.
    the division with DC input has right results but wronmg with triangular.The AD633 itself has right results with triangular, the issue is on the op amp or the design.I checked the op am datasheet and is is ok for this frequency (almost 40 khz)
    help ?Thanks
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Help us first with a schematic and a link to the datasheet(s).

    And clarify if you are dividing frequency or voltage.
     
  3. Nikos Mparoutis

    Thread Starter New Member

    Oct 8, 2016
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    i not not sure if i get what you mean about dividing frequency but i am sure that i am dividing voltage aka with the amlitude
     
  4. crutschow

    Expert

    Mar 14, 2008
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    I don't see any V+ power to the multiplier.
     
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  5. Nikos Mparoutis

    Thread Starter New Member

    Oct 8, 2016
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    Yes.Sorry for this,i need to sleep asap.
     
  6. Nikos Mparoutis

    Thread Starter New Member

    Oct 8, 2016
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    The multiplier works for triangular input but for the same Vpeak and frequency the sawtooth function i created throws simulation error.
    Can somebody explain why ?Is this a problem with the multisim ?
    I uploaded the simulations and the datasheet for help
    Vo=X1*Y1/10 from the multiplier
    Thanks !
     
  7. crutschow

    Expert

    Mar 14, 2008
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    The signal with the error you show is not a triangular wave (which has equal rise and fall times),
    The are both sawtooths with one having a fast risetime and the other having a fast falltime.

    Below is the LTspice simulation of the signal (I think) is causing you a problem.

    upload_2016-10-30_11-41-33.png
     
  8. Nikos Mparoutis

    Thread Starter New Member

    Oct 8, 2016
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    Thank you for the help Cruts,
    I show the triangular as an example becasue with triangular signal it works but with sawtooth (which is what i want for the almost the same frequency and amplitude) does not works.
    So as you said the problem is the fast rising time ? Βut i want a sawtooth not a traingular ,if i increase the risetime it is not a good enough sawtooth.Is there a way to solve this ?
     
  9. crutschow

    Expert

    Mar 14, 2008
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    But the signal you say is triangle is actually a sawtooth with a fast fall time.
    I see no triangle wave, which is why I'm confused about your problem.
    If there is a problem with a fast risetime, the only solution is to use a faster multiplier.
     
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  10. Nikos Mparoutis

    Thread Starter New Member

    Oct 8, 2016
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    The AD633 multiplier who takes input a triangular from 555 timer crashes. I tried many triangular from the function generator and it works but i tried many triangulars from 555timer and it fails.
    How to solve this,it is so confusing.
    Output from multiplier Vo =X1*Y1/10 it is from the datasheet
     
  11. crutschow

    Expert

    Mar 14, 2008
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    Do you mean the simulation fails and gives you an error message, or the output is not what you expect?
     
  12. Nikos Mparoutis

    Thread Starter New Member

    Oct 8, 2016
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    the simulation fails ,i would be very happy if the output was wrong,i could fix it but now it is confusing
     
  13. crutschow

    Expert

    Mar 14, 2008
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    Simulation failure is a common problem with all Spice simulators.
    What is the error message.
    Sometimes just a small change in some of the circuit values will eliminate this failure.
    Try simulating just parts of the circuit at a time to see if you can isolate he failure point.
     
  14. Nikos Mparoutis

    Thread Starter New Member

    Oct 8, 2016
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    i thought of this divide and conquer practice but still fails.I took only the multiplier with only the triangluar wave from the 555 timer's circuit...There is not something smaller than this :/
    The simulation Says: Error because the matrix is singular
     
  15. crutschow

    Expert

    Mar 14, 2008
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    Can you get the multiplier to work by itself?
     
  16. Nikos Mparoutis

    Thread Starter New Member

    Oct 8, 2016
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    the multiplier works with the traingular function from the function generator BUT from the 555 timer simulation crashes and the message says
    "Singular Matrix".
    Ι can send the circuit to simulte it with this multiplier to test it with multisim if you want,because it does not makes sense to me and i have stuck for 2 weeks.
     
  17. Nikos Mparoutis

    Thread Starter New Member

    Oct 8, 2016
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    I donne some research and i found that decoupling maybe is a problem
    The green is the output from the triangular ,the red from the multiplier.
    Also somebody else had the same hard problem and he found that with input +V to -V there is not problem with the AD633 but if we have input +V to 0V error occurs.
    Please comment
     
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