Ideas for Arbitrary Waveform Generator, 100V.

Discussion in 'The Projects Forum' started by Jimmytr, May 15, 2015.

  1. Jimmytr

    Thread Starter New Member

    May 15, 2015
    4
    0
    Hello,
    I am trying to build an electrical stimulator (not for being used in living things) for a biomedical project, some of the parameters to control are waveform (pulse,triangular), voltage around 100v, waveform period (500 us-250ms) and frequency (1Hz-30Hz)

    The approach i´m trying is to use a "high voltage" PWM signal + RC filtering. Now i realize that obtaining a "high voltage" PWM signal is not that easy, even though i´m using a pulse transformer.

    To avoid DC bias in the pulse transformer i tried this:
    Scan May 15, 2015, 1_04 AM-page1.jpg
    Every stage goes as planned until the rectifer bridge before the RC filtering. I think that maybe there is
    a more elegant approach for the task, so i would like to know and suggestions/ideas on the project.

    I really appreciate any help you can provide.
     
  2. pwdixon

    Member

    Oct 11, 2012
    488
    56
    What's wrong with using a boost regulator to generate 100Vdc and then just using a high voltage FET to switch the output to the filter? Are you trying to generate just a voltage at low current or at some high current level?
     
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  3. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
    2,780
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    Inasmuch as 'biomedical' translates nicely to 'life+health', your assertion that the project is not for application to organisms is a tad incongruous -- IOW, while I hesitate to suggest that the original post is 'oxymoronic', the fact remains...;) --- Thus it seems that, dependent upon the organism{s} involved, "VI AAC III" may prohibit substantive response to your inquiry -- Elucidation, however, may improve my perspective...

    With marked jocularity
    HP:D
     
    Last edited: May 15, 2015
  4. MrChips

    Moderator

    Oct 2, 2009
    12,421
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    In other words, what HP is saying is that discussion of your project is potentially in violation of AAC rules as stated in the Terms of Service.
     
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  5. Jimmytr

    Thread Starter New Member

    May 15, 2015
    4
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    Yes you are right, the post is somewhat 'oxymoronic', but that was not the intention.
    I'm a biomedical engineer student, and this project is just for learning purposes.
    The idea of using a transformer came from the university professor, working with the project
    i realized that maybe there was a more elegant solution. I just wanted ideas, suggestions to make a
    better project and to learn different approaches so maybe one day i'll be able to build a real one.
     
  6. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    A pulse transformer is better at delivering things with a rectangular pulse shape than other transformers, but don't think that its output will have nice square corners, like a clock source only bigger. As suggested, a better way is a 100 VDC source powering a linear wideband amplifier with pulse, triangle, whatever as its input. You'll have much better control over the output amplitude and load impedance matching.

    ak
     
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  7. Jimmytr

    Thread Starter New Member

    May 15, 2015
    4
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    Low current, max. 40-50 mA throug a ~220 Ohms load.
    I search for dc-dc converters and found R24-100B. As for the FET , is there any particular suggestions?.
    (I have mainly worked with BJT transitors so i don't claim to be an expert).
     
  8. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    50 mA across 220 ohms is only 11 V. More to the story?

    ak
     
  9. Jimmytr

    Thread Starter New Member

    May 15, 2015
    4
    0
    My mistake, it should said ~2,000 ohms. It's the analogous of skin impedance, that in not way is 220 Ohms! :)
     
    Last edited: May 15, 2015
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