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PWM to Analog Converter

Discussion in 'General Electronics Chat' started by engineergc, Sep 8, 2017.

  1. engineergc

    engineergc New Member

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    Dear All;

    I am trying to convert PWM to analog signal without any software. I tried use RC filter but freqeuncy range of PWM signal is 5 Hz to 500 Hz, so I can not use RC filter. I searched PWM to analog converter entegres, but their minimum frequency starts from 30 Hz. How I can convert pwm to analog in specified range without any software?
     
  2. Pommie

    Pommie Well-Known Member Most Helpful Member

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    What produces PWM that varies in frequency? PWM is normally at a fixed frequency and the on/off ratio is varied. Can you give more details about the signal?

    Mike.
     
  3. engineergc

    engineergc New Member

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    I have PWM signals that have different frequencies. I want to convert them to analog signals. Min. frequency of pwm signals is 5 Hz and max. frequency is 500 Hz.
     
  4. dave

    Dave New Member

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  5. Pommie

    Pommie Well-Known Member Most Helpful Member

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    PWM stands for pulse width modulation, there is no variable frequency, just variable width. Unless you can describe the signal better then I can't help you - repeating your previous post doesn't help.
     
  6. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    500hz = 2mSeconds
    5hz = 2oomS
    It is possible that you have a system where the "on time" is 2mS and the off time is variable from 2mS to 200mS in 2mS steps.
    (or the reverse of that)
    _-_-_-_-_-_-=fast and high dutycycle
    _-_________-________=slow and low dutycycle
    **************OR************
    Maybe you have different PWMers. One runs at 5hz and another runs at 500hz.
     
  7. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    Read this post. This is normally how you filter 500Hz PWM to produce a proportional DC level. Note the settling time. If you start with 5Hz PWM, it will take 100 times longer for the DC level to respond to a step change of the PWM duty-cycle.
     
  8. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    Perhaps, you really just need a frequency to voltage converter, as is sometimes used in tachometers. There are single chips to do that.

    John
     
  9. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Some birds flap their wings at 5Hz.
    I agree that it will take a long time for a filter to settle when the 5Hz PWM has very narrow pulses.
     
  10. simonbramble

    simonbramble Active Member

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    this part is what you are looking for:
    http://www.linear.com/product/LTC2645

    ... although your frequency is a bit low. We designed this part for people who cannot change their software, but want an instant response DAC output instead of using a low pass filter and the inherent delay that it introduces
     
    • Like Like x 1
  11. ci139

    ci139 Active Member

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    :p:p:p:p:p:p -- a dude from linear ;););)
     
  12. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    Can you substantiate that claim?

    John
     
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  13. schmitt trigger

    schmitt trigger Active Member

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    I believe that Simon has introduced himself previously as either a LT employee or rep.

    In any case, I have no problem with him providing suggestions. LT is a superb semiconductor company with a wide and innovative product portfolio.
     
  14. ci139

    ci139 Active Member

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    is from where you recon a true hardware engineer - all tough the app is up and running - there's a possibility it runs from the wrong bases (this' - about the nomination)
    such has happened (namely the deviceĀ“s operating range was narrow - and it didn't work because of what i thought it did) -- as there's a possibility someone passing a typo or miss wording
    (thinking of -- people who can design Op Amps are here - muhahaa - this is so sillily cool :woot:)
     
  15. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    Wow, what a "sentence." It is completely incomprehensible to me.

    Back to my original comment, it would help if I knew what " :p:p:p:p:p:p " and " ;););) " meant. The former apparently translates to "stick out tongue" and the latter to "wink". So, six tongues and three winks means what? How does that modify that he previously worked at Linear? Are you suggesting it is good, bad, or that his suggestion is clouded by that fact?
     
  16. simonbramble

    simonbramble Active Member

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    To be correct, I am now a dude from Analog... and no, I did not understand the sentence either (!). It sounds like an output from Google Translate. Thanks for the compliment on the product range. It is much appreciated :woot:
     
  17. schmitt trigger

    schmitt trigger Active Member

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    Make it three
     
  18. ci139

    ci139 Active Member

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    it's about sincere happiness . . .
    [​IMG]
    :p:p:p:p:p:p:p:p:p ! BOOM ! :) thinking of . . . centuries of pollution and contamination :woot:
    -----
    ((as in fact i think the china only should and can deal with those guys . . . in guiding their efforts to a longer perspectives ... for everyone ...))
    . . .
    as what to admire about this people is the capability to incorporate the existing no resources to actually output anything // in contrast to our plentiful world where the only brake is not getting along with each other o_O . . . continuously as and in this forum most unfortunately
     
    Last edited: Sep 17, 2017
  19. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Hmm. Don't think much of their manufacturing quality control. The nose cone of the missile in that pic is way off from the template. Makes you wonder how far off target the flight end-point would be! :eek:
     
  20. schmitt trigger

    schmitt trigger Active Member

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    That image is inside a laboratory or building.
    Yet, Kim is wearing a heavy, fur lined coat and hat.
    There is absolutely no heating in the building!
    And that is in premier lab.

    This image is not unique. There are many pictures of Kim touring rocket and weapons labs, showing the same garments.
     
  21. ci139

    ci139 Active Member

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    v-.-v Hi! Mr. Linear-Analog-Bomb :D:D:D
    :p (too catchy not to be posted) muhahaa
     

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