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Peak voltage detector...

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by ikelectro, Feb 25, 2013.

  1. ikelectro

    ikelectro Member

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    hi everybody,

    Once again I'm here with my questions..... This time I want to build a peak voltage detector for CMOS circuits.....i have googled it first and comes huge nos of circuit.... i chose This one( attached and from http://www.discovercircuits.com) and want to go with this circuit... now the question is : Can I use LM358 replacing the LM393???

    thanks in advance!!!!!:eek: View attachment peak voltage detector.......pdf
     
  2. ikelectro

    ikelectro Member

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    and can Anyone please explain this circuit for me!!!!!!!!!! :eek::eek::eek::eek::eek::eek::eek:
     
  3. ikelectro

    ikelectro Member

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    I have just done with LM358.... here are the result (picture attached) ....... Is it right??? please share your valuable comments on this
    input Photo0505.jpg

    output Photo0508.jpg
     
  4. dave

    Dave New Member

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  5. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    Without knowing the specs on your DVM and knowing what the input waveform is, there is no way of knowing if your results are correct.
     
  6. ikelectro

    ikelectro Member

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    But I dn't have any CRO to find out the wave shape .... but I gave the input from a 555 and i think that is square wave output....
    and I use LM358...
    Now anything is there for me.. waiting for your reply.....
     
    Last edited: Feb 26, 2013
  7. ronv

    ronv Well-Known Member Most Helpful Member

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  8. ikelectro

    ikelectro Member

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    yes this the same circuit from same source from I linked it here.
    so you are suggesting I should use 393???
    there is something that i want to asked >> how should I increase the input frequency. because there is only 150KHz range( in the above circuit) ...
     
  9. ronv

    ronv Well-Known Member Most Helpful Member

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  10. ikelectro

    ikelectro Member

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    what happen if I chose more voltage at VCC like 9V for LM 358 and say my input signal's source have only 5V, can this solve the problem and always it is square wave. I'll not go for sine wave (i dnt require that)....

    what will be your suggestion in that case? which IC should I use..
     
  11. ronv

    ronv Well-Known Member Most Helpful Member

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  12. audioguru

    audioguru Well-Known Member Most Helpful Member

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    The LM358 is an old very slow opamp that has trouble above only 2kHz. The LM393 is a fairly fast comparator that works up to about 150kHz.

    Like most cheap multimeters, yours is made to accurate show the level of a 50Hz or 60Hz sinewave from the mains electricity and reads low at higher frequencies.
    My expensive Fluke multimeter is accurate to 20kHz and reads low at 150kHz.
     
  13. ikelectro

    ikelectro Member

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    but I dont want to go for the sine wave... want to stick with square wave......
    are sure about that mine works perfectly only within 50-60Hz????? but the manual says 20MHz range it has!!!!! ( It is a CIE 8007)....
     
  14. ikelectro

    ikelectro Member

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    Is there any other way to do the thing??? I mean peak voltage detector....
     
  15. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Your cheap multimeter can measure a frequency as high as 20MHz but measure the level of a SINEWAVE accurately to only 500Hz.

    It does not have "true-RMS" so it cannot accurately measure the level of a square-wave.
     

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  16. ikelectro

    ikelectro Member

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    Hi Audioguru,
    then I think that to get an True RMS meter will be a good idea.... but I think that will be very expensive for me as I am a student who just started walking (2 years!!) into the sea of electronics.......

    So can you please suggest me how to get started with peak voltage detector circuit......
     
  17. audioguru

    audioguru Well-Known Member Most Helpful Member

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    You do not have the tools that will measure the peak voltage of a squarewave at a radio frequency.

    Your cheap multimeter measures the level of a low frequency sinewave so use a low frequency sinewave.
     
  18. ikelectro

    ikelectro Member

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    are you telling me to go with

    1) examine the circuit with sine wave or
    2) make a voltage peak detector for sine wave.....

    But I need a peak detector for square wave ......
     
  19. ronv

    ronv Well-Known Member Most Helpful Member

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    What will be your minimum and maximum voltage for your square wave?
    What will me the minimum time the square wave will be positive?
    What do you want the output voltage to be for the minimum and maximum input voltage?
    What are you measureing?
     
  20. ikelectro

    ikelectro Member

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    Hi ronv,

    maximum will be 5 volt.......

    it depends upon the circuit which one I'll check....

    cant understand you clearly, may be because I'm not so strong in English !!!!!:D

    as project I want to make a peak voltage detector.....
     
  21. audioguru

    audioguru Well-Known Member Most Helpful Member

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    You cannot buy modern high frequency parts and you cannot measure the level of the input signal.
    You don't even have an oscilloscope.
     

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