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measure peak to peak voltage?? how

Discussion in 'Electronic Design' started by 5hinka, Sep 21, 2004.

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  1. 5hinka

    5hinka Guest

    I have sinusoidal or triangle signal.
    I need to measure peak to peak voltage.
    How Can i do it?? I know that i should
    use some op amps, resistor, diods,
    but cannot find any design.
    Could You help me??
    Some links mayby??
  2. John Fields

    John Fields Guest

    1. Oscilloscope

    2. True RMS voltmeter.
    For an infinitely repeating sinusoidal signal multiply what your
    meter says by 2.828. For an infinitely repeating triangle, 3.464.
  3. 5hinka

    5hinka Guest


    I need to include it into my project.
    Oscilloscope is too big ;-))
  4. Rolavine

    Rolavine Guest

    Subject: Re: measure peak to peak voltage?? how
    You could use peak detectors made from op amps, positive and negative, and then
    measure the dc voltage between them with a volt meter. There are circuits that
    work in the 'Op amp Cookbook'.

    Or, how about the previous suggestion to just multiply the AC rms measured on a

  5. Tam/WB2TT

    Tam/WB2TT Guest

    A clamping circuit, followed by a rectifier. However you will have to take
    into account the two diode drops.

  6. John Fields

    John Fields Guest

  7. Ken Smith

    Ken Smith Guest

    Whats the frequency?
    You didn't say how exact you want the measurement. I'll assume you want
    it fairly good and that the frequency is fairly low.

    I think you may want a fast comparitor or two. If you are after the
    peak-peak, you basically want the circuit to measure the voltage that is
    there for a very short time.

    The purpose of the comparitor is to compare the output with the input. If
    the input ever exceeds the output, you need to raise the output. If not,
    you need to lower it.

    You may need a pair of comparitors, because you need to find the pos.
    and neg. peaks to subtract for the p-p measurement.
  8. Ken Smith

    Ken Smith Guest

    Or, make an recifier with no drop.
  9. Jim Thompson

    Jim Thompson Guest

    See "FullWaveRectifier.pdf" on the SED/Schematics page of my website
    for a starting point (note, there are four pages).

    ISTR that I posted a version that was peak-to-peak on a.b.s.e, but I
    can't locate it right now.

    ...Jim Thompson
  10. Jim Thompson

    Jim Thompson Guest

    On Tue, 21 Sep 2004 17:48:37 -0700, Jim Thompson


    Newsgroups: alt.binaries.schematics.electronic
    Subject: Peak-to-Peak Detector (S.E.D) - Peak-to-Peak-Detector.pdf
    Message-ID: <>

    ...Jim Thompson
  11. Ban

    Ban Guest

    Below is a nice peak detector circuit, it is fast enough for audio and quite
    precise. The negative half wave is done by another one with the diodes
    inverted. the final result is done by subtracting the 2 values. The
    pushbutton switch is to reset, can maybe replaced by a resistor for
    continuous reading.

    ___ ___
    10k | | 10k |
    | - |
    | |\ ^ BAV99 |
    +-|-\ | ___ |\ |
    | >-+---|<--|___|-+----+---------|+\ |
    +-|+/ 100 | | | >-+
    | |/ --- o | +-|-/ |
    | TL074 --- |=| | |/ |
    | 1n| o | +------+
    | | |
    created by Andy´s ASCII-Circuit v1.24.140803 Beta
  12. You missed off the output terminals.
  13. If you know the waveform in advance, just measure the average voltage
    (precision rectifier- easy up to a few kHz anyway) and low-pass filter
    and scale the output voltage correspondingly.

    Best regards,
    Spehro Pefhany
  14. Ad633 low cost multiplier with one input fed DC scaled to Jim's above
    mentioned constants, the other input fed with your input wave
    followed by a normal cheap AC panel voltmeter?

    AD633 has transfer function of (x1-x2) * (y1-y2)/10 +z
    where x and y are the differential inputs.

    Just a goofy idea that would drive professors who have never seen a
    Gilbert multiplier batty.

    Steve Roberts
  15. BobGardner

    BobGardner Guest

    They always told me 'there is no such thing as peak to peak voltage'. At one
    instant, there is a positive peak voltage, and at some other instant, there is
    a negative peak voltage, but the voltage is a function, and only has one value
    at an instant in time. Now lets argue about whether the product of rms voltage
    and rms current is rms power or average power.....
  16. Jim Thompson

    Jim Thompson Guest

    Track down, on a.b.s.e, the following post....

    Peak-to-Peak Detector (S.E.D) - Peak-to-Peak-Detector.pdf
    From: Jim Thompson Date: Tue, 21 Sep 2004 18:18:54 -0700 Size: 30.9k

    ...Jim Thompson
  17. Rich Grise

    Rich Grise Guest

    I get a feeling that bobgardner just wants to start a discussion over
    whether the term "peak-to-peak" voltage even has meaning in the context of
    a time-variant function.

    In the interim, I've found the answer to the angels on a head of a pin
    dilemma - an infinite number can dance on the head of a pin, since they're
    imaginary and don't take up any space. ;-)

  18. Ken Smith

    Ken Smith Guest

    Who are they and why do they always say these things.

    Peak to peak voltage:

    (a) The most positive voltage minus the most negitive voltage seen within
    the measurement time. This is what is normally meant by peak to peak.

    (b) The most positive minus the most negitive voltage that will ever be
    seen. This is what you use when designing for overvoltages etc.

    (c) The range of voltage that the signal spends 90% or 99% of its time
    between. This is used when refering to noise.

    (d) The same as any of the above with after the removal of some low
    frequency components. This is used when measuring the fur on a waveform.

    RMS voltage:

    You the the voltage at each instant or time square it, find the average of
    the squared value and the take the squareroot. This is very hand for
    rating things like lightbulbs that don't react quickly to the input

    Peak to peak current:

    (the same as the above with s/voltage/current/ )

    RMS current:

    (See RMS voltage )

    Peak to peak power:

    (a) Peak to peak voltage times the peak to peak current. This is used to
    get a number that impresses the uninformed.

    (b) In audio amplifiers this is the power produced when the pull up
    transistor first shorts, then blows open and then the pull donw transistor
    does the same. This is how many audio amplifiers are rated.

    (c) The peak power caused by the positive swing plus the peak power caused
    by the negitive swing. This is an almost honest measure of the pulsed
    output handling ability of a circuit, so it is never used.

    RMS power:

    (a) Take the instantanious power square it, average the squares and then
    squareroot the average. This is the RMS power but no-one ever means this
    when they say RMS power.

    (b) Average power misnamed RMS power. This is what most people mean if
    they say RMS power.

    (c) A completely fictional number created in the marketing department.
  19. legg

    legg Guest

    non sequitur

    Look it up the definition.

    Also check "peak and random deviation" (PARD).

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