oscilloscope invert mode and ADD mode

Discussion in 'General Electronics Chat' started by relicmarks, Apr 10, 2008.

  1. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    What can i use the "invert mode" on the oscillscope for?

    My channel B or channel#2 has a invert mode but i don't know what to use it for

    example :

    1.) If i have a 5 volts peak to peak AC waveform on Channel#1 and a 5 volt peak to peak AC waveform on Channel#2 invert mode = Cancel out to zero volts right?

    2.) If i have a 5 volt peak to peak AC waveform on channel#1 and a 2 volt peak to peak AC waveform on Channel#2 invert mode= negative -3 volts

    But why would i want to do this?


    What does using the INVERT mode or ADD MODE tell a electronic designer or technician ?

    I know if you use a the invert mode on channel#2 with the ADD mode is "substracts" channel#1 waveform with channel#2 waveform

    Subtration mode= invert mode+ add mode at the same time

    When would i use this "subtraction mode" on the oscilloscope? any examples please?

    When would i use the ADD mode on the oscilloscope ? any examples please?

    When would i use the invert mode on the oscilloscope? any examples please?
     
  2. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    Invert and "ADD" is a convenient null when you want to align to signals of the same frequency. I used that many times ensuring two signals were "aligned".

    If I didn't invert the channel B input, then the "ADD" would produce the maximum signal when two same frequency signals were aligned.

    I'm sure there are many more examples, but that was the predomiant usage by me. It was handy when there was a "difference" in my timers or transmitters.
     
  3. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    If there was a "difference" Wouldn't there be a voltage drop or lower amplitude?

    Invert and "ADD" is a convenient null when you want to align to signals of the same frequency. I used that many times ensuring two signals were "aligned".

    I would have to have trim pot or dialing or fine tuning a circuit to "align" the signals

    IF you didn't have these adjustment you would see the "difference"

    Add-inverted: Channel B is subtracted from channel A (A - B).
    The differential mode (A-B) is useful for rejecting common-mode signals. By measuring in differential mode, the common mode signal on one channel cancels out the common mode signal on the other channel, leaving the actual signal visible on the display. For example to eliminate hum from a signal

    What would i use theses differntial mode ( A - B ) For?
     
  4. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    If there were an amplitude difference, you would never get to a straight line null in the Invert and Add mode. I was aigning signals to be in situ.

    Only you know when you need to use that function. Your the person operating the oscilloscope and selecting the signals you wish to view and/or compare.
     
  5. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    aligning signals in voltage? and time? and phase?
     
  6. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    an amplitude difference, you would never get to a straight line null in the Invert and Add mode


    Why will it never go to a straight line?
     
  7. Distort10n

    Active Member

    Dec 25, 2006
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    Making an assumption here, there are two signals 180° out of phase so when you take the difference between them then you get 2*Vp(single-ended).
     
  8. bertus

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    Apr 5, 2008
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  9. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    How can i measure the phase difference and phase angle using the ADD and INVERT MODEs?

    I read that each division is = to 45 degrees

    Using the ADD mode you can see the phase difference ( horizontal distance ) between the reference waveform to the compared waveform
     
  10. relicmarks

    Thread Starter Active Member

    Oct 13, 2006
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    ELIMINATION OF UNDESIRED SIGNAL COMPONENTS

    Do you know how to do this one

    ELIMINATION OF UNDESIRED SIGNAL COMPONENTS
    The ADD feature can be conveniently used to cancel out the effect of an undesired signal component that is superimposed on the signal you wish to observe.

    Procedure:
    1. Apply the signal containing an undesired component to the CH 1 INPUT jacks and the undesired signal to the CH 2 INPUT jack.
    2 Set-the vertical MODE to CHOP and SOURCE to CH2 Verify that CH2 represents the unwanted signal, with an inverse polarity. The polarity can be reversed by setting CH2 to INV.
    Set the VERTICAL MODE to ADD, SOURCE to VERT. MODE and CH2 VOLTS/DIV and VARIABLE so that the undesired signal component is cancelled as much as possible. The remaining signal should be the signal you wish to observe alone and free of the unwanted signal


    HOW CAN YOU CANCEL OUT THE SIGNAL COMPONENT ? please give examples

    Because alot of RF and modulation, interlaced, video horizonatal sync, vertical sync are single ended so how would i be able to CANCEL the signal component ?
     
  11. bertus

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    Apr 5, 2008
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