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Oscilloscope EXT. INPUT , source Channel#2

Discussion in 'General Electronics Chat' started by Billy Mayo, Dec 11, 2013.

  1. Billy Mayo

    Billy Mayo Member

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    No, I'm measuring ONE waveform signal on O scope channel#1
    CHANNEL#1 has ONE waveform signal
    CHANNEL#2 has the 400hz sync signal , You "source" this to the trigger input ( there is a mode switch that say's SOURCE ) it's next to the add, chop, etc.

    Audio amplifiers has a sync signal at 60hz, all the frequencys from 20hz to 20khz are sourced to a 60hz sync signal that comes out of the wall 120 VAC at 60hz

    Why do you think they use 60hz out of the wall? because hum sounds nice and easy to filter? it's a sync signal , external sync signal

    The frequencys don't have to be multiples in order to be synced

    You can take a function generator and sweep it from 20hz to 20khz and get STABLE waveforms on the O-scope right? and all those frequency's from 20hz to 20Khz are sync to 60hz right?
     
  2. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Absolutely NOT!
    An audio amplifier DOES NOT have a 60Hz sync signal. 60Hz from its power transformer is full-wave rectified producing 120Hz positive pulses which are filtered into DC. Then the smoothed DC powers the amplifier circuit.
    The 'scope is internally sync'd to the viewed signal that is fed into the amplifier or internally sync'd to the signal produced at the amplifier's output, not sync'd to 60Hz.

    The 60Hz from the mains goes into a power transformer that steps down the voltage. Then it is full-wave rectified into 120Hz positive pulses and filtered. The 60Hz is not used to sync a 'scope unless the amplifier produces mains hum that you want to measure. Most amplifiers do not produce mains hum so they do not have a 60Hz sync output.

    Of course the signal and the sync must be multiples or the waveform will be free running. Usually the viewed signal provides sync to a 'scope.

    NO, the frequencies ARE NOT sync'd by the 60Hz ! The 60Hz has nothing to do with sync when viewing 20Hz to 20kHz frequencies. The signal you are viewing provides its own sync.
     
  3. kubeek

    kubeek Well-Known Member

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    None of that is correct. 60hz is not sync in any way, it is just a convenient number of cycles per second, based on the mechanics of AC generators. Why would, or even HOW could all the frequencies be synced to 60Hz, when most of them are not multiples of 60Hz?
     
  4. dave

    Dave New Member

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  5. ClydeCrashKop

    ClydeCrashKop Well-Known Member

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    I don't know if this will help visualize but it's a cool video.
    Pendulum Waves
    http://www.youtube.com/watch?v=mN_gjuoYlEM
     
  6. Billy Mayo

    Billy Mayo Member

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    How do a signal provides it's own sync? and how do you find that sync frequency?

    How does it provider it's own sync to a scope?


    The Oscilloscopes linear sweep generator for the horizontal sweep generator is at 60hz

    You're triggering off of channel#1 , so that makes it sync to 60hz

    Switch the trigger to LINE , and it will trigger off of the 60hz line outlet out of the wall
    Now switch the trigger to Channel#1 , it's the same thing , 60hz right?

    But you're saying the waveform is not in sync with 60hz , that the waveform it self is the external sync signal , how can that be?

    The waveform triggers the Oscope? Only when channel#1 is SOURCED to the triggers input
     
  7. Billy Mayo

    Billy Mayo Member

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    The Oscilloscope is plugged into the 60hz wall outlet , it is defaulted to 60hz

    The O-scope linear horizontal sweep is at 60hz , so it's measuring the time period of the waveform you inject into channel#1 that is based on the 60hz of the linear horizontal sweep display

    All the those waveform frequencys have to be tied or related to the O-scope 60hz horizontal sweep generator inside the O-scope
     
  8. Billy Mayo

    Billy Mayo Member

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    Those waveforms would be free running is there aren't sync to anything , the Oscope has to have a sync of something in order to display the waveform , it's related to the 60hz that the Oscope is plugged into

    If theses waveforms don't have a sync signal, why aren't they free running? The O scope is at 60hz defaulted
     
  9. 4pyros

    4pyros Well-Known Member Most Helpful Member

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  10. audioguru

    audioguru Well-Known Member Most Helpful Member

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    When the sync switch on a 'scope is set to the channel you are using then it takes the signal you are viewing, squares it with a Schmitt-trigger and uses the resulting pulse to sync the horizontal oscillator in the 'scope. The setting of the scope's sweep oscillator and the grid of lines on the screen can be used to determine the frequency of the signal.

    No it is NOT. It is any frequency you want and is set by the big knob that adjusts its frequency. 60Hz has nothing to do with it unless the sweep and its sync is set for LINE! Line is the 60Hz electricity line.

    No. If you are viewing channel #1 then you set the sync to come from channel #1. 60Hz has nothing to do with sync!

    Yes, for viewing the signals for synchronous (the abbreviation "sync" again) AC motors and old fashioned black and white TVs.

    No, it is completely different. Switching the sync trigger to channel #1 feeds the signal from channel #1 so it sync's the horizontal sweep.
    60Hz has nothing to do with it!

    The viewed signal is used to sync the horizontal sweep oscillator. 60Hz has nothing to do with it!

    The viewed waveform is squared into pulses then the pulses sync the horizontal sweep oscillator.

    Maybe the sync trigger switch on your 'scope is labelled SOURCE (of the sync). Then when it is set to channel #1 the sync comes from the squared signal viewed on channel #1.
     
  11. audioguru

    audioguru Well-Known Member Most Helpful Member

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    At work the 'scopes were old so they bought new Tektronix ones. I used mine for a few minutes to learn about it then I took its owner's manual home and read it. Then I knew how to use it.
     
  12. atferrari

    atferrari Well-Known Member

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    Serial killer: a person who has murdered three or more people over a period of more than a month, with down time (a "cooling off period") between the murders.

    So, how do you call a person able to post not less than 40 questions, if not more, in the same thread, more or less related to own previous or related answers, some of them with less than 1 hour interval and small short cooling off periods, in less than four days?

    Ritesh, "serial asker", "compulsive inquisitive", "my boss says" or troll?

    All for you to enjoy. Me? Had enough.
     
  13. Billy Mayo

    Billy Mayo Member

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    Only on a solid state O scope , it uses schmitt triggers , not on a tube O scope

    A Tube O scope uses Tubes to do the pulsing , the horizontal oscillator is a tube circuit also

    Only if the waveform inject into the channel is related to ground and not floating

    If the waveform is floating the horizontal oscillator in the scope wouldn't know what to do , that's why the waveform is free running

    How do you tell if the circuit is a line-powered and line-synchronized circuits?

    A line synchronized circuit has to use the LINE triggering at 60hz

    How do you tell on a schematic that the circuit is a line synchronized circuit?

    True I agree

    True , I agree

    Only on a solid state O scope , it uses schmitt triggers , not on a tube O scope

    A Tube O scope uses Tubes to do the pulsing , the horizontal oscillator is a tube circuit also

    No, My O-scope has a SOURCE mode , you can Source channel#1 or Channel#2 to eachother or to the triggers input

    example:

    You can have a sync signal on Channel#2 which you can uses as your Reference or external sync signal

    You can SOURCE channel#1 to Channel#2

    So that Channel#1 waveform is triggered by channel#2
     
  14. 4pyros

    4pyros Well-Known Member Most Helpful Member

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  15. ghostman11

    ghostman11 Well-Known Member

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    Having read the complete thread again, i think i see the problem. You are using the wrong type of scope! Have a look at this video, then when you go into work, you can show your boss exactly what you need.

    This will just about do what you want, the probes are a little pricey, but i suggest for what you need to do, a lump of coax with a nail in the end will suffice
     
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  16. audioguru

    audioguru Well-Known Member Most Helpful Member

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    You are absolutely WRONG! See my attachment.

    You can look at its schematic or connect the 'scope and view its sync.

    Yes but very few circuits are line synchronized.

    You can look at its schematic or connect the 'scope and view its sync.rue , I agree

    Of course. That is normal.
     

    Attached Files:

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  17. Billy Mayo

    Billy Mayo Member

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    The Block Diagrams on an Tube O-scope is different than a Block Diagram of a Solid state Oscope, what are the differences?

    A tube Sweep Generator is different than a solid state sweep generator, how so? are they both linear or other?
     
  18. 4pyros

    4pyros Well-Known Member Most Helpful Member

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    AG do you really think he will understand the trigger circuits?
    Now we will have to explain those to him.
     
  19. ghostman11

    ghostman11 Well-Known Member

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    Maybe this would be a better trigger
    gun-head-16437634496.jpeg
    trouble is i cant decide, if it would be better for us or him
     
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  20. audioguru

    audioguru Well-Known Member Most Helpful Member

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    I posted actual detailed schematics of Schmitt triggers, not simple block diagrams.
    They both do exactly the same thing. They produce a pulse that sync's the horizontal sweep oscillator. A sync pulse can also start a horizontal sweep.

    Of course both are linear. The trace sweeps across the screen at a steady speed. The horizontal oscillator produces a sawtooth waveform on both of them.
    The very fast drop of voltage of the oscillator is the retrace.
     
  21. Billy Mayo

    Billy Mayo Member

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    You're saying that a tube o scope block diagram of the whole circuit is the SAME as a solid state O scope block Diagram? they have the same block diagram

    The only difference it what between the two?

    You're saying that a tube and solid state horizontal sweep oscillator is the same, compared as of a block diagram
     

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