Trouble triggering DSO

Discussion in 'General Electronics Chat' started by spinnaker, Jan 21, 2014.

  1. spinnaker

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    Oct 29, 2009
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    I swear I am trigger challenged. I have always had trouble with triggering on analog scopes but eventually get it (just don't use them enough I guess).

    I have an input to two channels. Now I am having trouble with my DSO. It is fine as long as both inputs are the same frequency. But if they are different then I can't get a stable display on one channel.

    I can stabilize the channel I am trigger from but I can't stabilize both at the same time.

    If I play with the trigger level, both will stabilize or a second second then one or both channels will become unstable.


    There is also a Force button that I am not sure what it does but if I press it, the display will stabilize for a second then become unstable.

    Both signals are a digital signal with 50% duty cycle.

    The scope id a Rigol DS1102E.


    I even tried the Auto button but that does not help.

    Can anyone tell me how I can get both channels to stabilize at the same time?
     
  2. MrChips

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    Oct 2, 2009
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    Some analog scopes have a trigger selection CH1-BOTH-CH2 when using ALT sweep mode.
    I don't know if DSO allows independent trigger modes. I will have to look into this for you.
     
  3. spinnaker

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    As long as it does not violate any copyright laws, I can post the user guide. I would have you go to the site but you have to go through some crazy registration to download the manual.

    Not that the manual is worth much anyway.

    Let me know
     
  4. spinnaker

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    The scope does alone for AC line trigger but nothing stabilizes all with that setting and trigger level is disabled for some reason.
     
  5. vk6zgo

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    Jul 21, 2012
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    Have a look on eevblog.com----I'm pretty sure someone had the same problem.
    Or Google for W2AEW-----he has a Youtube video about the same subject,but I can't remember what type of DSO he used.
     
  6. JoeJester

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    Use the common clock as your trigger, if there is one. That will synchronize the signals.
     
  7. MrChips

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    I have a Tektronix TDS220 in front of me and I cannot get it to trigger on both CH1 and CH2.
     
  8. spinnaker

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  9. spinnaker

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    Thanks I did a real quick look and did not find anything but I am falling asleep here. I will look harder tomorrow. Unless you find it and want to post the link. It would be a big help but not necessary.
     
  10. spinnaker

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    It has an AC line trigger but you can't change the trigger level in that mode or some reason and neither channel syncs.
     
  11. JoeJester

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    I wasn't thinking of the AC line. What two signals are you attempting to view?
     
  12. spinnaker

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    I'm glad I am not the only one. And you got you one of those rich people scopes too. :)



    I am guessing to compare signals, you get it run then stop it. Ability to stop and memory is a really nice feature of the DSO. I remember using an old analog Tek scope years ago. The thing cost a fortune but it sure was nice.
     
  13. MrChips

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    So if the frequencies are independent why do you want to compare the signals?
     
  14. spinnaker

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    Two square wave signals. Different frequencies 50% duty cycle. One 3vpp the other 5vpp
     
  15. spinnaker

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    If have two different sources I should be able to compare the two so I an see what happens when, Or comparing the input of a chip to the output which made me a hero at work proving we had a huge bad batch of chips,
     
  16. JoeJester

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    There is no common starting point for them either, I assume.

    You will never synchronize them except during times of coincidence and that would be briefly.

    If you fed a common clock to two dividers to develop those signals, you certainly could synchronize them, if synchronizing them is important.
     
  17. MrChips

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    Page 2-35 of the Rigol manual shows the different Trigger Modes. You want Alternate Trigger.
    Page 2-42 shows how to use Alternate Trigger Mode.
     
  18. THE_RB

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    In a situation like that I would just run my digital 'scope in manual trigger mode, press the "force trigger" button and it captures and displays both waveforms.

    The waveforms are synced when captured, so you can then look closely at the timing or zoom in on the waves as needed.

    The more you use a digital scope the less you use it "live running" and the more you will just capture once and then look at it. :)
     
  19. spinnaker

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    That is exactly what I noticed. They "sync" when the scope is not capturing.
     
  20. atferrari

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    Do you actually could expect to have BOTH stable with one trigger signal?

    In my Owon DS7102V, there is the possibility to trigger each channel independently. Could be that you have it as well?

    IIRC, used it when developing code to read a PS2 mouse. In any case, worked OK.
     
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