Can I use a Digital Waveform Generator with my Analog Scope?

Discussion in 'General Electronics Chat' started by rc3po, Feb 15, 2014.

  1. rc3po

    Thread Starter Member

    Feb 12, 2014
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    I bought an Analog scope (Tektronix 2465A DV) because I wanted to learn how scopes work & how to operate them before moving to Digital scopes,(plus, Dave @ EEVBLOG suggested that).
    Can I use Digital Function/Waveform Generators with it?
    I checked the service manual with my scope and didn't find anything on the Block Diagram. So I went to the Schematics and noticed that the scope has a DAC (U170, 4051DMUX) that Channels 1 & 2 use before the Preamps. I checked and found the DAC is a 74HC4051. So I went to the Datasheet and it says that the IC also does Digital Multiplexing & De-multiplexing.
    So does that mean that I can use Digital Function/Waveform Generators with my scope, but I'll only be able to feed signals through Channels 1 & 2?
    That's how it looks to me.
    Thanks.
     
  2. takao21203

    Distinguished Member

    Apr 28, 2012
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    All digital voltages are also analog voltages but not the other way round.

    Digital is just an agreement some analogue level is considered H and some other level is considered L, ususally with a gap inbetween but not neccessarily or not neccessarily fixed or known.

    That in turns means, applying some analogue voltage to a digital input still would cause a reaction of some kind, depending on the internal circuitry.
     
  3. #12

    Expert

    Nov 30, 2010
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    Quick answer from an old fart: An analog scope should display a representation of anything you touch the probe to, as long as the voltage is not too high to stay on the screen or too small to see at the best amplification factor in the scope.

    I have not a clue how many IC's were inserted into the signal path or how many channels you have. Any analog scope that can not show you a sine wave, a square wave, and everything in between, can't possibly be in its right mind.
     
  4. takao21203

    Distinguished Member

    Apr 28, 2012
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    I hacked VS2008 to use the linker from VS2013 Express and I did not care if it is designed to be used that way (example).

    But I admit, such a reasoning process is not neccessarily natural.

    Sometimes we think too much in terms of technical specification, and forget thesse are only a helping to use the technology for some purpose that makes sense.

    You could make a persistance effect display from an old DVD drive if you wanted to- or even from a floppy drive if you are desperate.

    People who only think in terms of intended use and manual and memorized solutions from college don't make good technicians.

    Think all the manuals are only a helping in order to get along somehow.
     
  5. rc3po

    Thread Starter Member

    Feb 12, 2014
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    Thanks.
    I haven't bought a Digital F/W Generator yet. I just didn't want to buy one and find out my analog scope wouldn't display the signals.
    I've been looking on Ebay and sometimes they say they match certain Digital scopes, but they never mention if they work with Analog scopes.
    I think a lot of sellers on Ebay rip themselves off because they don't explain their products very well - they just assume everyone looking at it is an expert!
     
  6. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    No offense but I would think that most people looking for a scope are going to know the basics. I would not think anyone would be explaining that. They are going to list the specs and that is about it,


    That is not to say there aren't some good deals out there form ignorant sellers. People get this stuff from family members, estate sales, storage purchases etc. They really don't know the value of most of the stuff. Many sell a lot of things. If they had to research everything they dad to sell they could end up actually losing money in the time involved.
     
  7. crutschow

    Expert

    Mar 14, 2008
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    Digital scopes, in spite of their name, look at analog signals and display them similar to Analog scopes. Both Analog and Digital scopes can look at digital signals, but they are displaying the analog voltage level of those digital signals (for example 0V and 5V). The difference is that digital scopes process the signal by converting it to digital format with a fast A/D converter for subsequent digital processing and display, but the display is still an analog type display of voltage on the vertical axis versus time on the horizontal axis.

    Analog scopes, of course, process the analog signal with all analog circuits, nary a digit in sight.

    P.S. Digital waveform generators also output analog voltages. They are just generated by digital circuitry and converted to analog by a fast D/A converter.
     
    #12 likes this.
  8. rc3po

    Thread Starter Member

    Feb 12, 2014
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    Thanks crutschow,
    That's the way I understood it also. I read a DWG primer on the Tektronix website also. I just know that you guys really know your stuff and thought I would see what yall said before I invested $500 or so on a decent F/W Generator.
    I've been learning Electronics for a year, mainly about TV repair and stuff, and just bought my 1st scope a couple of weeks ago.
     
  9. rc3po

    Thread Starter Member

    Feb 12, 2014
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    1
    Hi Spinnaker,
    I was looking for Generators, not scopes. I did some reading and thought my Analog scope would work, but decided to ask you guys because I value your opinions and wanted to make sure I didn't make a costly mistake.
    Thanks.
     
  10. MrChips

    Moderator

    Oct 2, 2009
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    Want to avoid making costly mistakes? Don't buy something until you really need it.

    Right now, you don't need a function generator.
     
  11. rc3po

    Thread Starter Member

    Feb 12, 2014
    56
    1
    Thanks, but I'm disabled & retired and don't get much to work with. So I thought if I get a decent F/WF Generator I could get more practice with my scope analyzing waveforms and calculating stuff. And when I do need one, I'll have one.
     
  12. MrChips

    Moderator

    Oct 2, 2009
    12,442
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    Why not build a simple square and triangular wave generator using a 555 timer circuit?
    Total cost - under $5.
     
  13. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Agreed. Iknow I have used them in the past but frankly I can't remember why. :)
     
  14. Markd77

    Senior Member

    Sep 7, 2009
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    It would probably be more educational and cheaper to pull apart a small portable LCD TV and probe around in there, should be plenty of signals to look at. If you find one that runs from a DC wallwart and has LED backlighting rather than fluorescent tubes there should be few, if any, dangerous voltages, but have a good check around with a multimeter just to make sure.
     
  15. rc3po

    Thread Starter Member

    Feb 12, 2014
    56
    1
    Thanks guys, yall are the best!
    That's what I considered also. One of my nephews dropped a Sony LCD the other day and trashed the screen. I'm gonna pull the back and disconnect the HV board and probe around after I find a stand for it.
    Yes, I have a Tenma 72-1097 Variable Isolation Transformer.
     
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