Looking for first oscilloscope

Discussion in 'General Electronics Chat' started by Dyl71, Aug 5, 2012.

  1. Dyl71

    Thread Starter New Member

    Aug 5, 2012
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    As my first post I want to say it's great to be here and I would like to get some thoughts on a first oscilloscope, mainly DIY troubleshooting and hobby. I have some older A/V components as well as new, I like to get my hands dirty and generally see how things are working.

    When looking at channel distortion or individual component problems, I would like to be able to test these items. Seems alot of these scopes come up for sale rather cheap but i'm not sure how old is too old.

    Been eyeballing a few Tektronix scopes and one thing has come to mind and that's analog or digital. Would a digital scope be able to measure what an analog scope would or are they completely opposite one another?

    There is a Tek 2336 and a Tek TDS 460 for sale near me and the 2336 has a set of probes. Are these well dated enough to warrant me looking elsewhere? Would like to stay under $300 and both of these are around $200.

    All thoughts welcome.
     
  2. Austin Clark

    Member

    Dec 28, 2011
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    I'm actually in the market for my first scope as well. From what I've heard, if you had to have only one, a digital scope would be best. There are few occasions when an analog scope is wanted over a digital one, but usually digital is best.

    You may find this video interesting:
    http://www.youtube.com/watch?v=Xh9FNRpta9s

    Analog scopes are fairly cheap to get on Ebay it seems, so depending on your needs you may want to eventually invest in one.

    A similar scope to the one I will likely get: http://www.saelig.com/PSBEB100/PSBEB100005.htm
    I'm looking at a slightly more expensive version (to get greater sampling rate and bandwidth) but you get a good bit of power for the price. Just look at this OTHER scope from the same site: http://www.saelig.com/PSBEB100/PSBEB100009.htm it's only $100 or so cheaper and it's specs don't even come CLOSE. 100Mhz vs 500Mhz, 100 MS/s vs 500 MS/s, literally 5 TIMES better for only 100 bucks more.

    However, I'm speaking as one who's been looking to buy for months, not as an experienced user, so keep that in mind.
     
    Last edited: Aug 5, 2012
  3. Yakima

    Member

    Jan 23, 2012
    35
    2
    I recommend a used Techtronics or HP oscilloscope, and E-Bay is a good place to shop.
     
  4. Dyl71

    Thread Starter New Member

    Aug 5, 2012
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    What are the limitations of a digital scope when testing preamps or amps? What does the analog scope perform that digital units don't have the capabilities for?
     
  5. crutschow

    Expert

    Mar 14, 2008
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    One difference typically is the inherent noise level of the oscilloscope. Digital scopes tend to have more intrinsic noise so they can't measure as low a level of signal.

    Otherwise I believe a digital scope is superior to an analog scope. Especially convenient is the automatic memory feature of a digital which makes it easy to capture and store one-shot or low frequency signals that an analog scope can't readily do. The built-in measurement functions of a digital scope (voltage, frequency, time, etc.) are also very handy.
     
  6. Dyl71

    Thread Starter New Member

    Aug 5, 2012
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    So if I understand this correctly, also based on the little I have researched....analog scopes are basically real-time scopes and the memory of an analog is basically the user triggering manually to capture a value or set length of time value and digital can recall the problem by just digging into the memory since it's buffered?

    If so then I can see how they are superior in that regards. For fine measurements and not needing a large memory storage, then a high-bandwidth analog scope can work wonders I presume just needs more user attention?

    Seems a bench needs both and I can sorta see why.

    I may go for a good used analog scope and learn on it, likely keeping it around for a long time afterwards.
     
  7. MrChips

    Moderator

    Oct 2, 2009
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    Not quite.

    Analog scopes are based on older technology. Since they are being replaced with newer equipment you can pick up a decent analog scope for free or close to free.

    What you should be looking at is the maximum operation frequency. I have on my workbench a Tektronix 422 that is good to 15MHz and is better than having no scope at all.

    Any scope under 10MHz is good for testing audio equipment and just starting out in electronics in general. The good thing is that a used analog scope is inexpensive. So there is nothing wrong with this for a good starter scope.

    A digital scope allows capturing single events and storage features. For advanced troubling shooting of digital and microcomputer circuits you want a bandwidth of 50MHz or 100MHz. The good thing here is the price has become very affordable, under $350, for what used to be around $1500.
     
  8. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    +1 get dual trace, at least 50 MHz bandwidth.
     
  9. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    No digital scope is as good as the best analog scopes (like Tek 7904A for example) at giving a true display of very fast waveforms. My work benh had that scope as well as a TEK digital storage "lunchbucket" scope for taking data plots. But when you really want to see a waveform: go analog.
     
  10. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    Analogs are not being phased out because of inferior technology, it's strictly a cost issue. Superior analog scopes have so much front panel hand wiring and assembly for switches and controls, they can't compete with digital scopes that have a front panel with four buttons and a hundred menus.

    You can get some decent analog scopes cheap, the best ones like 7904A not so.
     
  11. MrChips

    Moderator

    Oct 2, 2009
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    Comparing a Tek 2336 and a TDS 460, age is not a factor here as much as price.
    Assuming both are in good working order, a Tek 2336 for under $100 or a TDS 460 for under $200 would both be a steal, imo.
     
  12. MrChips

    Moderator

    Oct 2, 2009
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    I am not comparing top of the line analog scopes with any digital scope. I am looking at scopes that a hobbyist would like to have on a workbench.
     
  13. Dyl71

    Thread Starter New Member

    Aug 5, 2012
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    Both were at $200, the 460 was sold though.

    Another local shop is selling his 465B and a beast 7854 with the waveform calculator. The 7854 is in excellent condition but again with age a factor, how well did the 7854 hold up?

    Every manufacturer has their lemons, but since i'm just getting my feet wet I don't know which models to avoid.

    I think I can get the 7854 for under $300, not sure by how much, has a set of probes and plug-ins (2)7A26, 7B85 and 7B87 and the "2D" option installed... It's a piece of furniture that's for sure.

    I hear the 465B is one of the better scopes to have for most work, somewhat portable.
     
  14. MrChips

    Moderator

    Oct 2, 2009
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    imo, I think $200 for a used scope is too much to pay when you can buy a new digital scope for $329.
     
  15. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    One of the best values ever, a very popular and versatile service scope.
     
  16. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    My point is today's hobbyist matures into a future engineer/designer. Buy a good scope now and keep it or by a crappy scope now and replace it later. I spent 35 years in the business and never heard anybody say:

    "Darn! I sure wish I had bought the cheaper scope that doesn't work as well."

    I could not print what I have heard said in reference to cheap scopes.....
     
  17. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    New is not always better.... new junk made in China is just that. Used Tek equipment is usually pretty good unless it's been abused. They key is to buy from a reputable seller.
     
  18. MrChips

    Moderator

    Oct 2, 2009
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    Point taken. Tektronix's reputation for quality is one of the best. I'm always impressed to find a small spool of silver solder inside an old Tek scope.

    A Tek 465 is a solid scope.
     
  19. crutschow

    Expert

    Mar 14, 2008
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    Not sure what you mean by "memory of an analog". An analog scope has no memory unless its an analog storage scope which are rare beasts. As you noted analog scopes are real-time which means a single trace is only there for a few milliseconds (the decay time of the phosphor). This makes it very difficult to observe single-shot or low frequency waveforms (below a few tens of Hz).

    A digital storage scope automatically stores all the sampled values in a memory from each sweep. This allows you to view each sweep as long as you desire or store it for comparison to other traces.
     
  20. PRFGADGET

    Active Member

    Aug 8, 2011
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    7
    Dyl71 : What part of the country are you located in ?
    If your close to me , I might be able to help.
     
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