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Oscilloscpe purchase

Discussion in 'Electronic Basics' started by Abstract Dissonance, Feb 22, 2006.

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  1. I'm looking to buy an oscilloscope and I don't really know where to start.
    One thing I definately will not do is buy ones from an auction
    house(specially from ebay).

    I'm not sure if I should go with a new or used one. I'm maybe willing to
    spend upwards of 1000$ but rather spend the least amount I can(obviously).
    Since I'm not a professional I don't need the latest and greatest but I'd
    like to get something that I will grow out of in a few months(or even a few
    years). I'm thinking, for now atleast, I need a bandwidth of atleast 1MHz.

    Right now I'm looking on tektronix web site and the cheapest one I can find
    is about 850$. Its the TDS1000 and has a bandwidth of about 40MHz.

    What I would really like to have is a logic analyzer and an oscilloscope(and
    it would be nice even to get the other stuff like signal generators and
    spectrum analyzers, etc...). I'd probably rather get used equipment but I'm
    afraid that I cannot find something easily that is decent(i.e., won't die in
    3 weeks of use) and isn't an antique that won't do me any good.

    Can someone point me in the right direction so I can get a start into
    finding something that will work? (Several people have mentioned getting
    stuff but most of it has been from ebay.... I will not purchase from ebay
    because I don't like the company for its business pratices. (so don't bitch
    about it, ok? ;)). Also don't mention hamfests cause there are none around
    me for several months(atleast according to some site I checked.) The closest
    one is like 300 miles away and is in a month or so... unless, ofcourse, you
    are sure the drive and wait is worth it(i.e., getting a good, cheap, and
    working oscilloscope/other stuff)...

    I've seen a few sites that are selling used oscilloscopes but they seem a
    little shoddy. I'm just not sure where to look and, ofcourse, if I buy new
    then I'll be paying out the but for something that I might not end up using
    to its fullest along not having the budget for other things that I probably
    need.

    Thanks,
    Jon
     
  2. Rich Webb

    Rich Webb Guest

    An o'scope is an investment -- although you don't need to invest $20K in
    one -- and any one of the TDS scopes would be a good choice. I've had a
    TDS220 for years as a "home" scope and it's great.
    PC-based o'scopes are no comparison to the little Tek scopes BUT you can
    do quite well for a PC-based logic analyzer. My favorite is a relative
    newcomer to the field, the LogicPort. Info (with demo software) at
    http://www.pctestinstruments.com/index.htm.
     
  3. Go buy one at DSE or Jaycar, since you say you want to grow out of it in a
    few months :).
    For a starter one of such would serve you quite a while while you save up
    for the logic analyser which would be a serious outlay !!
     
  4. Chris

    Chris Guest

    Hi, Jon. I'm hearing you say you want to buy a new scope. I'd try to
    beg or buy a used one first -- you should ask around. There's probably
    a good working scope sitting idle in someone's basement in your
    neighborhood. Ask around, particularly for older TV/Radio repair guys.

    But it might be best for you to buy new at this point, because it
    sounds like you'd be more comfortable with something new, and also you
    don't have the electronics background to be repairing things just yet.

    About 20 years ago, my scope got lost in baggage, and I just needed
    something to do a service call on a machine. I bought a low-end 40MHz
    dual trace Gold Star (now known as EZ Digital) analog scope. I've
    still got it as a spare (it's a little big for service calls), and it
    still works fine. I've had to repair it once (my fault).

    EZ Digital makes a number of good, reliable analog dual trace starter
    scopes. I would be looking at the OS5XXX, with the choice depending on
    your price range. Any of them would be a good first scope, but the
    more you spend, the more capabilities you have. The OS5030 is a 30 MHz
    dual trace analog that's available for less than $400 new from at least
    one source. If you're feeling a little more free with the bucks, the
    OS5040 is a 40MHz scope with delay (you can usually cobble together a
    delayed external trigger circuit if you really have to on the OS5030),
    and is available for less than $600. Either one would be a good
    choice. I'd pick the OS5030 myself.

    If you've got a budget of $1000, you can buy either of these scopes,
    buy a couple of linear power supplies for your bench and a good DMM,
    along with a good soldering iron and a protoboard, and spend the rest
    on whatever you can find at the hamfests that are coming along. You'll
    be "good to go".

    If you spend a lot of time in electronics, you'll probably eventually
    need another scope. But you'd be amazed at how seldom you actually
    have to have a digital storage scope. A 30 MHz scope will show
    something on the CRT at frequencies far above that, and "something" is
    frequently all you need.

    Just don't get one of those multi-function scopes with all kinds of
    other gadgets built in. They're a pain to fix.

    Good luck
    Chris
     
  5. ehsjr

    ehsjr Guest

    http://www.fairradio.com/oscill.htm

    They seem to be a decent outfit, and carry a number of
    Tek 'scopes like the 465.

    Ed
     
  6. Guest

    Too bad, ebay is a great place to buy. There is no reason why you cant
    bid for a scope thats local to your location then you can go round and
    inspect it yourself.
    You'll need a lot more than 1Mhz, I wouldn't look at anything less than
    60Mhz.
    Agilent (HP) do a mixed signal scope, 2 analoge channels plus 16
    digital, don't get the earlier version if you do alot of slow speed
    work.
     
  7. Phil Allison

    Phil Allison Guest

    "Abstract Dissonance"

    ** One like this will give you a lot of test equipment mileage for very few
    dollars.

    http://www.dse.com.au/cgi-bin/dse.storefront/43fd5edb058c47cc2740c0a87f9c071f/Product/View/Q1803





    ........ Phil
     
  8. Why not?
    Some excellent deals are to be had on eBay, and many companies selling
    them on there are legitiment test equipment refurbishers and will
    provide a warranty and guarantee it's performance etc.
    Start out small and work your way up. Only then will you know what your
    true requirements are.
    That is OK for the money, but read my notes below. You'll want a real
    analog scope too.
    Agilent do the only decent "mixed-signal" (scope+logic analyser) scope
    on the market, but it's well out of your price range.
    Get a used one, you'll save real $$$ and get a higher performance unit
    for the price.
    Seriously, get over it :->
    There are plenty of 2nd hand test equipment suppliers around, and many
    of them now sell on eBay as well. If you are US based then you are
    spoiled for choice. Even here in Australia we have a cople of 2nd hand
    scope dealers, the US seemingly has hundreds.
    I have heard people in the US buying scopes by the pallet load!
    Here is what you need to do:
    1) *essential* - Buy a cheap 2nd hand analog oscilloscope (20MHz will
    do for starters, but a 100MHz one would be nice). New analog scopes of
    any decent bandwidth offer poor value for money to someone in your
    position.

    2) Buy a new PC based USB logic analyser/scope. BitScope is one such
    example, but there are plenty around now, just check the ads in
    magazines like Circuit Cellar. They cost several hundred dollars
    upwards. It will give you a logic analyser as well as a digital storage
    scope and spectum analyser. The sample memory it has the better. A few
    KB sucks, 32KB is useful, several hundred KB to a MB is great. More
    memory allow you to zoom in to see packets of digital data etc - very
    handy.

    Dave :)
     
  9. I forgot to add *why* you need a higher bandwidth analog scope like
    100MHz+...
    If you are viewing digital signals (or anything other than a sinusoidal
    wave), a 20MHz scope *won't* display any detail in a 20MHz signal, so
    it can become quite limiting for anything but "seeing if a signal is
    there or not" at those sorts of frequencies.

    Dave :)
     
  10. blah

    blah Guest

    Here is what you need to do:
    Blah, blah, blah... Analog scopes suck. If analog scopes were so good,
    why don't Agilent, Tektronix, LeCroy, or any of the real scope
    manufacturers still make them? You, like many, are confusing sampling
    rate and bandwidth.

    First, you are making the mistaken assertion that sampling rate is twice
    the bandwidth, and hence if you are using a 20MHz scope, you will not see
    more than 2 points per period. This simply isn't true. Many scopes that
    can't achieve very high sample rates, will use equivalent time sampling to
    sample the same signal repeatedly with slight time offsets achieving quite
    good resolution.

    Second, if you have a 20MHz scope that means the bandwidth of the scope is
    20MHz. Signals that are greater than 20MHz will be rolled off, so
    a 20MHz square wave will look like a sine wave or closer to it than square
    to begin with and this applies to both analog and digital scopes.

    Digital scopes and analog scopes each have respective advantages.
    However, analog scopes advantages are only advantages when compared
    against crappy low-end or ancient digital scopes. Modern (good quality)
    digital scopes will readily outperform any 100MHz analog scope, let alone
    a 20MHz scope at virtually all applications. In some cases, where you are
    concerned about glitches, complicated triggering patterns, and one shots,
    there simply is no substitute for a digital scope. Digital scopes can
    also provide better persistence features, FFTs, frequency measurements,
    etc.
     
  11. Phil Allison

    Phil Allison Guest

    "blah" = another Yank compewter geek fuckwit


    ** Digital scopes suck big time - for nearly all analogue work.


    ** For the bloody obvious reason Asian scope makers beat them hollow on
    price.


    ** Absolute BULLSHIT.




    ......... Phil
     
  12. It is because the asian manufactuers can make them at a lower price.
    There probably isn't enough margin in it for the big names any more.
    I am not confusing anything.
    I know all about sample rate, bandwidth, equivalent time sampling etc.
    I have designed several DSOs over the years thank you very much.
    I know this, and I said nothing about about DSO's and their sample
    rates!

    Most scope manufactuers are going away from equivalent time sampling
    becuase it sucks, they are all going real-time with deep memories, with
    the sample rate at 10+ times the bandwidth.
    Only the crap very low end digital scopes and the extremely high end
    bandwidth scopes use equivalent time sampling these days. The crap ones
    do it because it's cheap, and the high end ones do it because they have
    no choice.
    You'd be silly to buy say a 100MHz DSO with 20MS/s sample rate working
    in equivalent time. Real-time is the way to go for a general purpose
    low to medium bandwidth DSO.

    Equivalent time scopes are of course next to useless for single shot
    work.
    Of course it does, I did not say anything to the contrary.
    Exactly!, and that is what we are talking about. The OP can't afford
    anyting but the crappiest low end DSO with a few KB of memory and the
    response time of a snail.
    Yes, modern DSOs like the Agilent 6000 series are brilliant.
    Can the OP afford one? - No.
    Of course.
    But the OP has a total budget of $1000 and wants a logic analyser too,
    you recon he should blow it on the crapiest low end DSO he can get?
    He would be *much* better served by a nice 100MHz analog scope for
    repetative work and a PC based DSO/logic anlyser for single shot work.
    He'd likely still have change from his $1000 too.

    Dave :)
     
  13. John Fields

    John Fields Guest

    ---
    Like you've got someone in Oz who's building world class scopes?
    ---
    ---
    Hmmm...

    Really???

    I've got an HP54602 which can run rings around my Tek 2465 when it
    comes to displaying an FFT.
     
  14. Phil Allison

    Phil Allison Guest

    "John Fields"


    " John Fields
    Professional Bullshit Artist "


    ** The psycho Texas jerk off is not even good at that.






    ......... Phil
     
  15. John Fields

    John Fields Guest

     
  16. Phil Allison

    Phil Allison Guest

    John Fields"


    " John Fields
    Professional Bullshit Artist "



    ** The fuckwit, psychotic Texas jerk off is not even good at that.







    ......... Phil
     

  17. It looks like that Austrailian parrot is stuck again. Will someone
    down under please rattle his cage? ;-)


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  18. I'm still not quite sure what to do.

    looking on ebay I see many logic analyzers for under $100 such as


    HP 1650A Logic Analyzer(40$)
    HP 5000A Logic Analyzer
    Bitscope USB 100MHz oscilloscope, logic analyzer, & AWG(100$)
    Tektronix 3001GPX Logic Analyzer w/opt 1M & P6490 Probe
    HP(HEWLETT PACKARD) 1672E LOGIC ANALYZER 68 CHANNELS(229$)


    and some oscilliscopes such as

    Tektronix 465 2Ch 100MHz Oscilloscope !!!(50$)
    TEKTRONIX 465/OSCILLOSCOPE
    TEKTRONIX 2236 OSCILLOSCOPE
    Agilent / HP 54112D 100 MHz Digitizing Oscilloscope(100$)
    TEKTRONIX MODEL 2235 100 MHZ DUAL TRACE OSCILLOSCOPE(160$)

    Tektronix 2465 Oscilloscope 300MHz(200$)
    (the prices are in ascending order)

    Are any of these good deals?(i.e., good equipment for the money and will get
    me on my way?)
    My main concern with ebay is not getting ripped off and not getting
    something that is broken. I've heard way to many horror stories about ebay
    and thats the main reason I'm trying to avoid them.



    HP 8165A Programmable Signal Generator, 1 mHz-10MHz(75$)
    WAVETEK 2410 SIGNAL GENERATOR 10KHZ-1100MHZ(100$)
    http://cgi.ebay.com/WAVETEK-2410-SI...591878990QQcategoryZ97198QQrdZ1QQcmdZViewItem

    The link to the wavetek... it says something about fail on the calibration
    table and things like this make me worry about buying something that its
    just going to end up giving me a headache and knows what else is wrong with
    it. When someone says "It powers up and everything seems to work but *I
    have no way of testing it*" it makes me wonder if they are trying to sell a
    piece of crap.

    Is there any reputable stores in the US that handle used equipment like this
    that has a website? (maybe even one that you yourself have experience with
    ;) I don't mind paying a little bit more so that I know that I'm getting
    something that works.

    Thanks,
    Jon
     
  19. Rich Webb

    Rich Webb Guest

    [snip...snip...]
    A couple of places that have refurbished test equipment that have had me
    on their catalog mailing list for several years:

    http://www.testequipmentdepot.com/
    http://www.tucker.com/

    And one that's (AFAIK) only new and not refurb:

    http://www.tequipment.net/

    I've bought a few things from TEquipment.net, have had no problems, and
    will probably look there first when it's time for another purchase.
    Haven't used the other two but AFAIK they are okay.
     
  20. Thanks.... Some of the used stuff seems a little expensive(cheapest I saw
    was 500$) but atleast its a start.

    Jon
     
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