I need an Oscope

Discussion in 'General Electronics Chat' started by ke5nnt, Apr 12, 2011.

  1. ke5nnt

    Thread Starter Active Member

    Mar 1, 2009
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    Pretty sure I've come to the point where I'm gonna need to get an oscilloscope, but I honestly have no idea where to start. Oscopes have a lot of different options and I don't really know what I need. How many channels? how fast? etc... Where do you discover what will work for you?

    I suppose it probably depends on what you plan to do with it? Well, I mostly would like to see transistor on/off cycles (square wave), voltage and current ripple, and things like that. Generally I'd like to stay away from an oscope that has low electrical limits like 12V max and the likes.

    Help point me in the right direction?
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
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    Get the best one you can afford.
     
  3. MattQ87

    New Member

    Apr 5, 2011
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    Buy used, look for a good corporate auction, check craigslist, O-scopes aren't too hard to fix, just make sure the tube is in good working condition (you'll see the filament inside start to glow when it's turned on, even if the electron beam isn't working. But new if you want features like USB output, or a nice digital display, or are measuring extremely high frequency signals (or if you have space constraints, the modern lunch box scope is much smaller and lighter than ones with a tube display). I got a free broken O-Scope that was on it's way to the junk yard that I was able to fix up by swapping out a blown fuse and playing with some calibration pots inside. Good luck, and have patience.
     
  4. monster_catfish

    Active Member

    Mar 17, 2011
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    B&K Precision produce quite a selection of affordable oscilloscopes. I would go for a dual trace, 30Mhz model such as the 2125A, if analog work will be your focus, as it has the facility to view input and output waveforms simultaneously.

    Test Equipment Depot has both new and reconditioned gear by numerous makers. Their price for a new B&K Model 2125 is steep at $646, BUT, you might luck out and snag a used one at the same location, for much less. Here is the link below

    http://www.testequipmentdepot.com/bk-precision/oscilloscopes/2125a.htm

    I decided to bite the bullet, and have just placed an order for a B&K Model 2125 'scope.
     
  5. retched

    AAC Fanatic!

    Dec 5, 2009
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    One thing about used and "need to be repaired" o'scopes, there is no way for you to know if the calibration is in check.

    So, if you are going to buy used, and a "fixer-upper", you should budget for calibration.

    Ask your friends and family, someone likely has one, or knows someone with one.
     
  6. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
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    If you buy a real o-scope then specifications like 12V(max) are not usually an issue. I got mine off ebay. There are plenty out there for pretty good deals. I went for a 2 channel 100 MHz analog scope.

    You say you are going to be looking at square waves from transistor on/off cycles. What is the frequency of the on/off? I always liked to multiply that number by 10 to get a good representation of the signal on the oscope. That's just me, others will probably have other opinions.

    It's always nice to have a four channel oscope if you need it, but do you want to spend the money for the occasional use.

    retched's advise "get the best you can afford" is really the best, especially if you are going to use the oscope a lot and are going to continue in the field...
     
  7. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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  8. ke5nnt

    Thread Starter Active Member

    Mar 1, 2009
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    A fair bit of my projects use microcontrollers clocked at 4MHz/4instructions per clock cycle so about 1MHz I believe would be my minimum requirement.

    Do you own one of these? How do you like it? I certainly like the pricetag, and even though portability isn't a must, it would be kinda nice not to have a tank to find a place for in a small apartment. My wife doesn't look as kindly on lab equipment as I do.
     
  9. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
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    The DSO Nano has a max sample rate of 1 MHz. It will not be fast enough to look at the 1 MHz cycles.
     
  10. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Try ebay for those $400 (new) digital storage scopes with colour screens. Most are 50MHz or 100MHz and store about 500k samples or 1 megasample of data.
     
  11. magnet18

    Senior Member

    Dec 22, 2010
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    I have a parallax usb oscilloscope, It's great and it was only $160, but it has a 20V max, so you might not want it.
    Has almost all the functionality of a normal scope though, just not good for HV stuff (you can always build a voltage divider)
    (not sure of the clock speed)
     
  12. Wendy

    Moderator

    Mar 24, 2008
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    You want a free oscope I have an old HP120B. It is out of calibration (badly) time wise but works pretty well other than that. It has an upper limit of 300Khz. It truely is a museum piece in every sense, I believe it was build during the early 50's. I have a manual in PDF format, and oh by the way, it takes about 2 minutes for all the tubes to warm up. It is easy to use, and a good training Oscope, as all the common features are there. It will sync to a signal very well, and will do lissajous patterns well also.

    When I say it is a museum piece, I really think this should be in a museum. If you take it and finish using it I would like it back, it would be a shame to throw something this old away.

    I bought a decent 60Mhz unit at the Dallas Ham Con (held every June) for $90, and put the old one into storage.
     
  13. t06afre

    AAC Fanatic!

    May 11, 2009
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    If you plan to get a scope. Get a "real scope" with proper scope functions like trigger. Many of the cheap DSO scopes are just flimflam. For a beginner an analog two channel 20 MHz scope will serve you well. If you can not get a new one get a second hand one.
     
  14. jt6245

    Member

    Feb 18, 2011
    21
    3
    "For a beginner an analog two channel 20 MHz scope will serve you well."
    Basically I agree with the above idea.
    I am using an analog two channel 20 MHz scope . But one time ,for measuring infrared coding from tv remote ,I need infrared sensor +sound card +free software.
    Although the above method solves the problem wonderfully,digital storage scope may be considered.
     
  15. Barnaby Walters

    Member

    Mar 2, 2011
    103
    4
    I too am looking to get a little scope, both for hobby use (robotics, misc. embedded stuff) and for troubleshooting my electric instruments.

    Has anyone had any experience with the DSO Nano V2? I hear that it can do most of the stuff an expensive 'big' scope can do if you install a certain firmware upgrade, just at lower voltages.

    Thanks,
    Barnaby
     
  16. DanRilley

    Senior Member

    Jan 13, 2008
    107
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    Of course if you need a scope just to visualize a waveform and don't need high resolution/ don't mind some software lag, I've found that using the soundcard of a laptop/iphone can work when you're in a jam. Just watch your voltage levels.

    I've used SignalScope for OSX.
     
  17. John P

    AAC Fanatic!

    Oct 14, 2008
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    I am thinking of getting a USB based storage scope like this one:
    http://business.shop.ebay.com/i.htm...=m270&_odkw=hantek+scope&_osacat=92074&bkBtn=

    Yes, one of those DSO units. They seem to be careful not to mention its maximum input voltage (I looked it up elsewhere: it's 35V) but apart from that, a storage scope for less than $200 sounds attractive, and of course it obviously has all the computer interface features you could ever want.

    How is it going to end up disappointing me?
     
  18. strantor

    AAC Fanatic!

    Oct 3, 2010
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    Look on E-bay for military surplus. The military hemorrages it's assets continuously, often unused or nearly unused. There are alot of instrument repair/calibration companies out there that buy up the military surplus instruments for next to nothing, fix them up, calibrate them, then sell them on ebay for a very fair price. I lucked into this knowledge when I bought a Tektronix 2430a for 250$ on ebay, calibrated. I noticed the old military calibration sticker on it. I later found a 900-something page military service manual for it that covers everything. It has testing, troubleshooting procedures, calibration procedures, part# for every component, diagrams, etc.; Way more information than Tektronix would ever give you. Plus, I found a military users manual for it that is just as great.
     
  19. tom66

    Senior Member

    May 9, 2009
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    I picked up my digitising HP 54501A (100 MHz, quad channel) from a used test equipment store nearby me. (They do exist!) It cost £150 including one probe, that was about $200 back then. Have a look around for one. It's been very useful and after dusting it out, it works well.
     
  20. Barnaby Walters

    Member

    Mar 2, 2011
    103
    4
    Changed my mind — I'm going to wait until this little beauty is released:

    DSO Quad Review

    Signal generator, 2 Analog + 2 Digital inputs — it sounds pretty good, and will certainly cover my needs: Basic hobbyist/going into commercial audio use at low voltages, and extremely portable.

    It is in development, but there are a couple of units available on eBay… Not that I'm trusting them.

    Thanks,
    Barnaby
     
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