Cheap oscopes ?

Discussion in 'General Electronics Chat' started by curry87, Jul 23, 2011.

  1. curry87

    Thread Starter Member

    May 30, 2010
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    Looking for a first oscope for your general hobbyist from the Uk am confused on what to go for analog or digital ? only would be working up to 20mhz frequency wise but it must have 2 channels and be in the 100GBP to 150GBP range any recommendations on what/where to buy ?
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    The answer to that depends mostly on your application, and your luck.

    If you are going to use the scope for analog stuff then you want frequency response IMO. If you are going to build a lot of digital stuff such as PICs then you need something that can capture and hold digital screen shots.

    Luck enters into it with what is available when you decide you must purchase one. If you can be patient very good deals will come your way, but if this must be done in a week you will likely have buyer's remorse at some point.

    My advice is to sit down and write a list of what it must have in features, what you would like, and what doesn't matter. Think about it for a while.

    I am in the States so my answer is different than yours. Even so don't overlook Amateur Radio (HAM) events. A lot of good stuff gets swapped around by these guys. My second Oscope cost me $10 around 1986 or so, it was an old HP with an upper freq response of 300Khz, had banana plug inputs, used nothing but tubes. I bought 2 good ones and 4 bad ones (at $5) for my friends, who did appreciate it. They were being dumped by a local HAM club. I've retired the scope, but never regretted the purchase.

    Funny thing about HAMs, by definition these guys love to talk, and are into it for the love of the hobby. You will likely find out every thing that was ever wrong, every modification they made, where it is most likely to fail next, what the weather is in 3 counties over, and anything else that comes to mind. They are good people.
     
    Last edited: Jul 23, 2011
  3. tom66

    Senior Member

    May 9, 2009
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    Look around for local surplus stores. I found a test equipment surplus store nearby.

    I picked up my 4 channel digitising 100 MHz HP 54501A for £150.
     
  4. someonesdad

    Senior Member

    Jul 7, 2009
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    Bill nailed a key point: patience. I once waited over 5 years to find an HP 428B (a clip-on milliammeter that I had used in the 1970's). I finally lucked into one that was essentially in new condition, had the probe in perfect shape, and I was the only bidder. I paid $50 for the thing (delivered!) and I was willing to go up to $200.

    If you're patient, you will find good deals -- it's virtually inevitable.

    Make your like-minded friends aware of what you're looking for and keep pinging your regular sources. Persistence and casting a wide net are what result in fish...
     
  5. TBayBoy

    Member

    May 25, 2011
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    You might also want to call some of your local radio/electronics repair shops as well as colleges and universities, they may have surplus just collecting dust.
     
  6. BrainFog

    Member

    Jan 24, 2011
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    I am also looking for my first oscilloscope and live in the UK.

    I don't think these kinds of things are as common here in the UK as they are in places like the USA. I have mostly been looking on ebay which has a few. I saw quite an interesting antique one that was used by NATO. I would say go second hand as new ones are either very expensive or made to the lowest of standards.

    I have a question if you don't mind me hijacking. Most second hand oscilloscopes use tubes like the old TVs and my parents have told me how they used to endlessly blow. Does this apply to Oscilloscopes? How reliable and fault prone are oscilloscopes?
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    Oscopes are like any electronics, there are some good models and some bad. Just look around and ask questions.

    Amateur Radio is alive and well in Britain. Look for the clubs.
     
  8. Jensen

    New Member

    Mar 9, 2011
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    Check eBay, there are usually several used but good and pretty cheap scopes
     
  9. tom66

    Senior Member

    May 9, 2009
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    I don't know about tubes blowing as such (it's quite a rare, and sometimes explosive incident.) But here are some facts about CRT scopes:

    - They use an acceleration voltage around 5-8kV, much lower than the 30-50kV used by a TV. This makes the flyback cheaper, and also more reliable.
    - The beam position is controlled through plates, not coils.
    - Many old scopes have bad capacitors and these can go faulty causing various odd issues.

    For £250 you can pick up a NEW Rigol DS1052E 50 MHz LCD digitising oscilloscope. It's getting pretty good reviews...
     
  10. curry87

    Thread Starter Member

    May 30, 2010
    101
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    Which to go for thats the tough one.
    OWON PDS5022S 25mhz for 210GBP
    Rigol DS1052E 50 MHz LCD for 250GBP
     
  11. tom66

    Senior Member

    May 9, 2009
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    Rigol.

    For £40 extra - you get 1 GS/s instead of 100 MS/s. (100 MS/s effectively limits you to 10 MHz bandwidth.)
    For £40 extra - you double the bandwidth. Some Rigols can be hacked to 100 MHz too.
    For £40 extra - you get USB Host support, so you can save data onto a memory stick. (OWON is limited to PC only - USB device only.)
     
  12. curry87

    Thread Starter Member

    May 30, 2010
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    Why is the OWON bandwidth spec'd at 25mhz if its 100 MS/s effectively limits you to 10 MHz bandwidth ?


    Will a newbie electrical hobbyist/engineer ever really need to fully use or exceed that 10 MHZ bandwidth ?
     
  13. BrainFog

    Member

    Jan 24, 2011
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  14. TBayBoy

    Member

    May 25, 2011
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    It's a personal choice, but no probes or manual is an issue for me.
     
  15. BrainFog

    Member

    Jan 24, 2011
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  16. tom66

    Senior Member

    May 9, 2009
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    Blame the marketing department. Although the analog frontend could do 25 MHz to display a proper 25 MHz signal you need 10 samples per cycle, so around 250 M/s. Some people say 4 per cycle is enough, but the result will be very distorted.

    As a quick guide most microprocessors operate at 16 - 40 MHz. So yes, you could exceed it easily. And 10 MHz is barely within the bandwidth of standard video signals.

    That old 40 MHz scope probably won't be worth it. Digitising is the way to go IMHO.

    Where are you in the UK? I found the store in question on the 'net, they were 10 miles from me, highly recommended to look there as you can get much better deals than eBay and as you are dealing person to person you're much less likely to be left with an expensive boat anchor!
     
  17. BrainFog

    Member

    Jan 24, 2011
    122
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    Speaking of boat anchors I found this: http://www.ebay.co.uk/itm/Tektronix..._Measurement_Equipment_ET&hash=item1c1d463964 The bit that says it is a 2 man job to lift it made me laugh. It is amazing how those giant vales were replaced by something that is so small you can fit billions onto a few cm^2 bit of silicon.

    I live in Milton Keynes where is this shop?

    This may be better placed on its own topic but where in my general area is a good place to take an electronics course? I have only heard places say things like "oh yeah we used to teach that subject" but that is it.
     
  18. tom66

    Senior Member

    May 9, 2009
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    This shop is just outside of Reading. "Stewart of Reading" is the name... I think it is still in business. I bought a power supply from him about 6 months ago.
     
  19. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
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    Many of the Tektronix vacuum tube scopes were absolutely superb and wonderful to use. I still fondly remember my favorite, a single channel 4 MHz scope that you could lug around with one hand. :) I think it was something like a model 310 or 317...
     
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