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Which oscilloscope and/or logic analyser?

Discussion in 'General Electronics Chat' started by earckens, Aug 31, 2016.

  1. case-sensitive

    case-sensitive Member

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    I just found Sigilent SDS1052DL and Hantek DSO5102P on ebay, for about AUD340. Its just for home, doing some analogue things, 50MHz is plenty. Got an age old Hameg 20MHz CRT, still working. But I think the contacts in the selectors are a buit iffy, makes a bit of its own noise. Bought the Hameg in 1996 for the equivalent of 170 Euro...
    Are any of the mentioned ones worth buying?
     
  2. spec

    spec Well-Known Member Most Helpful Member

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    A real time scope with a high frequency response, even for home electronics, is much more useful. I would recommend at least 50MHz but ideally 100MHz up.

    spec
     
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  3. case-sensitive

    case-sensitive Member

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    had a look, they are both real time, sampling rate 10 times their frequency response
     
  4. dave

    Dave New Member

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  5. atferrari

    atferrari Well-Known Member

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    My 100-Mhz Owon, able to capture non repetitive signals was what allowed decoding PS2 signals with little difficulty other than learning how to use it. I even got used to the horrible appearance of the trace on the screen.
     
  6. spec

    spec Well-Known Member Most Helpful Member

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    Hi arferrari

    What is the problem with the trace?

    spec
     
  7. atferrari

    atferrari Well-Known Member

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    Not sure how to express it properly, jagged? rough? certainly not as the smooth one in my previous analog scope. I am aware that this last was probably also cheating showing it nicer than what in reality it was. Lower BW, I know.

    The fact that there is an ADC involved and with a rather limited resolution, is the reason of what I get.
     
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  8. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    That's a 'feature' of digital scopes, and the better the scope (higher bandwidth) the more you can see the noise - you get the same noise on analogue scopes but you can't see it as it's continually refreshed.
     
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  9. case-sensitive

    case-sensitive Member

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    some said 8 bit resolution, well thats not much if you measure say 20V? And yes, they do look pixulated and the trace somewhat fatter
     
  10. earckens

    earckens Member

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    ..and in reply to StellarRat too: price range indeed not specified because I had no idea what to expect for what price. And to spec and JLNY, indeed I think it will be invevitable to get both an analog scope and a digital one. I like the reslution and stable triggering of the Tektronix scopes.
    I would have loved to get a TDS 340 (JLNY I am jealous of your USD100 acquisition) but I settled for a USD100 2235A import from Singapore.
    That unit blew up when powered up on arrival, but it was luckily only the filter capacitor on the main 220V line right before the rectifer, so I got that fixed. There is an issue with B-channel not reading properly on a few voltage settings (related to the rotary switch, probably wear) but I can live with that. I also added a ventilator in the PSU compartment.

    If I get a chance I would still love to get a TDS340. Or a digital scope, Rigol or similar. I may be wrong, but I think given the choice I would prefer the TDS even for pure digital signals, because of the memory capability.

    For a logic analyser I bought a clone Saleae 16 channel for €40, works perfect, very nice GUI.
     
  11. case-sensitive

    case-sensitive Member

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    thik I found it (the error), so the Hameg is going to live another day.
     
  12. JLNY

    JLNY Active Member

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    Hehe, my TDS 340 was indeed a lucky find. That said, the 2235A is very respectable scope, and I would say you did well to get it for that price. I'm glad to hear you were able to find a scope to use, and I expect you will get good use out of it. That's some rough luck on the bad capacitor, but it sounds like you did a nice job fixing it up.

    As you say, I imagine that eventually you will want to look for a DSO when the need arises, probably either a modern Siglent, Rigol, etc. or a vintage DSO such as the previously discussed Tek or HP scopes. For now, I would recommend spending some time familiarizing yourself with your 2235A. Even now that I have my own DSO, I still use my analog Hitachi scope quite a bit, especially when I need to use a scope in X-Y mode. After working with an analog scope for a while, you may have a more concrete list of criteria for what specs or features you will want for a DSO.
     
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  13. earckens

    earckens Member

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    Very sound advice, I will remember that.
    Thks!
     
  14. spec

    spec Well-Known Member Most Helpful Member

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    Not sure what mains voltage you scope was used on for most of it's life. But on ex USA equipment that has been running on 120V you can get problems with the input circuitry if you suddenly run of 240V mains.

    As a precaution I use a Variac and gradually increase the the mains input voltage to the equipment in 10V steps from 110V, to give the capacitors time to reform /breakdown and repair.

    spec
     
  15. earckens

    earckens Member

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    It was C904, I replaced it with an X2 rated 47nF 275V cap which is in fact too low (should be 240V*square(2)) but it is holding. I replaced the mains filter unit too and installed a ventilator powered off the 8.6V dc.
     

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  16. ChrisP58

    ChrisP58 Well-Known Member

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    That capacitor is fine. Since X2 capacitors are designed for use across the AC line, their rating is in AC Volts.
     
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  17. kinarfi

    kinarfi Well-Known Member

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    I have a DSO2150 and an old Tektronix dual trace scope and I only use the DSO, if you have a ''spare' laptop that you can leave at the bench most of the time, I would say go with the digital, you get the advantage of split screen via computer so you can use the usb scope and maybe usb camera or the spice schematic at the same time and if you need to do screen shots of the wave form etc. etc etc.
    Jeff
     
  18. spec

    spec Well-Known Member Most Helpful Member

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    Do you know, I tend to think of traditional scopes and digital storage scopes as completely different instruments.

    My unsupported view is that anyone in electronics should have a traditional scope.

    But a digital storage scope does things that a traditional scope can't do. One basic advantage is with digital work where you have a number of related logic signals, that only occur once.

    Anyone doing home electronics is now much better off than when I started. For one thing the basic instrument, a multimeter, is so cheap that they are within the grasp of anyone. In our local cheap shops you can buy a half decent digital mulltimeter for £5UK.

    And a basic digital storage scope is not too expensive.

    spec
     
    Last edited: Jan 24, 2017
  19. case-sensitive

    case-sensitive Member

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    tried a digital scope at the shops, has the same amount of self induced noise if you crank it up (max frequency, max amplification) as a CRT one (I was thinking its the probes or the rotten contacts on my old one). CRT one has way sharper lines and unlimited resulution (not 480 x 640 pixels).
    USB one would be fun, full screen resolution and way cheaper
     
  20. RadioRon

    RadioRon Well-Known Member

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    I used to think the same way, but times have changed. I had set up my latest hobby bench, years ago, with two scopes, the analog one an HP 1725A 275MHz scope and the digital one was a low cost Rigol 50MHz unit. Over a few years, I used the analog scope less and less until it basically just collected dust, while the inexpensive Rigol digital unit did everything I needed to do. Then I upgraded to a Rigol DS2202 digital scope and never looked back. I've still got the 1725A, but it sits on a storage shelf. Nowadays, a beginning hobbyist, with limited budget is probably better off buying one of these sub-$400 digital scopes brand new rather than buying an old, retired Tek or HP analog scope. It also becomes imperative that the new user study and understand the aliasing problem and sampling limitations inherent in such a device. I would recommend to the beginner a minimum spec of 1GSample/second and the more the better.
    Although I don't get out to commercial labs as much as I used to since retiring, none that I've seen use analog scopes anymore, but they do spend good money on high performance digital units like 10Gsa/sec and so on.
     
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  21. case-sensitive

    case-sensitive Member

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    better still, there are some osci kits on ebay for AUD70 or so
     

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