EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: roguewave2112 on December 05, 2013, 01:46:38 am
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Hello, I'm looking for small digital oscilloscope with dual trace ability. I am using it to run my synthesizer into to see what the waveforms look like when I patch different combinations on it. I have a local shop offering me a very nice analog 30 mhz dual trace oscilloscope at a good price but it is huge. I have limited space so I'm looking for an affordable compromise. I have seen these pocket models but I don't know what is good or bad. Any suggestions would be great, thanks in advance! Daniel
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What's your price range? You can get a Rigol DS1052E for $329 US.
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I think a low end digital scope like the DS1052E won't satisfy you. These have slow waveform rates and no intensity grading. The waveforms look very pixelated and have not a smooth motion dynamic (sorry, i don't how to describe it better). They are not good for looking at modulated waveforms. It looks ugly.
I think you need at least a digital scope with high waveforms per second and intensity grading. The displayed waveforms look more analog and feels more realtime. But they cost more. I think a real analog scope would be the best for this application.
Maybe I can make some screen shots tomorrow.
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Audio frequencies aren't very demanding of any decent scope.
Any reasonable analog scope would easily do the job, but they're all big and bulky. If you can tolerate the space, this would be your best value.
The DS1052E will certainly do the job, and it's about as small as any mains-powered two-channel scope. It's also cheap, with a mature, well tested design.
For just a bit more money and bulk, you can get a newer intensity-graded scope with a prettier, bigger, higher-resolution display. Probably a better value for demanding users, but it might be overkill for your purpose.
If the DS1052E is too big, there are smaller battery operated scopes. Many of these are single channel. In my limited experience, portable battery operated scopes are either very expensive (Fluke scopemeter class), or junk (TPI 440 class). They do give portability, but they don't offer good value per dollar compared to mains powered scopes.
I don't know exactly what your priorities are regarding size, price, and display quality, so I can't say whether you should go up or down from the DS1052E. But it sounds to me like the DS1052E might be a reasonable choice.
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The one I found locally is the BK precision 2121 dual trace 30 mhz oscilloscope. It's runs and looks brand new: comes with book, power supply, all included accessories and carry bag. 175.00 u.s. before tax. It seems like a great deal but it is big, compared to the tube models it is small though. Anyone know if this is a good one? If so, how would I connect it to my keyboard? Thanks!
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The one I found locally is the BK precision 2121 dual trace 30 mhz oscilloscope ..... how would I connect it to my keyboard?
All oscilloscopes will connect to an audio synthesizer's output in the same way. You'll connect a probe to the scope's input jack, and the probe to the audio output. A new scope will typically include a probe for each input channel. A used one, maybe not. For a 30MHz scope, new probes won't be terribly expensive, but not negligible. Probes do wear out, especially if abused (the cable doesn't like to be bent too tightly). Do budget for them if they're not already included, or if the ones that are included seem to have taken a beating.
That BK Precision scope is more than capable of displaying the audio waveforms. As you notice, it's not lightweight or small, mostly because the CRT display unit is very big compared to the LCD display unit of a modern digital scope.
If you're thinking about going the analog route, I think you might be able to find a cheaper used unit that will work as well. It may take some digging, but between hamfests, swapmeets, eBay, and craigslist, there are used analog scopes going for peanuts compared to what they used to cost. It shouldn't be too hard to find one in the $50 - $100 price range, and if you're patient and a bit lucky, going below $50 may be possible. Such a cheap used scope probably wouldn't be "like new", but would be usable.
Also, based on asking question about how to connect the scope to the keyboard, you may want to check out the oscilloscope training class on the sticky at the top of the "beginners" board. There's good info there about probes, and a lot of other stuff. It does take a while to watch the video, but it's time well spent. https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/ (https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/)
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That, ARM DSO203 Nano V2 / Quad Pocket Digital-Oscillo?scope (http://www.sainsmart.com/sainsmart-arm-dso203-nano-4-channel-mini-v2-quad-pocket-digital-oscillo-scope.html), might fit the bill.
A Google search lists several suppliers.
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I made a test with an analog and two digital scopes. I used an Arp Odessy as source. Both VCOs active plus some ring modulation and some LFO modulation. Not a very complex sound. The analog one won by a far margin. You can see the waveform changing in real time. The LFO modulation is displayed smoothly.
The first screen shot is from a Rigol DS1052E. It's a low end digital scope. The update rate is so low that you can't see the waveform evolving. It feels more like a slide show. You can't see the details of the waveform. The display resolution is too low and it has no intensity grading.
The second is from a Rigol DS1074Z. It's a far better scope but still a low cost one. It has a high waveform per second rate and intensity grading. This is usable. It stutter a bit. One annoying thing is that there is a small lag. You play a note and you see the attack only after it happen. It's not real time. I would say that the DS1074Z or a similar scope is the minimum for this application. But it costs $585.
Sorry, no pictures from the analog scope. The long exposure times of my phone camera made them useless.
I would recommend an analog scope. Yes, they are big but far better than the digital ones for this. My rating is 100% for the analog, <5% for the DS1052E and about 40% for the DS1074Z.
Have you considered using a computer with an oscilloscope program? I think it could be better that a low end scope like the DS1052E.
btw: Which synths you have?
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Thanks for the info Sync. I have a new Korg MS20 and I'm tryig to learn what the functions do and I think a visual depiction would be helpful. I am trying to learn about subtractive synthesis but am only finding dead ends online. Everyone has said give it a few years and you'll be able to do some cool stuff with it! :)
I no very little about electronics but want to learn so I don't know if the two subjects go hand in hand or if I should focus on one more than the other. I am very into modular synthesizers and I love the whole concept of patching things together and creating something new. (I am a big fan of Tangerine Dream, Kraftwerk, Vangelis, Devo, EDM, and Goblin( italian band who did soundtrack for original Dawn of the Dead), I also am really into guys like Richard Devine, Throbbing Gristle and similar acts..
I like creating things and I like funky noises too. (old school dr who fan too, that's another conversation.)
If anyone could suggest books on these things I'd be very apppreciative. Thanks and sorry to ramble. Also, I wouldn't mind using a pc program but I would like one where it has like a usb box so I can attach probes etc..
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I don't know what country you're in, but I would definitely look for an analog scope. Yes, they're heavy, yes, they're big. But there's that retro quality that cannot be matched by a modern scope (though the expensive ones can come pretty close.)
I landed a Tektronix 7633 mainframe style scope for $80 from an old employer. If you're in the US, eBay has lots of scopes which will be more than good enough for audio stuff.
Find one with an XY mode so you can plot stereo channels against each other. Depending on how you hook it up, the left channel will deviate the trace vertically, and the right channel will deviate the trace horizontally. This makes for some very neat effects, sometimes. Good stereo separation is the key for a good XY display.
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I don't know what country you're in, but I would definitely look for an analog scope. Yes, they're heavy, yes, they're big. But there's that retro quality that cannot be matched by a modern scope (though the expensive ones can come pretty close.)
I landed a Tektronix 7633 mainframe style scope for $80 from an old employer. If you're in the US, eBay has lots of scopes which will be more than good enough for audio stuff.
Find one with an XY mode so you can plot stereo channels against each other. Depending on how you hook it up, the left channel will deviate the trace vertically, and the right channel will deviate the trace horizontally. This makes for some very neat effects, sometimes. Good stereo separation is the key for a good XY display.
Hi Roguewave2112,
I read your posts as well as those of the other's, but frankly I second Rigby's post. For the money and for what you wanna do, I'd track down one of the older analog Tektronix scopes. There are some real gems out there for cheap. I've used many brands of analog scopes as well as expensive high-tech digital scopes. I personally own two 3 Tektronix scopes, one Tek 465B, a Tek 475B and a Tek 2446. But of them all, my Tek 465 is my favorite. I've used Tek 465s since 1975, and while the good quality digital scopes are very nice, small, productive, and they do have the ability to 'freeze' fast, transient, one time wave-shapes (such as a 100 pS 1PPS Cesium epoch), its difficult to beat a 465 for overall utility.
The general specs for a Tek465:
- 100 MHz
- Dual Trace
- Chop channels A & B
- Alternate Sweep channels A & B
- Algebraic 'add' channels A & B
- Delayed Sweep
- Trigger View
- Auto, Normal, XY Sweep modes
However, there is a significant drawback with these old Tek scopes, Tektronix no longer repairs or calibrates them. There are a few rental houses that still do, but they too are beginning to drop that service and the reason for it, is the lack of available components. Tektronix, as many American companies do, they relabel/mark all of the major semiconductors with in-house part-numbering. A commercially available, relabeled 22cent transistor that can no longer be sourced from Tektronix can be death of one of these scopes. But heck, they nearly last forever. Mine are over 30 years old, the triggering is becoming a little crusty on one of them, just needs a bit of a tune-up.
Take a look at this Tektronix 465 on www.eBay.com (http://www.eBay.com) for $175 free shipping (within US):
261347684388 (<-- put this number in the eBay search dialog)
Or this Tektronix 475 (same scope as above, but 200 MHz bandwidth) for $129 + $48 shipping - eBay: 251396410228
Then another (large) old scope, but a very good one is the Tektronix 7603 with the 7" square CRT (as I recall?).
Tektronix 7603 with 2x 7A26 Vertical Ch modules & a 7B50A module (4 ch at 100 MHz)
$295 + 60 shipping, ebay: 161120607859
This particular unit has a pair of module that are 100 MHz band-width, giving four channels with on-screen voltage and time measurements. This is a slick scope.
Also available for cheap is the Tek 16 channel 7D01+DF1 logic analyzer module that works with this scope sold by other eBay vendors. I've recently seen that modure selling for $20!! (worthless without the pods). Those sellers who seperate the pods from the logic-analyzers should be publically caned, along with a bunch of lawyers & politicians for good measure.
Then there's the Tektronix 2246, its a more recent manufactured scope. Its a 100 MHz 4 channel scope (the C & D channels don't exhibit full A & B feature set), while the scope implements 'on-screen' display of frequency, reciprocal of frequency, and various voltage measurements.
Tektronix 2246 (100MHz 4x channel): eBay 251396410228, $264 + free shipping (US)
I have no experience with the 'cheap' Chinese/Korean/Taiwanese digital scopes so I can make no comment there. I do however have several years continuous lab experience with several Tektronix digital DPOs, DSOs, and MSOs...scopes. If you can score one of those, you'll not be disappointed. The problem with modern Tektronix gear is that they are WAY OVER PRICED.
Cheers,
bench knob
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Roguewave2112, are you in the US? I have a BK Precision 5100 100 MHz combiscope with manual and 2 150 MHz "One Hung Low" probes that you can have for $170 shipped if you are in the US. It doesn't have the handle. I have 2 other scopes (Tektronix 2235 and Hantek DSO5102B) so it is excess to my needs. If you are interested, send me an email to NW0LF@dawoolfe.com.
Tom, NW0LF
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I bought the b and k scope but the wife was not pleased and I underestimated the size. I have little room in my house. I think I will maybe find a pc program or something smaller. Thanks for all of your great ideas.
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I bought the b and k scope but the wife was not pleased since I have little room in my house, any one want to buy it? :)
If size does matter, try DS203. When the time come, just hide it in your pocket.