SDS800X HD Actual Use Cases

[mawyatt]

OK, this thread is only for actual use cases for the Siglent SDS800X HD, the Rigol DHO800X use cases can start another independent thread so as to keep the "Mines better than yours" pissing contest away!!!

Also along with the only for actual use cases above, this is not about finding bugs, perceived bugs, manual confusion/discrepancies, user wants/wishes, my brand X can do too (better than yours), and so on, it's about actual use cases of the SDS800X HD where one actually uses the DSO for measuring/displaying something useful

Hopefully some potential DSO users will find the expected following use cases valuable, and not have to sift thru all the BS flying around when it comes to these new 12 bit low cost DSOs!

We'll start off with something that just came up.

Using a precision CMOS pulse generator to create a precise 0 to 5 volt low frequency pulse we noted some peculiarity on the pulse rising edge. To view this we needed to use the Zoom feature to expand the horizontal and the vertical offset to look into the waveform details of interest at 10mv/div while using a 5 volt offset. This is a fairly large range for the offset with a 10mv/div vertical scale factor. The waveform was bouncing around some due to the high and low frequency noise present, so we employed the math function to average the Zoom waveform not the usual Channel waveform (nice ability), to reveal the average of the Zoom and vertically expanded waveform. The pulse output is delivered directly to the DSO BNC without any cabling, and also deliverd to a KS34465A DMM with a ~350mm twisted pair. Power is from a cheap 12VDC SMPS Wall Wart.

First (#27) is the waveform as mentioned connected above, second (#28) is with leads to DMM reversed!!! Note the "ringing waveform" introduced by just flipping over the Dual Banana connector on the DMM!!!

Next we powered the pulse generator with a lab power supply, and repeated above. #29 is with DMM connected normal and #30 is reversed!! Note the lower level of "ringing" compared to Wall Wart Power Supply as expected, however some remnants of the "ringing" still appear!!!

Why this behavior, this is left as an exercise for the interested readers

Anyway, hope this thread proves out useful with others contributing actual use cases, and folks being able to witness meaningful examples without all the BS. Would be nice to include the new Rigol (and others) but fear this will just turn into another pissing contest as we've all seen in other threads

Edit: Here we go again with this site messing up all the images

Best,

[shabaz]

With high-res, new ways are needed to see information that older 8-bit 'scopes didn't need.
Your 'scope traces reveal a particular need and your solution, which was the need to do "something" about the noise, because especially when zoomed-in, a single capture in some cases can be almost meaningless, and the solution in your case was the averaging. It's not something one normally realizes unless they actually try it for real, which goes to show that real-life examples are extremely useful.

Does the 'scope support other possible solutions? Averaging is for sure a good solution, but there may be cases where 'something else' is preferred, to not get rid of peaks and troughs for instance, but to still see the trend without as much noise. I'm thinking are there color grading or other options present in the zoom view, that would also be interesting to see for this use-case.

I don't have this 'scope (or the Rigol), but am curious what capabilities these instruments contain.

[mawyatt]

Good point about using the advanced "Display" capabilities for revealing more useful information contained within the waveforms, something we're sure others are much more proficient with than us.

We took the above case using the Display Modes "Infinite Persistence" with "Dots" capability. Here you can see the discrete 12 bit quantization levels with the vertical scaled to 5mv/div with 4.98V Offset

First #33 is with Color Grade OFF, second #32 is with ON, last (#34) is with Persistence changed to 30 second Color Grade ON.

Best,

[Antonio90]

I'm quite interested as to why the polarity reversal on the DMM causes the ringing.
Could it be the input capacitance of the DMM, charged by the previous pulse? Or is that a completely stupid gamble?

Edit: stupid gamble. I don't know.

[mawyatt]

Yes, it's the highly asymmetrical input capacitance of the DMM +- inputs when measured to ground reference

The DMM - input has significantly more capacitance to ground than the + input, so when the pulse generator is reverse connected its' output "sees" a much larger effective capacitance thru the DSO input ground.

Best,

[Antonio90]

Yes, it's the highly asymmetrical input capacitance of the DMM +- inputs when measured to ground reference

The DMM - input has significantly more capacitance to ground than the + input, so when the pulse generator is reverse connected its' output "sees" a much larger effective capacitance thru the DSO input ground.

Best,

I didn't know that at all. Thank you very much!

[mawyatt]

If you have a bench DMM try measuring the +- input capacitance to ground and report over here:

https://www.eevblog.com/forum/testgear/dmm-input-capacitance/

Best,

[Njk]

BTW that use case shows that a floating scope can't be always substituted with an isolating transformer.