Anyone in for a volt step shootout? - Page 1
Forum section: electronics / testgear

author: eTobey
author_rank: Super Contributor
timestamp: January 05, 2025, 09:22:47 pm
content: Hi,i am wondering, how other scopes would compare with the following signal / settings:- A high level of 10V- High level for at least 500us- Falltime of < 200ns- 0V level measured for2ms10ms after that (it would be good to have some zoom (vertical) here or the csv file)- A sample rate of 10MSa/s- The Signal should vertically fill the screen, and the offset should be visible or noted.- Probe compensated- Could be both 1x10 and 1X Probe (Model would be nice to know)If anyone posts their trace data, i would put those into a logarithmic graph.I'll start with my scope, a SDS800X HD.Edit 09.01.25:Updated compare chart.

author: Martin72
author_rank: Super Contributor
timestamp: January 05, 2025, 10:30:22 pm
content: Hi,I don't understand the point of it.What do you want to achieve, what do you want to compare?At least try to explain your intentions.

author: eTobey
author_rank: Super Contributor
timestamp: January 06, 2025, 07:04:24 am
content: Quote from: Martin72 on January 05, 2025, 10:30:22 pmI want to do measurements. With this post i am interested in how other scopes would perform with this kind of measurement.

author: joeqsmith
author_rank: Super Contributor
timestamp: January 06, 2025, 03:07:45 pm
content: Quote from: eTobey on January 06, 2025, 07:04:24 amNot a helpful response.Quote from: eTobey on January 05, 2025, 09:22:47 pmYour plots do not show the entire 12V signal. "Then 0V" is a 2ms fall time? 1fs? Matter? By suggesting the signal vertically fills the screen, are you saying the 12 to 0V transition fills the screen. So you want to make sure the scope is in the linear region? Do you have some sort of recommended source and probing you want to use? How do you tell what is caused by the scope vs the source?At first I thought you were trying to see the recovery time but after reading your post, that doesn't seem to be what you are after. Try to add some details about your goals are.

author: iMo
author_rank: Super Contributor
timestamp: January 06, 2025, 03:29:22 pm
content: Here is mine old DS-1062CA, csv file..50ohm on both sides. 2V/DIV.The flatness seems to be ok after 20 usecs..

author: Martin72
author_rank: Super Contributor
timestamp: January 06, 2025, 09:05:04 pm
content: QuoteApart from the fact that I still can't imagine what it is, what is the goal (what do you want to compare with other scopes), some information is still missing.Because to make acomparison, the conditions mustalways be the same.So conditions must be set that then apply to all candidates.1.) The signal, which waveform, which amplitude, which frequency.2.) Vertical settings on the scope, which resolution (V/div), which input resistance, etc.3.) Horizontal settings on the scope, time (ms/div), which capture mode.4) How much memory/which sample rate5) Trigger: Which trigger, where to set the threshold?If you define these points, you can also do a “shootout”, a comparison.And to the processed image in Post1 a screenshot of the scope, where you can see the result.And finally the question again:What is the point, what do you want to compare between the scopes, which behavior?

author: eTobey
author_rank: Super Contributor
timestamp: January 06, 2025, 09:59:45 pm
content: Quote from: Martin72 on January 06, 2025, 09:05:04 pmI guess you want to know the right angle of the tongue too? Gosh, the more details i would give, the more details will get missed anyway.Just look a iMo, he just did it without asking all these questions. Allthough he missed some information.

author: TheoB
author_rank: Regular Contributor
timestamp: January 06, 2025, 11:08:50 pm
content: Your scope seems to have a slow feedback offset loop that's not perfectly compensated. Have you measured the LF frequency response flatness? Most scopes will perform better than yours, but your scope DC offset range might be much larger. What makes sense is to see if there is sample spread. Perhaps yours is not properly calibrated?On my previous scope I could measure 3V at 10mV/div (DC coupled) by just adding offset. My new scope can no longer do that. I would not be surprised your scope is much better but transient settling is worse.There are so many things you can do a shootout for, why pick this uninteresting one?

author: joeqsmith
author_rank: Super Contributor
timestamp: January 07, 2025, 01:08:10 am
content: Quote from: eTobey on January 06, 2025, 09:59:45 pmOk, so just for the sake of showing something pointless. Got it.Old LeCroy 64xi with $10 10x probe and long inductor for a ground to get that extra under/overshoot ringing effect. Using a 2N4401 or 2222 or 3904 something or other with a 10k pull-up to > 12V for a buffer (something for some other inductor self resonance demo). Frequency is 2Hz (more than enough to meet your high time. By 2ms, things have long settled out even with this crappy setup. If you wanted to plot it, just show a flat line.

author: Aldo22
author_rank: Super Contributor
timestamp: January 07, 2025, 09:27:46 am
content: I don't understand what this is about, but I'm in it for the cheapies.Hantek DSO2000 ($130), signal from Fnirsi SG-003a ($41)I just took a capture at 50ns/div so you can see something.Nothing exciting happens with a longer timebase.

author: Roehrenonkel
author_rank: Frequent Contributor
timestamp: January 07, 2025, 09:40:03 am
content: Here's mine,hope it helps.

author: eTobey
author_rank: Super Contributor
timestamp: January 07, 2025, 01:06:57 pm
content: I would like to thank you for your effort.But joeqsmith did not do 10V step, and the 2ms window if scaled down to one div.Roehrenonkel has a 0.x volt step? And the units on the x axis are unknown.

author: eTobey
author_rank: Super Contributor
timestamp: January 07, 2025, 01:10:16 pm
content: Quote from: TheoB on January 06, 2025, 11:08:50 pmI haven measured the LF flatness. It was calibrated before.My scope can not measure 10mv/div with offset neither! (Really lame).I am sure, you have measurments too, that are of no interest for me either.

author: eTobey
author_rank: Super Contributor
timestamp: January 07, 2025, 01:12:43 pm
content: Quote from: Aldo22 on January 07, 2025, 09:27:46 amI am really interested to get the trace data of that up to 2ms(1), even is it looks like there is nothing happening. I already have seen another scope that had 200 vertical pixels for 256 values (8 bits).

author: iMo
author_rank: Super Contributor
timestamp: January 07, 2025, 02:15:45 pm
content: So here it is with100kSa/s10Vpp1.28ms high/lowDC, BW OFF, no averaging50ohm terminated on the scope, HP3310B gen 50ohm outputPS: I do not see any flatness issue here, there is a little bit noise as the HP is old and quite loaded at 50Ohm load.When zooming in the transient it is the same as with my above measurements, thus some small undershoot for 20-30us long, then perfect flatness follows.Messing with probes has little sense, imho, as it is most probably not related to your issue.As a first step you have to observe your issue when scope input terminated by 50Ohm, with 50ohm 1-1.2m long coax and the 50ohm source impedance.That is the only way how to get some consistent results.All others is just chasing the ghosts..

author: joeqsmith
author_rank: Super Contributor
timestamp: January 07, 2025, 02:51:48 pm
content: Quote from: eTobey on January 07, 2025, 01:06:57 pmThese are new constraints. I provided at least 12V and at least 500us, then 0V from your original post.Quote from: eTobey on January 05, 2025, 09:22:47 pmIn your updated first post, you don't make it clear that you want that 2ms window if scaled down to one division. Is this something new?Note iMo does not drive to 0V and uses a 50 ohm system rather than your requested 1x or 10x probe. Does it matter?Quote from: eTobey on January 05, 2025, 09:22:47 pmQuoteMy scopes are all basically 8-bits. I had ERES active when I took that data (filtered). Are you wanting just the raw data?

author: TheoB
author_rank: Regular Contributor
timestamp: January 07, 2025, 03:00:35 pm
content: Quote from: eTobey on January 07, 2025, 01:10:16 pmI guess you want to see this (DHO804):Note this could also be my signal generator. It does not say anything.

author: joeqsmith
author_rank: Super Contributor
timestamp: January 07, 2025, 04:00:33 pm
content: While I am still clueless about the point of the thread, I just get this sinking feeling that we have a new first time scope owner. They feel they can add what ever offset and gain they want and the scope will remain linear. What is happening is they are zooming in by increasing the gain and adding offset to keep the waveform on the screen and pushing the scope's front end deep into saturation. What we are seeing is the recovery time.Again, I have no idea.

author: eTobey
author_rank: Super Contributor
timestamp: January 07, 2025, 04:02:07 pm
content: Quote from: joeqsmith on January 07, 2025, 02:51:48 pmYes, new constraints. I hoped that no one was going for the old ones. It didts work out. Sorry for the confusion.50Ohm or probe i think is not that important, if it is beeing stated, and one can account for.ERES would be fine.

author: eTobey
author_rank: Super Contributor
timestamp: January 07, 2025, 04:13:22 pm
content: Quote from: joeqsmith on January 07, 2025, 04:00:33 pmWrong... no saturation here. At least on my side - except my DSO QUAD, there i did exactly that, but it outperforms the SDS800X HD in this regard.

author: Fungus
author_rank: Super Contributor
timestamp: January 07, 2025, 04:15:31 pm
content: I have no idea what he's after.Are we talking about opamp recovery times here?

author: eTobey
author_rank: Super Contributor
timestamp: January 07, 2025, 04:20:07 pm
content: Quote from: TheoB on January 07, 2025, 03:00:35 pmIf you measure all 4 channels, then u might be able to tell if the Sig gen does it, or its a channel thing. On my side those are channel dependend.

author: eTobey
author_rank: Super Contributor
timestamp: January 07, 2025, 04:24:51 pm
content: Quote from: iMo on January 07, 2025, 02:15:45 pmThe data unfortunately no data between 0-10us. With my DSO Quad i did 2 runs with different timescale, and put them together (in the graph).Have you got some ERES or averaging available?

author: eTobey
author_rank: Super Contributor
timestamp: January 07, 2025, 04:28:42 pm
content: Quote from: TheoB on January 07, 2025, 03:00:35 pmThat looks very good! See graph in first post.I read, that Rigol did something to make the fan much quiter... Maybe i should get the rigol again.Just to put it in numbers (as humans cant fully judge/comprehend logarithmic scales as such):The Signal of the DHO800 and the DSO Quad have settled after about 30us. The SDS800X HD only after 20000us...Orders of magnitude!!!

author: Fungus
author_rank: Super Contributor
timestamp: January 07, 2025, 04:38:55 pm
content: Are we all supposed to own the exact same 12V pulse generator to make this valid?

author: joeqsmith
author_rank: Super Contributor
timestamp: January 07, 2025, 08:21:58 pm
content: Quote from: eTobey on January 07, 2025, 04:02:07 pmNo problem. I just missed you had updated the first post. 10V/2^8 = 40mV per count. Even with my poor probing, dangling wire, it settles to 1 count in a fairly quick. When looking at 100mV you are interested in, ERES seems to make sense.

author: joeqsmith
author_rank: Super Contributor
timestamp: January 07, 2025, 11:59:46 pm
content: Ditched the stupid ground cable for you to at least give it a chance for a decent edge. Same hardware setup otherwise. 10V to 0 switch. Also shown zoomed into this area. ERES set to 3.0. Probe looks like its a hair out of adjustment.Trimmed the data for 500us pre and 2ms post trigger. You may download it from here:https://www.dropbox.com/scl/fo/ovszm2w3w5c97frn53z9q/ADjYi2z4Zmh2BupflfAWK9M?rlkey=krqjebz37ax2s652n03hbdlb9&dl=0

author: thm_w
author_rank: Super Contributor
timestamp: January 08, 2025, 12:40:30 am
content: Quote from: Fungus on January 07, 2025, 04:38:55 pmI don't think it matters unless its a really bad gen?

author: joeqsmith
author_rank: Super Contributor
timestamp: January 09, 2025, 04:22:12 pm
content: I take it that the OP has realized this was a rather meaningless experiment. The take aways IMO, stay away from the long ground wires that come with your probes. Compensate your probes. Don't drive the scope's front end into it's non-linear region.

author: eTobey
author_rank: Super Contributor
timestamp: January 10, 2025, 07:50:02 pm
content: Quote from: joeqsmith on January 09, 2025, 04:22:12 pmWhy would you think so?Quote from: joeqsmith on January 09, 2025, 04:22:12 pmFunny thing is:My cheap DSO Quad, was (kind of?) overdriven like there is no tomorrow. It has only probes with long leads. Yet, the SDS800X HD looks much worse where it wasnotoverdriven, and the probe wasproperlycompensated (see yellow trace in original post) . BTW: probe compensation has no effect after 200us whatsoever.

author: eTobey
author_rank: Super Contributor
timestamp: January 17, 2025, 11:15:19 am
content: Quote from: eTobey on January 10, 2025, 07:50:02 pmWhat about an answers?I give you one, why your statement is complete rubbish...I just have a perfect example for something "meaningless". (Words become pretty worn out nowadays)Without knowing the extends of such deviations, one could end up looking for something on their circuit, that just dont exist...For your information:Those signals should be pretty flat. At least not in the hundreds of mV!