Tablet DSO <= $500 for the recording of sub ms duration DC voltage spike events

[Silver_Is_Money]

Any good recommendations?  2 channels will suffice, as only one is needed.  Need to be able to quantify the degree of voltage spike with precision.

[ebastler]

Any good recommendations?  2 channels will suffice, as only one is needed.  Need to be able to quantify the degree of voltage spike with precision.

Hmm... What do you mean by "degree of voltage spike"? Do you need to count the spikes, measure their average or maximum amplitude, or create a histogram of spike amplitudes, durations, integrated areas...? I.e. which analysis capabilities do you need in the scope?

Also, what duration of spikes are you looking at? I.e. what time resolution or bandwidth does the scope need to provide?

[csuhi17]

Any good recommendations?  2 channels will suffice, as only one is needed.  Need to be able to quantify the degree of voltage spike with precision.

Hmm... What do you mean by "degree of voltage spike"? Do you need to count the spikes, measure their average or maximum amplitude, or create a histogram of spike amplitudes, durations, integrated areas...? I.e. which analysis capabilities do you need in the scope?

Also, what duration of spikes are you looking at? I.e. what time resolution or bandwidth does the scope need to provide?

I think that's what he meant.

Yes.

But... on many 'scopes you can reduce the sample rate to get more time.

eg. If a 'scope lets you reduce the rate to 1Msa/sec then you can record for 8 seconds.

That's great to know.  But I'm trying to record a DC voltage spike event that will only last for about 1.8 ms from start to finish, and capture it in fine detail.  With the critical voltage rise peak occurring at about 0.25 ms after triggering, and with peak rise lasting for only about 0.02 ms. Or in other words, the most critical capture range will occur at between 0.24 and 0.26 ms post triggering on rise.

[Silver_Is_Money]

Any good recommendations?  2 channels will suffice, as only one is needed.  Need to be able to quantify the degree of voltage spike with precision.

Hmm... What do you mean by "degree of voltage spike"? Do you need to count the spikes, measure their average or maximum amplitude, or create a histogram of spike amplitudes, durations, integrated areas...? I.e. which analysis capabilities do you need in the scope?

Also, what duration of spikes are you looking at? I.e. what time resolution or bandwidth does the scope need to provide?

My intention is to measure the spike in voltage that expresses (relative) chamber pressure when a strain gage is glued to a barrel above mid-chamber in a shotgun or rifle.  The voltage will be derived from an amplified Wheatstone Bridge, utilizing a quality low noise amplifier.  Since resistance is linear to voltage, and voltage is linear to pressure, the voltage 'spike' as amplified and measured across a balanced Wheatstone bridge (with the condition of ohm balance equating to an initial zero voltage condition) can be equated to 'relative' pressure, whereby such pressure is 'relative' to a carefully chosen and selected reference load of known pressure (from which a system specific multiplier derived from the known pressure of the reference load can be related to voltages observed for other loads, and more specifically reloads). 

The entire curve of pressure (as converted into positive voltage via the Wheatstone Bridge) is anticipated to have a duration on the order of 1,6 ms, with the peak occurring roughly at 0.25 ms post ignition, and having a peak duration lasting (plateauing) for perhaps on the order of only about 5 to 10 ns.

[ebastler]

The entire curve of pressure (as converted into positive voltage via the Wheatstone Bridge) is anticipated to have a duration on the order of 1,6 ms, with the peak occurring roughly at 0.25 ms post ignition, and having a peak duration lasting (plateauing) for perhaps on the order of only about 5 to 10 ns.

Are you sure you mean 10 nanoseconds at the end of that sentence, not 10 microseconds?

[Silver_Is_Money]

Are you sure you mean 10 nanoseconds at the end of that sentence, not 10 microseconds?

Ah, sorry!  You are correct, and I stand corrected. 5 to at most 10 Microseconds.  With preferably the ability to capture this interval with some detail.

[csuhi17]

If anyone finds any mistakes in my thinking, please correct me.

I'll try to help and see if we can get closer to a solution.
According to them, each of your questions refers to which oscilloscope you can use to perform the measurements in the video.



Since you did not share with us a picture of your older measurements, which you had done by someone else if you got it from them at all, I could only find out something on the Internet.

You don't need super fast sampling.
Based on the video, I measured with a tape measure, maybe the time difference between the two samples could be 1us.
That is, 100kSa/s.
I think most of the instruments on the market are good for this.

The question is, what do you want to do with the result?
It is enough for you that the device displays it, or you also want to save it.

It is enough for you if you saved it as a screenshot or if you want to save it as a data set. which you can later load, for example, into Microsoft Excel and create a graph from it.
As a data set, you can later display several results on a graph to see the difference between measurements.

My tips.
Owon Tao3072, Micsig, Hantek,
Or I'm looking at the Fosc53C, but I don't think it would be good for you, I don't know what the Android app can do.

But maybe Hantek would be more than enough for you. If the vertical sensitivity suits you. The 250MSa version is only 10mV/div.
You can read about Hantek here on the forum.

If maybe not and you are thinking about 1GSa/S, then I would rather buy Owon, I think it has better quality and can do more things.
Both are around 500USD for me when I look at the prices.

[Silver_Is_Money]

The Pressure Trace II system is no longer on the market.  And that's a good part of why I'd like to attempt this.

I'd like to save pressure traces as CSV files for graphing in Excel or LibreOffice Calc, for comparative and reference storage purposes.

I agree that the OWON TAO3072 looks like a clear winner.  The storage capability of the Hantek's is only 8M deep. 

[ebastler]

Just to put things into perspective -- your time resolution and total capture time requirements are quite modest by today's entry-level oscilloscope standards:

• Even a sampling rate as low as 1 MHz should be enough to properly capture the event, giving you one data point every µs. (But 100 kSa/s, as mentioned by csuhi17 if I did not misunderstand, is off by a factor of 10.) Even toy scopes with 10 MHz sampling rate or so would be fine.
  
• On the other hand, even the "only 8 MSa" storage capacity you mentioned will let you capture e.g. 10 samples per microsecond (10 MHz) for 800 ms, i.e. nearly a full second! Compared to the 1.6 ms total duration of the event which you had mentioned, that's more than generous.
  

Hence you can't really go wrong regarding the acquisition capability. Since, as I understand, you don't need automated analysis but want to store the data and scrutinize them manually/visually, there are no special requirements on that front either -- apart from a decent interface and software that lets you pull the data over to a PC.

In case you don't have them already, put some money aside for the strain gauge and amplifier. I am not sure how much you expect to buoild yourself, but if you want an off-the-shelf solution with reasonable documentation and support, that part of the measurement solution might cost you money as well.

[csuhi17]

Yes, I wrote that wrong. what i want to write is 1MSa/s.

Maybe an Owon SDS242 would be enough for him.
My SDS272S has been tested and it is possible to save 4 .CSV files.
Unfortunately, no more than 4, but if you have a laptop at hand, you can save the data to it after 4 shots.

An 8k sample might be enough for him, based on what I saw in the video, but I might be wrong.

Maybe it would be enough for him, but it wouldn't be worth it, because the Hantek TO1112 is not much more expensive... And the Hantek has better features.

[Silver_Is_Money]

So for clarity, even the budget Hanek TO1112 tablet DSO that goes for about $189 would suffice here?

[csuhi17]

So for clarity, even the budget Hanek TO1112 tablet DSO that goes for about $189 would suffice here?

Yes.

I did a couple of quick tests so you can roughly see what the signal might look like in your case in specific cases.
Two images were taken with the Owon HDS272S, which has a memory of 8K, sampling 250MSa, but reduced it to 5MSa due to low memory.

The other is a Micsig TO1104 with 28M memory and 1GSa sampling.

I take a few pictures with Micsig, the name of the picture shows how much sampling and how much memory it was made with.
I made them all with 100us.

If the pictures are not clear, ask, I'll try to explain.

[Silver_Is_Money]

So for clarity, even the budget Hanek TO1112 tablet DSO that goes for about $189 would suffice here?

Yes.

I did a couple of quick tests so you can roughly see what the signal might look like in your case in specific cases.
Two images were taken with the Owon HDS272S, which has a memory of 8K, sampling 250MSa, but reduced it to 5MSa due to low memory.

The other is a Micsig TO1104 with 28M memory and 1GSa sampling.

I take a few pictures with Micsig, the name of the picture shows how much sampling and how much memory it was made with.
I made them all with 100us.

If the pictures are not clear, ask, I'll try to explain.

Thank you kindly for this!

[Silver_Is_Money]

So for clarity, even the budget Hanek TO1112 tablet DSO that goes for about $189 would suffice here?

Yes.

I did a couple of quick tests so you can roughly see what the signal might look like in your case in specific cases.
Two images were taken with the Owon HDS272S, which has a memory of 8K, sampling 250MSa, but reduced it to 5MSa due to low memory.

The other is a Micsig TO1104 with 28M memory and 1GSa sampling.

I take a few pictures with Micsig, the name of the picture shows how much sampling and how much memory it was made with.
I made them all with 100us.

If the pictures are not clear, ask, I'll try to explain.

The FNIRSI 1013D digital tablet is on sale for $120 US.  Do you think it would suffice in this application?  Here are the specs:

[csuhi17]

The FNIRSI 1013D digital tablet is on sale for $120 US.  Do you think it would suffice in this application?  Here are the specs:

According to the specs of FNIRSI-1013D it has 128Kpts storage but 4 screens seems very little.

The specs of the FNIRSI-1013D are a big lie. The original Altera FPGA has 270Kbits of available embedded memory and the newer ones with Anlogic FPGA's have more. (496Kbits or 700Kbits) But what counts is how many of these bits they used, and that is only 32768 bits per channel. So 4KByte per channel of which only about 3500 bytes are usable.

The sampling rate is only max 200MSa/s per channel instead of the 1GSa/s marking on the front and the bandwidth is 30MHz at best.

No. Fnirsi should be forgotten, because either they lie and do not provide the performance they claim, or they do not know what you want.

As far as I know, it is not possible to save the results only as an image, you cannot later load them into an Excel table.

I couldn't find anything better than the Hantek TO1112 in this price category.

IF I didn't have the two Owon HDS, I would have bought the Hantek TO1112 instead.

But I wouldn't buy the 1GSa/s version from the Hantek TO1000 series, because the Owon TAO series offers more and is only a little more expensive.

In other words, it's not worth it.
Under $200, I think the HANTEK TO1112 is the winner.
You don't need C, D edition, because if I think correctly, you are not in the electrical business.

[Silver_Is_Money]

The specs of the FNIRSI-1013D are a big lie. The original Altera FPGA has 270Kbits of available embedded memory and the newer ones with Anlogic FPGA's have more. (496Kbits or 700Kbits) But what counts is how many of these bits they used, and that is only 32768 bits per channel. So 4KByte per channel of which only about 3500 bytes are usable.

The sampling rate is only max 200MSa/s per channel instead of the 1GSa/s marking on the front and the bandwidth is 30MHz at best.

No. Fnirsi should be forgotten, because either they lie and do not provide the performance they claim, or they do not know what you want.

As far as I know, it is not possible to save the results only as an image, you cannot later load them into an Excel table.

I couldn't find anything better than the Hantek TO1112 in this price category.

IF I didn't have the two Owon HDS, I would have bought the Hantek TO1112 instead.

But I wouldn't buy the 1GSa/s version from the Hantek TO1000 series, because the Owon TAO series offers more and is only a little more expensive.

In other words, it's not worth it.
Under $200, I think the HANTEK TO1112 is the winner.
You don't need C, D edition, because if I think correctly, you are not in the electrical business.

I must thank you sincerely yet again!  You are correct, as I am not in the electrical business and my focus is only on this single task.

[ebastler]

I agree with csuhi17, the FNIRSI is not adequate. For your application it would fail even if it meets all its specs: The storage depth is only "240 kbit", i.e. only 30k data points of 8 bit each. That translates into less than a millisecond of recording time if you sample at 50 MSamples/second; too short to capture your pressure pulse.

If you want the portability of a tablet scope, I agree that the Hantek TO1112 is a good balance of "good enough" at a decent price.