Author Topic: I Need Help With Choosing a Budget Oscilloscope!  (Read 6253 times)

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Offline David Hess

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Re: I Need Help With Choosing a Budget Oscilloscope!
« Reply #100 on: November 13, 2020, 01:51:48 am »
My DS1102E seems to have peak mode. If envelope mode requires multiple trigger events[1] then it won't work in single shot mode.

And that is exactly why it is mislabeled peak detection, which works with single shot acquisitions.

Today I had a chance to test with a DS1102E myself and peak-detect is definitely doing peak detect and not envelope mode. However I'm not ruling out that firmware for this oscilloscope has changed over the years.

If it does do peak detection when set to envelope mode, that would sure be annoying for routine use when you really wanted peak detection on individual acquisitions.

I distinctly remember trying to do that when I tested it and having no luck.  It operated like it had envelope mode, which is what the manual shows and describes, and single shot acquisitions in envelope mode were identical to single shot acquisitions in normal mode which was the only way to test it.

 

Offline rf-loop

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Re: I Need Help With Choosing a Budget Oscilloscope!
« Reply #101 on: November 13, 2020, 03:51:22 am »
My DS1102E seems to have peak mode. If envelope mode requires multiple trigger events[1] then it won't work in single shot mode.

And that is exactly why it is mislabeled peak detection, which works with single shot acquisitions.

Today I had a chance to test with a DS1102E myself and peak-detect is definitely doing peak detect and not envelope mode. However I'm not ruling out that firmware for this oscilloscope has changed over the years.

If it does do peak detection when set to envelope mode, that would sure be annoying for routine use when you really wanted peak detection on individual acquisitions.

I distinctly remember trying to do that when I tested it and having no luck.  It operated like it had envelope mode, which is what the manual shows and describes, and single shot acquisitions in envelope mode were identical to single shot acquisitions in normal mode which was the only way to test it.

As you can see, and many others who know, there is always peoples and even manufactures who do not even know or care what is digital oscilloscope peak detect mode and how it work and how it need work. Sad.

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Offline Fungus

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Re: I Need Help With Choosing a Budget Oscilloscope!
« Reply #102 on: November 13, 2020, 05:14:31 am »
Today I had a chance to test with a DS1102E myself and peak-detect is definitely doing peak detect and not envelope mode.

So it seems a safe bet that it has it.

However I'm not ruling out that firmware for this oscilloscope has changed over the years.

Occam's razor would suggest it hasn't.
 

Offline Shiv

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Re: I Need Help With Choosing a Budget Oscilloscope!
« Reply #103 on: November 13, 2020, 08:27:42 am »
Hello again!

So today a new ad popped up, it's a Philips PM3315 125MHz, 2 channel 'scope with 3 waveform memories and good amounts of trigger options for less than $90. The tube seems bright and consistent, the chassis looks extra clean but the seller says that some volts/divs need calibration and they're a bit off and he says the main power button sometimes doesn't turn it on and it can probably be fixed with some cleaning. It doesn't have any probes though. I don't know, do you guys think I should just go for it and buy separate probes? (Most probes available are Chinese with crappy plastic :( ) I can see a 60MHz Taiwanese probe for about $20 and from the same company but 250MHz is $50, more than half the price of the scope LOL.


WARNING

PM3315 is a good thing amd good price BUT I doubt it reaches 125MHz, I don´t find it, but if I´m correct, it will be 125MHz SAMPLING RATE, thats 60MHz on sines and crappy squares.

The calibration of v/div can be done at home with a well known DMM, a DC generator and pacience, but the frequency response is quite dificult without equipment, same as timebase (you need a good reference)


EDIT: Yeah, I was late, I didn´t see it has been discarded.

Same with TDS200, I have a 220 at work and is a BAD scope.
Everything of it breaks appart.

I mean: screen backlight, CH1 connector dead and irreparable, plastics broken,...
I think is the worse tek scope by far.

« Last Edit: November 13, 2020, 08:44:48 am by Shiv »
 

Offline tautech

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Re: I Need Help With Choosing a Budget Oscilloscope!
« Reply #104 on: November 13, 2020, 08:51:10 am »
Hello again!

So today a new ad popped up, it's a Philips PM3315 125MHz, 2 channel 'scope with 3 waveform memories and good amounts of trigger options for less than $90. The tube seems bright and consistent, the chassis looks extra clean but the seller says that some volts/divs need calibration and they're a bit off and he says the main power button sometimes doesn't turn it on and it can probably be fixed with some cleaning. It doesn't have any probes though. I don't know, do you guys think I should just go for it and buy separate probes? (Most probes available are Chinese with crappy plastic :( ) I can see a 60MHz Taiwanese probe for about $20 and from the same company but 250MHz is $50, more than half the price of the scope LOL.


WARNING

PM3315 is a good thing amd good price BUT I doubt it reaches 125MHz, I don´t find it, but if I´m correct, it will be 125MHz SAMPLING RATE, thats 60MHz on sines and crappy squares.

The calibration of v/div can be done at home with a well known DMM, a DC generator and pacience, but the frequency response is quite dificult without equipment, same as timebase (you need a good reference)


EDIT: Yeah, I was late, I didn´t see it has been discarded.

Same with TDS200, I have a 220 at work and is a BAD scope.
Everything of it breaks appart.

I mean: screen backlight, CH1 connector dead and irreparable, plastics broken,...
I think is the worse tek scope by far.
Easy fixes both of them and there's plenty of info on the forum of how to.
Avid Rabid Hobbyist
 

Offline nctnico

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Re: I Need Help With Choosing a Budget Oscilloscope!
« Reply #105 on: November 13, 2020, 09:34:25 am »
My DS1102E seems to have peak mode. If envelope mode requires multiple trigger events[1] then it won't work in single shot mode.

And that is exactly why it is mislabeled peak detection, which works with single shot acquisitions.

Today I had a chance to test with a DS1102E myself and peak-detect is definitely doing peak detect and not envelope mode. However I'm not ruling out that firmware for this oscilloscope has changed over the years.

If it does do peak detection when set to envelope mode, that would sure be annoying for routine use when you really wanted peak detection on individual acquisitions.
On the DS1102E I used it is called 'peak detect'; not envelope mode.


Same with TDS200, I have a 220 at work and is a BAD scope.
Everything of it breaks appart.

I mean: screen backlight, CH1 connector dead and irreparable, plastics broken,...
I think is the worse tek scope by far.
Easy fixes both of them and there's plenty of info on the forum of how to.
But you still end up with a poor oscilloscope. Fine if you pay $40 (or less) for it but not more.
« Last Edit: November 13, 2020, 09:36:34 am by nctnico »
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline tautech

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Re: I Need Help With Choosing a Budget Oscilloscope!
« Reply #106 on: November 13, 2020, 09:41:15 am »
Same with TDS200, I have a 220 at work and is a BAD scope.
Everything of it breaks appart.

I mean: screen backlight, CH1 connector dead and irreparable, plastics broken,...
I think is the worse tek scope by far.
Easy fixes both of them and there's plenty of info on the forum of how to.
But you still end up with a poor oscilloscope. Fine if you pay $40 (or less) for it but not more.
Of course, by today's standards they're a POS but still better than no scope.
Broken BNC's were common in these as Tek only used a 2 prong fitting and zero chassis fixing.
They were built to break !  ::)
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Offline Shiv

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Re: I Need Help With Choosing a Budget Oscilloscope!
« Reply #107 on: November 13, 2020, 10:11:43 am »
Hello again!

So today a new ad popped up, it's a Philips PM3315 125MHz, 2 channel 'scope with 3 waveform memories and good amounts of trigger options for less than $90. The tube seems bright and consistent, the chassis looks extra clean but the seller says that some volts/divs need calibration and they're a bit off and he says the main power button sometimes doesn't turn it on and it can probably be fixed with some cleaning. It doesn't have any probes though. I don't know, do you guys think I should just go for it and buy separate probes? (Most probes available are Chinese with crappy plastic :( ) I can see a 60MHz Taiwanese probe for about $20 and from the same company but 250MHz is $50, more than half the price of the scope LOL.


WARNING

PM3315 is a good thing amd good price BUT I doubt it reaches 125MHz, I don´t find it, but if I´m correct, it will be 125MHz SAMPLING RATE, thats 60MHz on sines and crappy squares.

The calibration of v/div can be done at home with a well known DMM, a DC generator and pacience, but the frequency response is quite dificult without equipment, same as timebase (you need a good reference)


EDIT: Yeah, I was late, I didn´t see it has been discarded.

Same with TDS200, I have a 220 at work and is a BAD scope.
Everything of it breaks appart.

I mean: screen backlight, CH1 connector dead and irreparable, plastics broken,...
I think is the worse tek scope by far.
Easy fixes both of them and there's plenty of info on the forum of how to.



Why?

Oscilloscopes here (only my lab):
DPO4104
TDS3064
TDS3054
TDS784D
TDS520D
2465B (x2)
2445B
PM3375 (x2)
CSA804 (40GHz)
TDS8200 (50GHz)

Oh, I forget the "trash":
465
468
TDS320
TDS310

And failing/mules :
2465´s
PM33´s
TDS7000
TDS3xxx
TDS5xx

And that crappy 220 used as signal/config checker before plug the test leads on measurement system.

Basically is used as a fuse :-DD

Is the only Tek Scope that I don´t like.

Is better than nothing? yes

But the question is... is better than something? :-//

For me, I prefeer that shitty boards of aliexpress and play for 10 bucks audio frecuencies while wait to get 100-200 bucks more and get something useful and durable.
« Last Edit: November 13, 2020, 10:26:05 am by Shiv »
 

Offline dave j

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Re: I Need Help With Choosing a Budget Oscilloscope!
« Reply #108 on: November 13, 2020, 02:46:19 pm »
My DS1102E seems to have peak mode. If envelope mode requires multiple trigger events[1] then it won't work in single shot mode.

And that is exactly why it is mislabeled peak detection, which works with single shot acquisitions.

Quote
Attached are two images of my DS1102E's probe compensation waveform captured in single shot mode and zoomed in. Displayed as dots and vectors.

That does not show anything.
Can you explain why the screenshots in my previous post have differing high/low values? My understanding of envelope mode with a single shot capture is that it will only have one sample to update each high/low pair with so they should be the same. The screenshots clearly show differing values.
I distinctly remember trying to do that when I tested it and having no luck.  It operated like it had envelope mode, which is what the manual shows and describes, and single shot acquisitions in envelope mode were identical to single shot acquisitions in normal mode which was the only way to test it.
Attached are two screenshots showing single shot captures in normal acquisition mode and what the scope calls peak detect acquisition mode. As you can see, they are different which implies the latter is not envelope mode.

My scope is on the latest firmware and I believe it's the latest hardware (version 58). I don't know which hardware/firmware combination you used but there does seem to be some difference in the behaviour between the two scopes.
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Offline David Hess

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Re: I Need Help With Choosing a Budget Oscilloscope!
« Reply #109 on: November 14, 2020, 08:54:41 pm »
If it does do peak detection when set to envelope mode, that would sure be annoying for routine use when you really wanted peak detection on individual acquisitions.

On the DS1102E I used it is called 'peak detect'; not envelope mode.

That is right, the DS1102E calls it peak detect mode.  But what the manual describes and how it operated when I tested it was what other manufacturers and DSOs, including later Rigol DSOs, called envelope mode.

Attached are two screenshots showing single shot captures in normal acquisition mode and what the scope calls peak detect acquisition mode. As you can see, they are different which implies the latter is not envelope mode.

That might be what it should look like, but how exactly did you force a single shot acquisition for the second screenshot?

The screenshows do not show but what is the record length in the two modes?  Peak detection almost always halves the record length but envelope detection may not depending on the implementation.

Quote
My scope is on the latest firmware and I believe it's the latest hardware (version 58). I don't know which hardware/firmware combination you used but there does seem to be some difference in the behaviour between the two scopes.

When I tested the DS1000D/E series it was a couple years before the DS1000Z series was released.  It seems odd that they would update the hardware or firmware without fixing the user interface leaving peak detection crippled and also not update the manual.
 

Offline dave j

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Re: I Need Help With Choosing a Budget Oscilloscope!
« Reply #110 on: November 14, 2020, 09:49:08 pm »
That might be what it should look like, but how exactly did you force a single shot acquisition for the second screenshot?
Trigger menu->Sweep->Single for both.

Quote
The screenshows do not show but what is the record length in the two modes?  Peak detection almost always halves the record length but envelope detection may not depending on the implementation.
Record length Normal for both (you only get a choice of Normal or Long Mem on this scope). Zooming in, the samples are displayed at 200ns intervals for both traces. The 'peak detect' one has the same high/low zigzag pattern shown in my earlier screenshots so a high/low pair is over 400ns. That doubling of the sample time fits with the record length being halved as you suggest since it has to store high/low pairs instead of single samples. If the zigzag display is just a presentation thing because the hardware can't display two separate lines for high and low values it seems a reasonable compromise to make - you have to zoom in over 10x in order to see individual dots so it won't normally be an issue.

Quote
When I tested the DS1000D/E series it was a couple years before the DS1000Z series was released.  It seems odd that they would update the hardware or firmware without fixing the user interface leaving peak detection crippled and also not update the manual.
When I first looked at 'peak detect' I noticed the discrepancy between what the scope appears to do and the manual. I'd just assumed they hadn't updated the manual.

I freely admit I'm largely a novice at electronics, I'm really a software guy who's recently started looking at electronics as a hobby. I'd like to understand what the scope is actually doing but discrepancies between what the scope does and the manual says together with more experienced people saying it does peak detect/it's really envelope mode leave me a bit puzzled. What I can see the scope doing seems to fit with peak detect rather than envelope mode so I'm going with that for now but I'm open to hearing an explanation for what I'm seeing that fits envelope mode.
I'm not David L Jones. Apparently I actually do have to point this out.
 


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