New 2ch pocket DSO+SG - Zeeweii DSO2512G

[jebem]

Hi Aldo,

Thanks for your input.

Concerning the bandwidth/amplitude relationship issues:
 
I realize now that my signal generator that I left at home is a FeelTech FY6900-40 with just a 0 to 40MHz sinusoidal range.
I would need the newer FeelTech FY6900-100 that goes to 100MHz sinusoidal.


Time to think on another acquisition...

[Aldo22]

Hi jebem!

Thanks!

Do you mean one of these?
https://de.aliexpress.com/item/4001224498670.html

For our question you don't gain that much with it though, afaics.

> 20MHz: 1mVpp ~ 5Vpp;

If I read this right, you get max 5Vpp above 20MHz.
The amplitude drop with 500mV+ sensitivity starts only at about 45Mhz.

So you get only 1.7V more than the $4 Si5351 module?
That probably doesn't make a big difference?

Cheers!

[tatel]

Hi jebem!

Thanks!

Do you mean one of these?
https://de.aliexpress.com/item/4001224498670.html

For our question you don't gain that much with it though, afaics.

> 20MHz: 1mVpp ~ 5Vpp;

If I read this right, you get max 5Vpp above 20MHz.
The amplitude drop with 500mV+ sensitivity starts only at about 45Mhz.

So you get only 1.7V more than the $4 Si5351 module?
That probably doesn't make a big difference?

Cheers!

@aldo22: Córtate un pelo, hombre   

That €4 thing that you are using is screwing you badly. Trust me, there's a reason why most people here pays more than a hundred bucks to get one of these.

Please have a look here: https://eleshop.eu/test-measure/function-generators/all-function-generators.html

EDIT: do you realize that DSO2512 has a signal generator that puts square waves up to 2 MHz and sine waves up to 20 MHz?

[Aldo22]

Thank you tatel.

Yes, I am aware that the DSO2512 has a signal generator up to 10MHz sine, but that is not the frequency range we are interested in.
The Si5351 produces square waves up to 160 MHz and I think it is not too bad for testing the bandwidth.

Of course, it's not a real function generator.

[tatel]

Thank you tatel.

Yes, I am aware that the DSO2512 has a signal generator up to 10MHz sine, but that is not the frequency range we are interested in.
The Si5351 produces square waves up to 160 MHz and I think it is not too bad for testing the bandwidth.

Of course, it's not a real function generator.

So far we don't even known for sure your Si5351 module output impedance, amplitude, etc. We don't know if it goes flat up to 160 MHz (which I somewhat doubt). Not really useful then. Perhaps you could ask the seller?

I don't think DSO2512 needs to be tested up to advertised specs. Should it be proven aliasing-free, reasonably accurate, with a stable trace up to 20 MHz, I could recommend it to a newbie on a short budget. I for one wouldn't care how it behaves above 20 MHz if it works good up to that. I wouldn't call it a "toy" in that case, even if it just takes 40 V on its inputs, 10 mV/div max and memory deep just 128 K. It does *almost* all a 20-30 MHz Hameg could do, plust it has 14 measurements, while these Hamegs don't have even one unless you do the math. Let alone any FFT.

Even HDS242/272 doesn't have RMS measurement nor FFT. Also, DSO2512 doesn't seem to have quite a bit of temperature drift, which is something HDS242/272 does have. Zeeweii seems to be more responsive to users than Owon. Plus it is brand new, small, portable, works on batteries...

That said, 4thDoctorWhoFan already tested it, so for me, it's (almost) done.

Yet I would like to see a video of that or a similar test, just because my DSO154, which is also from Zeeweii, when dealing with a square wave whose harmonics exceed device's bandwidth, shows the infamous amphetaminic trace. So I would like to see how a 5-12Vpp square wave behaves on DSO2512, before recommending it. Screenshots show it much more stable than it really is.

HM303-3, which I paid a hundred bucks for (delivered), is now in the same price range than DSO2512, but doesn't have any amphetamine addiction. So it would be "better" even if it's advertised as a 30 MHz oscilloscope. That said, I'm been hunting it for more than two months, it's 1995 vintage, heavy, takes a lot of benchtop space, came without any probes, doesn't give any measurements automatically and, worse of all, I'm afraid it needs to be adjusted ASAP. Which requires at least a multimeter, a known-good function generator, and perhaps another oscilloscope. That's not in most newbies' reach. 

So I'm still not really sure what I could recommend to that hypotetycal guy on a budget. Surely a "60 MHz" oscilloscope shouldn't show any amphetamine addiction if a 30 MHz one doesn't either.

That's why I would like to see that video showing a 20 MHz sweep on DSO2512. Square... and sine, please.

BTW, a rise time measurement done with a fast enough pulser would be helpful, too. Too bad the guys who have a 200 MHz function generator an fast pulsers don't care about this new-entry-level osciloscopes.

[Aldo22]

Hi tatel!

So I'm still not really sure what I could recommend to that hypotetycal guy on a budget. Surely a "60 MHz" oscilloscope shouldn't show any amphetamine addiction if a 30 MHz one doesn't either.

I really don't have a long experience, but on this point I think you are wrong.
Your honorable hameg (I mean that, I like old things. It's just that my apartment has too few rooms for that kind of stuff) does show a nice, thin, soft line, but what good is that if it has nothing to do with the signal?
In your video I don't really see a "square" wave anyway.
It's already pretty rounded on one side at 2 or3 MHz. I don't suppose the SG is the problem.
Why should I look for details if the basic shape is already wrong?
I prefer to see a somewhat fuzzy square wave instead of a fine sine wave when there is a square wave at the input.
That gives me more information.
Right?

Edit: See attachment please. Both at  ~10MHz.
Which image shows more information about the signal?
If the Hameg signal would be a bit wobbly, at least you would be warned that you can't trust what you see. You know what I mean? 
It's also a different technology, so it's not a good comparison anyway.

[tatel]

It's the scope. It needs an adjustment but first and foremost a thorough contact clean. You wiggle the knobs and suddenly you get a nice square wave, then you get crap again. Pushing any button makes all types of noise appear on the screen. If I put a finger on the probe BNC connector on channel 2, the trace becomes a serious case of Parkinson disease. And time base isn't really right, I think. That's why I said I don't really think the usual advice to get an old cheap analog oscilloscope is that sound. One could get, not a scope but a problem instead. No good for a newbie with little equipement.

I have to remind you how the thing is in DSO154. Please see attachment. Should DSO2512 behave the same way under 20 MHz, I wouldn't recommend it either. So, for me, the jury is still out.

At this moment I would say the only safe way for a newbie is to get the typical Rigol-Siglent-GW Instek entry-level benchtop scope, unless a known-good, really working analog scope can be found for cheap, or DSO2512 is proven good up to 20 MHz.

I would like the latter, really. I think it would be the best solution -and the cheapest.

Now, excuse me, but I'm going to digress a bit:

Please note this old HM303 is a 30 MHz device and manual says square wave is good up to just 3 MHz. However I thought it could be quite good after fixing, because of stability when not touching anything. But I was not happy with that square wave.

So, since video was recorded with a 70 MHz probe, and remembering that Keysight and others of that kind recommend to use probes with "at least" 3x oscilloscope's bandwidth (see https://edadocs.software.keysight.com/kkbopen/how-can-you-avoid-selecting-an-oscilloscope-probe-with-the-wrong-bandwidth-587208673.html) I decided to try a 150 MHz probe. Things got a lot better. Really. Even if still in need of cleaning and adjustment.

Then I realized that HM303 user manual suggest to use probes with adjustement both for low and high frequency. Digging a little bit it turned out the recommended probe (HZ52) was a 250 MHz probe! Plase see attachments. For a 30 MHz oscilloscope. Talk about overkill. But HM303 actually has a probe calibrator that can work at 1 MHz and <5 ns rise time square wave. GW Instek's probe calibration can go just up to 200 KHz

Also it turns out 250 MHz probes should put my GW Instek (about 109 MHz from risetime<3,3 ns) really into 100 MHz overall system bandwidth range. It looks as if these HZ probes were produced by Testec, a brand often recommended in this forum. Please see https://www.batronix.com/shop/measurement/probes/Testec-TT-MF-312.html It really looks a lot like the probes pictured in Hameg's manuals. Again, please see attachments.

Taking it all into account, right now I have four of these probes on the way, to be used with both oscilloscopes. Also a bunch of equipement able to cope with HV, not because I think I will need it to fix that Hameg, but because I'm going to play with mains (VFDs and so on)

So I think I got all the test equipement I'm going to need for some years to come. Quite excited about it, but my wallet got a little bit of anorexia. Talk about cry once. Not really a good way for a newbie with a short budget.

[Aldo22]

That's why I said I don't really think the usual advice to get an old cheap analog oscilloscope is that sound. One could get, not a scope but a problem instead. No good for a newbie with little equipement.

I fully agree with that.
You have to be experienced not to fall on your face when buying a used device.

I have to remind you how the thing is in DSO154. Please see attachment. Should DSO2512 behave the same way under 20 MHz, I wouldn't recommend it either. So, for me, the jury is still out.

No, it is quite a bit better. Not perfect, but better.
There are many videos on YouTube that show the DSO2512 in action.
You can easily get an impression of what it looks like.
For example, this one below. By the way, he is mostly in the 500mV+ range and sometimes in 2Ch. mode, so what you see is a bit bandwidth limited.
It is also an older HW/FW-version of the device. The "Secondary Functions" are not printed next to the buttons and it still shows the "SigPeak" brand.
Nevertheless he goes up to about 50MHz at 7:35.
There you can see the bandwidth drop when it approaches 60MHz. That doesn't happen at 200mV (or more) sensitivity.
Have a look at it, it should be enough for a first impression.

[jebem]

Hi jebem!

Thanks!

Do you mean one of these?
https://de.aliexpress.com/item/4001224498670.html

For our question you don't gain that much with it though, afaics.

> 20MHz: 1mVpp ~ 5Vpp;

If I read this right, you get max 5Vpp above 20MHz.
The amplitude drop with 500mV+ sensitivity starts only at about 45Mhz.

So you get only 1.7V more than the $4 Si5351 module?
That probably doesn't make a big difference?

Cheers!

Hi Aldo,

Yes, that is the one, it also appears under several brands, like FeelElec or FeelTech, among others.

I am quite happy with my low cost FeelElec Fy6900-40 (40MHz) AWG.
I bought it a couple of years ago and it serves me well on my hobby, despite all the ranting here in another thread where other members rightly pointed out the obvious weak points.

I see your point concerning the diminished gains of spending 160EUR on a Fy6900-100 against a 4EUR board to get just a few more mV of amplitude.
 
As I understand from the above posts, in order to be able to trigger the amplitude/bandwidth relationship issue, we need a signal generator able to deliver a stable, non distorted signal over a 50R load with an amplitude higher than those infamous 300mVrms from almost DC and up tor 100MHz.
I believe this Fy6900-100 can do it.
But I am not sure I need yet another low cost signal generator.
I think I will wait for the scope delivery and enjoy it for a while before taking decisions 


By the way, did someone figured out at what exact vertical sensitivity setting will the scope start to exhibit the amplitude/bandwidth relationship issue?
Or the issue happens based only on the signal amplitude independently of the scope vertical sensitivity setting?

[Aldo22]

Hi jebem

But I am not sure I need yet another low cost signal generator.
I think I will wait for the scope delivery and enjoy it for a while before taking decisions 

That sounds reasonable to me.
I also have to be careful not to pay more for accessories and test equipment than for the oscilloscope itself. 

By the way, did someone figured out at what exact vertical sensitivity setting will the scope start to exhibit the amplitude/bandwidth relationship issue?
Or the issue happens based only on the signal amplitude independently of the scope vertical sensitivity setting?

It's simple: the relay clicks when you switch from 200mV to 500mV vertical sensitivity in 1x mode or 2V to 5V in 10x mode and vice versa.
That makes the difference here afaics.
Actually I think the problem is not so dramatic. Up to ~50MHz it works anyway.
If you want something seriously better, you have to pay $100 more at least.
But it sure is good to know the limitations. It should be documented like the FY6900-100 does for the output voltage >20MHz.

[tatel]

No, it is quite a bit better. Not perfect, but better.
There are many videos on YouTube that show the DSO2512 in action.
You can easily get an impression of what it looks like.
For example, this one below. By the way, he is mostly in the 500mV+ range and sometimes in 2Ch. mode, so what you see is a bit bandwidth limited.
It is also an older HW/FW-version of the device. The "Secondary Functions" are not printed next to the buttons and it still shows the "SigPeak" brand.
Nevertheless he goes up to about 50MHz at 7:35.
There you can see the bandwidth drop when it approaches 60MHz. That doesn't happen at 200mV (or more) sensitivity.
Have a look at it, it should be enough for a first impression.

Well, I just watched half a dozen videos about DSO2512. The one you linked is the best one. Almost all the others don't get over 10 MHz and most of them doesn't get over 1 MHz. So crap.

To me, the good moment is the one in the attachment. However I would say it's just with one channel active. I can't really see what the voltages are, etc. And it does 10 MHz increment.

If you watch the DSO154 square wave video again, you can see that the previously attached picture taken at 7 MHz is the critical moment for DSO154, which is advertised as a 18 MHz device and is seen aliasing as soon as it gets at 20 MHz and above. So that would be first higher odd harmonic of square wave getting above bandwith or near it. So I think that could also happen on DSO2512 with both channels active (so 60 Mhz bandwidth) near that 20 MHz mark

I have to insist: to recommend DSO2512 wholeheartedly, I still have to see:

a) A screenshot showing rise time. It's advertised as <3 ns on the specs, that means 120 MHz bandwidth. It could be true, but I have to put my finger into the wound before thinking the Mesiah is resurrected. At that bandwidth, something like Leo Bodnar's pulser would be needed.

b) A 5-12Vpp square wave sweep, from DC to 20 MHz, 1 MHz increments, both channels activated.

Am I asking for too much? I don't think so, yet it looks as if no one of those youtubers thought about it. That evgeny you linked is about the only exception to that rule.

That said, probably DSO2512 would pass those tests with flying colors. Significant word here is "probably"

Edit: Oops, I forgot the attachment

Edit2: That 20 MHz "not-so-square" wave would be good enough to me

[tatel]

That sounds reasonable to me.
I also have to be careful not to pay more for accessories and test equipment than for the oscilloscope itself. 

You'll do it.

[Aldo22]

To me, the good moment is the one in the attachment. However I would say it's just with one channel active. I can't really see what the voltages are, etc. And it does 10 MHz increment.

That is the smaller 1-channel brother DSO1511G. I don't know why he put that one in the video. But it's similar in specs.

If you watch the DSO154 square wave video again, you can see that the previously attached picture taken at 7 MHz is the critical moment for DSO154, which is advertised as a 18 MHz device and is seen aliasing as soon as it gets at 20 MHz and above. So that would be first higher odd harmonic of square wave getting above bandwith or near it. So I think that could also happen on DSO2512 with both channels active (so 60 Mhz bandwidth) near that 20 MHz mark

My observation is that always 1/10 of the bandwidth shows a decent square wave and at 1/3 you still see the 3rd harmonic.
So in 2 channel mode not overclocked: 48Mhz -> 4.8Mhz -> 16MHz
2-channel mode overclocked: 60Mhz -> 6Mhz -> 20MHz

a) A screenshot showing rise time. It's advertised as <3 ns on the specs, that means 120 MHz bandwidth. It could be true, but I have to put my finger into the wound before thinking the Mesiah is resurrected. At that bandwidth, something like Leo Bodnar's pulser would be needed.

I played here with the rise time: https://www.eevblog.com/forum/testgear/new-2ch-pocket-dsosg-sigpeak-dso2512g/msg4840475/#msg4840475
That was 4ns. No idea if this is meaningful.

[Aldo22]

That sounds reasonable to me.
I also have to be careful not to pay more for accessories and test equipment than for the oscilloscope itself. 

You'll do it.

I know... 

[tatel]

That is the smaller 1-channel brother DSO1511G. I don't know why he put that one in the video. But it's similar in specs.

Didn't realized it. I was looking at the frequency measurement... 

My observation is that always 1/10 of the bandwidth shows a decent square wave and at 1/3 you still see the 3rd harmonic.
So in 2 channel mode not overclocked: 48Mhz -> 4.8Mhz -> 16MHz
2-channel mode overclocked: 60Mhz -> 6Mhz -> 20MHz

I don't like overclocking. HDS242/272 is said to suffer from temperature drift, probably the overclocking does have a influence on it. Some user even returned the device, calibrating it  some time after turning on wasn't enough, it seems. OTOH, it looks like even 5ºC temperature difference makes recalibrating convenient (for HDS242/272). So it could be oversensitive to temperature for some other reason. Should DSO2512 be able to work fine without temperature drift, I gladly would take the overclocking. It would be sweet  to get a good working, portable 20 MHz dual channel device at the €100 or less price mark.

I played here with the rise time: https://www.eevblog.com/forum/testgear/new-2ch-pocket-dsosg-sigpeak-dso2512g/msg4840475/#msg4840475
That was 4ns. No idea if this is meaningful.

Yeah, real time, analog bandwidth is said to be =0.35/risetime. Little more or less. You can learn more about it here: https://edadocs.software.keysight.com/kkbopen/how-can-you-avoid-selecting-an-oscilloscope-probe-with-the-wrong-bandwidth-587208673.html

It's considered even more meaningful than measuring the -3dB attenuation point. But signal risetime has to be like 1/10 scope's supposed risetime. Else it has an influence on the measurement. If your module has a risetime about 1 ns, that could explain a 4 ns measurement on a 3 ns device. Leo Bodnar's pulser has a risetime about 35 ps. He's a fellow forum member and there's a thread about it.

[Aldo22]

I don't like overclocking. HDS242/272 is said to suffer from temperature drift, probably the overclocking does have a influence on it. Some user even returned the device, calibrating it  some time after turning on wasn't enough, it seems. OTOH, it looks like even 5ºC temperature difference makes recalibrating convenient (for HDS242/272). So it could be oversensitive to temperature for some other reason. Should DSO2512 be able to work fine without temperature drift, I gladly would take the overclocking. It would be sweet  to get a good working, portable 20 MHz dual channel device at the €100 or less price mark.

I paid $80 including delivery.
If it would cost $100, they could have made it better by 139 yuan. 

I consider the overclocking mode on the DSO2512G a special option, not necessarily suitable for normal operation.

So assume a bandwidth of 96 and 48 MHz in normal operation.

The disadvantages of the overclocking mode are
- a fixed time base of 5ns / 10ns.
- a higher battery consumption (my impression).
- It is a bit tedious to switch on and off.

But if you need it, e.g. to see on which frequency your FM test station is transmitting, then it is there as an option and it works.

I haven't noticed any thermal problems so far, though.

[gitm]

Attached are the screenshots of the internal SG and coax. The first with LR, the second without.
The one with LR looks better, but I don't understand the voltage.

Edit: Btw. I soldered a small connector for the internal SG (3rd picture).

What's missing from your analysis is the output impedance of the internal signal generator, which is 160 Ohms calculated from tests on my DSO2512G.  It does vary based on frequency, measuring 160 ohms from 1 kHz through 1 MHz (a little peaking there to 165 ohms) but then falls off to 101 ohms at 10 Mhz.  I didn't test at 2 MHz, but at 5 MHz the output impedance was 106 ohms.

So, doing a little math:  With the LR on the coax you've got a resistor divider of approximately 160R in series with 50R||1MR.  Using a nominal 2.5Vpp internal SG output unloaded, the voltage seen at the scope would about 595 mVpp.  Remove the 50R LR and you've got 160R in series with 1MR to give full scale 2.5Vpp.

A general comment about the DSO2512G.  It's bandwidth is not 100/120 MHz.  That's bullshit. It's actual bandwidth is about 35/37 MHz and that's with decent probes, 250 Mhz 1X/10X from Probemaster.  I think the correct definition of bandwidth should include not only the -3dB Fc, but also the waveform distortion and frequency response being monotonic, otherwise you'll always be guessing and wondering if the signal you see is a big lie or a little lie.  Yes, scopes always lie, it's just a matter of how big those lies are and how gullible you are.

Regarding your tests, you are wrapping yourself around the axle, so to speak.  If you want to investigate such things, you should refer back to your university labs where you did experiment write-ups with expected outcomes and calculations to guide you.

Best of luck.

[Aldo22]

A general comment about the DSO2512G.  It's bandwidth is not 100/120 MHz.  That's bullshit. It's actual bandwidth is about 35/37 MHz and that's with decent probes, 250 Mhz 1X/10X from Probemaster.  I think the correct definition of bandwidth should include not only the -3dB Fc, but also the waveform distortion and frequency response being monotonic, otherwise you'll always be guessing and wondering if the signal you see is a big lie or a little lie.  Yes, scopes always lie, it's just a matter of how big those lies are and how gullible you are.

Hmm, for me it has a bandwidth of 120MHz because it can follow the signal and it stays within -3dB up to there.
The signal dances a bit, but I wouldn't know that that is part of the bandwidth definition.
How do you come up with "actual bandwidth is about 35/37 MHz" and more importantly, how is that defined?
Is that your subjective view, or can you define it in a comprehensible way?

I agree that the "comfort zone" of this device is up to 20 or 30 MHz and that is sufficient for a 2-channel device for $80.

But you use the word "bullshit" so you have to provide facts. 

[gitm]

Hmm, for me it has a bandwidth of 120MHz because it can follow the signal and it stays within -3dB up to there.
The signal dances a bit, but I wouldn't know that that is part of the bandwidth definition.
How do you come up with "actual bandwidth is about 35/37 MHz" and more importantly, how is that defined?
Is that your subjective view, or can you define it in a comprehensible way?

I agree that the "comfort zone" of this device is up to 20 or 30 MHz and that is sufficient for a 2-channel device for $80.

But you use the word "bullshit" so you have to provide facts. 

No good deed.... 

It doesn't stay above -3db to 120 MHz.  In fact, the -3dB Fc is located just above 36 MHz and turning on "TURBO" mode doesn't improve it.  That's the facts.  So, I'm going to further qualify my "bullshit" technical jargon with "IT'S COMPLETE AND TOTAL BULLSHIT"  .  You can quote me on that.

With that said, at this point you want to calm down, grab a cup of coffee, relax, and then come back to view the fine collection of facts I've prepared.  This might take more that one post to hold all the screen shots and pictures, etc.

Using a DG1062Z, a 2.5Vpp sine wave was sent via 50 ohm coax through a 50 ohm inline terminator into the 2512G at frequencies of 36MHz, 40, 45, 50, 55, and 60MHz. Only CH1 was turned on.  Keep in mind the  -3dB of 2.5Vpp is 1.77Vpp.

F (Mhz)	Vpp	Attenuation (dB)
36	1.80	-2.85
40	1.72	-3.25
45	1.54	-4.21
50	1.19	-6.45
55	1.17	-6.60
60	0.842	-9.59
60 "TURBO" mode	0.862	-9.25

I'm attaching the 2512G screenshots for the table above as well as a screenshot from my Rigol MSO5204 of the 60 MHz signal which shows 2.39Vpp or -0.39dB. 

[gitm]

And just to put a finer point on it  ....

This is a 20MHz square wave being generated by the DG1062Z through that same 50 ohm coax/inline feed into the MSO5204.  It's recognizable as a square wave.


===================

And this is what that same 20MHz square wave sent to the 2512G displays....


Is that a distorted sine wave or what? 

[Aldo22]

Hi gitm!

And this is what that same 20MHz square wave sent to the 2512G displays....

Is that a distorted sine wave or what? 

I don't know what's wrong with your device.
A square wave doesn't look that rounded at 20MHz here (no overclocking).

[gitm]

Try a 2.5Vpp square wave.

[Aldo22]

Try a 2.5Vpp square wave.

I can't at the moment.

Btw. Why does the square wave look so rounded on your Rigol MSO5204?
20MHz should be nothing for this device.
And why bother with a toyscope at all if you have something like that?

[gitm]

The DG1062Z's highest square wave frequency is 25MHz.  The MSO5204 is showing what the DG1062Z is producing as a 2.5Vpp 20MHz sq. wave and it's rounded somewhat, i.e. reaching the limits of the DG1062Z.

You're using a 1Vpp square wave which I believe is within the 2512G's amplifier slew rate.  Increasing the amplitude to 2.5Vpp, as in my example, shows both the 2512G's slew rate and frequency attenuation above Fc for the harmonics.  This is what I was referring to as waveform distortion in a previous post.  You either didn't notice it or you did and just didn't care when it was 1Vpp.  But at 2.5Vpp and now "my 2512G" is defective.  All scopes lie, some with bigger lies than others, but what also plays into it the user's gullibility.

ETA: this is called the Large Signal Step Response.

I picked 20MHz for 2 reasons, it was within the DG1062Z's reach and its 3rd and 5th harmonics are all above the Fc~36MHz.  2.5Vpp was just to show waveform distortion needs to be considered for bandwidth.  That gif you attached to one of your posts shows awful waveform distortion.  Remember the rule-of-thumb that you should use a scope with bandwidth that is 5X of the signal's largest frequency component you want to see?  That's why.

Best of luck.

[gitm]

And why bother with a toyscope at all if you have something like that?

Being battery powered, it is isolated (as long as you don't connect up the USB port at the same time).
Being portable, it's handy and works fine for many low frequency jobs like probing around in a power supply.
It's cheap and I don't care if I damage it.