EEVblog #359 - QDSO Pocket Oscilloscope Review

Forum Topic:
Dave reviews and tears down the QDSO ("MiniDSO") Pocket Oscilloscope.

UPDATE: Since this and Mike's review, DIYertool have voluntarily removed this product from sale.

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[RichardsWorld]

This video was almost 3 years old, but you were being to biased before even testing this. I don't think anyone was expecting this to replace a lab scope.

[FGuilt]

You know he's desperate when he starts complimenting the input connector jack...

[i]

I do believe there is a place for those cheap Digital oscilloscopes.

For example a car/moto mechanic may need to check the waveform of a signal of a sensor or at least the waveform from the alternator or the regulator/rectifier.

In that line of business, accuracy at hight bandwidths (above the KHz range) is not top priority but lightness portability and ease of use a must.
Now add to that, that while working under the hood you are most likely to damage the device by dropping it or burning it or smashing it etc and you can see why (relatively) cheap is important for the job you try to do.

[das]

So when you tried to measure the Sine wave initially you tried auto measure with a x10 on probe = 100mV signal .

[leberkassemmel]

You can just use a old sound card and it gives a better result.

[mfbfreak]

Surpression cap isn't Y class... May fail with the cap shorting out instead of failing open circuit.

[colinyuan]

it was definitely a MP4 case before, i think the original maker of this case had a lot of stock in warehouse, and that Instrustar found this opportunity, they made a hardware design, then put it in the abandoned case, so that's what you see

[FrozenHaxor]

Their page states:

"Very sorry for this stupid product! Fortunately, we invited Dave and Mike to post their professional review. Facts have proved, this is a failed product.
Here we promise: We will never sell this product and promote products from this manufacturer!"

Yet they have it in stock and put it on a sale. Rofl. Also they site is severely broken in various ways.

[robertnicoll]

Didn't realize this scope had an Easter egg.
Anyone else spot Bart Simpson @ 13:10 ?

[EEVblog]

Yes, I don't think it's too much to ask for it to just work as claimed... The front end hardware has major signal integrity issues, and lack of features like AC coupling and DC offset. But the rest are just software/UI issues

[QlueDuPlessis]

I'm guessing this was a prototype model. 
Maybe Dave should design his own pocket scope and show them how it's done?

[cpucrust]

I love the comment: "Full wave rectifiers. They spared no expense!"

[EEVblog]

What are you talking about? I have promoted many affordable beginner scopes.

[EEVblog]

You forget. This thing is claimed to be an "oscilloscope". With any oscilloscope you expect at least a certain level of signal integrity and features (given it's price and forma factors etc), and to meet it's claimed specs being a test instrument. This fails both. I compared this thing to what any basic oscilloscope should do.

[yueibm]

How long were the probes? Maybe the ringing at 10MHz was from reflections due to impedance mismatch between Agilent, coax, and the DUT. The cable's characteristic impedance can be simulated in Q3D Extractor if the dimensions and dielectric strength are known.

[RPiSpy]

Very entertaining. I'll cross that off my Christmas list!

[EEVblog]

It just need to work, and work properly. Not give crap measurements, have good signal fidelity, AC coupling with DC offset adjust, have a usable user interface with some decent dedicated buttons. 10MHz bandwidth would be more than enough for a usable pocket scope. Maybe even 1MHz is worth something. It's certainly doable, even if it's a bit bigger. No one needs an actual "pocket" scope (where does the probe go?), just a portable battery powered small scope you can throw in the tool box.

[LifeOnHoth]

Hehehe, I've watched 8 minutes now, and I agree with you all the way up until now hehe. What I don't get is why would they send you this stuff to test? More sales...? Instead of spending 130 dollars on this, I'd rather spend twice that and buy a real scope...

The battery indicator jumped out at me too, and the casing... man... When spending 130 dollars on a product like this, you would expect a real case... I mean, recycling is a positive thing, but there are limits to how far you can stretch it...

[blakesmith]

Fantastic review.  I was interested to see if I could use this for a single purpose scope and you went through every little detail so well that I was able to see if it would fit.  Thanks so much!  

One tiny thing though...dial the drama down a notch.  Someone apparently told you that this device will be able to give all the quality and functionality of a laboratory bench DSO and barring that, at every point you call it a "FAIL" (insert drama here).  The first 20 times you go over the top I can handle, but on the 21st "FAIL" you get a little irritating.  For instance, another way to look at it might be the re-purposing of the MP5 case is also pretty clever way to save a lot of money.  I've done product design and enclosure tooling (even in China) isn't cheap.  If the product inside was a little bit better I wouldn't give a hoot if the case said "LEGO" on it.

Back to my main point though...fantastic review, even looking under the hood at the chips they are using!  Nice  

[goodwillhart]

Have you tried inserting an electric drill during operation. I have found that for high quality equipment with minor issues like this, some of the problems can be drilled out during operation. Insert 3mm drill from top, sides, front and bottom of apparatus. I'm pretty sure you won't have any problem with it again.