DMMCheck Plus Multimeter Reference(and other References) - Experiences..

[Fungus]

Here's my $5 Aliexpress special against my two best meters: 

[KungFuJosh]

Here's my $5 Aliexpress special against my two best meters: 

Got a link for that one? I can't find it.

[Fungus]

Got a link for that one? I can't find it.

The sticker says I bought it in 2017 so exact models have changed since then.

Today's equivalent is probably this: https://www.aliexpress.com/item/32658819804.html

The ad says "10. Each board at the factory to be detected with Aglient 6 digit multimeter, and marked with the output voltage, user-friendly."

(nb. Random seller...I have no idea if they're good but they've sold 65 and got good reviews)

[Shonky]

AD584LH on the linked one is likely fake on these as they haven't been made in quite a while - 10 years or more. The picture does show a 1223 date code, but well... you know...

Some of the pictures show terrible quality and indicate they don't include any "cal data"

[Fungus]

AD584LH on the linked one is likely fake on these as they haven't been made in quite a while - 10 years or more. The picture does show a 1223 date code, but well... you know...

I think they're likely to be second hand chips pulled out of old devices.

(i.e. well burned-in  )

Some of the pictures show terrible quality and indicate they don't include any "cal data"

If they send garbage you can just open a claim and get your money back. It's easy.

(I have no idea where people see "risk" on Aliexpress. Returns and refunds are just as easy as Amazon - you don't like something? Just get your RMA barcode and drop it off at the kiosk on the corner, no questions asked...)

[tomud]

Got a link for that one? I can't find it.

The sticker says I bought it in 2017 so exact models have changed since then.

Today's equivalent is probably this: https://www.aliexpress.com/item/32658819804.html

The ad says "10. Each board at the factory to be detected with Aglient 6 digit multimeter, and marked with the output voltage, user-friendly."

(nb. Random seller...I have no idea if they're good but they've sold 65 and got good reviews)

This is just a description, and the photos in the comments clearly show that there is no voltage measurement sheet attached. When I was buying mine, I had to do some research at auctions to find one with a handwritten card, because there were also printed cards where all the copies sold had the same voltage values (cheating).

Currently, in the same way, you have to look in the photos attached in the comments if there is a sheet with voltage measurements.

Here, for example, there is a comment that the PCB is described, but there is no message with what accuracy. On the other hand, in other auctions I have seen descriptions only up to the third decimal place.

https://www.aliexpress.com/item/1005004617368378.html

https://www.aliexpress.com/item/1005004186281432.html

Here again you can see on the printed sheet - but it's hard to tell if these are real voltage measurements (too small photo in the comment).

https://www.aliexpress.com/item/1005005609015568.html

Here again the version I have in the acrylic housing, in one comment there is information about the attached voltage measurements.

https://www.aliexpress.com/item/32813473384.html

Here again versions with LM399:

https://www.aliexpress.com/item/1005002791469664.html

But these are just examples of found auctions and I am not sure about the quality of the offered goods.

AD584LH on the linked one is likely fake on these as they haven't been made in quite a while - 10 years or more. The picture does show a 1223 date code, but well... you know...

I think they're likely to be second hand chips pulled out of old devices.

(i.e. well burned-in  )

Yes, in mine there is a 100% old chip desoldered from some device, you can see it by the condition of the metal housing.

[Fungus]

This is just a description, and the photos in the comments clearly show that there is no voltage measurement sheet attached.

My sheet was stuck to the bag it came in (see pic).

But yeah, I just picked that seller because the sold a lot and had a good rating. If you go through all the reviews there's a couple that say there's no "passport" so maybe that's not the one to get.

Get one that clearly shows numbers in the listing photos so you can reclaim easily if it doesn't have them. :-)

[tomud]

This is just a description, and the photos in the comments clearly show that there is no voltage measurement sheet attached.

My sheet was stuck to the bag it came in (see pic).

That's all I know That's why I looked at the pictures in the package and I didn't notice that the voltage measurements were glued to the bag. And of course, information in the comments about the lack of voltage measurements:

"Everything works. Asked the seller to put a passport of factory measurements, but whether he forgot, or scored, or he does not have that. Ignored the request in short. Did not answer anything. Measured on a precision voltmeter-all in admission."

"There is no passport for the microcircuit and no factory control measurement. What exactly voltage gives out and how to calibrate something with this voltage is not clear. In general, within the margin of error in the dataite, The microcircuit fits well. For instruments with 2 decimal places will come down."

btw there are still such "reference modules" RLC available https://www.aliexpress.com/item/33040571353.html

[Veteran68]

Got a link for that one? I can't find it.

The sticker says I bought it in 2017 so exact models have changed since then.

Today's equivalent is probably this: https://www.aliexpress.com/item/32658819804.html

The ad says "10. Each board at the factory to be detected with Aglient 6 digit multimeter, and marked with the output voltage, user-friendly."

(nb. Random seller...I have no idea if they're good but they've sold 65 and got good reviews)

This is the one I mentioned earlier I have that takes the wonky 15V battery, unless you use a DC barrel jack (which is what I do now after buying a couple of those expensive batteries). Mind did come with the highly desirable AD584LH version of the reference. Obviously pulled from something.

Mine came with a "cal" sheet as shown. Haven't used it in forever, just checked and measured 5.00112 and 10.00183 with my 34401A. Not too bad I guess for 8 years old, if that cal date is even accurate. But the fact they went to the trouble to type & print this cal sheet makes me suspicious that they just printed off a bunch and stick the same one in each shipment, lol.

[Shonky]

Got a link for that one? I can't find it.

The sticker says I bought it in 2017 so exact models have changed since then.

Today's equivalent is probably this: https://www.aliexpress.com/item/32658819804.html

The ad says "10. Each board at the factory to be detected with Aglient 6 digit multimeter, and marked with the output voltage, user-friendly."

(nb. Random seller...I have no idea if they're good but they've sold 65 and got good reviews)

This is the one I mentioned earlier I have that takes the wonky 15V battery, unless you use a DC barrel jack (which is what I do now after buying a couple of those expensive batteries). Mind did come with the highly desirable AD584LH version of the reference. Obviously pulled from something.

Mine came with a "cal" sheet as shown. Haven't used it in forever, just checked and measured 5.00112 and 10.00183 with my 34401A. Not too bad I guess for 8 years old, if that cal date is even accurate. But the fact they went to the trouble to type & print this cal sheet makes me suspicious that they just printed off a bunch and stick the same one in each shipment, lol.

There are some suppliers that definitely were supplying the exact same printed sheet similar to that one with every unit. The ones that come with hand written sheets appear to be more genuine.

The ones that actually are tested seemed to be closer to their cal sheets than yours is.

[Fungus]

Mine came with a "cal" sheet as shown.

I've seen that cal sheet before... 

https://www.eevblog.com/forum/metrology/are-cheap-ad584-units-worth-it/msg920924/#msg920924

[rsjsouza]

My unit came with a hand written sticker and it has been quite stable over the years. I can't complain for throwaway money. The AD586 device on it is clearly re-used from somewhere else but, as Fungus mentioned, it gives more confidence the initial drift has been surpassed and the unit is much more stable.

[all_repair]

AD584LH on the linked one is likely fake on these as they haven't been made in quite a while - 10 years or more. The picture does show a 1223 date code, but well... you know...

I think they're likely to be second hand chips pulled out of old devices.

(i.e. well burned-in  )

Some of the pictures show terrible quality and indicate they don't include any "cal data"

If they send garbage you can just open a claim and get your money back. It's easy.

(I have no idea where people see "risk" on Aliexpress. Returns and refunds are just as easy as Amazon - you don't like something? Just get your RMA barcode and drop it off at the kiosk on the corner, no questions asked...)

Old volt-nut chips are much sought after item in the Chinese volt-nut community.  It is a desirable feature as that means it is a much stable chip that shall have lesser drift later.

Checkup the price and availabilty of the new chip and you shall see the makers are doing a great service.  And the literature are in Chinese show that these goods are meant for, and by, the local volt-nut community

[Veteran68]

I've seen that cal sheet before... 

https://www.eevblog.com/forum/metrology/are-cheap-ad584-units-worth-it/msg920924/#msg920924

I'm shocked, SHOCKED!, I tell you! 

I knew when I got it that there was no way they were typing up, printing, and cutting out each of these for each unit. The handwritten ones are much more believable.

[Fungus]

The handwritten ones are much more believable.

Yep.

Mine actually seems to have a transcription error.

Attentive readers might have noticed I didn't post the 7.5V reading in the previous post:


Everything I've ever measured it with has shown around 7.506V so I think whoever wrote the number on the sticker inserted an extra zero by mistake (there's usually two zeros after a '5', right?)

To me it makes it even more authentic. 

[Fungus]

I'm shocked, SHOCKED!, I tell you! 

I knew when I got it that there was no way they were typing up, printing, and cutting out each of these for each unit. The handwritten ones are much more believable.

The date on it should be a giveaway. When did you buy yours?

[mawyatt]

Some folks might find these interesting.

Here's some DIY voltage references based upon LM399, LTZ1000 and some others, also a means to produce an accurate AC rms waveform.

https://www.eevblog.com/forum/projects/building-a-calibration-device/msg3485874/#msg3485874

https://www.eevblog.com/forum/projects/diy-dvm-simple-dvm-cal-device/msg4576009/#msg4576009

https://www.eevblog.com/forum/testgear/ac-rms-dmm-tests/msg3940957/#msg3940957

Best,

[KungFuJosh]

I emailed DMMCheck about their fancy new higher accuracy product, and this was their response:

"Thank for your interest in our products. When available, the new higher stability model will be higher in price but will include all options. The current model you pick and choose options which affects cost. The new LT1021 has higher stability due to the unit being always on and no longer being exposed to ambient air. I hope this helps."

[Martin72]

Today I test our ST2830 at work with the L/C option and resistance of the DMMCheck.
Put the results to the table I´ve made for the ET4410 from East Tester.
Remarkable: Both meters have their runaways in the same places, is that still coincidence....
I think I will have the checker calibrated externally after all.

[Martin72]

Ref.Voltage measuring, DC, AC100hz, AC10khz all with the SDS1104X-E from siglent, the SDS2504X HD will soon follow.
Have a look at the statistics(at ac, dc was too short)....nice.

[alm]

Ref.Voltage measuring, DC, AC100hz, AC10khz all with the SDS1104X-E from siglent, the SDS2504X HD will soon follow.
Have a look at the statistics(at ac, dc was too short)....nice.

Thanks for the measurements. I'm surprised by the droop in the AC 100 Hz signal showing a high pass effect. I'd expect them to generate a square wave at very close to the reference amplitude with the idea that the fewer components contribute to the output signal, the fewer components that can drift. Now any temperature-dependent effect in the coupling capacitor will effect the output.

[KungFuJosh]

Now any temperature-dependent effect in the coupling capacitor will effect the output.

That seems relevant given what claims they made about the new device they're releasing.

[Martin72]

At the moment my SDS2504HD measure the same signal - without "deforming"...
Must investigate this.

[alm]

At the moment my SDS2504HD measure the same signal - without "deforming"...
Must investigate this.

The SDS1104X-E was not set to AC coupling, was it?

[Martin72]

Look at the pics, right side..
Meanwhile I did several measures with the HD, with probe, without probe, everytime fine and looks great, post the pics soon.
But now I´m turning the SDS1104X-E on again, want to know what´s going on.