Wanted: Someone that can measure 10 V DC within 30ppm

[The Soulman]

My two 4,5 digit meters disagree by about two lsd, and for normal people that isn't a problem but for me..   
So I'm planning to build a 2,5 volt reference (or perhaps two, or ...) and after some testing/aging send them to someone
who is able to measure them within 100 ppm uncertainty of a traceable standard.
Preferable in the Netherlands but Germany is OK also.
Is this even feasible?

Reactions here or PM.

[The Soulman]

Do you have a local KS/KEI/Tek sales? Maybe you can pay them a visit and "demo" their units...
Or just go to a university to get someone to do this for you.
You don't need a traceable equipment. It's highly likely even a calibration overdue 6.5 digit meter is way more accurate than your 4.5 digit.

Don't take this offensively and I appreciate your input but:

1) I don't like salespeople.
2) I haven't stepped inside an educational institute other than elementary schools for a long time, and not sure who or how to contact anyone.

Some 6.5 digit should do..

[Vgkid]

Try sending a pm to Pa4tim, he is in the Netherlands. There are most likely others as well.

[SvanGool]

Bummer, I can't make the 100 ppm on my 34401A, but if 123 ppm is enough (https://www.eevblog.com/forum/metrology/lt1021cmh-based-mini-reference/msg1172332/#msg1172332)? Or if you can bring them within 90-14 days=76 days from now, my 10.00000 V is even 15 ppm better = 108 ppm, very close !  .
Unless Alex invalidates the intermediate results.

[HighVoltage]

If you can not find anyone in NL, you can send it to me and I will take measurements on my 3458A, 34470A, DMM7510

[try]

Soulman,

how fast do you need it?

I can be reached near Venlo a couple of times over the year.
Could bring in a 34401A.

Regards
try

[blackdog]

Hi The Soulman,

I can help you if you want.
100PPM is not a problem for me.
DMM4050 DMM's en a HP3458A on the bench :-)

Location Amsterdam
Send me a e-mail.

Kind regards,
Blackdog

[PA0PBZ]

Maybe if the Soulman can reveal his location a bit it would be easier. I guess my 34461A is up to the task too.

[SvanGool]

Bummer, I can't make the 100 ppm on my 34401A, but if 123 ppm is enough (https://www.eevblog.com/forum/metrology/lt1021cmh-based-mini-reference/msg1172332/#msg1172332)? Or if you can bring them within 90-14 days=76 days from now, my 10.00000 V is even 15 ppm better = 108 ppm, very close !
Unless Alex invalidates the intermediate results.

Just for the record: I mixed my Vs and Rs, for the 10V range my 34401A's accuracy is now 4+3+25=32 ppm for the 90 days period and 4+3+40=47 ppm for the 1 year period, well within the requested 100 ppm   

[TiN]

Gotta give credit to TS, great way to lure those voltnuts out. Just ask to measure something with low accuracy, and suddenly whole crowd is out in the daylight. 

[Theboel]

TiN, try to lure out the Voltnut in my country I think You need a full fleet of Fish ship to get a few 

[The Soulman]

Wow thanks for the response guys!
If someone is near me (west Drenthe) maybe we could meet so I don't have to build a reference, but on the other hand it is not bad to have one , or two..

[PA0PBZ]

but on the other hand it is not bad to have one , or two..

And that's how it starts... 

[SvanGool]

If someone is near me (west Drenthe) ..

And now he is also luring the German Voltnuts out, because that is close to their border   

BTW, I am not too close, mid-south.

[e61_phil]

If someone is near me (west Drenthe) ..

And now he is also luring the German Voltnuts out, because that is close to their border   

BTW, I am not too close, mid-south.

I looked into google maps and you'r absolutely right. I'm near Bremen. It's about 190km from Drenthe. I'm also able to measure 5V much better than a 100ppm.

[The Soulman]

I guess now I can build a reference and thermal cycle and age that a bit.
That could take at least one month or probably two, will contact people that responded here when I'have something put together.
Tomorrow I'm receiving a bunch of used precision wire wound resistors so I can include some of those as well to my travelling standard.

Any ideas for a ref IC that can be used? Maybe LM399 (8ppm/1000hr) or perhaps something cheaper and more simple so that multiples can be fitted in a small box?
Also 2,5 volts would be preferred but long term stability is a must.

Thanks again guys! 

[TiN]

Go for LM399.  But keep in mind that in 2-3 years you may end up having 2 x 8.5-digit DMMs, 4 x 7.5-digits ones, few standards, few calibrators, and bags of 50+$ components in your lab. 

[try]

Soulman,

Any ideas for a ref IC that can be used? Maybe LM399 (8ppm/1000hr) or perhaps something cheaper and more simple so that multiples can be fitted in a small box?
Also 2,5 volts would be preferred but long term stability is a must.

Thanks again guys! 

Taking into account your current uncertainty of 100ppm building some transfer standard is a no-brainer.
Buy the KKMoon reference, it already has a nominal 2,5V setting.
Please doublecheck before how far if at all your 2.5V measurement range exceeds that 2,5V barrier.
It's not useful having a reference giving 2,50080V which forces your DMM to switch into the next bigger range. 

If you want to build something yourself, use the MAX6325, p.e.
There is no need to use expensive wire wound resistors at this stage of your precision discovery.

Building some LM399 based reference is only important when having a longer term time horizon in mind as you can't buy aging time.

There is no need for building some device with multiple references at your current stage.
That is as useful as gold plating the cooler in your car.

Always bear in mind the precision you are targeting at and the cost involved. Both factors are highly likely to be left out when people are discussing their unrealized plans in this forum.

Have fun!

[The Soulman]

My main meter is 30.000 count, hence the 2,5 Volt.
Long term stability is a must to be able to recheck stuff and when the two meters and the reference drift apart (unlikely but you never know..)
it is useful to have multiple reference standards to determine what is drifting where..

Regarding cost, it should be possible to keep this project under 100 euro's (aprox. 60 for the device and 40 to ship it a couple of times?)
In my opinion that is still a fair price to pay to strengthen the confidence in the accuracy of my daily measurements for years to come.

[try]

Soulman,

with all respects to your needs for stability, this is where ignoring the quantitative aspects is not a smart decision as I critized above.

Your DMM has 30.000 counts.

One count represents a change in value of 33ppm.
Your device probably allows for 1-2 counts of variation.

Obviously your still to build reference has to move a lot before that change is showing up on or DMM which only has 4 2/3 digits.
How much time do you think will that take?

You might want to look up some drift numbers for a buried zener.
Checkout the last column on page 2:

http://www.ti.com/analog/docs/litabsmultiplefilelist.tsp?literatureNumber=sbva001&docCategoryId=1&familyId=720

I guess your device will not cost more than €15,- even with a metal housing and a LM399 if you insist on it (power supply excluded).

[Andreas]

Hello,

the sad truth is: you will need a minimum of 3 (better 4) references to judge about the long term stability.
If you have only one: how can you tell wether the reference driftet on its way back from calibration if you do not have the possibility to check against your home references.
And how can you tell which one of the references drifts most if you have only 2?

The mentioned MAX63xx/MAX62xx are not bad. But all my samples of MAX6250A/MAX6350 (in PDIP8 package) are drifting by about +10 ppm/year.

Many LM399 are much lower (in the range of 1-2 ppm/year) but of cause you have to select out the "stinkers" to get a good result.
To get around the 2.5V a good (long term stable) possibility is the use of a capacitive 3:1 divider with help of a LTC1043 + a unity gain buffer.

With a 30000 count DMM and a stable reference one should also be able to determine the tempco of the instrument.
My 80000 count DT80000 multimeter has a T.C. of about 84 ppm/K.

with best regards

Andreas

[try]

Andreas,

your proposed solution is overkill - shooting with canons at sparrows as the German saying goes.

Regards
try

[Andreas]

perhaps in the "beginners" section.
But never in the metrology / volt-nut section.

There is no such thing having too much DMMs and voltage references. see:

https://www.eevblog.com/forum/chat/test-equipment-anonymous-(tea)-group-therapy-thread/msg1114480/#msg1114480

With best regards

Andreas

[The Soulman]

Here is the plan: 5V (usb) input-> isolated dc/dc converter -> linear voltage regulator with 1mA current limit -> LT1021DCN8-7 -> over voltage/reverse voltage protection diodes-> glass fuse -> binding post output.
Parallel to the protection diodes a 10uf tantalum in series with a 4,7 Ohm resistor and obviously some capacitance around the linear regulator.
The above copied 3 or 5 times in one enclosure with one shared input, with the isolated converters I can connect the reference outputs in series for
higher voltage output.

Sounds like a reasonable plan?

Also and perhaps in the same enclosure I would like to build some sort of a resistance standard, 0R1,0R9,9R,90R,900R, in series with dual binding post in between so the individual resistors can be measured with 4 way connections but also multiple in series, could also act as a current shunt.
and 10K,10k (matched to 1ppm) and 100K,100K (matched to 1ppm) also with dual binding post for 4 way connection, could also act as single sides of a wheatstone bridge.
These resistors I already own, but also want to include higher values (1M and 10M) but not sure what resistors and connections to use?

While we are at it also add some capacitors to be calibrated, 100nF, 1uF, 10,uf ? Wima MKP10 good enough?

Suggestions much appreciated, parts will be ordered this week.

So the question changes a bit, Who can measure 6,95V, a large range of resistor values and some capacitors, to within 100ppm?

Having this device measured by several people probably isn't a bad idea and that way others can get some use-full data from it as well.

[TiN]

Capacitors within 100ppm going to be real challenge here .

I'd say loose USB input (it's very noisy), loose dc/dc converter and power the linear preregulator with some decent quality linear brick mains power supply.
Glass fuse will not do anything there too, if you reach currents that will break even smallest fuse (plugging mains into output? ), then whatever is behind fuse would be already charcoal dead.