Author Topic: How much would you pay for a assembled 10V reference?  (Read 1701 times)

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Offline The Soulman

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How much would you pay for a assembled 10V reference?
« on: June 12, 2019, 07:57:43 pm »
Because my hand assembled nicely aged and highly beloved dual lt1021 voltage reference is missing in action thanks to DHL.  :--

edit: arrived safely after two weeks. :)

I'm looking at building a new one, or better two, or..
To ease assembly a nice pcb will be designed.

The focus will be:

* "low cost"
* good long-term stability (buried zener either way)
* can be shipped as a letter (or book) max height 30mm
* metal housing
* on-board temp. sensor


Similar devices are:

Doug Malone's voltage standard:
http://shop.voltagestandard.com/product.sc;jsessionid=070D2648EEAA7B01A9A816457C444946.p3plqscsfapp004?productId=6&categoryId=1)

and

AB -precision DVR1 voltage standard:
https://www.ab-precision.de/products/electrical-standards/


Is there an interest in such a product? and if so what features/specs would you like and in what price range?
« Last Edit: June 15, 2019, 10:15:09 am by The Soulman »
 

Offline RandallMcRee

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Re: How much would you pay for a assembled 10V reference?
« Reply #1 on: June 12, 2019, 09:02:59 pm »
I think a lot would also depend on the type of calibration that you can offer. Can you specify?

For example, Doug Malone specifies an in-cal 3458a and the burn-in time. He also allows for a re-calibration after some amount of time.

 

Offline bob91343

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Re: How much would you pay for a assembled 10V reference?
« Reply #2 on: June 12, 2019, 09:06:25 pm »
I have five 10V reference DIP ICs selected by a switch.  They are very good, run off a wall wart, mounted on the bench.

Have you looked into that sort of thing?  I think they are very accurate; certainly they all correlate very well with my HP3456A.
 

Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #3 on: June 12, 2019, 09:35:36 pm »
I think a lot would also depend on the type of calibration that you can offer. Can you specify?

For example, Doug Malone specifies an in-cal 3458a and the burn-in time. He also allows for a re-calibration after some amount of time.

It depends, at the moment I could offer 0,05% initial accuracy, if I could sell one hundred devices I'd purchase a traceable fluke 732
and null against that.  :)

 

Offline maginnovision

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Re: How much would you pay for a assembled 10V reference?
« Reply #4 on: June 12, 2019, 09:39:05 pm »
.05% is sort of useless for a reference. Handheld meters have better accuracy. How long would you age them? Would you include your data from ageing? Would you measure and include noise specifications? For comparison I paid about €200 for an ltz1000 ref aged >10000 hours, have data from that time, noise specs, calibration data(including copy of Cal cert from device used for Cal) and 1 free calibration.
« Last Edit: June 12, 2019, 09:44:39 pm by maginnovision »
 

Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #5 on: June 12, 2019, 09:56:28 pm »
I have five 10V reference DIP ICs selected by a switch.  They are very good, run off a wall wart, mounted on the bench.

Have you looked into that sort of thing?  I think they are very accurate; certainly they all correlate very well with my HP3456A.

Yes, but I like a more finished product that could easily shipped around.
As per my original plan, let other voltnuts measure my reference (to a better accuracy) and ship it back to me so I could compare it with my
"gold-standard" and measure the difference.

How would you know your DIP ICs and 3456 aren't all of by a couple volts?  :)

 

Offline Macbeth

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Re: How much would you pay for a assembled 10V reference?
« Reply #6 on: June 12, 2019, 10:09:41 pm »
I will start the bids. I would pay a tenner for a 10 volt ref, and sick squid for a 6.8 volt ref. This is The Queens GBP here, not that EURO/USD rubbish.  :-DD
 

Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #7 on: June 12, 2019, 10:12:02 pm »
.05% is sort of useless for a reference. Handheld meters have better accuracy. How long would you age them? Would you include your data from ageing? Would you measure and include noise specifications? For comparison I paid about €200 for an ltz1000 ref aged >10000 hours, have data from that time, noise specs, calibration data(including copy of Cal cert from device used for Cal) and 1 free calibration.


That is a pretty good deal, is that a board or a completed ref including housing and connectors?
Also 10.000 hours ageing is a pretty long time, something I'm not able to offer on the short term.

Can you post a link were these are available?
 

Offline Magnificent Bastard

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Re: How much would you pay for a assembled 10V reference?
« Reply #8 on: June 12, 2019, 10:28:31 pm »
.05% is sort of useless for a reference. Handheld meters have better accuracy. How long would you age them? Would you include your data from ageing? Would you measure and include noise specifications? For comparison I paid about €200 for an ltz1000 ref aged >10000 hours, have data from that time, noise specs, calibration data(including copy of Cal cert from device used for Cal) and 1 free calibration.

The initial accuracy of the reference is nearly irrelevant.  The uncertainty of the calibration is what is important.  In other words, the output could be 10.050012V, but this value is known to (say) +/-5ppm at a k-factor of 3 (which is ~99.97% uncertainty).  5ppm would be difficult to achieve with a non-heated reference that is not kept in an oven at a continuous temperature-- and even with that you are limited by the output 1/f noise <= 1Hz.  You might be able to get an LM399 (heated) reference to hold still for 2ppm, but below that you would need to change to an LTZ1000.  So, it kind of depends on what you want to do with this reference-- if it is just for standard jelly-bean handheld DMMs, then the specs can be relaxed-- if is for calibration of a 6+1/2 digit DMM, then the 2ppm device will be needed, and for better than 6+1/2 digits, then an LTZ1000 will be needed.

Remember, the artifact (voltage reference) must have at least 4X less uncertainty than the instrument you are calibrating with it.
 

Offline Terry01

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Re: How much would you pay for a assembled 10V reference?
« Reply #9 on: June 12, 2019, 10:29:44 pm »
I think that's a tough market your trying to break into there buddy considering what is already on offer for a very reasonable $65!
I hope it works out for you but I think it will be a very hard sell.
Sparks and Smoke means i'm nearly there! 8)
 

Offline Magnificent Bastard

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Re: How much would you pay for a assembled 10V reference?
« Reply #10 on: June 12, 2019, 10:37:00 pm »
I think that's a tough market your trying to break into there buddy considering what is already on offer for a very reasonable $65!
I hope it works out for you but I think it will be a very hard sell.

I think that the hardware is nearly irrelevant.  The hardware only has to be good enough to transfer the value of a metrology-grade reference (732A/B/C at very low uncertainty), and maintain that calibration for at least 30 days through shipping, temperature swings, etc.  What you are buying is the calibration-- the hardware is only a necessary evil.  A calibration of about 0.5ppm will set you back about $200, and Fluke's 0.06ppm calibration will be around $550 (plus shipping and insurance).  So, a $100 would be a good price for 1ppm, and maybe $50 to $75 for a 2ppm calibration (not including the hardware).  There is no way around the economic math on this.
 

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Re: How much would you pay for a assembled 10V reference?
« Reply #11 on: June 12, 2019, 10:40:22 pm »
I'm looking at building a new one, or better two, or..
To ease assembly a nice pcb will be designed.

The focus will be:

* "low cost"
* good long-term stability (buried zener either way)
* can be shipped as a letter (or book) max height 30mm
* metal housing
* on-board temp. sensor


Similar devices are:

Doug Malone's voltage standard:
http://shop.voltagestandard.com/product.sc;jsessionid=070D2648EEAA7B01A9A816457C444946.p3plqscsfapp004?productId=6&categoryId=1)

and

AB -precision DVR1 voltage standard:
https://www.ab-precision.de/products/electrical-standards/


Is there an interest in such a product? and if so what features/specs would you like and in what price range?
This one too from member IanJ:
https://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-v2-detail

Not low cost but as always you get what you pays for.  :P
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Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #12 on: June 12, 2019, 10:49:08 pm »
I will start the bids. I would pay a tenner for a 10 volt ref, and sick squid for a 6.8 volt ref. This is The Queens GBP here, not that EURO/USD rubbish.  :-DD

That sick squid sounds tempting but I'm looking for something around/below the 50 euro area, all depends
on the specs/features people come up with.

If it is just me I'd go for the LT1021DMH-10 again, to minimize long-term drift leave the trim pin not connected, so no trimming and/or temperature compensation.
Instead something like a lm35 temperature sensor on the same board close to the v-ref to keep track of temperature and made available on a separate output.
Power input would be a common barrel jack, that would accept 15 to 30 volts dc, current consumption below 10mA.

Calibration is the main reason for me to have started this whole journey, I currently don't own anything traceable or even very accurate by specs.
 

Offline Terry01

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Re: How much would you pay for a assembled 10V reference?
« Reply #13 on: June 12, 2019, 11:01:12 pm »
I will start the bids. I would pay a tenner for a 10 volt ref, and sick squid for a 6.8 volt ref. This is The Queens GBP here, not that EURO/USD rubbish.  :-DD

That sick squid sounds tempting but I'm looking for something around/below the 50 euro area, all depends
on the specs/features people come up with.

If it is just me I'd go for the LT1021DMH-10 again, to minimize long-term drift leave the trim pin not connected, so no trimming and/or temperature compensation.
Instead something like a lm35 temperature sensor on the same board close to the v-ref to keep track of temperature and made available on a separate output.
Power input would be a common barrel jack, that would accept 15 to 30 volts dc, current consumption below 10mA.

Calibration is the main reason for me to have started this whole journey, I currently don't own anything traceable or even very accurate by specs.

Save yourself a PITA buddy and buy one of the few on offer already from various tried and tested means?  :)
Sparks and Smoke means i'm nearly there! 8)
 

Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #14 on: June 12, 2019, 11:07:06 pm »
I think that's a tough market your trying to break into there buddy considering what is already on offer for a very reasonable $65!
I hope it works out for you but I think it will be a very hard sell.

(I assume you are referring to Doug Malone's voltage reference)

It's not the type of device I would buy only because of the housing and connectors.
And him being in the US shipping costs to the EU might be prohibitive, also he is out of stock at the moment just like
the last couple of times I've check.
 

Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #15 on: June 12, 2019, 11:16:01 pm »
I will start the bids. I would pay a tenner for a 10 volt ref, and sick squid for a 6.8 volt ref. This is The Queens GBP here, not that EURO/USD rubbish.  :-DD

That sick squid sounds tempting but I'm looking for something around/below the 50 euro area, all depends
on the specs/features people come up with.

If it is just me I'd go for the LT1021DMH-10 again, to minimize long-term drift leave the trim pin not connected, so no trimming and/or temperature compensation.
Instead something like a lm35 temperature sensor on the same board close to the v-ref to keep track of temperature and made available on a separate output.
Power input would be a common barrel jack, that would accept 15 to 30 volts dc, current consumption below 10mA.

Calibration is the main reason for me to have started this whole journey, I currently don't own anything traceable or even very accurate by specs.

Save yourself a PITA buddy and buy one of the few on offer already from various tried and tested means?  :)

What would be the fun in that.  :)
If there is already a good supplier of this type of thing (50 euro ballpark) in the eu area please let me know, because I couldn't find one.

Anyway whatever I come up with will be made better than Awesome!  :-DD  :box:
 

Offline maginnovision

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Re: How much would you pay for a assembled 10V reference?
« Reply #16 on: June 12, 2019, 11:29:55 pm »
.05% is sort of useless for a reference. Handheld meters have better accuracy. How long would you age them? Would you include your data from ageing? Would you measure and include noise specifications? For comparison I paid about €200 for an ltz1000 ref aged >10000 hours, have data from that time, noise specs, calibration data(including copy of Cal cert from device used for Cal) and 1 free calibration.

The initial accuracy of the reference is nearly irrelevant.  The uncertainty of the calibration is what is important.  In other words, the output could be 10.050012V, but this value is known to (say) +/-5ppm at a k-factor of 3 (which is ~99.97% uncertainty).  5ppm would be difficult to achieve with a non-heated reference that is not kept in an oven at a continuous temperature-- and even with that you are limited by the output 1/f noise <= 1Hz.  You might be able to get an LM399 (heated) reference to hold still for 2ppm, but below that you would need to change to an LTZ1000.  So, it kind of depends on what you want to do with this reference-- if it is just for standard jelly-bean handheld DMMs, then the specs can be relaxed-- if is for calibration of a 6+1/2 digit DMM, then the 2ppm device will be needed, and for better than 6+1/2 digits, then an LTZ1000 will be needed.

Remember, the artifact (voltage reference) must have at least 4X less uncertainty than the instrument you are calibrating with it.

I don't know what those numbers have to do with anything, he said .05%(500ppm) not 0.05ppm. Unless I'm wrong about that. If .05ppm I'd buy one.
« Last Edit: June 12, 2019, 11:31:37 pm by maginnovision »
 

Offline Terry01

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Re: How much would you pay for a assembled 10V reference?
« Reply #17 on: June 12, 2019, 11:39:06 pm »
I will start the bids. I would pay a tenner for a 10 volt ref, and sick squid for a 6.8 volt ref. This is The Queens GBP here, not that EURO/USD rubbish.  :-DD

That sick squid sounds tempting but I'm looking for something around/below the 50 euro area, all depends
on the specs/features people come up with.

If it is just me I'd go for the LT1021DMH-10 again, to minimize long-term drift leave the trim pin not connected, so no trimming and/or temperature compensation.
Instead something like a lm35 temperature sensor on the same board close to the v-ref to keep track of temperature and made available on a separate output.
Power input would be a common barrel jack, that would accept 15 to 30 volts dc, current consumption below 10mA.

Calibration is the main reason for me to have started this whole journey, I currently don't own anything traceable or even very accurate by specs.

Save yourself a PITA buddy and buy one of the few on offer already from various tried and tested means?  :)

What would be the fun in that.  :)
If there is already a good supplier of this type of thing (50 euro ballpark) in the eu area please let me know, because I couldn't find one.

Anyway whatever I come up with will be made better than Awesome!  :-DD  :box:

Something you make yourself will be awesome for sure.

Message Doug and he'll let you know when there will be more available and the costs. He'll give you a shout when yours is ready if you decide to go with it. I had to wait on one but it wasn't that long and costs to the UK was bearable. I got the DMM check but the 10v ref for $65 isn't a bad deal at all.

Good luck however you go buddy.  :)
Sparks and Smoke means i'm nearly there! 8)
 

Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #18 on: June 12, 2019, 11:56:04 pm »
.05% is sort of useless for a reference. Handheld meters have better accuracy. How long would you age them? Would you include your data from ageing? Would you measure and include noise specifications? For comparison I paid about €200 for an ltz1000 ref aged >10000 hours, have data from that time, noise specs, calibration data(including copy of Cal cert from device used for Cal) and 1 free calibration.

The initial accuracy of the reference is nearly irrelevant.  The uncertainty of the calibration is what is important.  In other words, the output could be 10.050012V, but this value is known to (say) +/-5ppm at a k-factor of 3 (which is ~99.97% uncertainty).  5ppm would be difficult to achieve with a non-heated reference that is not kept in an oven at a continuous temperature-- and even with that you are limited by the output 1/f noise <= 1Hz.  You might be able to get an LM399 (heated) reference to hold still for 2ppm, but below that you would need to change to an LTZ1000.  So, it kind of depends on what you want to do with this reference-- if it is just for standard jelly-bean handheld DMMs, then the specs can be relaxed-- if is for calibration of a 6+1/2 digit DMM, then the 2ppm device will be needed, and for better than 6+1/2 digits, then an LTZ1000 will be needed.

Remember, the artifact (voltage reference) must have at least 4X less uncertainty than the instrument you are calibrating with it.

I don't know what those numbers have to do with anything, he said .05%(500ppm) not 0.05ppm. Unless I'm wrong about that. If .05ppm I'd buy one.

The original question and answer:

I think a lot would also depend on the type of calibration that you can offer. Can you specify?

For example, Doug Malone specifies an in-cal 3458a and the burn-in time. He also allows for a re-calibration after some amount of time.

It depends, at the moment I could offer 0,05% initial accuracy, if I could sell one hundred devices I'd purchase a traceable fluke 732
and null against that.  :)



To clarify, at this moment I can't offer a calibration with useful uncertainties, let a alone traceable to any national standard.
I could order 0,05% accurate parts so that would be something.

The idea I have is to make something sturdy and compact that can be mailed around in a cal-club type fashion,
so it will gather calibration points just like rolling stones gathers moss, or something like that.
And if it gets lost or damaged a replacement is readily available (for purchase..).

No can do on 0.05ppm accuracy, however I might know a competitor that is willing to sell you that.
 

Offline maginnovision

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Re: How much would you pay for a assembled 10V reference?
« Reply #19 on: June 13, 2019, 12:28:02 am »
I understand. I think what you could do is find someone to help or work with you to do this. You could design/build and someone else could calibrate and ship. You do need to at least make sure the lt1021s you'd be using are stable.
 

Offline bob91343

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Re: How much would you pay for a assembled 10V reference?
« Reply #20 on: June 13, 2019, 02:33:34 am »
While it's true that I don't really know how close my ICs and my 3456A are, they come from different sources and agree amazingly well.  I also got hold of a 3455A that stopped working but until that happened it agreed with the 3456A to the last digit.

So I think that, statistically, I am pretty much spot on with this gear.  And if I am off a few microvolts I would neither know nor care.  Certainly more accurate than any other instrument I or my friends have.
 

Offline Magnificent Bastard

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Re: How much would you pay for a assembled 10V reference?
« Reply #21 on: June 13, 2019, 02:51:40 am »
Evidently, people did not read my post.  I NEVER mentioned 0.05ppm.

I have asked, "what is this for, and what do you expect it to do for you?"

STILL no answer...    |O
 

Offline maginnovision

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Re: How much would you pay for a assembled 10V reference?
« Reply #22 on: June 13, 2019, 03:00:53 am »
He mentions voltage-standard.com's and ab-precision.de's standards so I assume he's going for a proper calibrated voltage reference.
« Last Edit: June 13, 2019, 08:06:02 am by maginnovision »
 

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Re: How much would you pay for a assembled 10V reference?
« Reply #23 on: June 13, 2019, 05:16:12 am »
Word proper has different meaning for different people.  :popcorn:
In reality there is market for all various references, be it $50, or $500, or $5K one. Heck, there is market even for $500k reference, but it's very little and niche :)
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Offline tggzzz

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Re: How much would you pay for a assembled 10V reference?
« Reply #24 on: June 13, 2019, 07:21:22 am »
Because my hand assembled nicely aged and highly beloved dual lt1021 voltage reference is missing in action thanks to DHL.  :--

I'm looking at building a new one, or better two, or..
To ease assembly a nice pcb will be designed.

The focus will be:

* "low cost"
* good long-term stability (buried zener either way)
* can be shipped as a letter (or book) max height 30mm
* metal housing
* on-board temp. sensor


Similar devices are:

Doug Malone's voltage standard:
http://shop.voltagestandard.com/product.sc;jsessionid=070D2648EEAA7B01A9A816457C444946.p3plqscsfapp004?productId=6&categoryId=1)

and

AB -precision DVR1 voltage standard:
https://www.ab-precision.de/products/electrical-standards/


Is there an interest in such a product? and if so what features/specs would you like and in what price range?

As stated, component cost plus £10.

If aged and calibrated, significantly more.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #25 on: June 13, 2019, 09:47:14 am »
Evidently, people did not read my post.  I NEVER mentioned 0.05ppm.

I have asked, "what is this for, and what do you expect it to do for you?"

STILL no answer...    |O

Sorry about that, the original plan was to have a little reference that could be shipped back and forth to other forum members to
import "The Volt" back to my lab, however on the very first return trip DHL lost my package (that also included my resistance standards  :'( ).

So I'm looking at building about five (never put all your eggs in the same basket..) new ones for my personal use, and design a pcb
and probably out-source machining of the housing, just to speed up the process.
And as I'm doing that I could also build twenty or fifty in a single batch.
If there is a need for such type of thing and what people would be willing to pay for it also influences the design and parts used a bit.
 
5½ digit of accuracy (=10ppm/=0,001%)
is fine for me.

I hope that clarifies it a bit.
« Last Edit: June 15, 2019, 10:18:54 am by The Soulman »
 

Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #26 on: June 13, 2019, 10:07:55 am »
I understand. I think what you could do is find someone to help or work with you to do this. You could design/build and someone else could calibrate and ship. You do need to at least make sure the lt1021s you'd be using are stable.

Aging as a assembled product would be 1000 hours minimum I'd also gather data in that time and weed out any drifters
or ones with unreasonably high temp-co.
Also at this moment I'm not committed to use the lt1021, if people have better idea's please let me know.
It also appears that lt1021 H(ermetic) versions are EOL, not sure it's because there is a new one coming or because they (LT/AD) are phasing out all all 10V v-refs in favor of low noise 2,048V ones.  :-\
 

Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #27 on: June 13, 2019, 10:20:25 am »
While it's true that I don't really know how close my ICs and my 3456A are, they come from different sources and agree amazingly well.  I also got hold of a 3455A that stopped working but until that happened it agreed with the 3456A to the last digit.

So I think that, statistically, I am pretty much spot on with this gear.  And if I am off a few microvolts I would neither know nor care.  Certainly more accurate than any other instrument I or my friends have.

Exactly, I was pulling your leg a bit.

In the end it all comes down to the confidence that you have in your measurements, if your meter agrees with a number of external
independent references the confidence is good.
Now if one of those references gets measured by a another meter (from a fellow volt-nut) and that agrees as well
confidence is even higher.
Do that more frequently and add a couple of high-spec and or traceable meters in the mix, confidence is optimal.  :popcorn:
 

Offline exe

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Re: How much would you pay for a assembled 10V reference?
« Reply #28 on: June 13, 2019, 11:17:36 am »
I'd be interested in a product like DMMCheck, but in Europe :). So, not just 10V, but also resistance, capacitance, and ac voltage. Probably I want too much :).

As of calibration voltage, it's tough question. My understanding is, 10V is used to calibrate "old" gear. In my personal projects I use 3.3V reference as this is the voltage needed for the stm32 mcu.
 

Offline guenthert

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Re: How much would you pay for a assembled 10V reference?
« Reply #29 on: June 13, 2019, 04:28:41 pm »
I sense some confusion.  If you
* just want to "import" the volt to your lab, then why not participate in one of the existing "calibration clubs"?
* build/sell a device for such "calibration clubs" (tiny market), such a device would be a "transfer standard" and as such needs to be
  -- low noise to allow determining the DC value with great confidence
  -- ruggedized (as shippers and members *will* drop them, *cough*, *cough*)
  -- protected input (overvoltage, reversed polarity) and output (short circuit)
  -- small and light to reduce shipping costs
  -- withstand temperature extremes while showing only minimal hysteresis
  -- should use a standard voltage (so that it can be compared easily), that'll be 10V these days and
  -- standard connectors 4mm "banana" 5 way binding posts pretty please with possibility to screw in bare copper wires
  -- not too expensive, as it might get lost during shipping
 it does *not* need to be
  -- long term stable, as it is "re-calibrated" (or current value recorded) every few days (few weeks at the most), when returning to home base

* If, on the other hand, you want build/sell a home reference (much larger market, but apparently not large enough for e.g. Mr. Geller's reference to be economically viable), you want it to be first and foremost long term stable (which is time consuming and hence expensive to determine and demonstrate)
 
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Offline Magnificent Bastard

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Re: How much would you pay for a assembled 10V reference?
« Reply #30 on: June 13, 2019, 08:38:22 pm »
I sense some confusion.  If you
* just want to "import" the volt to your lab, then why not participate in one of the existing "calibration clubs"?
* build/sell a device for such "calibration clubs" (tiny market), such a device would be a "transfer standard" and as such needs to be
  -- low noise to allow determining the DC value with great confidence
  -- ruggedized (as shippers and members *will* drop them, *cough*, *cough*)
  -- protected input (overvoltage, reversed polarity) and output (short circuit)
  -- small and light to reduce shipping costs
  -- withstand temperature extremes while showing only minimal hysteresis
  -- should use a standard voltage (so that it can be compared easily), that'll be 10V these days and
  -- standard connectors 4mm "banana" 5 way binding posts pretty please with possibility to screw in bare copper wires
  -- not too expensive, as it might get lost during shipping
 it does *not* need to be
  -- long term stable, as it is "re-calibrated" (or current value recorded) every few days (few weeks at the most), when returning to home base

* If, on the other hand, you want build/sell a home reference (much larger market, but apparently not large enough for e.g. Mr. Geller's reference to be economically viable), you want it to be first and foremost long term stable (which is time consuming and hence expensive to determine and demonstrate)

It should not require batteries during shipping, which entails a whole bunch of problems.  In today's world, things that show batteries inside on an X-Ray, will get flagged for further investigation-- and may get lost or destroyed as a consequence of that.  It should not be affected by the input voltage much (with an input range of say, 12V to 16V)-- and it should not be affected by humidity or barometric pressure.

What this means is that every reference that is NOT in a hermetically sealed package is NOT acceptable.  Unfortunately, almost all hermetically sealed references are being phased out by the idiotic bean counters at the various semiconductor companies, with the possible exception of the LM399 and the LTZ1000.

The (heated) LM399 has lower mechanical hysteresis than even the LTZ1000A, let alone the LTZ1000.  The LTZ1000(A) references are better off if they are continuously powered.

So, this absolutely SCREAMS to use the LM399.  You *could* use 4 of them in parallel to get the low frequency noise down, without getting too ridiculous on the final price of the reference.  I once talked to my Linear Tech rep about the LM399.  I asked what the big DMM manufacturers were doing to sort these into acceptable parts.  He would not say what they were doing, but he did tell me that only about 1 out of 10 references ever made it into the 6-1/2+ digit meters.  They are selecting for low 1/f noise (1Hz and below), low popcorn noise, low temperature drift, and low temporal drift.  Some of these have to be monitored for over a year to find the "shining jewels".  Probably, they will need some kind of artificial aging schedule before the drift testing is done.  This could easily turn a $7 part into a $70 part (plus labor and fixturing).

Now, the LM399 has very poor initial accuracy, but very good stability.  There are some very old DMMs that have this reference in them, that have a surprisingly low annual drift rate (less than 1ppm), but this is only after 10 years or so of power-on time.  Using the LM399 would mean that you need to have a highly adjustable 7V to 10V boost circuit that does not drift over time, and this (in turn) indicates a PWM scheme.  This also provides the opportunity to trim the reference for temperature and barometric pressure related drift.  There is already work being done on this on the LM399 thread here:

https://www.eevblog.com/forum/metrology/lm399-based-10-v-reference/

This could be initially adjusted and calibrated at a Cal-Lab (ENI Labs maybe?)-- and then calibrated each year just after the Cal-Lab gets their 732B calibrated at Fluke for minimum uncertainty.  (Here, "calibrated" means "accurately measure" and "adjust" means "change the absolute output value closer to 10V".)

This reference could then be circulated around through the Cal-Club, so users could calibrate and/or adjust their in-house 10V standards, DMMs, and calibrators.
 
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Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #31 on: June 13, 2019, 10:34:24 pm »
I'd be interested in a product like DMMCheck, but in Europe :). So, not just 10V, but also resistance, capacitance, and ac voltage. Probably I want too much :).

As of calibration voltage, it's tough question. My understanding is, 10V is used to calibrate "old" gear. In my personal projects I use 3.3V reference as this is the voltage needed for the stm32 mcu.

Resistance could be added in the same device or perhaps a separate apparatus, capacitance and AC are a different animal
but maybe, if this seems viable, in the distant future.

What voltage to use is a easy as it is difficult,

10V seems a tradition perhaps because a particular expensive dmm over-ranges at 12V..
7V is the native voltage of a buried zener, and the best to use for long-term stability, but apart from that a completely oddball value
that is unpractical to use with a meter that isn't limited to 8.000 or 10.000 counts (or the same with more zero's)  because of
the lost amount of resolution.
3,5V might be the ticked and useful for the home hobbyist to check his/hers 4000 or 6000 count (or 40.000 etc.) dmm
The 3,5V could be derived from the 7V zener voltage with a switched capacitor divider that has less of a an impact on stability than
a "simple" resistor divider, but the added components also add cost and might push it out of the price range for that type of user, i.e.
 a "normal" (not a volt-nut) hobbyist..

 
 

Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #32 on: June 13, 2019, 10:50:21 pm »
I sense some confusion.  If you
* just want to "import" the volt to your lab, then why not participate in one of the existing "calibration clubs"?
* build/sell a device for such "calibration clubs" (tiny market), such a device would be a "transfer standard" and as such needs to be
  -- low noise to allow determining the DC value with great confidence
  -- ruggedized (as shippers and members *will* drop them, *cough*, *cough*)
  -- protected input (overvoltage, reversed polarity) and output (short circuit)
  -- small and light to reduce shipping costs
  -- withstand temperature extremes while showing only minimal hysteresis
  -- should use a standard voltage (so that it can be compared easily), that'll be 10V these days and
  -- standard connectors 4mm "banana" 5 way binding posts pretty please with possibility to screw in bare copper wires
  -- not too expensive, as it might get lost during shipping
 it does *not* need to be
  -- long term stable, as it is "re-calibrated" (or current value recorded) every few days (few weeks at the most), when returning to home base

Yes all that, for voltage see my previous post, long term stability is use-full for any type of standard including a transfer standard,
as it helps to build confidence.

* If, on the other hand, you want build/sell a home reference (much larger market, but apparently not large enough for e.g. Mr. Geller's reference to be economically viable), you want it to be first and foremost long term stable (which is time consuming and hence expensive to determine and demonstrate)

Well I wan't it to be both, it could be the twentieth standard for a incurable volt-nut and a "gold-reference" for a
electronics hobbyist to check his 40.000 count 0,1% hand-held dmm once a week.

 

Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #33 on: June 13, 2019, 11:03:41 pm »

It should not require batteries during shipping, which entails a whole bunch of problems.  In today's world, things that show batteries inside on an X-Ray, will get flagged for further investigation-- and may get lost or destroyed as a consequence of that.  It should not be affected by the input voltage much (with an input range of say, 12V to 16V)-- and it should not be affected by humidity or barometric pressure.

What this means is that every reference that is NOT in a hermetically sealed package is NOT acceptable.  Unfortunately, almost all hermetically sealed references are being phased out by the idiotic bean counters at the various semiconductor companies, with the possible exception of the LM399 and the LTZ1000.

The (heated) LM399 has lower mechanical hysteresis than even the LTZ1000A, let alone the LTZ1000.  The LTZ1000(A) references are better off if they are continuously powered.

So, this absolutely SCREAMS to use the LM399.  You *could* use 4 of them in parallel to get the low frequency noise down, without getting too ridiculous on the final price of the reference.  I once talked to my Linear Tech rep about the LM399.  I asked what the big DMM manufacturers were doing to sort these into acceptable parts.  He would not say what they were doing, but he did tell me that only about 1 out of 10 references ever made it into the 6-1/2+ digit meters.  They are selecting for low 1/f noise (1Hz and below), low popcorn noise, low temperature drift, and low temporal drift.  Some of these have to be monitored for over a year to find the "shining jewels".  Probably, they will need some kind of artificial aging schedule before the drift testing is done.  This could easily turn a $7 part into a $70 part (plus labor and fixturing).

Now, the LM399 has very poor initial accuracy, but very good stability.  There are some very old DMMs that have this reference in them, that have a surprisingly low annual drift rate (less than 1ppm), but this is only after 10 years or so of power-on time.  Using the LM399 would mean that you need to have a highly adjustable 7V to 10V boost circuit that does not drift over time, and this (in turn) indicates a PWM scheme.  This also provides the opportunity to trim the reference for temperature and barometric pressure related drift.  There is already work being done on this on the LM399 thread here:

https://www.eevblog.com/forum/metrology/lm399-based-10-v-reference/

This could be initially adjusted and calibrated at a Cal-Lab (ENI Labs maybe?)-- and then calibrated each year just after the Cal-Lab gets their 732B calibrated at Fluke for minimum uncertainty.  (Here, "calibrated" means "accurately measure" and "adjust" means "change the absolute output value closer to 10V".)

This reference could then be circulated around through the Cal-Club, so users could calibrate and/or adjust their in-house 10V standards, DMMs, and calibrators.

Totally agree on the hermetic enclosure, as mentioned LT1021-H are eol, but at this moments remaining stocks are plenty full..
LTZ1000 are overkill for what I'm attempting here, LM399 could be it but a boost stage to 10V hurts stability and adds a lot of cost
for good parts (VHP?).
PWM is another option also adds cost thru complexity.
As mentioned above, a switched capacitor divider could be used for a non-traditional but useful 3,5V output.
 

Offline Magnificent Bastard

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Re: How much would you pay for a assembled 10V reference?
« Reply #34 on: June 14, 2019, 03:53:25 pm »
{snip!}
PWM is another option also adds cost thru complexity.
{snip!}

Uhmmm.... no.  PWM is arguably cheaper and more stable than ANY resistor-boost scheme of any kind.  The "complexity" is in the firmware, which is not that bad, can be done by an expert here on this forum, and should only take 2 weeks or so.
 

Offline alex-sh

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Re: How much would you pay for a assembled 10V reference?
« Reply #35 on: June 15, 2019, 07:58:13 pm »
I think that's a tough market your trying to break into there buddy considering what is already on offer for a very reasonable $65!
I hope it works out for you but I think it will be a very hard sell.

(I assume you are referring to Doug Malone's voltage reference)

It's not the type of device I would buy only because of the housing and connectors.
And him being in the US shipping costs to the EU might be prohibitive, also he is out of stock at the moment just like
the last couple of times I've check.

I have ordered from Doug and shipping to Europe is very reasonable.
Most important is that I can return the reference for re-calibration.
 

Offline alex-sh

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Re: How much would you pay for a assembled 10V reference?
« Reply #36 on: June 15, 2019, 07:59:59 pm »
I will start the bids. I would pay a tenner for a 10 volt ref, and sick squid for a 6.8 volt ref. This is The Queens GBP here, not that EURO/USD rubbish.  :-DD

That sick squid sounds tempting but I'm looking for something around/below the 50 euro area, all depends
on the specs/features people come up with.

If it is just me I'd go for the LT1021DMH-10 again, to minimize long-term drift leave the trim pin not connected, so no trimming and/or temperature compensation.
Instead something like a lm35 temperature sensor on the same board close to the v-ref to keep track of temperature and made available on a separate output.
Power input would be a common barrel jack, that would accept 15 to 30 volts dc, current consumption below 10mA.

Calibration is the main reason for me to have started this whole journey, I currently don't own anything traceable or even very accurate by specs.


At Euro 50, I'd be looking at LM399 board with an excellent long-term stability LT1021 cannot match.
A few of these boards were up for sale on this forum at Euro 50.

 

Offline alex-sh

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Re: How much would you pay for a assembled 10V reference?
« Reply #37 on: June 15, 2019, 08:09:37 pm »
Quote
LM399 could be it but a boost stage to 10V hurts stability and adds a lot of cost
for good parts (VHP?).


Really? And what costs does it add? A couple of 1% resistors for a correct op-amp gain? A buffer op-amp is needed anyway.
 

Offline The Soulman

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Re: How much would you pay for a assembled 10V reference?
« Reply #38 on: June 16, 2019, 11:42:11 am »
The lm399 has more noise (by typical specification)



Quote
LM399 could be it but a boost stage to 10V hurts stability and adds a lot of cost
for good parts (VHP?).


Really? And what costs does it add? A couple of 1% resistors for a correct op-amp gain? A buffer op-amp is needed anyway.

Op-amp is indeed required anyway for lm399, and the absolute values of the gain resistors aren't important but the stability of the ratio is,
generic resistors aren't good enough for that.
If you think it is:

https://www.ebay.nl/itm/LM399H-10V-Precision-voltage-Reference-Calibrated-LM399/254200638725?hash=item3b2f89ed05:g:RtsAAOSwPA1cOaqw
 


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