Cheap, not Chinese, Voltage reference for DIY meter calibration

[dazz1]

With respect to the 68F label, it means the unit was calibrated at that temperature, meaning 20C.

Please excuse my poor attempt at sarcasm.

[jrharley]

For what it's worth, I have found the LB02A to be fantastic!
Wouldn't call it a true standard, but it's incredibly capable and easy to use. - JRH

[dazz1]

For what it's worth, I have found the LB02A to be fantastic!
Wouldn't call it a true standard, but it's incredibly capable and easy to use. - JRH

I am looking at this as the complimentary opposite to a bench top multi-meter.  Where a multi-meter measures A,V, Ohms and sometime other things, the LB02A generates these.  I could see this being useful for prototype development. 
At a pinch, it could be used as a basic transfer standard, but not in a certified calibrated way.

I don't see the LB02A as a voltage standard like I don't see a voltage standard being a process calibrator. 

[tonyalbus]

Here the LB02A , SG003A, SG004A and DMMcheckplus rev.6 and rev.8  side by side.

[KungFuJosh]

I recently got Doug's VREF10-001 r9 and it's 10V which is more standard for a voltage ref, and it's higher accuracy than the DMMCheckPlus. I'd only get the latter if you need the LCR references v8 includes.

[BennoG]

I recently got Doug's VREF10-001 r9 and it's 10V which is more standard for a voltage ref.

Yes I am looking at this for a while now planning on buying one sometime (to add to my addiction collection)
I have a 7 1/2 dmm and a couple of 6 1/2 dmm. I would like to use it as some transfer calibration tool, an calibration check tool.

Benno

[skander36]

I recently got Doug's VREF10-001 r9 and it's 10V which is more standard for a voltage ref.

Yes I am looking at this for a while now planning on buying one sometime (to add to my addiction collection)
I have a 7 1/2 dmm and a couple of 6 1/2 dmm. I would like to use it as some transfer calibration tool, an calibration check tool.

Benno

A reference with LT1021 with 5 ppm drift should never be used in calibration process of a 7,5 digit DMM or even in 6,5 digit. Their internal references are at least ten times stable that LT 1021 so you may alter calibration process. Use at least LM 399, or LTZ1000 or newer references.

[J-R]

Doug's VREF10-001 r9 has a few changes to make it better.  The price also includes 2 years of free calibrations.  However, if you have the money, there is the PDVS2mini: https://www.wrytech.eu/products/pdvs2

[KungFuJosh]

I agree it probably shouldn't be used to calibrate those meters, but it's still a great reference for them. The stability I found with my 6.5 digit meter was excellent.

I wanted the PDVS2mini for a while, but spending more than double the cost of the VREF10-001 r9 wasn't cool with my wallet. If I'm going to invest that much for a ref, I'd rather build the Elektor project Martin72 was doing. I'm still tempted, maybe someday.

[dazz1]

I agree it probably shouldn't be used to calibrate those meters, but it's still a great reference for them. The stability I found with my 6.5 digit meter was excellent.

I wanted the PDVS2mini for a while, but spending more than double the cost of the VREF10-001 r9 wasn't cool with my wallet. If I'm going to invest that much for a ref, I'd rather build the Elektor project Martin72 was doing. I'm still tempted, maybe someday.

I have a fond spot for Elektor because back in the day, I considered them to be a source of advanced or professional quality circuits.  Although this Elektor Voltage Reference project  https://www.elektormagazine.fr/labs/voltage-current-calibrator-0-to-10v-and-0-to-40ma-0001 appears to be community contributed, it looks like an Elektor project.  I haven't priced the BOM (Elektor projects were never cheap) I suspect it would be good value for the money.  It looks fairly straight forward to build.

Has anyone built one of these?

[KungFuJosh]

Has anyone built one of these?

Martin72 has: https://www.eevblog.com/forum/testgear/elektor-voltage-current-calibrator-project/



I modified the PCB design a bit, and was planning on building one, but the cost is high. The LCD and some of the chips are expensive. If not for cost, and then wanting to have it calibrated (and significantly increase the investment), I would have made one too.

[dazz1]

I found the YT video
where the author/designer indicates a build price of around €300.  Ouch, ouch, ouch.

For that price I can buy a used precision bench multi-meter plus a Chinese process calibrator.  That combination would be far more useful and versatile.

[KungFuJosh]

the author/designer indicates a build price of around €300.  Ouch, ouch, ouch.

Yeah, that's old. That's before covid made the world more expensive. It's more like 500 now. 300 will literally get 2 of the chips and the LCD now.

[dazz1]

the author/designer indicates a build price of around €300.  Ouch, ouch, ouch.

Yeah, that's old. That's before covid made the world more expensive. It's more like 500 now. 300 will literally get 2 of the chips and the LCD now.

At that price the Elector unit is a non-starter for me.  It would be nice to build the Elector unit, but value for money is not there for my use-case.

[KungFuJosh]

At that price the Elector unit is a non-starter for me.  It would be nice to build the Elector unit, but value for money is not there for my use-case.

Same for me. Even the VREF10-001 r9 I bought is well beyond my needs...and more than I should have spent, but you know. TEAS.

[GigaJoe]

since 587 not available in overall

AD588 + thermal correction
https://www.ebay.com/itm/323780690966?

[dazz1]

Hi
I updated the BOM for the Elector Voltage Reference here:  https://www.eevblog.com/forum/testgear/elektor-voltage-current-calibrator-project/msg5643277/#msg5643277
It looked like a viable option until I priced the DAC and LCD.

This leads me to conclude that the most cost effective and versatile option would be an old bench multimeter (7 1/2 or 8 1/2 digit) with an aged and stable voltage reference, combined with a reasonably priced process calibrator.
That combination would provide the same capability, with greater functionality, than the Elektor device.    That doesn't mean I wouldn't like to build the Elektor reference.

[tggzzz]

Too complex 

Why not reuse the concepts in old differential voltmeters? That avoids the need for calibrated high resolution voltmeters; all you need is something that reads 0V accurately (e.g. the crappy 20kohm/V 2% moving coil meter at the back of your storecupboard!)

A high voltage is divided down by a Kelvin-Varley divider. The divided voltage is compared with the known reference voltage, and the KVD ratio twiddled until they are the same. From that you can calculate the high voltage.

You can get 7-decade KVDs on fleabay, capable of having 1kV as the high voltage.

If you look at the Fluke 893 manual, you will see that's what is inside.

That's the mechanism we used at school to measure voltage to 0.1% using a 2% meter and 1m of wire. We could have measured to 0.01%, but that would have required a 10M piece of wire.

[dazz1]

Too complex 
...

That's the mechanism we used at school to measure voltage to 0.1% using a 2% meter and 1m of wire. We could have measured to 0.01%, but that would have required a 10M piece of wire.

Too simple 
You obviously don't understand the concept of over-engineering.

Although I did help my daughter with a school science project.  She was able to measure the weight of air compressed in a balloon with a stick, string and paper clips.  That was waaaay too simple, but remarkably accurate.   

My main problem is that the Elektor Voltage reference is the solution to a problem I don't have. 

[tggzzz]

Too complex 
...

That's the mechanism we used at school to measure voltage to 0.1% using a 2% meter and 1m of wire. We could have measured to 0.01%, but that would have required a 10M piece of wire.

Too simple 
You obviously don't understand the concept of over-engineering.

Although I did help my daughter with a school science project.  She was able to measure the weight of air compressed in a balloon with a stick, string and paper clips.  That was waaaay too simple, but remarkably accurate.   

My main problem is that the Elektor Voltage reference is the solution to a problem I don't have.

Playing like that with your daughter is fun Now ask her to calculate the weight of a fully developed cumulo nimbus cloud. Zero it ain't

(Since you are in NZ, start your daughter flying gliders before she can start to drive a car. My daughter had great fun learning a lot of things that way.)

And apparently you do have a problem, whether or not the Elektor reference would solve it  Welcome to the rathole 

[dazz1]

Playing like that with your daughter is fun Now ask her to calculate the weight of a fully developed cumulo nimbus cloud. Zero it ain't

(Since you are in NZ, start your daughter flying gliders before she can start to drive a car. My daughter had great fun learning a lot of things that way.)

And apparently you do have a problem, whether or not the Elektor reference would solve it  Welcome to the rathole 

My daughter is now old enough to be married and own her own house.  She is still my little girl.

I remain in a constant state of internal conflict.  The rational part says: don't need it, don't buy it.  The irrational part says: I want it, therefore I need it.  When will it end?

[KungFuJosh]

I remain in a constant state of internal conflict.  The rational part says: don't need it, don't buy it.  The irrational part says: I want it, therefore I need it.  When will it end?

There is no end. The TEAS thread has 136,715 replies and counting. But hey, at least you're not alone. 😉

[tggzzz]

Playing like that with your daughter is fun Now ask her to calculate the weight of a fully developed cumulo nimbus cloud. Zero it ain't

(Since you are in NZ, start your daughter flying gliders before she can start to drive a car. My daughter had great fun learning a lot of things that way.)

And apparently you do have a problem, whether or not the Elektor reference would solve it  Welcome to the rathole 

My daughter is now old enough to be married and own her own house.  She is still my little girl.

Snap!

I remain in a constant state of internal conflict.  The rational part says: don't need it, don't buy it.  The irrational part says: I want it, therefore I need it.  When will it end?

The internal conflict has two endpoints. One is too soon and too permanent. The other is when you say "I'm worth it, and I've earned it". Time fpr you to join the TEA thread.

The next form of angst is that your daughter may choose to wind you up by saying "when I have to clear out the house, it's all going straight to the tip". You can (attempt to) counter that by startling her by showing what people pay on fleabay for that boring little box/wire/etc.

She will then take delight in sending you this...