Calibratory D-105 DC Precision Voltage Reference Standard

[HighVoltage]

I bet $100 that mini actually works, and is much better!

JonnyBerg,
Your standard looks really good.
How much are you selling them for?

Care to trade?
I have an awesome voltage standard with great claims, that is even inspired by the almighty God.
I just don't have any needs for it anymore. You might need it for comparison to your own design?
LOL

[JohnnyBerg]

Your standard looks really good.

Thanks

How much are you selling them for?

Well, selling is perhaps a big word. I made one for myself, and have gotten 11 boards. I made 7 boards compete, of witch I have sold 3 for € 14,50 + postage. That boils down to the price of the components + the boards.
I also can offer the boards, without components for €3,00 + postage. The REF5025 is pin compatible with the LT1021. Could be a nice experiment.
 

Care to trade?
I have an awesome voltage standard with great claims, that is even inspired by the almighty God.

Hmm .. does not sound to a good deal to me. On the other hand, I only claim te be as accurate as TI in the datasheet, although I think that the actual accuracy is much higher.

What chip is on the almighty reference?

[saturation]

Thanks folks, this has been very helpful.  In my experience too, the original SVR, not temp controlled, is very sensitive to temperature given what its rated at in ppm and what can be experienced in an uncontrolled lab: temperature, and possibly humidity change.  Putting the old Geller in a plastic box improved its stability for me against diurnal variations; something so simple could explain the performance of the D-105 as shown in your regression line.



Aside, much other discussion on this thread has unfortunately, developed quite a bit of noise  , it could use a large ground plane and shielding  . 

Richiem, I took the liberty of plotting your data. See attachment. Jan

I mentioned on the LTZ1000 thread that I was interested to see what Awesome14's D-105 could do so I was buying one. It came yesterday. In the interest of more light and less heat, here is what I've found so far. The results are not metrology lab measurements -- they are a guide only, but I've provided enough info to make the results useful. One note -- I have thought for a while that my HP 3458A is reading 10VDC about 6ppm high, although it is in spec....

Calibratory D-105 10V standard evaluation, started on 2-7-15
Instruments used in evaluation:
— HP 3458A, calibration checked on 7 Aug. 2014, by Keysight in Loveleand — no adjustments made, found to be completely in spec; this is the standard model — 8ppm ref board. Used to monitor 10V standard outputs. 3458A powered on for last 6 days; internal temp 36.5 °C. ACAL 1 (DC) run at 4:30PM. NPLC=60, NDIG=8
— HP 3456A, cal’d against HP 3458A. Used for monitoring ambient temps with Pt100 RTD.
— Heath 2718 Linear Triple Bench Supply — each 20V supply powering one standard..
— Geller SVR (not the temp comp unit), purchased in 2007, used for approximately 12 hours total since then up to this time. On for the last 8 hours (included in total of 12), since 8AM with 15VDC power. Geller’s 2007 certificate says 10.000 00V, Tolerance 5ppm/°C, 15ppm/1k hrs. Cal’d at 23°C ambient.

D-105 unboxed in lab at 4PM. Connected to bench supply at 14.5VDC, initial ambient temp at case 23.0 °C.  Ambient measured immediately adjacent to and in between the two standards, all sitting on top of an HP 8904A that was powered off — makes a handy stand with some thermal mass.. D-105 output started a few hundred microvolts below 10V, quickly rose to 10.000 05VDC. Calibratory’s certificate says 10.000 0014V, cal’d at 20°C ambient.

Both the Geller SVR and the D-105 outputs are connected with 24ga. solid copper insulated wires (old-school telephone extension wire) to gold flashed dual banana plugs to ease connections to the 3458A. The wires are soldered to the Geller SVR and clamped in the gold-flashed bindind posts of the D-105.

Elapsed time     Ambient   Geller SVR     D-105
for D-105      °C
0.6 hr               23.5           10.000 060     10.000 058
3.4 hr      22.9            10.000 071     10.000 068
5.3 hr      23.6            10.000 060     10.000 066
6.4 hr      23.8            10.000 053     10.000 068
Overnight break in measurements with lab cool-down to thermostat set 66°F, reheat in AM to 71°F; standards left powered on.
20.1 hr           22.4      10.000 092     10.000 078
22.5 hr           22.5      10.000 088     10.000 078
Moved to warmer location on top of HP 3456A, standards and RTD grouped as before.
22.8 hr           28.9      10.000 017     10.000 047
23 hr              29.3          10.000 002     10.000 042
24 hr              29.5        9.999 997     10.000 043
Standards powered down. Will begin from room ambient start in 18 hours or so.

At this point, a simple "box" of drift v. temp shows that average drift for the D-105 is approximately 0.5ppm/°C; the Geller SVR average drift is approximately 1.4ppm/°C (pretty good).

[HighVoltage]

Well, selling is perhaps a big word. I made one for myself, and have gotten 11 boards. I made 7 boards compete, of witch I have sold 3 for € 14,50 + postage. That boils down to the price of the components + the boards.
I also can offer the boards, without components for €3,00 + postage. The REF5025 is pin compatible with the LT1021. Could be a nice experiment.

I would like to get one of your boards completely assembled.
How much would you charge for shipping to Germany?
Thanks

[JohnnyBerg]

@HighVoltage: send you a personal message with all details. Woeh .. in German 

[TunerSandwich]

no offense to the gentleman who makes the alternate ref mentioned here.....but why do people keep buying these things w/o seeing ANY specs or data.....

Generally surface mount REF IC's aren't as stable as their through hole counterparts.....

http://www.ti.com/lit/ds/symlink/ref5025.pdf

[JohnnyBerg]

no offense to the gentleman who makes the alternate ref mentioned here.....but why do people keep buying these things w/o seeing ANY specs or data.....

You are absolutely right. I did not give any spec's, but referred to the datasheet. And I did not make any promises, just relaying the datasheet. 

My intension has never bin to sell this reference. I made one for myself, and sold the leftovers. Min order was 10 PBC's.
No offense taken.

Generally surface mount REF IC's aren't as stable as their through hole counterparts.....

True again.
I aged all my references, and the datasheet shows clearly that the difference after 1000 hours is only 5 ppm/1000 hours.

I am thinking of making a second version, and perhaps I use a dip. I even consider putting the ref on a "island", to minimize the mechanical stress on the device.

[nctnico]

no offense to the gentleman who makes the alternate ref mentioned here.....but why do people keep buying these things w/o seeing ANY specs or data.....

Generally surface mount REF IC's aren't as stable as their through hole counterparts.....

Is that just due to mechanical stress (where does that come from?) or are other factors at play?

[JohnnyBerg]

no offense to the gentleman who makes the alternate ref mentioned here.....but why do people keep buying these things w/o seeing ANY specs or data.....

Generally surface mount REF IC's aren't as stable as their through hole counterparts.....

Is that just due to mechanical stress (where does that come from?) or are other factors at play?

I think that soldering plays an important role. When soldering a dip device, package and die get not as hot as with reflow. The plastic of the casing and the metal of the chip have different temp. coef. After aging that stress settles, and the dip and smd version come to a same level of drift.

I have reflowed my pcb's with the exception of the reference. That is quick soldered with hot air, to minimize stress.

[TunerSandwich]

@JohnnyBerg

I am most def. NOT trying to admonish you or your REF.  I can't fault it's design.  My comment was meat more towards HiGhVoltage.  He seems to be ordering every ref he finds, w/o really getting the facts.  So he is going to be disappointed, or at the lest not really have a basis for testing it when it arrives.  That most certainly isn't the manufacturers fault. 

@nctnico

Typically the surface mount REF IC suffer more from thermal gradient issues....also the big one is thermocouple effects......you can limit this somewhat by routing the PCB around the IC itself.....the main drift is coming from issues of surface area vs. PCB thermal gradient interactions....at least that is how I understand those issues.....a DIP or TO package has more "buffer" space? 

an interesting discussion.....I will link some articles later when I get home.....

[HighVoltage]

@JohnnyBerg
I am most def. NOT trying to admonish you or your REF.  I can't fault it's design.  My comment was meat more towards HiGhVoltage.  He seems to be ordering every ref he finds, w/o really getting the facts.  So he is going to be disappointed, or at the lest not really have a basis for testing it when it arrives.  That most certainly isn't the manufacturers fault. 

Well, I am working on several projects for a client and I will need a good and stable reference and if I do not have to design it myself, I will save some time that I can use for other parts of the project. In this case I will test the reference myself and see if it will fulfill my requirements. It is low cost enough, that I do not worry, if it does not work perfectly.

[EEVblog]

I did not ask for help. I found this miserable thread already started, disparaging me and my product, based purely on conjecture. I tried to make the truth known, but the community wasn't interested.
*snip*
I've never required technical assistance from anyone. That may seem difficult to believe, and I tried to explain how I do it, but I was berated for about six pages for even mentioning it. Thanks for all the help. I came to resolve an issue regarding a product. I'm leaving with more than what I came with. I'll never forget this board and the members I met here.

Your inability to answer technical questions, or even the most basic questions about things you claimed is very well noted by all.
Thanks for playing. Bye.

[TunerSandwich]

@JohnnyBerg
I am most def. NOT trying to admonish you or your REF.  I can't fault it's design.  My comment was meat more towards HiGhVoltage.  He seems to be ordering every ref he finds, w/o really getting the facts.  So he is going to be disappointed, or at the lest not really have a basis for testing it when it arrives.  That most certainly isn't the manufacturers fault. 

Well, I am working on several projects for a client and I will need a good and stable reference and if I do not have to design it myself, I will save some time that I can use for other parts of the project. In this case I will test the reference myself and see if it will fulfill my requirements. It is low cost enough, that I do not worry, if it does not work perfectly.

The problem is that it's virtually impossible to know if it's "working properly", without a baseline or point of reference to benchmark against.....one option is to grab a known "certified" transfer standard, and then cal 2 meters against it.....then it's easy to make less subjective determinations about random ebay or UN-doccumented "standards".....

[TunerSandwich]

I am thinking of making a second version, and perhaps I use a dip. I even consider putting the ref on a "island", to minimize the mechanical stress on the device.

The other big consideration is what happens to the REF IC during soldering.....it's a trade off between shocking the "chip" and sticking it in a socket.....the socket is going to suffer its own thermo-electric effects.....and "overheating" the IC is going to cause it's own problems.....kind of a catch 22 situation I suppose.....I have a feeling TO packages, spaced up off the PCB will yield a better result....could be wrong about that though.....however it's easy to clamp "heatsinks" to the legs of the TO when soldering each one....that is a potential solution.....it's how I have done it in the past, but i have no real data to prove that makes any substantial difference.....it's just one of those "seems logical" things....but I suppose we all know that ain't worth squat at the end of the day 

[timb]

When soldering the REF50xx chips, I put the boards on a pre-heater and slowly bring them up to 150c over the course of 30-45 minutes, then I apply a small heatsink to the chip itself and quickly drag solder each side at 265c with eutectic solder. Afterwards I ramp the pre-heater down to 85c over 15 minutes, then 50c over 15 minutes. Then I turn the heater off and leave the boards in place, so they're still receiving heat while the heater cools. I give it an hour or two to come back to ambient.

Overkill? Maybe. But I've got 8 of them going in a 25c chamber for the last 6 months gathering data, so I wanted to give them the best shot I could.

Next I want to put 10 REF5010's in series and make a 100 volt reference to classify.


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[TunerSandwich]

When soldering the REF50xx chips, I put the boards on a pre-heater and slowly bring them up to 150c over the course of 30-45 minutes, then I apply a small heatsink to the chip itself and quickly drag solder each side at 265c with eutectic solder. Afterwards I ramp the pre-heater down to 85c over 15 minutes, then 50c over 15 minutes. Then I turn the heater off and leave the boards in place, so they're still receiving heat while the heater cools. I give it an hour or two to come back to ambient.

Overkill? Maybe. But I've got 8 of them going in a 25c chamber for the last 6 months gathering data, so I wanted to give them the best shot I could.

Next I want to put 10 REF5010's in series and make a 100 volt reference to classify.


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I played with some quad eutectic solder on a few boards a while back.....I didn't notice any significant improvement in the quality of the joints or heat vs time issues.....also played with some N2, using lead free....that most def yielded superior results....in terms of temps and times.....nice shiny joints....it's entirely possible I don't have the equipment or patience to track down the "ultimate result"....generally I found that a proper tip and nice multicore silver solder yielded very acceptable results....without the hassle etc....I know there are compendiums of information on these subjects, and i have read quite a bit, but never had a huge problem with the more traditional (hassle free) methods.....a simple heatsink on the IC or lead = totally acceptable results....and with a simple thermocouple fixed to the IC case or legs I was able to get at least ballpark temps going into the IC.....

I do believe there is a lot of validity to the socket vs shock concept though.....pick your poison.....I did notice VERY little negative impact from premium quality sockets though....however "bargain bin" sockets did change things for the worse in virtually every test I could conceive....

I played with all kinds of systems for suspending REF IC's above PCB's and even the opposite....dead bug thermally bonded to a common thermal layer.....in the end the results were mixed, and no appreciable differences were made in drift, over the sDEV of the components themselves....it's kind of like chasing 0.5ppm when the difference from IC to IC can be orders of magnitude higher.....

I did notice that aging and binning "premium chips" yielded substantially improved results though.....however that is shockingly expensive (on all resource fronts)....

The easiest solution to all of these "problems", for me, has simply been proper temp control in the system....best solution we came up with was a simple aluminum enclosure....with a TeC and TeC controller....bond the TeC to common thermal layers....ceramic coat the enclosure (external) and line the inside with some foil (we saw no impact between gold foil and the cheap stuff).....also simple heaters made from resistance wire, sandwiched between glass slides....yielded very nice results....less control and monitoring, but no issue about isolation the "cold" side of the TeC....which is a hell of a bear to implement....

routing around the REF IC on the PCB was another appreciable benefit (when the REF IC has an internal heater).  Obviously the issues of supporting components comes up as well.....we found that "ovenizing" the entire package offered the best price to performance benefits.....the more esoteric stuff just seemed like time/money pissed away (lots of fun though)

[HighVoltage]

@JohnnyBerg
I am most def. NOT trying to admonish you or your REF.  I can't fault it's design.  My comment was meat more towards HiGhVoltage.  He seems to be ordering every ref he finds, w/o really getting the facts.  So he is going to be disappointed, or at the lest not really have a basis for testing it when it arrives.  That most certainly isn't the manufacturers fault. 

Well, I am working on several projects for a client and I will need a good and stable reference and if I do not have to design it myself, I will save some time that I can use for other parts of the project. In this case I will test the reference myself and see if it will fulfill my requirements. It is low cost enough, that I do not worry, if it does not work perfectly.

The problem is that it's virtually impossible to know if it's "working properly", without a baseline or point of reference to benchmark against.....one option is to grab a known "certified" transfer standard, and then cal 2 meters against it.....then it's easy to make less subjective determinations about random ebay or UN-doccumented "standards".....

I have a friend here in Germany not far from me, who has a full professional calibration lab.
I use his equipment to verify my SVR-T voltage standard.

[TunerSandwich]

@JohnnyBerg
I am most def. NOT trying to admonish you or your REF.  I can't fault it's design.  My comment was meat more towards HiGhVoltage.  He seems to be ordering every ref he finds, w/o really getting the facts.  So he is going to be disappointed, or at the lest not really have a basis for testing it when it arrives.  That most certainly isn't the manufacturers fault. 

Well, I am working on several projects for a client and I will need a good and stable reference and if I do not have to design it myself, I will save some time that I can use for other parts of the project. In this case I will test the reference myself and see if it will fulfill my requirements. It is low cost enough, that I do not worry, if it does not work perfectly.

The problem is that it's virtually impossible to know if it's "working properly", without a baseline or point of reference to benchmark against.....one option is to grab a known "certified" transfer standard, and then cal 2 meters against it.....then it's easy to make less subjective determinations about random ebay or UN-doccumented "standards".....

I have a friend here in Germany not far from me, who has a full professional calibration lab.
I use his equipment to verify my SVR-T voltage standard.

huh?  Just above you said "Well, I am working on several projects for a client and I will need a good and stable reference "

[timb]

Most likely to implement on the client's board. Either that or he wants a stable reference in his lab so he doesn't have to drag his work over to the cal lab and tie it up each time he needs to measure something.


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[HighVoltage]

huh?  Just above you said "Well, I am working on several projects for a client and I will need a good and stable reference "

Yes, this is the case.
May be it is not the most perfect solution, but so far it has worked for me.
In order to verify and confirm the voltage reference at my clients facility, I do the following:

1. Take my Geller Labs SVR-T (battery powered) to the professional calibration lab and get it verified.
2. Also take my Agilent 34410A to the same professional lab and get it calibrated.
3. Take both to the clients facility and get the 34410A warmed up.
4. Check the transfer of the SVR-T to be accurate to the 34410A
5. Verify the clients voltage reference with the 34410A.
6. If verified, give the client a paper of conformity based on these steps

Repeat this procedure every 6 month.
So far, my client has accepted this procedure and has also fulfilled his obligations to his customers.

 

[TunerSandwich]

huh?  Just above you said "Well, I am working on several projects for a client and I will need a good and stable reference "

Yes, this is the case.
May be it is not the most perfect solution, but so far it has worked for me.
In order to verify and confirm the voltage reference at my clients facility, I do the following:

1. Take my Geller Labs SVR-T (battery powered) to the professional calibration lab and get it verified.
2. Also take my Agilent 34410A to the same professional lab and get it calibrated.
3. Take both to the clients facility and get the 34410A warmed up.
4. Check the transfer of the SVR-T to be accurate to the 34410A
5. Verify the clients voltage reference with the 34410A.
6. If verified, give the client a paper of conformity based on these steps

Repeat this procedure every 6 month.
So far, my client has accepted this procedure and has also fulfilled his obligations to his customers.

ah.....grab a Fluke 734A, and load it with two 732B.  You will save yourself so much time and grief.....it's designed to do exactly what you need to do....by the time you try ever "cheap" "standard" on the market, you could have bought the Fluke.  The cheaper boxes will nickel and dime you to death, and you won't get what you are looking for in the end....

If what you have already gets the job done, I can't see the benefit in flushing money and time down the toilet, on things that simply won't meet or exceed the tools you already have....

If you really do need another "cheap" "standard"....check out www.voltagestandard.com .....documentation is provided on specs, and there are lots of units out there proving their "worth"....

As the old automotive saying goes.....fast cheap reliable.....pick two 

[engineer_in_shorts]

It has closed-chassis calibration controls. That means you don't need to open the chassis to calibrate the unit.

And how do you do that exactly?
Please be precise in your detailed explanation.
Also, please explain by what mechanism removing the rear case causes damage to the circuitry or calibration.
Once again, please be precise.

Dave not sure why you need this detail.  He is correct, you do not need to open it to calibrate it.
Calibration means comparison between measurements.
Clearly you can calibrate it without opening it 


When there is a discussion about calibration with a non-technical person, it helps for simplicity sake to use phrase "Calibration-Verification" and "Calibration-adjustment" to differentiate.

[engineer_in_shorts]

When soldering the REF50xx chips, I put the .............

SNIP

Ref50xx is a bandgap device, what the point 

[timb]

When soldering the REF50xx chips, I put the .............

SNIP

Ref50xx is a bandgap device, what the point 

Heat still affects it? Just like all encapsulated silicon devices. The thermal shock creates rapid expansion and contraction leading to micro-fissures in the die. They start at the edges and spread inward. It can affect anything from the initial accuracy to long term drift.

Exactly the same as on a Zener based device. Why would you think it wouldn't?

(Incidentally, these cracks tend to appear when a wafer is diced. Laser "trimming" of resistors etc. before encapsulation can worsen them.)


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[timb]

It has closed-chassis calibration controls. That means you don't need to open the chassis to calibrate the unit.

And how do you do that exactly?
Please be precise in your detailed explanation.
Also, please explain by what mechanism removing the rear case causes damage to the circuitry or calibration.
Once again, please be precise.

Dave not sure why you need this detail.  He is correct, you do not need to open it to calibrate it.
Calibration means comparison between measurements.
Clearly you can calibrate it without opening it 


When there is a discussion about calibration with a non-technical person, it helps for simplicity sake to use phrase "Calibration-Verification" and "Calibration-adjustment" to differentiate.

In the case of modern test equipment it's almost always the latter. Stop being pedantic, nobody likes that guy; don't be that guy.


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