Calibratory D-105 DC Precision Voltage Reference Standard

[rx8pilot]

Made my day! 

TIG welding is a hobby of mine, makes it even better.

[timb]

I just read trough this entire thread. You should really charge money for that kind of entertainment, we really laughed out behinds off instead of getting any work done today

Somehow this guy reminds me of Chris-Chan or Drachenlord, with more religious WTF added.

Now for the productive part, did anybody try to build the same circuit without the special god-grade magic and special-needs soldering? I would, but i dont have anything to verify the performance to see if it works just as well or better.

Man, I had completely forgotten about Sonichu (aka ChrisChan). What a blast from the past! I was never completely comfortable with the internet trolling a retarded guy, but it was really funny.

Speaking of special needs, I wonder how the OP is doing.

[retiredcaps]

It sure looks like the same device in the ebay listing, but I could be wrong.  I followed this thread here and there, but not 100% carefully, so there could be another reference that uses the same housing?

Martin mentions this device in his latest video at around 17:20 and ends at 17:48 ...

[Macbeth]

Martin mentions this device in his latest video at around 17:20 and ends at 17:48 ...

Also mentioned at 02:40 - 03:40.

More interesting is Ian's voltage source. Very nice. Shame it's "only" 10ppm compared do the fantasy 2ppm of Calibratory

[Andreas]

More interesting is Ian's voltage source. Very nice. Shame it's "only" 10ppm compared do the fantasy 2ppm of Calibratory

Hello,

From 17:28 the 2 ppm "Scam" device drifted 200uV in a few months.

Ians voltage source has also one weakness: (12:29)
Where do I get those 9V-Blocks with 600mAh?
With a current draw of 40 mA even those will not last for a 24 hour period.
And after exchange of the batteries (with opening the case) I have to wait 15-30 minutes to stabilize.
So a charger input would be a large benefit.

With best regards

Andreas

[IanJ]

More interesting is Ian's voltage source. Very nice. Shame it's "only" 10ppm compared do the fantasy 2ppm of Calibratory

Hello,
Ians voltage source has also one weakness: (12:29)
Where do I get those 9V-Blocks with 600mAh?
With a current draw of 40 mA even those will not last for a 24 hour period.
And after exchange of the batteries (with opening the case) I have to wait 15-30 minutes to stabilize.
So a charger input would be a large benefit.
With best regards
Andreas

600mAh re-chargeable lithium-Ion PP3's are available on Ebay.......albeit I never tested to see if that figure is 100% correct. I just know they last a lot longer than your standard PP3 battery. I also have a few 900mAh Lithium-Ion batteries, well thats what the sticker says!......I haven't tested them yet.

With two 600mAh PP3's my Voltage Source lasts for 14hrs continious operation......from first switch on to auto-power down when the low limit is reached.

If you change the batteries, i.e. switch the unit off, change batteries and then power up again immediately then you are probably looking at less than a minute to stabilize.
A charger/external DC supply is something I did look at early on, but it opens up a whole new ballgame in terms of interference and also CE marking........so I abandoned.......for now.

Btw, I am gobsmacked at the D-105........how on earth anyone can have the gall to sell something like that and then try and defend it beats me!

Ian.

[manganin]

This use profile will also minimize reference drift, because the LM399 "drifts very little" when powered off [according to the chip's designer-- Bob Dobkin].

In 1980's Tinsley manufactured a voltage standard which had two LM399 references. The "working" reference was always powered, but the "primary" reference was switched off, except one hour every month when it was used for calibrating the "working" reference.

The idea was very good. The product itself wasn't.

[plesa]

This use profile will also minimize reference drift, because the LM399 "drifts very little" when powered off [according to the chip's designer-- Bob Dobkin].

In 1980's Tinsley manufactured a voltage standard which had two LM399 references. The "working" reference was always powered, but the "primary" reference was switched off, except one hour every month when it was used for calibrating the "working" reference.

The idea was very good. The product itself wasn't.

Whats the benefit of powering only one instead of both?

[Andreas]

A charger/external DC supply is something I did look at early on, but it opens up a whole new ballgame in terms of interference and also CE marking........so I abandoned.......for now.

Btw, I am gobsmacked at the D-105........how on earth anyone can have the gall to sell something like that and then try and defend it beats me!

Ian.

Hello Ian.

It´s always good to know why a design decision was made.
And it´s true: even a charging connector creates a different class of device (with additional tests) for the CE-marking.

For the D-105: everyone who has some experiences in the precision range knows that without a hermetically (metal can or CerDip) voltage reference a stability of below 20 ppm is too optimistic. Unfortunately not all potential customers are aware of that and might believe the 2 ppm spec for the reference in plastic package.

With best regards

Andreas

[IanJ]

Hello Ian.

It´s always good to know why a design decision was made.
And it´s true: even a charging connector creates a different class of device (with additional tests) for the CE-marking.

For the D-105: everyone who has some experiences in the precision range knows that without a hermetically (metal can or CerDip) voltage reference a stability of below 20 ppm is too optimistic. Unfortunately not all potential customers are aware of that and might believe the 2 ppm spec for the reference in plastic package.

With best regards

Andreas

My first prototype (as per Dave's mailbag video) used a MAX6350 in a plastic package, and what killed it for me was the thermal hysterysis. Right enough I was pushing it well beyond where it should be.......and the result was quite bad!
I looked at other references but nothing came close to the spec I was after. It was the LM399AH or nothing at all.

My own experience, and what should have rung alarm bells for the likes of the D-105 designer, is that every aspect surrounding the reference has to be right. Wing and a prayer doesn't cut it, nor does having no explanation as to why it "appears" to work great.

Diligentmind.com........will be following your design if you are making it public....sounds good!
I built a 10ch pcb so I could age my 399's. As ever I went overboard as it uses 10 chopper op-amps as well to self power the 399's. There are sockets for the 399's.

Ian.

[Macbeth]

Ian, do you mount the LM399 upside down? I've noted the volt-nuttery have proven this is best for battery powered designs (presumably wastes less power on heater). Either that, or TiNs LM399 Kx boards were a fuck up - I remember trying to follow the excellent super hi-res PCB layouts and scratching my head... 

One thing I would have liked to see on your reference is a x10 amplifier to get up to 100V.

[timb]

Ian, do you mount the LM399 upside down? I've noted the volt-nuttery have proven this is best for battery powered designs (presumably wastes less power on heater). Either that, or TiNs LM399 Kx boards were a fuck up - I remember trying to follow the excellent super hi-res PCB layouts and scratching my head... 

One thing I would have liked to see on your reference is a x10 amplifier to get up to 100V.

I'm working on a 1mv to 100V design based on a high end DAC and using an LT6090 for the 25-100V range. I've been testing it in a composite amplifier configuration with feedback to a chopper amp to get around the offset and drift.

The other option I explored was to make a discrete HV amplifier out of transistors, but I figure for the price of the LT6090 it's not worth the hassle.

[TiN]

LM399 Kx boards were a fuck up

I wanted to have option to control LM399 temperature externally, hence they are on bottom side. Doesn't matter once it all in the foam..

[IanJ]

My LM399's are upside down.........but just due to layout, not specifically intentional.

100v......never thought of that one......there are soooo many different ideas!

Ian.

[Awesome14]

"Despite that, it DOES WORK as built and calibrated by Awesome14, and it holds it's value to the best of my ability to measure it. The naysayers need to keep that in mind.   The temperature compensation works, I've not seen any changes in output and my home lab fluctuates about 10 deg C from morning to night (it quickly cools down over night!). So if i'm getting 2 ppm/C then I can't see the 20 ppm change on my meter (which is expected, since I only have a 5-1/2 digit meter).  When I get a better meter I'll be able to measure it better.

The value in your product is in the calibration you offer.  I can build it just as easily as you did, but I can't get it trimmed near 10V like you did, so that's valuable to me."


I agree with this statement excerpted from codeboy2k's response above.  My measurements also are consistent with the spec, and I thought the price was reasonable for the calibration included.

OK, the reviewer didn't allow the unit to settle, so the output in the video didn't correspond to the advertised accuracy of the device.

[Awesome14]

All units with temperature compensation use the TIREF102C.

Thanks for the update awesome14! That's good to know, I like the REF102 specs better.

I was really disappointed to see it hand wired, and would have preferred to see a manufactured PC board in there. Please don't say it's not meant to be opened.  It should be safe to open any reference, as long as I don't mess with the settings. People open up 8 digit DMM's and Fluke 732's.  Opening it should not be a problem.

Despite that, it DOES WORK as built and calibrated by Awesome14, and it holds it's value to the best of my ability to measure it. The naysayers need to keep that in mind.   The temperature compensation works, I've not seen any changes in output and my home lab fluctuates about 10 deg C from morning to night (it quickly cools down over night!). So if i'm getting 2 ppm/C then I can't see the 20 ppm change on my meter (which is expected, since I only have a 5-1/2 digit meter).  When I get a better meter I'll be able to measure it better.

The value in your product is in the calibration you offer.  I can build it just as easily as you did, but I can't get it trimmed near 10V like you did, so that's valuable to me.

Good to see that you decided to make a PCB (I think you said so in one of your previous posts).  There's a lot of good information here in the forum, and lots of smart people who have good advice to offer you. You can make a really nice, clean and small PCB to fit in there, and it will significantly reduce your construction time and effort, and the product will still function as it should, and will ultimately be better in the end.  So consider that advice when you do, and you'll make a good product. With Gellar Labs no longer making temperature compensated references, you are in a unique position and have a head start on anyone else jumping in to fill that void. Go for it!

No one likes smoke and mirrors, so they might poke you on that, so remember to stick with the measured facts, only science and engineering here.

Cheers!

If the unit is opened the calibration pots can be moved, although I have disassembled several to no ill effect on the calibration.

[Awesome14]

Any updates on long-term stability measurements of the device?

With 1kHr. burn-in the device was within 1ppm/120 days. A Florida cal. lab sent their unit recalibration after 27 months, and it had drifted 8ppm. That's about equal to 1ppm/102 days.

Recently we increased the burn-in to 70 days (1.6 kHr.), and will begin evaluating the results on long-term drift shortly..

[Awesome14]

Oh lord, here we go again!

Let's see the empirical data to back up these statements. How often were measurements taken? Was the device connected to the same meter(s) and left undisturbed the entire time? Post a dump of the raw data for the entire 120 day period, please.


Sent from my Tablet

Yes, we just hung one off the meter and let it sit there until it drifted.

[Awesome14]

It has been made obvious throughout this blog that this design is, at best, a hobbyist approch to supply a somewhat precise (but in the end unknown) 10V reference voltage. And to be fair, more is not expectable at that price.

From a principle design perspective, using a reference (with an unknown tempco, could be up to plus or minus 10ppm/C for the LT1021C)  and compensating it with a thermistor may result in some temp compensation by coincidence, but this is by no means guaranteed, it may actually become worse. So in real life use, it may or may not compensate environmental temp drifts. That allone makes the 2ppm statement useless (ignoring anyway the fact that the 2ppm number misses any tolerance information with reference to national standards).
Overall, when you do a error propagation calc of all the possible contributors of error, lets face it, this item probably is rather in the 50ppm (K=2) level uncertainty worst case or more once on a users desk (initial drift, initial standard tolerance, worst case temp drift...).
One could go on, like no low EMF binding posts used (not expectable at that price). And so on and so on.
All this makes it an item with undefined specification, maybe usable to check 3.5 or 4.5 meters in a hobbyist environment, but thats it.
Any more statistics will not change this, given its basic design and build standards.

Do you have one? It sounds like speculation and nothing more. I have hard data to prove that the temperature drift through the entire temperature range is usually < 1ppm. The actual accuracy of the device is typically <= +-1ppm over 5 minutes, with a standard deviation <=1uV, but typically 500-800nV.

The temperature compensation is tunable, so it isn't just a thermistor sitting there. The amount of compensation is adjusted to match the drift of the individual regulator IC. Depending on the direction of the drift, the TC is adjusted in the opposite direction, until the plot over temperature is flat.

It is possible that shipping inside an airplane cargo hold could cause drift, although we have no hard evidence to demonstrate this. Nevertheless, there is a test underway to check what the drift is in cold temperatures. Thus far 15 days at -18C produced drift of 13ppm. But, over 24 hours at -18C, drift was 0.2ppm for a standard that had not previously undergone freezing, and 0.02 ppm for a unit that had been previously frozen and warmed up, cooled again, and then warmed up again after 24 hours.

Similar results were obtained with heating to 50C. Initially the heating and subsequent cooling caused drift, but after the initial heating, further heating and cooling resulted in very small drift. We have integrated new safeguards into the manufacturing process to account for possible drift due to extreme environmental conditions encountered during shipping.

Please keep in mind that the specs we assign to the units are worst-case. Most of the units perform much better. And, as with all standards, this one requires periodic calibration. It does not become useless when it is out of cal. It just requires recal..

[Awesome14]

The device is a hit, worldwide. In our latest eBay listings there are about 100 units sold. And we have a 100% feedback score.

There are multiple hypothesis that could be consistent with these results. You have a hypothesis that you have a natural bias towards, the one that proves you right, and makes you money.

An alternate hypothesis is that your customers don't know what they don't know, and aren't able to adequately validate your claims. And further, that you have, through cunning or dumb luck, chosen a combination of price point and claimed precision such that anyone with the knowledge and equipment to validate your claims isn't willing to invest the time, money and energy necessary to prove or disprove them.

I love the idea of an outsider proving the experts wrong. I know though that that can cloud my judgement. So, I look for independent sources of evidence. If you are both genuine and truly clever, you'll find ways to turn some of your critics into allies, rather than continuing to use them as foils to promote an underdog narrative.

More speculation. We've sold this item in Asia, Japan, every western European nation, South America, Africa, Russia, every US state, UK, China, Australia, New Zealand! WHY, because residents of these locations cannot find something better for the price. It's a revolutionary product unlike anything else in the world. We've sold to university labs, calibration labs, industrial labs. One of our buyers said he bought our unit so he wouldn't have to lug around his Fluke 732B! 

It is possible that everyone who purchases the unit is incorrect, and one person who hasn't purchased one 'is' correct. But it's probably the other way around. At least that's what seems rational to me. I've seen the results with my own eyes, many times. Our quality control has improved greatly since the beginning.

There is one problem I have. I cannot go into detail on the principles involved in exactly how the various parts of the device work. This creates doubt on this board. But when I first came here it was to simply ask that people not judge the device and its capabilities without examining one. I don't care if a DC standard follows every conventional maxim, if it doesn't perform, junk it. Because I keep trade secrets, several members here have made the rash assumption that there are no founding theories to explain why this device works better than others like it.

I'll give everyone a freebee. Enclosing the device is key.   

Finally, anyone can easily check whether they have an thermoelectric error by just reversing the leads on the meter. If negative is the same as positive, it's an accurate reading. If they're different, you have to wait until the temperature equalizes. You can actually watch this effect by holding one of the leads attached to the standard. The heat from the skin will change the meter reading. Then, later it will return to what it was.   

[Awesome14]

The construction of these units is superb. There is nothing left to chance.

Here comes an offer. Let me do a proper printed circuit board and mechanical redesign for your product. Free of charge.

It costs you absolutely nothing. PCB and mechanical design was my day job for many many years, so I am sure that you will get more than you pay for.

Electrical, mechanical and thermal things taken into account. Binding posts mounted directly on the PCB, no wiring required. Probably saves your assembly time by 90%.

You will receive a set of ready processed manufacturing files. All you need to do is send them to a board manufacturing house of your choice.

The new design probably replaces some of the "magic" with improved reliability and stability, but I believe your customers can live with that.

For some reason I have a feeling what the answer is, but you never know...

I accept. How can I refuse? I'm just seeing this post for the first time, today. PM me please.

[rx8pilot]

More speculation. We've sold this item in Asia, Japan, every western European nation, South America, Africa, Russia, every US state, UK, China, Australia, New Zealand! WHY, because residents of these locations cannot find something better for the price. It's a revolutionary product unlike anything else in the world. We've sold to university labs, calibration labs, industrial labs. One of our buyers said he bought our unit so he wouldn't have to lug around his Fluke 732B! 

If a calibration lab purchased it for anything other than to satisfy a curiosity - I would be baffled. Please provide the name of any lab that is using these for any type of reference so I know who NOT to call on for calibration.
At the price you are selling these things, it is not a challenge to get customers to buy it once and take their chances. Once they see the reality, it is very hard to imagine anyone buying a second, third, or more.

[Awesome14]

In the end of August I couldn’t resist buying a D105 just out of curiosity. It arrived in a week to Sweden but at the same day it arrived I went on a two week trip abroad so the D105 was left in my home for two more weeks before power-up. It showed +8ppm against my other voltage references but that may not say so much as I am not fortunate to have a calibrated Fluke 732. But what caught my attention was that it seemed to drift with temperature. So I did a temperature scan between 16 and 26°C. It showed a 13ppm difference. I contacted Calibratory LLC and they were very helpful. I got an instruction how much to turn the temperature compensation pot. Adjusted and did another temperature scan and the difference between 16 and 26 was just 1ppm. As the second-order temperature coefficient is quite high on the REF102 (and most all other buried zener based 10V refs) around room temperature I didn´t bother about the last ppm over 10°C range. I set the output to what I believed is 10V.

On October 6 I started to continuously check the D105 (which I call D105-1 in the chart below as it was my first D105). In the first two weeks the output dropped 7ppm and when was relative stable until I started a humidity test a week ago. On Oct 13 I got my second D105 (I call it D105-2). This time the D105 was spot on!! But in the next one and half weeks it moved 4ppm upwards before it stabilized.

Now afterwards I have checked my weather station and found the indoor humidity was almost 60% in September that is quite normal here in autumn. In the beginning of October it fell very quickly to about 40% and has stayed at 35-50% since when (We have had very nice weather in October and November)

On Nov 11 I placed both D105´s together with one of my Geller labs SVR boards in a two liter ice cream box together with 150grams of silica gel I have prepared earlier to have almost 90% relative humidity. Now after a week the SVR hasn´t changed but the D105´s has went up about 15-20ppm.

This test is very similar to tests I have done on six SVR boards with AD587LN´s with different datecodes from 1994 to 2006 (Note: the AD587LN were not ones supplied by Geller Labs). That test also revealed a change of up to 20ppm for 40-50%RH change. The interesting with the AD587LN was that one with datecode from 2004 had a very fast negative change with time constant of about a day or two and that counseled the long term positive change. So for slow humidity changes this looked very good. The other has just a small or almost zero fast negative sensitivity to humidity and the positive long term humidity sensitivity were shown as seasonal variations.

After having said this I still hope we can keep the discussion on a technical level and that nobody says wasn´t this what I already thought. I think we really should encourage Calibratory LLC to develop this standard more and be open minded. I really liked the SVR-T boards as simple voltage transfer standards from a Fluke 732. I also liked that Geller Labs was so open with design, schematic and BOM´s (including my NTC compensation with both first and second order compensation that Joe could have kept for himself). What I missed on the SVR was a box, banana jacks, reverse power polarity and EMC filtering. At least three of these requirements are satisfied with the D105. For EMC protection I can live without that by just turning off my mobile. In my lab I have no high EMI sources and no large transmitters nearby.

So my conclusions are: My two D105 are humidity sensitive but I like the design and concept of a voltage transfer standard in small package. And I really hope for a good open discussion.

Lars

Lars' review is an actual review. Data presented from an objective viewpoint with rational conclusions. I offer an explanation for why the first standard we sent was so far off: exposure to airplane cargo hold temps. We have tested exposure to low temperatures, and have instituted measures to insure the device remains stable after exposure to temperature extremes. The humidity extremes are outside the bounds of a laboratory, which NIST claims to be a maximum of 55% RH. 

[rx8pilot]

What cargo hold temps are you talking about? They are not all that cold 5-10C minimum on most I think.

[Awesome14]

We also purchased another 732A, three Fluke 8846As, (2) multiplexer rigs by Keithley (7001 ), and standard resistors. We tested and calculated the internal resistance (0.017 Ohm) of the units and the current draw at 10MOhm (3.0mA).

I'm currently working on an automated cal/measure rig, which uses a Keithley 7001. Which cards are you using? What cabling? How are the standards connected to the DUT? I'm particularly interested in the resistance side of things. How did you wire the 4-wire ohms through the 7001 (+I, +S, Ohm G and -I, -S, Ohm G)?

I used 3M 28 AWG (24) twisted pair flat cable with shield to a breakout box with (10) silver-plated BNC jacks on an aluminum box and bare leads connected to the standard relay 7001/7002 mainframe cards. I'm not using resistance with the 7001s. You just have to get the timing right with the multiplexer.